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The present study has been designed to investigate the potential of peroxisome proliferator-activated receptor-gamma ([PPAR]-γ) agonists, pioglitazone, and rosiglitazone in hyperhomocysteinemia-induced vascular dementia of rats. l-methionine was administered for 8 weeks to induce hyperhomocysteinemia and associated vascular dementia. Pioglitazone and rosiglitazone were administered to l-methionine-treated rats for 4 weeks (starting from 5th to 8th weeks of methionine treatment). Donepezil served as a positive control in this study. On 52nd day onward, the animals were exposed to Morris water maze (MWM) for testing learning and memory abilities. Vascular endothelial function, serum nitrite/nitrate levels, brain thiobarbituric acid reactive species (TBARS), brain reduced glutathione (GSH) levels, and brain acetylcholinesterase (AChE) activity were also measured. l-methionine-treated animals have shown impairment of learning, memory, endothelial function, decrease in serum nitrite/nitrate levels, and brain GSH levels along with increase in brain TBARS levels and AChE activity. Pioglitazone, rosiglitazone, and donepezil significantly improved hyperhomocysteinemia-induced impairment of learning, memory, endothelial dysfunction, and changes in various biochemical parameters. It is concluded that pioglitazone and rosiglitazone may be considered as potential pharmacological agents for the management of hyperhomocysteinemia-induced vascular dementia.

Neuropathic pain is a debilitating form of treatment resistant chronic pain and responds poorly to the clinically available therapies. Studies from animal models of neuropathic pain have led to understanding of its pathobiology which includes complex interrelated pathways leading to peripheral and central neuronal sensitization. Advancements in the elucidation of neuropathic pain mechanisms have revealed a number of key targets that have been hypothesized to modulate clinical status. The present review discusses these therapeutic targets including noradrenaline and 5-HT reuptake inhibitors; sodium, calcium and potassium channels; inhibitory and excitatory neurotransmitters; neuropeptides including bradykinin, tachykinin, cholecystokinin, neuropeptide Y, vasoactive intestinal peptide, and CGRP; pro-inflammatory cytokines; MAP kinases; PPAR γ; Na(+)/Ca(2+) exchanger; nitric oxide; purinergic receptors; neuronal nicotinic receptors; cation-dependent chloride transporters; oxidative stress; matrix metalloproteinase and plasminogen activators; growth factors; transient receptor potential (TRP) channels; endocannabinoids; histamine receptors; dopamine; sigma receptors, beta adrenergic receptors, endothelins, and D-amino acid oxidase. The exploitation of these targets may provide effective therapeutic agents for the management of peripheral nerve injury-induced neuropathic pain.

The present study was designed to investigate the possible role of endogenous opioids and KATP channels in glycerol-induced acute renal failure (ARF) in rats. The rats were subjected to rhabdomyolytic ARF by single intramuscular injection of hypertonic glycerol (50% v/v; 8 mL/kg), and the animals were sacrificed after 24 h of glycerol injection. The plasma creatinine, blood urea nitrogen, creatinine clearance, and histopathological studies were performed to assess the degree of renal injury. Naltrexone (2.5, 5.0 and 10.0 mg/kg s.c.), glibenclamide (5.0 and 10.0 mg/kg i.p.), and minoxidil (25 and 50 mg/kg) were employed to explore the role of endogenous opioids and KATP channels in rhabdomyolysis-induced ARF. Pretreatment with naltrexone and glibenclamide attenuated hypertonic glycerol-induced renal dysfunction in a dose-dependent manner, suggesting the role of endogenous opioids and KATP channels in the pathogenesis of myoglobuniric renal failure. However, the simultaneous pretreatment with naltrexone (10 mg/kg s.c.) and glibenclamide (10 mg/kg i.p.) did not enhance the reno-protective effects of individual drugs, suggesting that release of endogenous opioids and opening of KATP channels constitute a single pathway in acute renal injury triggered by hypertonic glycerol-induced rhabdomyolysis. Furthermore, administration of minoxidil abolished the attenuating effects of naltrexone in glycerol-induced renal failure, suggesting that opening of KATP channels is downstream to opioid receptor activation. It is concluded that hypertonic glycerol-induced rhabdomyolysis may involve release of endogenous opioids that in turn modulate KATP channels to contribute in the pathogenesis of ARF.

Neuropathic pain has been described as the "most terrible of all tortures which a nerve wound may inflict" and arises as a consequence of nerve injury either of the peripheral or central nervous system. Following peripheral nerve injury, a cascade of events in the primary afferents leads to peripheral sensitization resulting in spontaneous nociceptor activity, decreased threshold and increased response to supra-threshold stimuli. A series of molecular changes in spinal cord and brain centers are associated with central sensitization which is responsible for the pain to non-injured extra-territory regions (extraterritorial pain) and contralateral parts (mirror-image pain). The peripheral nerve injury has been reported to induce neuroplastic changes in different brain regions including the anterior cingulate cortex, insular cortex, ventrolateral orbitofrontal area, amygdala, striatum, thalamus, hypothalamus, rostral ventromedial medulla, periaqueductal gray, pons (locus coeruleus), red nucleus, and medulla oblongata. The present review article discusses the involvement of these different brain areas in the development of peripheral nerve injury-induced neuropathic pain.

Animal models are pivotal for understanding the mechanism of neuropathic pain and development of effective therapy for its optimal management. A battery of neuropathic pain models has been developed to simulate the clinical pain conditions with diverse etiology. The present review exhaustively discusses the methodology, behavioral alterations, limitations, and advantages of about 40 different animal models of neuropathic pain along with their modifications. Development of these models has contributed immensely in understanding the chronic pain and underlying peripheral as well as central pathogenic mechanisms. Furthermore, research has resulted in the development of new therapeutic agents for neuropathic pain management, and the preclinical data obtained using these animal models have been successively translated to effective pain management in clinical setup also. As each animal model has been created with specific methodology and results tend to vary largely with the slight changes related to methodology, therefore, it is essential that data from different models should be reported and interpreted in the context of the specific pain model.

This study was designed to investigate the therapeutic potential of hydroalcoholic extracts of Acorus calamus (AC) in tibial and sural nerve transection (TST)-induced neuropathic pain in rats. The hot plate, paw heat allodynia, acetone drop, and pinprick tests were performed to assess the degree of heat hyperalgesia, heat and cold allodynia, and mechanical hyperalgesia, respectively, at different time intervals, i.e., day 0, 1, 3, 6, 9, 12, 15, 18, and 21. The tissue superoxide anion and total calcium were measured as markers of oxidative stress. Tissue myeloperoxidase activity was measured as a specific marker of inflammation. Histopathological evaluation was also performed in the nervous tissue to assess the axonal degeneration. Pregabalin served as positive control in this study. TST in rats significantly induced thermal hyperalgesia and allodynia, mechanical hyperalgesia, and increased the levels of superoxide anion, total calcium, and myeloperoxidase (MPO) activity. Moreover significant histological changes were also observed. Oral administration of AC hydroalcoholic extract (100 and 200 mg/kg for 14 days) attenuated TST-induced behavioral, biochemical, and histological changes. Acorus calamus has ameliorative potential in TST-induced painful neuropathy, and this effect may be attributed to its multiple actions including anti-inflammatory, antioxidant, and neuroprotective actions.

Poly(ADP-ribose) polymerases (PARPs) are a family of cell signaling enzymes present in eukaryotes, which are involved in the poly(ADP-ribosylation) of DNA binding proteins. While an 18 member superfamily of PARPs has been identified, however PARP-1 the most abundant isoform accounts for more than 90% of its functions. PARP-1 works as DNA damage nick sensor, which uses NAD(+) to form polymers of ADP-ribose (PAR) and nicotinamide. Three consequences of the activation of PARP-1 are particularly important for drug development: first, its role in DNA repair; second, its capacity to deplete cellular energetic pools, which culminates in cell dysfunction and necrosis; and third, its capacity to promote the transcription of proinflammatory genes. Consequently, pharmacological inhibition of PARP has the potential to enhance the cytotoxicity of certain DNA-damaging anticancer drugs, reduce cell necrosis (for example, in stroke or myocardial infarction) and downregulate multiple simultaneous pathways of inflammation and tissue injury (for example, in circulatory shock, colitis or diabetic complications). Through this article we have tried to develop a brief and simplified picture of the principal physiological and pathophysiological roles governed by PARP-1 and its therapeutic implications.

