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Pulmonary fibrosis is an important complication of subacute paraquat (PQ) poisoning. Here, we reported a novel nanotherapeutic platform for PQ-induced pulmonary fibrosis in animal inhalation models using simvastatin (SV)-loaded into poly(lactic-co-glycolic acid) (PLGA) nanoparticles (NPs).Eight inhalations of normal saline, PQ (24 mg/kg), PQ plus SV (20 mg/kg), PQ plus SV-loaded PLGA NPs at doses of 5, 10 or 20 mg/kg or PQ plus PLGA NPs were given to rats. After the end of the treatment period, inflammatory factors and creatine phosphokinase as well as lung pathological changes and tracheal responsiveness were evaluated.Inhalation of SV-loaded PLGA NPs could significantly prevent the progression of PQ-induced pulmonary fibrosis especially at a dose of 10 mg through decreasing the serum level of inflammatory factors as well as contractile responses (p 0.001) compared to PQ group. Pathological findings also confirmed the results. However, inhalation of non-formulated SV could not prevent tissue damage and fibrosis in comparision with SV-loaded PLGA NPs.Taken together, the present work provides us an idea about the pulmonary delivery of PLGA-SV NPs using nebulizer for the treatment of PQ poisoning. However, the efficacy of this formulation in human beings and clinical use needs to be more investigated.

Objective:G protein-coupled receptor 55 (GPR55) is an orphan G protein-coupled receptor with various physiological functions. Recent evidence suggests that this receptor may be involved in the control of motor functions. Therefore, in the present study, we evaluated the effects of intra-striatal administration of GPR55 selective ligands in a rat model of Parkinson’s disease.Methods:Experimental Parkinson was induced by unilateral intra-striatal administration of 6-hydroxydopamine (6-OHDA, 10 µg/rat). L-α-lysophosphatidylinositol (LPI, 1 and 5 µg/rat), an endogenous GPR55 agonist, and ML193 (1 and 5 µg/rat), a selective GPR55 antagonist, were injected into the striatum of 6-OHDA-lesioned rats. Motor performance and balance skills were evaluated using the accelerating rotating rod and the ledged beam tests. The sensorimotor function of the forelimbs and locomotor activity were assessed by the adhesive removal and open field tests, respectively.Results:6-OHDA-lesioned rats had impaired behaviours in all tests. Intra-striatal administration of LPI in 6-OHDA-lesioned rats increased time on the rotarod, decreased latency to remove the label, with no significant effect on slip steps, and locomotor activity. Intra-striatal administration of ML193 also increased time on the rotarod, decreased latency to remove the label and slip steps in 6-OHDA-lesioned rats mostly at the dose of 1 µg/rat.Conclusions:This study suggests that the striatal GPR55 is involved in the control of motor functions. However, considering the similar effects of GPR55 agonist and antagonist, it may be concluded that this receptor has a modulatory role in the control of motor deficits in an experimental model of Parkinson.

G protein-coupled receptors (GPCRs) are a large family of transmembrane proteins that are expressed in many organs and serve as important drug targets. A new subgroup, namely orphan GPCRs, comprising many of these receptors has been discovered. These receptors exhibit diverse physiological functions and have been considered in many neurological disorders including Alzheimer's disease, Parkinson's disease, and multiple sclerosis (MS). GPR17, GPR30, GPR37, GPR40, GPR50, GPR54, GPR56, GPR65, GPR68, GPR75, GPR84, GPR97, GPR109, GPR124, and GPR126 are orphan GPCRs that have been reported with considerable effects in the prevention and/or treatment of MS in preclinical studies. In the present article, we reviewed the most recent findings regarding the role of orphan GPCRs in the treatment of MS.

Objective Dihydromyricetin (DHM), a natural flavonoid, is used to reduce alcohol hangover. It has a modulatory role on GABAA receptors with significant effects on seizure and anxiety in animal models. We aimed to evaluate the effect of DHM on morphine conditioned place preference (CPP) and withdrawal sings following morphine dependence using animal models. Methods The effect of DHM (1, 2 and 5 mg/kg, intraperitoneal; ip) on the acquisition and expression of morphine-induced CPP was evaluated in male mice. Administration of morphine for three consecutive days induced physical dependence. The withdrawal signs such as jumping and defecation were precipitated by administration of naloxone (8 mg/kg, ip). The effect of DHM on the development of physical dependence was assessed by injection of DHM before morphine administrations. Results DHM, at the dose of 5 mg/kg, reduced expression of morphine CPP with an increase in the locomotor activity. DHM, at the doses of 2 and 5 mg/kg, also reduced development of morphine CPP. DHM alleviated development of morphine-induced physical dependence at the dose of 1, 2, and 5 mg/kg by decreasing jumping and defecation. Conclusion These results indicated that DHM decreased acquisition and expression of morphine CPP and inhibited development of morphine-induced physical dependence.