Preconditioning, a well established phenomenon had been used since 1980s to attenuate ischaemia-reperfusion induced injury. However, inability to predict the onset of ischaemia in clinical settings led to the discovery of a new concept of postconditioning (PoCo), in 2000s whereby brief repetitive cycles of ischaemia with intermittent reperfusion followed by prolonged ischaemia-elicited tissue protection. There is an impressive array of molecular mechanisms contributing to PoCo-mediated tissue-protection, which include triggers like adenosine (ADO), opioid, erythropoietin (EPO), endogenous nitric-oxide, reactive oxygen species, acetylcholine, tissue factors, pro-inflammatory cytokines and bradykinin; mediators like reperfusion injury salvage kinase pathways including phosphoinositide-3-kinase, extra-cellular signal regulated kinase(1/2) pathway, protein kinase G and protein kinase C; end-effectors like mitochondrial permeability transition pore and mitochondrial potassium ATP channel. The clinical applicability of PoCo has been extended with the use of PoCo mimetic agents like insulin, glucagon like peptide, EPO, statins and ADO before reperfusion in patients with ischaemia reperfusion injury. Remote PoCo has also emerged as a new concept; however, considerable research is required for understanding its molecular mechanisms. In this review, an exhaustive attempt has been made to unearth some molecular aspects of PoCo.

The present study was designed to investigate the cardio-protective effect of Ac-LEDH-cmk a selective caspase-9 inhibitor and 5-aminoisoquinolinone a selective Poly (ADP-ribose) polymerase inhibitor on ischemia and reperfusion induced apoptotic and necrotic cell death in rats. Isolated rat hearts were exposed to 30 minutes of global ischemia followed by 120 minutes of reperfusion using Langendorff's apparatus. Myocardial injury was assessed in the terms of infarct size, release of lactate dehydrogenase, creatine kinase enzymes and apoptotic index was assessed by DNA smearing on agarose gel electrophoresis. Pretreatments with specific inhibitor of caspase-9, Ac-LEHD-cmk (0.07 muM and 0.105 muM), and inhibitor of PARP, 5-aminoisoquinolinone (5 microM and 7.5 muM), significantly attenuated I/R induced increase in infarct size, release of lactate dehydrogenase and creatine kinase in the coronary effluent, and apoptotic index. Therefore, it may be concluded that inhibition of caspase-9 and PARP prevent ischemia and reperfusion-induced activation of apoptotic cascade and necrosis in rat myocardium.

The present study was designed to investigate the ameliorative potential of Punica granatum in dextran sulfate sodium (DSS) induced ulcerative colitis. DSS (2%) was administered orally in drinking water for 7 days to induce ulcerative colitis. The extent and severity of ulceration was analysed macroscopically, histopathologically and using a disease activity index. Myeloperoxidase (MPO), a specific marker of inflammation; histamine, a marker of mast cell degranulation; superoxide anion generation and, lipid peroxides were analysed. Administration of DSS resulted in a significant development of ulceration in the colon along with a rise in histamine, MPO activity and oxidative stress. Treatment with Punica granatum extract and its ellagic acid rich fraction (100 mg/kg and 200 mg/kg p.o.) significantly attenuated DSS-induced colonic inflammation along with attenuation of histamine, MPO and oxidative stress. The antiulcerative effect of Punica granatum extract and its ellagic acid rich fraction were comparable to sulphasalazine (100 mg/kg, p.o.) and sodium cromoglycate (40 mg/kg i.p). It is concluded that Punica granatum has a potential for ameliorating DSS-induced colitis and its ellagic acid rich fraction may be responsible for this effect. Further, the antiulcerative effects may be attributed to mast cell stabilizing, antiinflammatory and antioxidant actions.

Donepezil (acetyl cholinesterase inhibitor) is a mainstay of clinical intervention to contain memory deficits of Alzheimer’s disease. However, its beneficial role in endothelial dysfunction-associated dementia i.e. vascular dementia still needs to be explored. The present study wa sd esigned to investigate the effect of donepezil on vascular endothelial dysfunction, and associated memory deficits in rats. Atorvastatin (3-hydroxy-4-methyl-glutaryl (HMG)-CoA inhibitor) was taken as the standard. Rats were administered L-methionine (1.7 g/kg per day, p.o. ,4 weeks and 4 days i.e. chronic treatment) to produce endothelial dysfunction and dementia. Serum nitrite level was estimated as a marker of endothelial function. Morris water maze (MWM) test was employed for assessment of memory. Brain tissue thiobarbituric acid reactive substances (TBARS) and reduced glutathione (GSH) were estimated to assess oxidative stress. Brain acetylcholine esterase (AChE) activity and serum total cholesterol level were also estimated. L-methionine produced endothelial dysfunction as reflected by significant decrease of serum nitrite concentration. L-methionine-treated rats performed poorly on MWM indicating impairment of memory as well. These rats also showed a significant rise in brain oxidative stress, AChE activity and serum total cholesterol levels. Donepezil (0.1 mg/kg p.o. )a nd atorvastatin (10 mg/kg p.o. )a ttenuated L-methionine-induced endothelial dysfunction. This intervention reversed L-methionine-induced rise of brain oxidative stress and AChE activity. Furthermore, atorvastatin produced a reduction of L-methionine-induced rise in serum cholesterol. The beneficial effects of donepezil may be attributed to its multiple effects and this study highlights the potential of donepezil in vascular dementia.

Background : High cholesterol levels have been positively correlated with a higher incidence of memory impairment and dementia. Aim : The study was undertaken to investigate the potential of the lipid-lowering drug, ezetimibe, in memory deficits associated with dementia of Alzheimer's (AD) type in mice. Methods : Dementia was induced with chronic administration of a high-fat diet (HFD) or intracebroventricular streptozotocin (ICV STZ, two doses of 3 mg/kg) in separate groups of animals. The memory of the animals was assessed by employing a Morris water maze. Brain thio barbituric acid-reactive species and reduced glutathione levels were measured to assess the total oxidative stress. Brain acetyl cholinesterase (AChE) activity and total serum cholesterol levels were also measured. Results : STZ/HFD produced a significant impairment of memory along with an increase in brain AChE activity and oxidative stress. HFD mice also showed an increase in cholesterol levels. Ezetimibe (10 mg/kg, orally for 15 days) significantly attenuated STZ/HFD-induced memory deficits and biochemical changes. It also prevented HFD-induced rise in the cholesterol level. Conclusions : The memory-restorative effect of ezetimibe can be attributed to its cholesterol-dependent as well as cholesterol-independent effects. The study highlights the potential of ezetimibe in memory dysfunctions associated with dementia of AD.

The present study was designed to investigate a possible role of vanilloid receptors, CGRP and spleen in the induction of diabetes induced hyperalgesia in mice. Tail flick latency, an index of hyperalgesia, was assessed using analgesiometer. Serum nitrite levels and an index of nitric oxide were analyzed using Griess reaction. Mice were rendered diabetic with streptozotocin (200 mg/kg(-1), i.p.) and kept for 30 days for development of diabetic pain. To explore the involvement of spleen in diabetic pain, spleen homogenate supernatant (SHS) was prepared from spleen of 30th day diabetic mice and administered in normal mice for 14 days. Both in diabetic and SHS treated mice, significant degree of hyperalgesia was developed, suggesting the possible role of spleen derived factor in induction of diabetic pain. Moreover, the levels of nitric oxide were also elevated in 30 day diabetic mice and SHS treated mice. Administration of ruthenium red (1 mg/kg(-1), i.p.), vanilloid receptor antagonist, and sumatriptan (50 mg/kg(-1), i.p.), a CGRP release inhibitor, attenuated diabetes and SHS induced decrease in nociceptive threshold and increase in serum nitrite oxide levels. These results suggest that spleen derived factor induced activation of vanilloid receptors and CGRP release may be contributing in the development of hyperalgesia in diabetic mice.