Neuroinflammation has a key role in seizure generation and perpetuation in the neonatal period, and toll-like receptor 4 (TLR4) pathway has a prominent role in neuroinflammatory diseases. Administration of antioxidants and targeting TLR4 in the embryonic period may protect rat offspring against the next incidence of febrile seizure and its harmful effects. Curcumin and hesperidin are natural compounds with anti-inflammatory and antioxidant properties and have an inhibitory action on TLR4 receptors. We evaluated the effect of maternal administration of curcumin and hesperidin on infantile febrile seizure and subsequent memory dysfunction in adulthood. Hyperthermia febrile seizure was induced on postnatal days 9–11 on male rat pups with 24 h intervals, in a Plexiglas box that was heated to ~45 °C by a heat lamp. We used enzyme-linked immunosorbent assay, Western blotting, malondialdehyde (MDA), and glutathione (GSH) assessment for evaluation of inflammatory cytokine levels, TLR4 protein expression, and oxidative responses in the hippocampal tissues. For assessing working memory and long-term potentiation, the double Y-maze test and Schaffer collateral-CA1 in vivo electrophysiological recording were performed, respectively Our results showed that curcumin and hesperidin decreased TNF-α, IL-10, and TLR4 protein expression and reversed memory dysfunction. However, they did not provoke a significant effect on GSH content or amplitude and slope of recorded fEPSPs in the hippocampus. In addition, curcumin, but not hesperidin, decreased interleukin-1β (IL-1β) and MDA levels. These findings imply that curcumin and hesperidin induced significant protective effects on febrile seizures, possibly via their anti-inflammatory and antioxidant properties and downregulation of TLR4.

Vincristine (VCR) induces peripheral neuropathy. We aimed to assess the efficacy of modafinil on VCR-induced neuropathy in rats. Neuropathy was induced by intraperitoneal (i.p.) injections of VCR (0.1 mg/kg). Neuropathic groups received modafinil (5, 25 and 50 mg/kg); gabapentin (20 mg/kg); and a combination of modafinil (5 and 50 mg/kg) and gabapentin (20 mg/kg,). Then, electrophysiological, behavioural, biochemical and pathological evaluations were performed. Latencies of tail-flick and von Frey filament tests, motor nerve conduction velocity (MNCV) and excitation of nerve conduction were decreased. Moreover, the transient receptor potential cation channel ankyrin 1 (TRPA1) level was increased, while TRPV1 and N-Methyl-D-aspartate (NMDA) levels remained unchanged. Tumour necrosis factor-alpha (TNF-α) and interleukin-1beta (IL-1β) levels were markedly elevated. Pre-treatment with modafinil prevented sensorimotor neuropathy by raising latencies, MNCV and excitation, reducing TRPA1, TNF-α and IL-1β levels. Modafinil improved behavioural, electrophysiological and pathological disturbances. The results showed that TRPA1 has a more important role than NMDA and TRPV1, in VCR-induced neuropathic pain. In addition, inflammatory mediators, TNF-α and IL-1β, were involved. Further, the combination of modafinil and gabapentin improved the neuroprotective effect of gabapentin. So, modafinil might be a neuroprotective agent in the prevention of VCR-induced neuropathy.

Neuroinflammation and fever are the main triggers in febrile seizures (FS). Focusing on inflammatory pathways and anti-inflammatory drugs could compensate for the limitations of existing medications. The aim of this study is to evaluate the neuroprotective effect of specific antagonizing Toll-like receptor 4 (TLR4), as a prominent inflammatory axis, on the consequences of FS and adulthood using animal models. Complex FS was induced on 9-11 day old male rat pups using a heated chamber. TAK-242, as a specific TLR4 inhibitor, was injected intraperitoneally before seizure induction. Seizure threshold, duration, and spike number were measured by electrocorticography. The levels of inflammatory cytokines, TLR4 protein expression, and oxidative stress markers were detected by enzyme-linked immunosorbent assay, western blotting, malondialdehyde (MDA), catalase (CAT), and superoxide dismutase (SOD) assessments in the cortex and hippocampus. Also, spatial and non-spatial memory were evaluated using the novel object recognition test (NORT) and double Y-maze test during adulthood. The results revealed that provoked inflammatory responses in neonate rats, after FS, were associated with the increase of the tumor necrosis factor alpha, interleukin-1β, and enhanced TLR4 protein expression. Meanwhile, based on performed behavioral tests, the inflammatory process was also involved in adulthood memory deficit. Pretreatment with TAK-242 reduced the inflammatory cytokines and TLR4 protein expression in the cortex and hippocampus of neonate rats and improvement in memory deficit in NORT and double Y-maze tasks. Also, pretreatment with TAK-242 elevated seizure threshold, SOD, and CAT activities, and decreased seizure duration and MDA level with no significant change in spike number. TAK-242 possibly controlled FS via inhibiting inflammation.

Background Current antiepileptic drugs are not able to prevent recurrent seizures in all patients. Orexins are excitatory hypothalamic neuropeptides that their receptors (Orx1R and Orx2R) are found almost in all major regions of the brain. Pentylenetetrazol (PTZ)-induced kindling is a known experimental model for epileptic seizures. The purpose of this study was to evaluate the effect of Orx2 receptor antagonist (TCS OX2 29) on seizures and anxiety of PTZ-kindled rats. Results Our results revealed that similar to valproate, administration of 7 µg/rat of TCS OX2 29 increased the latency period and decreased the duration time of 3rd and 4th stages of epileptiform seizures. Besides, it significantly decreased mean of seizure scores. However, TCS OX2 29 did not modulate anxiety induced by repeated PTZ administration. Conclusion This study showed that blockade of Orx2 receptor reduced seizure-related behaviors without any significant effect on PTZ-induced anxiety.

Melatonin has long been known for its apparent effects on sleep and circadian rhythm. It may participate as a possible therapeutic agent in neurodegenerative, cardiovascular, and endocrine disorders as well. Autophagy is a lysosomal degradation process that occurs in response to starvation and other stresses. Recent studies have reported that melatonin may modulate the autophagy process. We reviewed the current literature that has reported on how different diseases and/or experimental models change autophagy parameters. We also discussed the effect of melatonin on autophagy parameters in the central nervous, cardiovascular, gastrointestinal and endocrine systems as reported in nonclinical studies. Moreover, the molecular targets for melatonin are discussed in details. In summary, melatonin has been reported to enhance significant protective effects in different in vitro and in vivo studies either through enhancement or inhibition of the autophagy process. Melatonin holds promise in the treatment of several major diseases. Regulation of autophagy by melatonin is a determinant parameter that should be considered in the future studies.

Cholecystokinin (CCK) is one of the most studied neuropeptides in the brain. In this study, we investigated the effects of CCK-8s and LY225910 (CCK2 receptor antagonist) on properties of neuronal r...

Exercise preconditioning has been shown to be effective in improving behavioral and neuropathological indices after cerebral ischemia. We evaluated the effect of exercise preconditioning, 17β-estradiol, and their combination on stroke outcome using an experimental model of stroke in ovariectomized (OVX) mice. OVX mice were randomly assigned to 4 groups as follows: control (stroke), exercise (exercise and stroke), estradiol (17β-estradiol and stroke), and exercise+estradiol (exercise and 17β-estradiol and stroke). Exercise preconditioning was performed on a treadmill 5 days/week, 40 min/day, at a speed of 18 m/min for 4 weeks. 17β-estradiol was gavaged (40 μg/kg per day) for 4 weeks. Stroke was induced by permanent middle cerebral artery occlusion (pMCAO), and neurological deficits were evaluated 1, 2, and 7 days after stroke. Then, the serum concentrations of matrix metalloproteinase-9 (MMP-9) and interleukin-10 (IL-10) and infarct volumes were assessed. Exercise preconditioning and 17β-estradiol induced a better outcome compared with the control ischemic mice, which was manifested by decrease in MMP-9, increase in IL-10, diminished infarct volume, and improved neurological deficits. Concomitant administration of 17β-estradiol and exercise also significantly improved these parameters. Exercise preconditioning or administration of 17β-estradiol alone or in combination before pMCAO induced significant neuroprotection in OVX mice.