Objectives The present study was aimed at investigating the ameliorative effect of Ocimum sanctum in sciatic nerve transection (axotomy)-induced peripheral neuropathy in rats. Materials and methods Sciatic nerve transection-induced axonal degeneration was assessed histopathologically. Paw pressure, Von Frey Hair, tail cold-hyperalgesia, motor in-coordination tests were performed to assess the extent of neuropathy. Biochemical estimations of thiobarbituric acid reactive species (TBARS), reduced glutathione (GSH), and total calcium levels were also performed. Methanolic extract of Ocimum sanctum at different doses (50, 100 and 200 mg/kg p.o.) was administered for 10 consecutive days starting from the day of surgery. Results Administration of Ocimum sanctum attenuated sciatic nerve transection-induced axonal degeneration, reduction of nociceptive threshold and motor in-coordination. Moreover, it also attenuated axotomy-induced rise in TBARS, total calcium and decrease in GSH levels in a dose-dependent manner. Conclusion Anti-oxidant and calcium attenuating actions may be responsible for observed ameliorative effects of Ocimum sanctum in axotomy-induced neuropathy.

The present study was undertaken to investigate the beneficial effect of HIV protease inhibitor Indinavir on memory deficits associated with experimental dementia of Alzheimer disease's (AD) type. Dementia was induced in Swiss albino mice by administration of Celecoxib (100 mg kg− 1 orally, daily for 9 days) or Streptozotocin (3 mg kg− 1 administered intracerebroventricularly on 1st and 3rd day) and the cognitive behaviors of Swiss albino mice were assessed using Morris water maze test. Brain acetyl cholinesterase (AChE) activity was measured by Ell Mann's method. Brain thiobarbituric acid reactive species (TBARS) levels and reduced glutathione (GSH) levels were measured by Ohokawa's and Beutler's method respectively to assess total oxidative stress. Donepezil (0.1 mg kg− 1 i.p.) served as positive control in the present investigation. Celecoxib as well as Streptozotocin (STZ) produced a significant loss of learning and memory. Indinavir (100 and 200 mg kg− 1 orally) successfully attenuated Celecoxib as well as STZ induced cognitive deficits. Higher levels of brain AChE activity, TBARS and lower levels of GSH were observed in Celecoxib as well as STZ treated animals, which were significantly attenuated by Donepezil and Indinavir. Study highlights the potential of Indinavir in memory dysfunctions associated with dementia of AD.

Remote preconditioning is a unique phenomenon in which brief episodes of ischemia and reperfusion to remote organ protect the target organ against sustained ischemia-reperfusion (I/R)-induced injury. Protective effects of remote renal preconditioning (RRPC) are well established in heart, but their mechanisms still remain to be elucidated. So, the present study was designed to investigate the possible role of oxygen-sensing hypoxia inducible factor-prolyl 4-hydroxylases (HIF-P4Hs) in RRPC-induced cardioprotection in rats. Remote renal preconditioning was performed by four episodes of 5 min renal artery occlusion and reperfusion. Isolated rat hearts were perfused on Langendorff apparatus and were subjected to global ischemia for 30 min followed by 120 min reperfusion. The levels of lactate dehydrogenase (LDH) and creatine kinase (CK) were measured in coronary effluent to assess the degree of myocardial injury. Extent of myocardial infarct size and coronary flow rate was also measured. Ethyl 3,4-dihydroxybenzoate (EDHB) and alpha-ketoglutarate (alpha-KG) were employed as HIF-P4Hs inhibitor and activator, respectively. Diethyldithiocarbamic acid (DDCA) was employed as NFkB inhibitor. Remote renal preconditioning prevented I/R-induced myocardial injury and produced cardioprotective effects. Pharmacological preconditioning with EDHB (100 mg kg(-1) i.p.) mimicked the cardioprotective effects of RRPC. However, alpha-KG (200 mg kg(-1) i.p.) and DDCA (150 mg kg(-1) i.p.) abolished cardioprotective effects of RRPC and EDHB. So, it may be concluded that inhibition of HIF-P4H has a key role in RRPC-induced cardioprotection. Further, remote preconditioning-induced HIF-P4H inhibition may have triggered a transduction pathway involving activation of NFkB.

The present study was designed to investigate the possible role of opioids and K(ATP) channels in ischemic postconditioning-induced reversal of global cerebral ischemia and reperfusion (I/R) induced neuronal injury. Mice were subjected to global ischemia by bilateral carotid artery occlusion for 10 min followed by reperfusion for 24 h, to produce neuronal injury. Ischemic postconditioning was induced by three episodes of carotid artery occlusion and reperfusion of 10 s each, immediately after global ischemia. Morphine postconditioning was induced by administration of morphine (5 mg/kg i.v.), 5 min prior to reperfusion. Naloxone (5 mg/kg i.v.), opioid receptor antagonist, and glibenclamide (5 mg/kg i.v.), K(ATP) channel blocker were administered 10 min before global ischemia. Extent of cerebral injury was assessed by measuring cerebral infarct size using triphenyl tetrazolium chloride (TTC) staining. Short-term memory was evaluated using the elevated plus maze test, while degree of motor incoordination was evaluated using inclined beam-walking, rota-rod and lateral push tests. Bilateral carotid artery occlusion followed by reperfusion resulted in significant increase in infarct size, impairment in short-term memory and motor co-ordination. Ischemic/morphine postconditioning significantly attenuated I/R induced neuronal injury and behavioural alterations. Pretreatments with naloxone and glibenclamide attenuated the neuroprotective effects of ischemic/morphine postconditioning. It may be concluded that ischemic/morphine postconditioning protects I/R induced cerebral injury via activating opioid receptor and K(ATP) channel opening.

The present study has been designed to investigate the effect of amniotic fluid derived stem cells on focal cerebral ischaemia-reperfusion injury induced behavioural deficits in mice. Middle cerebral artery occlusion of 60 min followed by reperfusion for 7 days was employed in present study to produce ischaemia and reperfusion induced cerebral injury in mice. Assessment of cognitive behaviour was done using elevated plus maze. Assessment of neurological severity score was employed to assess motor, sensory, reflex, and balance tests in a composite manner. Adhesive-removal somatosensory test was employed to evaluate somatosensory deficit. Partial occlusion of middle cerebral artery markedly impaired memory, motor coordination, sensorimotor ability and somatosensory functions as inferred from the results of elevated plus-maze test, adhesive-removal test and neurological severity score test. Intracerebroventricular administration of amniotic fluid derived stem cells/embryonic neuronal stem cells significantly reversed the focal cerebral ischaemia-reperfusion induced behavioural deficit measured in terms of loss of short-term memory, motor coordination, sensorimotor ability and somatosensory functions. Therefore, it may be concluded that stem cells derived from amniotic fluid exert beneficial effect on the ischaemic brain to an extent comparable to the neuroprotective effect of embryonic neuronal stem cells.

The present study has been designed to investigate the role of insulin, endogenous opioids and calcitonin gene related peptide (CGRP) on remote mesenteric ischaemic preconditioning induced reversal of global cerebral ischaemia-reperfusion injury in mice. Bilateral carotid artery occlusion of 10 min followed by reperfusion for 24 hour was employed in present study to produce ischaemia and reperfusion induced cerebral injury in mice. Cerebral infarct size was measured using triphenyltetrazolium chloride staining. Short-term memory was evaluated using elevated plus maze. Inclined beam walking and resistance to lateral push response, tests were employed to assess motor incoordination. Bilateral carotid artery occlusion followed by reperfusion produced cerebral infarction and impaired short-term memory, motor co-ordination and lateral push response. A preceding episode of mesenteric artery occlusion for 15 min and reperfusion of 15 min (remote mesenteric ischaemic preconditioning) prevented markedly, ischaemia-reperfusion-induced cerebral injury measured in terms of infarct size, loss of short-term memory, motor coordination and lateral push response. Anti-insulin serum, naloxone (an opioid receptor antagonist) and alpha-CGRP (8-37) (a selective CGRP receptor blocker) attenuated the neuroprotective effect of remote mesenteric ischaemic preconditioning. It may be concluded that neuroprotective effect of remote mesenteric ischaemic preconditioning probably is mediated through insulin, endogenous opioids and CGRP released as a consequence of mesenteric ischaemia and reperfusion in mice.