There are various types of receptors in the central nervous system (CNS). G protein-coupled receptors (GPCRs) have the highest expression with a wide range of physiological functions. A newer sub group of these receptors namely orphan GPCRs have been discovered. GPR3, GPR6, GPR17, GPR26, GPR37, GPR39, GPR40, GPR50, GPR52, GPR54, GPR55, GPR85, GPR88, GPR103, and GPR139 are the selected orphan GPCRs for this article. Their roles in the central nervous system have not been understood well so far. However, recent studies show that they may have very important functions in the CNS. Hence, in the present study, we reviewed most recent findings regarding the physiological roles of the selected orphan GPCRs in the CNS. After a brief presentation of each receptor, considering the results from genetic and pharmacological manipulation of the receptors, their roles in the pathophysiology of different diseases and disorders including anxiety, depression, schizophrenia, epilepsy, Alzheimer's disease, Parkinson's disease, and substance abuse will be discussed. At present, our knowledge regarding the role of GPCRs in the brain is very limited. However, previous limited studies show that orphan GPCRs have an important place in psychopharmacology and these receptors are potential new targets for the treatment of major CNS diseases.

The immediate and the late effects of inhaled Paraquat (PQ) on systemic and lung inflammation and oxidative stress were investigated. Rats were exposed to saline (control group) and two doses of inhaled PQ (27 and 54 mg/m3) and studied variables were measured: 1) one day after the end of PQ exposure as “immediate condition”, 2) 16 days after the end of PQ exposure as “late condition”. Total and differential white blood cells (WBC) counts, lipid peroxidation and nitrite were increased but thiol, superoxide dismutase and catalase in the blood and BALF as well as methacholine EC50 was reduced in both conditions in the animals exposed to PQ compared to control groups (p

Carotenoids are a large class of natural antioxidants that occur in many vegetables, foods and other natural sources. To date, a large number of biological properties have been reported from carotenoids, particularly protective effects against diabetes mellitus (DM), cancer, and neurodegenerative, metabolic and cardiovascular diseases. However, recent studies including clinical evidences, have shown that carotenoids play a role in the treatment of diabetes via enhancing insulin sensitivity. They are also able to protect the body from long-term consequences of diabetes including infectious diseases, nephropathy, neuronal and eye abnormalities. In this review, we try to discuss the mechanisms behind the biological effects of carotenoids for the prevention and treatment of DM and its complications. The authors believe that carotenoids will have a prominent place in the treatment of DM and its complications in the future.

Methamphetamine (METH) is a highly potent and addictive drug with major medical, psychiatric, cognitive, socioeconomic, and legal consequences. It is well absorbed following different routes of administration and distributed throughout the body. METH is known as psychomotor stimulant with potent physiological outcomes on peripheral and central nervous systems, resulting in physical and psychological disorders. Autophagy is a highly conserved and regulated catabolic pathway which is critical for maintaining cellular energy homeostasis and regulating cell growth. The mechanism of autophagy has attracted considerable attention in the last few years because of its recognition as a vital arbiter of death/survival decisions in cells and as a critical defense mechanism in undesirable physiological conditions. The purpose of the current article was to review available evidence to find a relationship between METH toxicity and mechanisms associated with autophagy in different organs.

MicroRNAs (miRNAs) are small non-coding RNAs that act as post-transcriptional gene regulators. They are involved in the pathogenesis of different disorders including heart diseases. MiRNAs contribute to ischemia/reperfusion injury (I/RI) by altering numerous key signaling elements. Together with alterations in the various potential signaling pathways, modification in miRNA expression has been suggested as a part of the response network following ischemia/reperfusion (I/R). In addition, cardiac mitochondrial homeostasis is closely associated with cardiac function and impairment of mitochondrial activity occurred after ischemia/reperfusion injury. MiRNAs play a key role in the regulation of mitochondrial apoptotic pathway and signaling proteins. In this review, we summarize the knowledge currently available regarding the molecular mechanisms of miRNA-regulated mitochondrial functions during ischemia/reperfusion injury. This regulation occurs in different stages of mitochondrial apoptosis pathway.