Remote ischemic preconditioning is a well reported therapeutic strategy that induces cardioprotective effects but the underlying intracellular mechanisms have not been widely explored. The current study was designed to investigate the involvement of TRP and especially TRPV channels in remote hind limb preconditioning-induced cardioprotection. Remote hind limb preconditioning stimulus (4 alternate cycles of inflation and deflation of 5 min each) was delivered using a blood pressure cuff tied on the hind limb of the anesthetized rat. Using Langendorff's system, the heart was perfused and subjected to 30-min ischemia and 120-min reperfusion. The myocardial injury was assessed by measuring infarct size, lactate dehydrogenase (LDH), creatine kinase (CK), LVDP, +dp/dtmax, -dp/dtmin, heart rate, and coronary flow rate. Gadolinium, TRP blocker, and ruthenium red, TRPV channel blocker, were employed as pharmacological tools. Remote hind limb preconditioning significantly reduced the infarct size, LDH release, CK release and improved coronary flow rate, hemodynamic parameters including LVDP, +dp/dtmax, -dp/dtmin, and heart rate. However, gadolinium (7.5 and 15 mg kg(-1)) and ruthenium red (4 and 8 mg kg(-1)) significantly attenuated the cardioprotective effects suggesting the involvement of TRP especially TRPV channels in mediating remote hind limb preconditioning-induced cardioprotection. Remote hind limb preconditioning stimulus possibly activates TRPV channels on the heart or sensory nerve fibers innervating the heart to induce cardioprotective effects. Alternatively, remote hind limb preconditioning stimulus may also activate the mechanosensitive TRP and especially TRPV channels on the sensory nerve fibers innervating the skeletal muscles to trigger cardioprotective neurogenic signaling cascade. The cardioprotective effects of remote hind limb preconditioning may be mediated via activation of mechanosensitive TRP and especially TRPV channels.

The present study was designed to explore the role of GSK-3β and NF-kB signaling in electric foot shock-induced stress and stress adaptation. Mice were subjected to foot shocks of 0.5mA intensity and 1s duration of 1h to produce acute stress. Animals were exposed to the same stressor for 5 days to induce stress adaptation. The behavioral alterations were assessed using the actophotometer, hole board, open field and social interaction tests. The serum corticosterone levels were assessed as a marker of the HPA axis. The levels of total GSK-3β, p-GSK-3β-S9 and p-NF-kB were determined in the hippocampus, frontal cortex and amygdala. Acute electric foot shock stress produced behavioral and biochemical changes; decreased the levels of p-GSK-3β-S9, produced no change in total GSK-3β levels and increased p-NF-kB levels in the brain. However, repeated exposure of foot shock stress restored the behavioral and biochemical changes along with normalization of p-GSK-3β-S9 and p-NF-kB levels. Administration of AR-A01, a selective GSK-3β inhibitor, or diethyldithiocarbamic acid (DDTC), a selective NF-kB inhibitor, diminished acute stress-induced behavioral and biochemical changes. Furthermore, AR-A014418 normalized acute stress-induced alterations in p-GSK-3β-S9 and p-NF-kB levels, however, DDTC selectively restored NF-kB levels without any change in p-GSK-3β-S9 levels. It probably suggests that NF-kB is a downstream mediator of the GSK-3 signaling cascade. It may conclude that acute stress associated decrease in p-GSK-3β-S9 and increase in p-NF-kB levels in the brain contribute in the development of behavioral and biochemical alterations and normalization of GSK-3β/NF-kB signaling may contribute in stress adaptive behavior in response to repeated electric foot shock-subjected mice.

Ischemic conditioning is an intrinsic protective mechanism in which repeated short episodes of reversible ischemia protects the tissue and increases its tolerance against a subsequent longer period of ischemia (index ischemia). Bradykinin is a physiologically and pharmacologically active peptide of the kallikrein-kinin system. Besides the involvement of bradykinin in a variety of physiological and pathological responses such as pain, inflammation and in cardiovascular system as a potent vasodilator, it also acts as an endogenous cytoprotective mediator in the ischemic tissue. Pretreatment with various pharmacological modulators of bradykinin has confirmed the involvement of bradykinin in ischemic conditioning-induced protection. The protective actions of bradykinin in three major paradigms of ischemic conditioning i.e. ischemic preconditioning, ischemic postconditioning and remote ischemic preconditioning involves activation and regulation of various endogenous signaling cascades to render the heart resistant to infarction. In ischemic preconditioning, bradykinin exerts cardioprotective effect via activation of PI3K/Akt/eNOS signaling pathway and regulation of redox state via NO release. The role of bradykinin and its B2 receptors in ischemic-postconditioning induced neuroprotection has been described mainly due to its increased redox signaling cascade and activation of mitochondrial anti-apoptotic pathway. Furthermore, its cardioprotective role during remote ischemic preconditioning has been associated with activation of B2 receptors mediated neurogenic pathway and internalization of B2 receptors along with the formation of signalosomes that activates intracellular cytoprotective transduction pathways. The present review focuses on the potential role of bradykinin in mediating different forms of ischemic conditioning (pre/post/remote)-induced cardioprotection and neuroprotection along with the possible mechanisms.

TRPV4 channels are non-selective cation channels permeable to Ca(2+), Na(+), and Mg(2+) ions. Recently, TRPV4 channels have received considerable attention as these channels are widely expressed in the cardiovascular system including endothelial cells, cardiac fibroblasts, vascular smooth muscles, and peri-vascular nerves. Therefore, these channels possibly play a pivotal role in the maintenance of cardiovascular homeostasis. TRPV4 channels critically regulate flow-induced arteriogenesis, TGF-β1-induced differentiation of cardiac fibroblasts into myofibroblasts, and heart failure-induced pulmonary edema. These channels also mediate hypoxia-induced increase in proliferation and migration of pulmonary artery smooth muscle cells and progression of pulmonary hypertension. These channels also maintain flow-induced vasodilation and preserve vascular function by directly activating Ca(2+)-dependent KCa channels. Furthermore, these may also induce vasodilation and maintain blood pressure indirectly by evoking the release of NO, CGRP, and substance P. The present review discusses the evidences and the potential mechanisms implicated in diverse responses including arteriogenesis, cardiac remodeling, congestive heart failure-induced pulmonary edema, pulmonary hypertension, flow-induced dilation, regulation of blood pressure, and hypoxic preconditioning.

This study was designed to investigate the effectiveness of nisoldipine, an L-type voltage-sensitive calcium channel blocker, to ameliorate anxiety and fear response in a mouse model of post-traumatic stress disorder (PTSD). Acute trauma was induced in Swiss albino mice in a 2-day electric foot-shock paradigm consisting of 15 intermittent foot-shocks of 0.8 mA intensity, 10-s duration and 10-s intershock interval, during 5 min, followed by 3 weekly situational reminders, that is, once per week in the same context on three successive weeks. PTSD-induced behavioral changes were assessed using actophotometer, open-field, social interaction test, and freezing behavior. Biochemically, the serum corticosterone levels were estimated. Electric foot-shock and situational reminders produced behavioral alterations and decreased corticosterone levels, assessed on the 21st day following the traumatic event. Administration of sertraline (Ser 15 mg/kg), a selective serotonin reuptake inhibitor (SSRI) and nisoldipine (20 and 40 mg/kg), significantly attenuated the foot-shock-trauma-induced behavioral changes along with normalization of the corticosterone levels. It may be concluded that nisoldipine produces beneficial effects in re-establishing behavioral alterations, which may be due to normalization of reduced corticosterone levels in PTSD in mice.

Remote hind limb preconditioning (RIPC) is a protective strategy in which short episodes of ischemia and reperfusion in a remote organ (hind limb) protects the target organ (heart) against sustained ischemic reperfusion injury. The present study was designed to investigate the possible role of thromboxane A2 in RIPC-induced cardioprotection in rats. Remote hind limb preconditioning was performed by four episodes of 5 min of inflation and 5 min of deflation of pressure cuff. Occlusion of the hind limb with blood pressure cuff is most feasible, non-invasive, clinically relevant, and safe method for inducing RIPC. Isolated rat hearts were perfused on Langendorff apparatus and were subjected to global ischemia for 30 min followed by 120-min reperfusion. The levels of lactate dehydrogenase (LDH) and creatine kinase (CK) were measured in coronary effluent to assess the degree of myocardial injury. The extent of myocardial infarct size along with the functional parameters including left ventricular developed pressure (LVDP), dp/dtmax, and dp/dtmin were also measured. Ozagrel (thromboxane synthase inhibitor) and seratrodast (thromboxane A2 receptor antagonist) were employed as pharmacological modulators of thromboxane A2. Remote hind limb preconditioning significantly attenuated ischemia/reperfusion-induced myocardial injury and produced cardioprotective effects. However, administration of ozagrel and seratrodast completely abolished the cardioprotective effects of RIPC suggesting the key role of thromboxane A2 in RIPC-induced cardioprotection. It may be concluded that brief episodes of preconditioning ischemia and reperfusion activates the thromboxane synthase enzyme that produces thromboxane A2, which may elicit cardioprotection either involving humoral or neurogenic pathway.

Recent studies have projected the renin-angiotensin system as a central component of the physiological and pathological processes of assorted neurological disorders. Its primary effector hormone, angiotensin II (Ang II), not only mediates the physiological effects of vasoconstriction and blood pressure regulation in cardiovascular disease but is also implicated in a much wider range of neuronal activities and diseases, including Alzheimer’s disease, neuronal injury, and cognitive disorders. Ang II produces different actions by acting on its two subtypes of receptors (AT1 and AT2); however, the well-known physiological actions of Ang II are mainly mediated through AT1 receptors. Moreover, recent studies also suggest the important functional role of AT2 receptor in the brain. Ang II acts on AT1 receptors and conducts its functions via MAP kinases (ERK1/2, JNK, and p38MAPK), glycogen synthase kinase, Rho/ROCK kinase, receptor tyrosine kinases (PDGF and EGFR), and nonreceptor tyrosine kinases (Src, Pyk2, and JAK/STAT). AT1R-mediated NADPH oxidase activation also leads to the generation of reactive oxygen species, widely implicated in neuroinflammation. These signaling cascades lead to glutamate excitotoxicity, apoptosis, cerebral infarction, astrocyte proliferation, nociception, neuroinflammation, and progression of other neurological disorders. The present review focuses on the Ang II-triggered signal transduction pathways in central nervous system.

The cardioprotective effects of remote hind limb preconditioning (RIPC) are well established, but its mechanisms still remain to be explored. Therefore, the present study was aimed to explore the possible involvement of 5-lipoxygenase-derived leukotrienes in RIPC. The hind limb was tied by a pressure cuff and was subjected to four episodes of inflation and deflation (5min each) to induce remote hind-limb preconditioning. Thereafter, the hearts were isolated and were subjected to global ischemia (30min) followed by reperfusion (120min) on the Langendorff apparatus. The extent of myocardial injury was assessed by measuring lactate dehydrogenase (LDH) and creatine kinase (CK) levels in the coronary effluent; the infarct size using TTC staining, and the hemodynamic parameters including LVDP, dp/dtmax and dp/dtmin. RIPC significantly decreased ischemia and reperfusion-induced increase in LDH, CK release, infarct size and improved LVDP, dp/dtmax and dp/dtmin. Administration of montelukast, leukotriene receptor antagonist (10 and 20mg/kg) and zileuton, 5-lipoxygenase inhibitor, (2.5 and 5mg/kg) abolished RIPC-induced cardioprotection. It may be concluded that hind limb ischemia stimulates 5-lipoxygenase to release leukotrienes which may elicit cardioprotection by humoral or neurogenic pathway.

Aim The present study aimed to investigate the role of angiotensin II in repeated immobilization stress exposure of varying duration. Methods Mice were subjected either to short (30 min) or long duration (120 min) immobilization stress for 5 days. The behavioral changes were assessed by actophotometer, hole board, open field and social interaction tests on day 1 and day 5. The serum corticosterone levels were measured as an index of HPA axis on day 5. Key findings A single exposure of short or long duration stress produced behavioral deficits and increased corticosterone levels. However, repeated exposure of stressors was followed by restoration of behavioral and biochemical changes, suggesting the development of stress adaptation. A single administration of telmisartan (5 mg/kg) exacerbated the short stress-induced decrease in behavioral activity and increase in corticosterone levels on the first day of stress exposure, suggesting the anti-stress role of angiotensin II. In contrast, the normalization of behavioral and biochemical response was observed in prolonged stress-subjected mice following telmisartan treatment on the 1st day of stress exposure, suggesting stress inducing action of angiotensin II. Furthermore, telmisartan treatment for 5 days abolished the restoration of behavioral and biochemical response following 5 consecutive exposures of short immobilization stress, without altering stress adaptation in prolonged stress, suggesting that angiotensin II has stress adaptive role in short stress. Significance It is concluded that angiotensin II acts as anti-stress agent and promotes adaptation during short stress, whereas it acts as stress promoting agent, without affecting stress adaptation during prolonged stress.

Na+/H+ exchangers (NHEs) are the transporter proteins that play an important role in intracellular pH (pHi) regulation, cell differentiation and cell volume and that mediate transepithelial Na+ and HCO3- absorption on the basis of chemical gradients across the plasma membrane. Its activation causes an increase in intracellular Na+, which further leads to Ca+ overload and cell death. The pharmacological inhibition of these transporter proteins prevents myocardial infarction and other heart diseases like congestive heart failure in experimental animal models as well as in clinical situations. The more recent studies have implicated the role of these exchangers in the pathophysiology of brain diseases. Out of nine NHE isoforms, NHE-1 is the major isoform present in the brain and regulates the trans-cellular ion transport through blood-brain barrier membrane, and alteration in their function leads to severe brain abnormalities. NHEs were shown to be involved in pathophysiologies of many brain diseases like epilepsy, Alzheimer's disease, neuropathic pain and ischemia/reperfusion-induced cerebral injury. Na+/H+-exchanger inhibitors (e.g., amiloride and cariporide) produce protective effects on ischemia/reperfusion-induced brain injury (e.g., stroke), exhibit good antiepileptic potential and attenuate neuropathic pain in various animal models. The present review focuses on the pathophysiological role of these ion exchangers in different brain diseases with possible mechanisms.

Remote ischemic preconditioning (RIPC) is a phenomenon whereby transient non-lethal ischemia and reperfusion episodes confer protection against prolonged ischemia-reperfusion-induced injury. However, the underlying intracellular signaling has not been extensively explored. The present study aims to inspect the putative involvement of TRPV1-dependent CGRP release in mediating remote hind limb preconditioning-induced cardioprotection. In the present study, remote hind limb preconditioning stimulus was delivered (4 consecutive episodes of 5 minutes of ischemia-reperfusion) using a blood pressure cuff tied at the inguinal level of the rat. The isolated rat hearts were perfused on the Langendorff's system and were subjected to 30 minutes global ischemia-120 minutes reperfusion. Prolonged ischemia and subsequent reperfusion led to myocardial injury that was evaluated in terms of infarct size, LDH release, CK release, LVDP, +dp/dtmax, -dp/dtmin and coronary flow rate. The pharmacological agents used in the present study included capsaicin as TRPV1 channel activator, sumatriptan and CGRP8-37 as CGRP blockers. Remote hind limb and capsaicin preconditioning (10 mg kg−1) significantly reduced the infarct size, LDH release, CK release and significantly improved LVDP, +dp/dtmax, -dp/dtmin and coronary flow rate. However, remote hind limb and capsaicin preconditioning-induced cardioprotective effects were remarkably reduced in the presence of sumatriptan (8 mg kg−1) and CGRP8-37 (1 mg kg−1). This indicates that remote hind limb preconditioning stimulus probably activates TRPV1 channels which subsequently induces CGRP release to produce cardioprotective effects. This article is protected by copyright. All rights reserved.

Apart from the well-documented role of the renin-angiotensin-aldosterone system (RAAS) in regulating the blood pressure and other related parameters, its role in modulating different physiological/pathological functions, including pain, has also been described. Like its dual role in regulating stress-related anxiety and cognitive functions, its dual role has also been documented in pain modulation in different disease states. Drugs blocking the RAAS activation, viz., renin inhibitors, angiotensin converting enzyme (ACE) inhibitors, AT(1) receptor antagonists and aldosterone antagonists, have been shown to produce beneficial effects in migraine and neuropathic and nociceptive pain. Their beneficial effects have been mainly attributed to inhibition of the inflammatory cascade of reactions by inhibiting the generation of key cytokines, including tumor necrosis factor (TNF)-α. On the contrary, clinical as well as preclinical studies have also shown the pain-inducing actions of renin-angiotensin system (RAS) blocking drugs. Furthermore, the pain-relieving actions of angiotensin II (AngII) and pain-inducing actions of AT(1) blockers have also been described. The pain-inducing actions of ACE inhibitors have been mainly attributed to interference with metabolism of bradykinin and substance P, while the analgesic actions of AngII have been mainly related to activation of brain localized AT(2) receptors and release of endogenous opioids. The present review describes the dual role of the RAAS in different states of pain.