Convulsive seizures are due to abnormal synchronous and repetitive neuronal discharges in the central nervous system (CNS). Finding new therapeutics to overcome the side effects of the current drug therapies and to increase their effectiveness is ongoing. Orexin-A and orexin-B are brain neuropeptides originating from postero-lateral hypothalamic neurons. Studies show that orexins, through activation of OX1 and OX2 receptors, have excitatory effects in the CNS. Accordingly, this study was designed to evaluate the effect of OX1 receptor antagonist (SB-334867) on seizure- and anxiety-related behaviors of pentylenetetrazol (PTZ)-kindled rats. Kindling was induced by repeated intraperitoneal (IP) injections of PTZ (32 mg/kg) with two-day intervals for 24 days in male Wistar rats. Three groups received intracerebroventricular (ICV) injections of SB-334867 (2.5, 5, and 10 μg/rat) before PTZ injections. Two control groups received vehicle (2 μL/rat, ICV) and valproate (26 μg/rat, ICV) before PTZ injections. An extra group of control animals received saline both ICV and IP. Seizure-related behaviors were monitored for 30 min following PTZ administration. The anxiety-like behaviors were also assessed using elevated plus-maze in the first and last days of the study. The results revealed that ICV injection of SB-334867, mainly at the dose of 10 μg/rat, decreased the median of seizure stages, prolonged the latency and reduced the duration of different seizure stages, and reversed the PTZ-induced anxiety-like behaviors. Based on the presented results, it is suggested that pharmacological blockade of the OX1 receptor is a potential target in the treatment of seizure and concomitant anxiety disorders.

Background Previous studies show that some non-CB1/non-CB2 effects of cannabinoids are mediated through G protein coupled receptor 55 (GPR55). As this receptor is activated by some of cannabinoid receptor ligands and is involved in the modulation of pain, it was hypothesized that this receptor may also interact with opioids. This study examined the effect of atypical cannabinoid O-1602 as a GPR55 agonist on morphine-induced conditioned place preference (CPP) and physical dependence. Methods We used a biased CPP model to evaluate the effect of O-1602 (0.2, 1 and 5 mg/kg, intraperitoneal; ip ) on the acquisition and expression of morphine-induced CPP in male mice. The locomotor activities of mice were also recorded. Moreover, repeated administration of morphine (50, 50 and 75 mg/kg/day) for three days, induced physical dependence. The withdrawal signs such as jumps and diarrhea were precipitated by administration of naloxone (5 mg/kg, ip ). The effect of O-1602 on the development of morphine physical dependence was assessed by injection of O-1602 (0.2, 1 and 5 mg/kg) before morphine administrations. Results Morphine (40 mg/kg, subcutaneous; sc ), but not O-1602 (5 mg/kg) elicited significant preference in the post-conditioning phase. O-1602 at the doses of 0.2 and 1 mg/kg, but not 5 mg/kg reduced acquisition of morphine CPP with an increase in locomotor activity at the dose of 5 mg/kg. O-1602 at the doses of 0.2, 1 and 5 mg/kg also reduced expression of morphine CPP with an increase in locomotor activity at the dose of 5 mg/kg. O-1602 had a significant inhibitory effect on development of morphine-induced physical dependence at the dose of 5 mg/kg by decreasing jumps and diarrhea during withdrawal syndrome. Conclusions The present results indicate that O-1602 decreased acquisition and expression of morphine CPP and inhibited development of morphine-induced physical dependence.

The aim of this study was to evaluate the effects of orexin-A (OX-A) on behavioral and pathological parameters and on gene expression of some multiple sclerosis-related peptides in a model of experimental autoimmune encephalomyelitis (EAE). EAE was induced by subcutaneous administration of MOG 35-55. Following immunization, the treatment was initiated by using SB.334867 (orexin-1 receptor antagonist) and/or OX-A. Locomotor activity and exploratory behaviors were monitored using open field and T-maze continuous alternation task (T-CAT) respectively. Pain sensitivity was assessed by hot-plate test. Histopathological assessments were performed by H&E staining. The expression of TGF-β, MBP, MMP-9, IL-12, iNOS and MCP-1 were measured using real-time PCR method in lumbar spinal cord. OX-A administration in EAE mice remarkably attenuated the clinical symptoms, increased latency response in hot plate test, inhibited infiltration of inflammatory cells, up-regulated mRNA expression of TGF-β as well as MBP and down-regulated mRNA expression of iNOS, MMP-9 and IL-12. In contrast SB.334867 administration in EAE mice deteriorated the clinical symptoms, decreased the alternation in T-CAT, increased infiltration of inflammatory cells, down-regulated mRNA expression of TGF-β and MBP and up-regulated mRNA expression of iNOS. Results of this study suggest that the orexinergic system might be involved in pathological development of EAE. These findings suggest orexinergic system as a potential target for treatment of multiple sclerosis.