Aims The present study was designed to investigate the existence of cross adaptation between immobilization and foot shock stress, and to identify the role of endogenous opioids in cross adaptation. Methods Mice were subjected to acute stress using a single episode of immobilization of 2 h duration; while stress adaptation was induced by repeated exposures to homotypic stressor for 5 days. To explore the existence of cross adaptation, homotypic stressor was replaced with a heterotypic stressor on the 6th day and foot shocks of 0.5 mA intensity, 1 s duration with an interval of 2 min were delivered for 1 h. Stress-related behavioral alterations were assessed using the actophotometer, hole board, open field and social interaction tests. Key findings A single exposure of immobilization produced the significant behavioral alterations that were restored on the 5th day following repeated applications of immobilization stress, indicating the development of stress adaptation. Furthermore, acute exposure of foot shock (heterotypic stressor) did not produce the behavioral alterations in immobilization stress adapted animals, indicating the development of cross adaptation. Administration of naloxone abolished the restoration of behavioral changes as a part of adaptive/cross adaptive process in repeated immobilization stress-subjected mice. Significance It may be concluded that immobilization stress adapted mice exhibit cross adaptation to foot shock stress, with the possible involvement of opioids as endogenous adaptogenic/cross adaptogenic factors.

Ghrelin is orexigenic hormone primarily synthesized by endocrine X/A-like cells of gastric oxyntic mucosa to stimulate appetite and food intake along with regulation of growth hormone and insulin secretion; glucose and lipid metabolism; gastrointestinal motility; blood pressure, heart rate and neurogenesis. Furthermore, peripherally (after crossing the blood brain barrier) as well as centrally synthesized ghrelin (in the hypothalamus) regulates diverse functions of central nervous system including stress-associated behavioral functions. Exposure to stress alters the ghrelin levels and alteration in ghrelin levels significantly affects neuro-endocrinological parameters; metabolism-related physiology, behavior and mood. Studies have shown both anxiolytic and anxiogenic role of ghrelin suggesting its dual role in modulating anxiety-related behavior. However, it is proposed that increase in ghrelin levels during stress condition is an endogenous stress coping behavior and increased ghrelin levels may be required to prevent excessive anxiety. In preclinical and clinical studies, an elevation in ghrelin levels during depression has been correlated with their antidepressant activities. Ghrelin-induced modulation of stress and associated conditions has been linked to alteration in hypothalamic-pituitary-adrenal (HPA) axis; autonomic nervous system (mainly sympathetic nervous system and serotonergic neurotransmission. A reciprocal relationship has been reported between corticotropin-releasing hormone (CRH) and ghrelin as ghrelin increases the release of CRH, ACTH and corticosteroids; while CRH decreases the expression of ghrelin. Similarly, ghrelin increases the serotonin turnover and in turn, serotonin controls ghrelin signaling to modulate anxiety-related behavior. The present review discusses the dual role of ghrelin in stress and related behavioral disorders along with possible mechanisms.

Besides the involvement of TRPV channels in exhibiting various cellular functions including thermoregulation, pain perception, maintenance of bone homeostasis and gastrointestinal function; certain studies have also implicated the putative role of these channels in mediating ischemic conditioning-induced cardioprotection. The potential role of TRPV1 channels in different forms of ischemic conditioning (pre/post/remote)-induced cardioprotection has been described by employing TRPV1 knockout mice and various pharmacological modulators. The cardioprotective effects of TRPV1 activation during ischemic conditioning have been linked with increased CGRP, substance P release and augmented ALOX expression. Furthermore, the role of TRPV4 channels in mediating preconditioning-induced preservation of vascular function in terms restoring NO- and further improving EDH(F)-mediated endothelial relaxation has been described. The present review discusses the putative role of TRPV1 and TRPV4 channels in mediating different forms of conditioning (pre/post/remote)-induced cardioprotection along with the possible mechanisms. Future perspectives have also been described to fully understand the cascade of signaling and contribution of TRPV channel activation during myocardial ischemic conditioning.

Background Cerebral ischemia–reperfusion (I–R) injury is one of the primary causes of ischemic stroke. Ischemic postconditioning (iPoCo) is evolving as an important adaptive technique to contain I–R injury. Some recent studies have shown neuroprotective effects of iPoCo. However, the neuroprotective mechanism of iPoCo is not clear. So, the present study has been undertaken to investigate the possible role of Sirtinol, a selective class III histone deacetylase (HDAC) inhibitor in the neuroprotective mechanism of iPoCo in mice. Material and methods Bilateral carotid artery occlusion (BCAO) for 12 min followed by reperfusion for 24 h was used to produce I–R-induced cerebral injury in Swiss albino mice. iPoCo involving three episodes of 10-s carotid artery occlusion and reperfusion instituted immediately after BCAO just before prolonged reperfusion of 24 h. Cerebral infarct size was measured using triphenyltetrazolium chloride staining. Memory was evaluated using a Morris water maze test. Rotarod test, inclined beam-walking test, and neurologic severity score (NSS) were used to assess motor incoordination. Acetylcholine esterase levels, brain thiobarbituric acid reactive species (TBARS), and glutathione level were also estimated. Results BCAO for 12 min followed by reperfusion for 24 h produced a significant rise in cerebral infarct size and NSS along with impairment of memory and motor coordination and biochemical alteration (↑acetylcholine esterase, ↓glutathione, and ↑TBARS). iPoCo, involving three episodes of 10-s carotid artery occlusion with intermittent reperfusion of 10 s applied just after ischemic insult of 12 min produced a significant decrease in cerebral infarct size and NSS along with the reversal of I–R-induced impairment of memory and motor coordination. iPoCo-induced neuroprotective effects were significantly abolished by pretreatment with selective SIRT 1 (class III HDAC) blocker Sirtinol (10 mg/kg intraperitoneal). Conclusions It may be concluded that the neuroprotective effect of iPoCo probably involves activation of SIRT 1 (class III HDAC) enzyme.

The present study has been designed to investigate the potential of Cilostazol a phosphodiesterase-3 (PDE-3) inhibitor in diabetes-induced vascular dementia (Vad) employing Wistar rats. A single dose of Streptozotocin (STZ) was used for the induction of diabetes and subsequent Vad in rats. Memory and learning abilities of rats were evaluated with Morris water maze (MWM) test. Serum glucose, body weight, vascular endothelial function, serum nitrite/nitrate levels, brain oxidative stress levels (viz. brain thiobarbituric acid reactive species and reduced glutathione levels), inflammatory markers (viz. brain myeloperoxidase activity and neutrophil infiltration in the brain hippocampal area) and brain acetylcholinesterase activity were also tested. Donepezil was used as positive control. Streptozotocin treated animals showed poor performance on MWM indicating impairment of learning and memory abilities with a significant reduction in body weight, vascular endothelial function, serum nitrite/nitrate levels, along with an increase in serum glucose, brain oxidative stress levels, inflammatory changes and brain acetylcholinesterase activity. Treatment with selective PDE-3 inhibitor, Cilostazol significantly attenuated, diabetes-induced impairment of learning and memory; endothelial dysfunction, and changes in various biochemical parameters. It is concluded that selective PDE-3 inhibitor, Cilostazol may be considered as the potential pharmacological agent for the management of diabetes-induced vascular dementia.

Herein, atom-based 3D-QSAR analysis was performed using receptor-guided alignment of 46 flavonoid inhibitors of aldose reductase (ALR2) enzyme. 3D-QSAR models were generated in PHASE programme, and the best model corresponding to PLS factor four (QSAR4), was selected based on different statistical parameters (i.e., Rtrain(2), 0.96; Qtest(2) 0.81; SD, 0.26). The contour plots of different structural properties generated from the selected model were utilized for the designing of five new congener molecules. These designed molecules were duly synthesized, and evaluated for their in vitro ALR2 inhibitory activity that resulted in the micromolar (IC5022μM) activity of all molecules. Thus, the newly designed molecules having ALR inhibitory potential could be employed for the management of diabetic complications.