G protein-coupled receptors (GPCRs) comprise a large number of receptors. Orphan GPCRs are divided into six families. These groups contain orphan receptors for which the endogenous ligands are unclear. They have various physiological effects in the body and have the potential to be used in the treatment of different diseases. Considering their important role in the central and peripheral nervous system, their role in the treatment of pain has been the subject of some recent studies. At present, there are effective therapeutics for the treatment of pain including opioid medications and non-steroidal anti-inflammatory drugs. However, the side effects of these drugs and the risks of tolerance and dependence remain a major problem. In addition, neuropathic pain is a condition that does not respond to currently available analgesic medications well. In the present review article, we aimed to review the most recent findings regarding the role of orphan GPCRs in the treatment of pain. Accordingly, based on the preclinical findings, the role of GPR3, GPR7, GPR8, GPR18, GPR30, GPR35, GPR40, GPR55, GPR74, and GPR147 in the treatment of pain was discussed. The present study highlights the role of orphan GPCRs in the modulation of pain and implies that these receptors are potential new targets for finding better and more efficient therapeutics for the management of pain particularly neuropathic pain.

G-protein-coupled receptor 55 (GPR55) has been proposed as an atypical cannabinoid receptor, which is activated by lysophosphatidylinositols and some synthetic or endogenous cannabinoid molecules. The exact role of GPR55 receptors in the central nervous system especially in anxiety needs to be evaluated. In this study, the effects of intracerebroventricular (i.c.v.) administration of agonist and antagonist of GPR55 receptor on anxiety-related behaviors in rats were investigated. Here, O-1602 (GPR55 agonist) at the doses of 0.2, 1, and 5 μg/rat increased %OAT and %OAE but not the locomotor activity, showing an anxiolytic response, whereas i.c.v. injection of ML193 (GPR55 antagonist) at the doses of 0.1 and 1 μg/rat increased anxiety-like behaviors while causing locomotor impairment. The antagonistic effect of ML193 on the anxiolytic-like effect of O-1602 was also evaluated. The results showed that ML193 decreased the anxiolytic-like effect of O-1602. Based on these results, it may be concluded that central GPR55 may have a role in modulation of anxiety-like behaviors in rats. Further experiments are needed to elucidate the exact role of these receptors in anxiety.

GABA

Transient receptor potential vanilloid 1 (TRPV1) is a non-selective cation channel that is involved in modulation of diverse physiological processes. The role of this receptor in epilepsy has not been studied well. Therefore, we investigated the role of central TRPV1 receptors on the development of pentylenetetrazole (PTZ) and amygdala-induced kindling in rats. Male Wistar rats received subconvulsive dose of PTZ intraperitoneally, every other day. TRPV1 receptor agonist, OLDA and its antagonist, AMG-9810 were injected intracerebroventricularly 30 min prior to PTZ administration. In electrical kindling, stimulating and recording electrodes were implanted in the right amygdala of male rats. After kindling, the effect of TRPV1 receptor agonist or antagonist on afterdischarge duration (ADD), latency to the onset of bilateral forelimb clonuses (S4L) and duration of loss of equilibrium (stage 5 seizures, S5D) were measured. The results demonstrated that, OLDA at the doses of 0.01, 0.1 and 1 μg/rat, significantly accelerated the incidence of all seizure stages, increased S5D and decreased S4L in the PTZ model of kindling. Also, in amygdala kindling, S5D and ADD were significantly reduced following the administration of AMG-9810. In contrast, OLDA significantly aggravated the indices of seizure in both models of epileptic seizure. This study demonstrated that central TRPV1 receptors may be involved in the development of electrical and PTZ-induced kindling.

Stroke is a major cause of mortality and long-term disability in adults. Transient receptor potential vanilloid-1 (TRPV1) plays a crucial role in neuroinflammation. In this study, the effects of TRPV1 agonist (capsaicin) and antagonist (AMG9810) on cerebral ischemia were investigated. Forty male Wistar rats were assigned to the following experimental groups: sham, vehicle) ischemic), AMG9810 (selective TRPV1 antagonist, 0.5 mg/kg; 3 h after stroke), and capsaicin (1 mg/kg; 3 h after stroke). Stroke was induced by permanent middle cerebral artery occlusion and neurological deficits were evaluated 1, 3, and 7 days after stroke. Then, infarct volume, brain edema, body temperature, mRNA expression of TRPV1, and serum concentrations of tumor necrosis factor-alpha (TNF-α) and IL-10 were measured. Compared to the vehicle group, AMG9810 significantly decreased the infarct volume (P < 0.01). Latency for the removal of sticky labels from the forepaw and the hanging time were significantly decreased and increased, respectively, following administration of AMG9810 (P < 0.01 and P < 0.001 vs. vehicle) 3 and 7 days after stroke. Compared to the sham group, the mRNA expression of TRPV1 was significantly increased in vehicle group (P < 0.01). Administration of AMG9810 significantly increased the anti-inflammatory cytokine IL-10 and decreased the inflammatory cytokine TNF-α (P < 0.05). Moreover, our results indicate that AMG9810 might a promising candidate for the hypothermic treatment of stroke. The findings also suggest a key role for AMG9810 in reducing inflammation after stroke and imply that TRPV1 could be a potential target for the treatment of ischemic stroke.

Background The role of transient receptor potential vanilloid type 1 (TRPV1) channels in learning and memory processes has recently been recognized. In the present study, the role of this receptor in the multisensory integration process was investigated. Methods This study was done using 96 male Wistar rats, which were kept in a reverse 12–12 h dark/light cycle. Unimodal and multimodal object recognition task was performed by four variations of the spontaneous object recognition (SOR) test including standard SOR, tactile SOR, visual SOR, and cross-modal visual-tactile SOR (CMOR). AMG9810 (selective TRPV1 antagonist) was injected into the right lateral cerebral ventricle prior to sample and choice phases of SOR. A discrimination ratio was calculated to assess the preference of the animal for the novel object. Results Results demonstrated that administration of AMG9810 prior to the sample phase, as encoding phase, and prior to the choice phase, as retrieval phase, impaired discrimination between the novel and the familiar objects in all standard SOR, tactile SOR, visual SOR, and CMOR tasks (all p Conclusion The results of this study showed that TRPV1 receptors might be implicated in both unimodal and cross-modal encoding of information in rats.

Wireless internet (Wi-Fi) electromagnetic waves (2.45 GHz) have widespread usage almost everywhere, especially in our homes. Considering the recent reports about some hazardous effects of Wi-Fi signals on the nervous system, this study aimed to investigate the effect of 2.4 GHz Wi-Fi radiation on multisensory integration in rats. This experimental study was done on 80 male Wistar rats that were allocated into exposure and sham groups. Wi-Fi exposure to 2.4 GHz microwaves [in Service Set Identifier mode (23.6 dBm and 3% for power and duty cycle, respectively)] was done for 30 days (12 h/day). Cross-modal visual-tactile object recognition (CMOR) task was performed by four variations of spontaneous object recognition (SOR) test including standard SOR, tactile SOR, visual SOR, and CMOR tests. A discrimination ratio was calculated to assess the preference of animal to the novel object. The expression levels of M1 and GAT1 mRNA in the hippocampus were assessed by quantitative real-time RT-PCR. Results demonstrated that rats in Wi-Fi exposure groups could not discriminate significantly between the novel and familiar objects in any of the standard SOR, tactile SOR, visual SOR, and CMOR tests. The expression of M1 receptors increased following Wi-Fi exposure. In conclusion, results of this study showed that chronic exposure to Wi-Fi electromagnetic waves might impair both unimodal and cross-modal encoding of information.

Autophagy is a lysosomal degradation process through which long-lived and misfolded proteins and organelles are sequestered, degraded by lysosomes, and recycled. Autophagy is an essential part of cardiomyocyte homeostasis and increases the survival of cells following cellular stress and starvation. Recent studies made clear that dysregulation of autophagy in the cardiovascular system leads to heart hypertrophy and failure. In this manner, autophagy seems to be an attractive target in the new treatment of cardiovascular diseases. Although limited activation of autophagy is generally considered to be cardioprotective, excessive autophagy leads to cell death and cardiac atrophy. Natural products such as resveratrol, berberine, and curcumin that are present in our diet, can trigger autophagy via canonical (Beclin-1-dependent) and non-canonical (Beclin-1-independent) pathways. The autophagy-modifying capacity of these compounds should be taken into consideration for designing novel therapeutic agents. This review focuses on the role of autophagy in the cardioprotective effects of these compounds.