BACKGROUND Aldose reductase is primarily involved in development of long-term diabetic complications due to increased polyol pathway activity. The synthetic aldose reductase inhibitors are not very successful clinically. Therefore, the natural sources may be exploited for safer and effective aldose reductase inhibitors. METHODS In the present study, the aldose reductase inhibitory potential of hydroalcoholic and alkaloidal extracts of Piper nigrum, Murraya koenigii, Argemone mexicana, and Nelumbo nucifera was evaluated. The hydroalcoholic and alkaloidal extracts of the selected plants were prepared. The different concentrations of hydroalcoholic and alkaloidal extracts of these plants were evaluated for their goat lens aldose reductase inhibitory activity using dl-glyceraldehyde as substrate. The aldose reductase inhibitory potential of extracts was assessed in terms of their IC50 value. RESULTS Amongst the hydroalcoholic extracts, the highest aldose reductase inhibitory activity was shown by P. nigrum (IC50 value 35.64±2.7 μg/mL) followed by M. koenigii (IC50 value 45.67±2.57 μg/mL), A. mexicana (IC50 value 56.66±1.30 μg/mL), and N. nucifera (IC50 value 59.78±1.32 μg/mL). Among the alkaloidal extracts, highest inhibitory activity was shown by A. mexicana (IC50 value 25.67±1.25 μg/mL), followed by N. nucifera (IC50 value 28.82±1.85 μg/mL), P. nigrum (IC50 value 30.21±1.63 μg/mL), and M. koenigii (IC50 value 35.66±1.64 μg/mL). CONCLUSIONS It may be concluded that the alkaloidal extracts of these plants possess potent aldose reductase inhibitory activity and may be therapeutically exploited in diabetes-related complications associated with increased activity of aldose reductase.

Aldose reductase is the rate-limiting enzyme of the polyol pathway that leads to conversion of glucose to sorbitol. Its increased activity, which results in abnormal activation of the polyol pathway, is implicated in the development of long-term complications of diabetes mellitus. Different plant species and their active components have shown potent in vitro and in vivo aldose reductase inhibitory activity. Among different phyto-constituents, alkaloids that contain isoquinoline/bis(isoquinoline)and related ring structures (such as berberine, palmatine, coptisine, and jateorrhizine) have shown very potent aldose reductase inhibitory activity. The structural activity relationship has revealed the importance of hydrophobic and hydrophilic groups of isoquinoline/bis(isoquinoline)for binding to an enzyme. The dioxymethylene group in the D ring (hydrophobic group) of these alkaloids binds tightly to the site adjacent to the anionic binding site (active site), while the methoxyl groups (polar) bind to the site adjacent to the nicotinamide ring of the coenzyme. On the basis of these findings, it may be proposed that the presence of isoquinoline/bis(isoquinoline)ring structures is the most important requirement for alkaloids to behave as potent aldose reductase inhibitors. Thus, other plants may also be screened for the same activity. The present review discusses these isoquinoline/bis(isoquinoline)-based alkaloids as aldose reductase inhibitors that may be used to manage diabetic complications and may substitute for the chemically synthesized aldose reductase inhibitors.

Angiotensin and endogenous opioids are important bioactive neuropeptides, which are widely distributed in the brain and peripheral regions to produce diverse biological and neurobiological activities. An endogenous opioid system includes proopiomelanocortin-derived enkephalin, dynorphin and endorphin that act on their specific receptors such as delta (δ), kappa (κ) and mu (μ) receptors. Research evidence demonstrates significant positive as well as negative interactions between renin angiotensin system (RAS) and endogenous opioids in the brain and periphery. The diverse actions of Ang II are possibly mediated indirectly through endogenous opioids, while opioids are also shown to activate RAS components suggesting the up-regulation of each system in concern with each other. On the contrary, there are reports suggesting a negative correlation between RAS and opioid system. Research evidence also supports the notion that Ang II acts as anti-opioid peptide to decrease the actions of opioids. Moreover, opioids-induced decline in angiotensin release and functioning has also been reported. Co-administration of ACE inhibitors with opioids exhibits significant interactions possibly due to decreased metabolism of opioids leading to potentiation of their actions. The present review describes the complexities of positive and negative interactions between RAS and opioids along with possible mechanisms responsible for these interactions.

This study was designed to investigate the role of angiotensin neuropeptides in mild electric foot shock stress-induced cognitive enhancement in mice. Mild stress was induced by applying mild electric foot shocks of 0.15 mA intensity for 0.5 s. The stress-induced alteration in cognition was assessed using a Morris water maze test. The animals were subjected to mild electric foot shocks 5 min before we recorded escape latency time (ELT), an index of learning, during the first 4 days of a 5-day trial in the Morris water maze. The time spent in target quadrant (TSTQ), an index of retrieval, was noted on the fifth day without prior administration of electric foot shock. The angiotensin-converting enzyme inhibitor lisinopril (5, 10 and 20 mg/kg), and telmisartan (1, 2 and 5 mg/kg), an angiotensin II receptor blocker, were employed to assess the role of angiotensin neuropeptides. The application of mild electric shocks significantly decreased ELT and increased TSTQ, indicating enhancement in stress-induced learning and memory. However, administration of lisinopril and telmisartan significantly attenuated the stress-induced decrease in ELT and increase in TSTQ. It may be concluded that mild electric foot shock-induced stress triggers the release of angiotensin neuropeptides that may be responsible for memory enhancement.

BACKGROUND The involvement of sodium-hydrogen exchangers (NHE) has been described in the pathophysiology of diseases including ischemic heart and brain diseases, cardiomyopathy, congestive heart failure, epilepsy, dementia, and neuropathic pain. Synthetic NHE inhibitors have not achieved much clinical success; therefore, plant-derived phytoconstituents may be explored as NHE inhibitors. METHODS In the present study, the NHE inhibitory potential of hydroalcoholic and alkaloidal fractions of Malus domestica, Musa × paradisiaca, Daucus carota, and Symphytum officinale was evaluated. The different concentrations of hydroalcoholic and alkaloidal extracts of the selected plants were evaluated for their NHE inhibitory activity in the platelets using the optical swelling assay. RESULTS Among the hydroalcoholic extracts, the highest NHE inhibitory activity was shown by M. domestica (IC50=2.350 ± 0.132 μg/mL) followed by Musa × paradisiaca (IC50=7.967 ± 0.451 μg/mL), D. carota (IC50=37.667 ± 2.517 μg/mL), and S. officinale (IC50=249.330 ± 1.155 μg/mL). Among the alkaloidal fractions, the highest NHE inhibitory activity was shown by the alkaloidal fraction of Musa × paradisiacal (IC50=0.010 ± 0.001 μg/mL) followed by D. carota (IC50=0.024 ± 0.002 μg/mL), M. domestica (IC50=0.031 ± 0.005 μg/mL), and S. officinale (IC50=4.233 ± 0.379 μg/mL). The IC50 of alkaloidal fractions was comparable to the IC50 of synthetic NHE inhibitor, EIPA [5-(N-ethyl-N-isopropyl)amiloride] (IC50=0.033 ± 0.004 μg/mL). CONCLUSIONS It may be concluded that the alkaloidal fractions of these plants possess potent NHE inhibitory activity and may be exploited for their therapeutic potential in NHE activation-related pathological complications.

This study investigates the beneficial role of lisinopril, an angiotensin converting enzyme inhibitor (ACEI) and telmisartan, an angiotensin receptor blocker (ARB), in intracerebroventricular (i.c.v.) streptozotocin (STZ) induced dementia of Alzheimer's disease (AD) type in mice. This study also aimed to explore the role of PPAR-γ in lisinopril and telmisartan mediated effects in i.c.v. STZ mice. Donepezil served as the positive control in the study. Mice underwent i.c.v. injection of STZ. The Morris water maze (MWM) test was employed for assessment of learning and memory. Various biochemical estimations, namely brain acetylcholinesterase (AChE) activity, myeloperoxidase (MPO) activity, nitrite/nitrate and thiobarbituric acid reactive species (TBARS) levels and reduced glutathione (GSH) levels, were also performed. The study showed that i.c.v. STZ significantly impaired learning and memory of the animals along with a significant enhancement in brain AChE, MPO, TBARS, nitrite/nitrate levels and reduction in brain GSH levels. Treatments of lisinopril/telmisartan/donepezil significantly attenuated STZ induced behavioral and biochemical changes. Pre-treatment with bisphenol-A-diglycidyl ether (BADGE), a selective PPAR-γ antagonist, significantly abolished the beneficial effect of lisinopril/telmisartan in i.c.v. STZ treated animals. The results of this investigation document a potential role of PPAR-γ in the beneficial effects of lisinopril and telmisartan in i.c.v. STZ dementia of AD type.

Drug abuse has become a major social problem of the modern world and majority of these abusive drugs or their metabolites are excreted through the kidneys and, thus, the renal complications of these drugs are very common. Morphine, heroin, cocaine, nicotine and alcohol are the most commonly abused drugs, and their use is associated with various types of renal toxicity. The renal complications include a wide range of glomerular, interstitial and vascular diseases leading to acute or chronic renal failure. The present review discusses the renal toxicity profile and possible mechanisms of commonly abused drugs including morphine, heroin, cocaine, nicotine, caffeine and alcohol.

Cerebral ischemia-reperfusion (I-R) injury is one of the primary causes of ischemic stroke. Ischemic postconditioning (iPoCo) is evolving as an important adaptive technique to contain I-R injury. Some recent studies have shown neuroprotective effect of iPoCo. However, neuroprotective mechanism of iPoCo is not clear. So, the present study has been undertaken to investigate the possible role of P2X7 purinoceptors in neuroprotective mechanism of iPoCo in mice. Bilateral carotid artery occlusion for 12 min followed by R for 24 h produced a significant rise in cerebral infarct size and neurological severity score (NSS) along with impairment of memory and motor coordination. iPoCo, involving three episodes of 10-s carotid artery occlusion with intermittent R of 10 s applied just after ischemic insult of 12 min, produced a significant decrease in cerebral infarct size and NSS along with reversal of I-R-induced impairment of memory and motor coordination. iPoCo induced neuroprotective effects were significantly abolished by pretreatment with selective purinergic P2X7 receptor blocker Brilliant Blue G (40 mg/kg intraperitoneal). It may be concluded that neuroprotective effect of iPoCo probably involves in activation of purinergic P2X7 receptors.

Stress-induced increase in intracellular calcium (Ca(2+)) has been demonstrated to produce various deleterious effects in the body. The rise in intracellular Ca(2+) (particularly neuronal) in response to stress has been mainly attributed to opening of voltage gated L-type Ca(2+) channels. The role of P/Q-, N-, R- and T-type Ca(2+)channels, and plasma membrane localized exchangers such as Na(+)/Ca(2+) exchanger and Ca(2+) ATPase has also been implicated in increasing intracellular Ca(2+) in response to stress. Stress-induced changes in Ca(2+) currents has been mainly attributed to increased release of corticosterone (activation of glucocorticoid receptors in the hippocampus) and catecholamine release as a consequence of activation of Hypothalamic-Pituitary-Adrenal (HPA) axis and sympathetic neural system, respectively. Stress-induced increase intracellular Ca(2+) may trigger various deleterious signaling pathway including free radical generation, apoptosis, increased synaptic release of glutamate and synthesis/release of cytotoxic cytokines that may be responsible for damaging effects associated with stress. The present review discusses the mechanisms involved in stress-induced rise in intracellular Ca(2+) levels and subsequent implications of increased Ca(2+) levels in stress.

The study was designed to investigate the efficacy of bosentan a dual endothelin (ETA and ETB) receptor antagonist in experimental diabetes induced vascular endothelial dysfunction and associated dementia. Diabetes was induced in rats by administration of a single dose (50mg/kg, i.p.) of streptozotocin (STZ). Drug treatment was started after 1 month of STZ administration and treatment was continued until the end of the study. Morris water maze (MWM) test was employed for testing spatial learning and memory. Endothelial function was measured on isolated aortic rings using student physiograph. Serum glucose, body weight, serum nitrite/nitrate, brain thiobarbituric acid reactive species (TBARS), reduced glutathione (GSH) levels, and brain acetylcholinesterase activity were also tested. STZ treatment resulted in significant development of cognitive and vascular endothelial deficits, manifested in the terms of endothelial dysfunction, impairment of learning and memory, reduction in body weight and serum nitrite/nitrate levels along with increase in serum glucose, brain acetylcholinesterase activity, TBARS, and decreased GSH levels. Treatment of bosentan attenuated diabetes induced impairment of learning, memory, endothelial function, and various biochemical parameters. It may be concluded that bosentan has shown efficacy in STZ induced cognitive and vascular endothelial deficits. Thus, endothelin receptors can be considered as a potential pharmacological target for the management of experimental diabetes induced vascular endothelial dysfunction and associated dementia.

Prolyl 4 hydroxylases (P4H) are iron- and 2-oxoglutamate-dependent dioxygenase enzymes and hypoxia-inducible transcription factor (HIF)-P4Hs play a critical role in the regulating oxygen homeostasis in the local tissues as well in the systemic circulation. Over a period of time, a number of prolyl hydroxylase inhibitors and activators have been developed. By employing the pharmacological tools and transgenic knock out animals, the critical role of these enzymes has been established in the pathophysiology of number of diseases including myocardial infarction, congestive heart failure, stroke, neurodegeneration, inflammatory disease, respiratory diseases, retinopathy and others. The present review discusses the different aspects of these enzymes including their pathophysiological role in disease development.

The present study was designed to investigate the ameliorative potential of Ocimumsanctum and its saponin rich fraction in chronic constriction injury-induced neuropathic pain in rats. The chronic constriction injury was induced by placing four loose ligatures around the sciatic nerve, proximal to its trifurcation. The mechanical hyperalgesia, cold allodynia, paw heat hyperalgesia and cold tail hyperalgesia were assessed by performing the pinprick, acetone, hot plate and cold tail immersion tests, respectively. Biochemically, the tissue thio-barbituric acid reactive species, super-oxide anion content (markers of oxidative stress) and total calcium levels were measured. Chronic constriction injury was associated with the development of mechanical hyperalgesia, cold allodynia, heat and cold hyperalgesia along with an increase in oxidative stress and calcium levels. However, administration of Ocimumsanctum (100 and 200 mg/kg p.o.) and its saponin rich fraction (100 and 200 mg/kg p.o.) for 14 days significantly attenuated chronic constriction injury-induced neuropathic pain as well as decrease the oxidative stress and calcium levels. It may be concluded that saponin rich fraction of Ocimum sanctum has ameliorative potential in attenuating painful neuropathic state, which may be attributed to a decrease in oxidative stress and calcium levels. O presente estudo foi delineado para avaliar-se o potencial efeito analgésico de extratos de Ocimum sanctum e uma fração enriquecida em saponinas na dor neuropática induzida pela lesão por constrição crônica de nervos periféricos em ratos. A lesão foi induzida pela colocação de quatro ligaduras apostas ao nervo ciático, proximalmente à sua trifurcação. Hiperalgesia mecânica, alodínia ao frio, hiperalgesia ao calor nas patas e hiperalgesia ao frio na cauda foram determinadas usando-se testes de picada de agulha, exposição à acetona, placa quente e teste de imersão em solução gelada, respectivamente. Análises bioquímicas com conteúdo de espécies reativas ao tiobarburato em tecidos e conteúdo de ânion super-óxido (ambos marcadores de estresse oxidativo) e os níveis totais de cálcio foram realizadas. A lesão por constrição crônica do nervo ciático foi acompanhada de desenvolvimento de hiperalgesia mecânica, alodínia ao frio, hiperalgesia ao calor e ao frio, acompanhadas de aumento de marcadores de estresse oxidativo e níveis de cálcio. A administração de extratos de Ocimum sanctum (100 e 200 mg/kg, via oral) e sua fração enriquecida em saponinas (100 e 200 mg/kg, via oral) por 14 dias atenuou significativamente a dor neuropática associada à constrição crônica do nervo ciático, bem como associou-se à diminuição de estresse oxidativo e níveis de cálcio. Conclui-se que a fração enriquecida em saponinas de Ocimum sanctumtem potencial atenuante da dor neuropática, que poderia ser atribuída à diminuição do estresse oxidativo e níveis teciduais de cálcio.

The present study was designed to investigate the potential of aliskiren, a direct renin inhibitor, in chronic constriction injury (CCI)-induced neuropathic pain in rats. Neuropathic pain was induced by placing four loose ligatures around the sciatic nerve. Acetone drop, von Frey hair, pin-prick and hot plate tests were performed to assess cold allodynia, mechanical allodynia, mechanical and heat hyperalgesia, respectively. The levels of Tumor necrosis factor-alpha (TNF-α) were measured in the sciatic nerve as an inflammatory marker. CCI was associated with the development of cold allodynia, mechanical allodynia, mechanical and heat hyperalgesia along with a rise in the levels of Tumor necrosis factor-alpha (TNF-α). Administration of aliskiren (25 or 50 mg/kg intraperitoneal (i.p.)) for 14 days in CCI-subjected rats significantly attenuated CCI-induced pain-related behavior and rise in TNF-α level. It may be concluded that aliskiren-mediated anti-inflammatory actions may be responsible for its beneficial effects in neuropathic pain in rats.