Orexin A and B are hypothalamic peptides with a wide variety of effects such as anti-inflammation and neuroprotection. Impaired function of orexin system has been reported in some neurodegenerative diseases like Parkinson, Huntington and Alzheimer. In this study, the mRNA expression levels of some hypothalamic peptides were investigated in C57BL/6 female mice with experimental autoimmune encephalomyelitis (EAE). Animals were randomly divided into two control and EAE groups. EAE was induced by administration of myelin oligodendrocyte glycoprotein (MOG) with complete Ferund's adjuvant and pertussis toxin. Twenty-first days following immunization, mice were decapitated to remove the brains. Then, the expression profiles of prepro-orexin, orexin 1 receptors (OX1R) and orexin 2 receptors (OX2R) in hypothalamic region were assessed using real-time PCR method. In this study, we found a considerable increase in the mRNA expression of OX1R and OX2R following EAE induction in C57BL/6 mice. Elevation levels of OX1R and OX2R following EAE induction suggest that alteration in orexinergic system may involve in pathogenesis of multiple sclerosis.

Ethnopharmacological relevance Valeriana officinalis L. (valerian) root extract has been used as an antiepileptic herbal medicine in Iran. Aim of this study In the present study the effect of valerian extracts on an experimental model of temporal lobe epilepsy (TLE) was evaluated. Moreover, the involvement of adenosine system in the actions of aqueous extract of valerian was evaluated. Materials and methods Bipolar stimulating and monopolar recording electrodes were implanted stereotaxically in the right basolateral amygdala of male Sprague–Dawley rats. After kindling, the effect of aqueous (200, 500 and 800 mg/kg; intraperitoneal) and petroleum ether (PE; 50 and 100 mg/kg; intraperitoneal) extracts of valerian and CPT (selective A 1 receptor antagonist; 10 and 20 μM; intracerebroventricular) on afterdischarge duration (ADD), duration of stage 5 seizure (S5D) and latency to the onset of bilateral forelimb clonuses (S4L) were measured. The effect of CPT (10 μM) on the response of aqueous extract of valerian (500 mg/kg) was also determined. Results The results showed that aqueous extract of valerian had anticonvulsant effect. However, PE extract and CPT (20 μM) had proconvulsant effect. Administration of CPT (10 μM) before the administration of aqueous extract decreased the anticonvulsant effect of valerian. Conclusions The results showed significant anticonvulsant effect for aqueous but not PE extract of valerian. Moreover, CPT as a selective adenosine A 1 receptor antagonist decreased the anticonvulsant effect of valerian aqueous extract. Therefore, we concluded that part of anticonvulsant effect of valerian probably is mediated through activation of adenosine system.

Peroxisome proliferator-activated receptor-gamma (PPAR-gamma) agonists have been found to have potent anti-inflammatory actions and suggested as potential therapies for brain ischaemia. Glutamate is the most common excitatory neurotransmitter in the central nervous system and is released excessively during ischaemia. Stroke therapy will require combinations of drug classes, because no single drug class has yet been proven efficacious in human beings. The present study was conducted to assess whether N-methyl-d-aspartate (NMDA) receptor antagonist (MK-801) treatment can improve recovery from ischaemic brain injury and whether rosiglitazone, a PPAR-gamma ligand, can increase its neuroprotective effect in an embolic model of stroke. Stroke was induced in rats by embolizing a preformed clot into the middle cerebral artery. Rosiglitazone (0.1 mg/kg, intraperitoneally) and MK-801 (0.1 mg/kg, intravenously) were injected immediately after embolization. Forty-eight hours later, the brains were removed, sectioned and stained with triphenyltetrazolum chloride and analysed by a commercial image processing software programme. Rosiglitazone and MK-801 alone or in combination decreased infarct volume by 49.16%, 50.26% and 81.32%, respectively (P < 0.001). Moreover, the combination therapy significantly decreased the infarct volume when compared to any drug used alone (P < 0.05). MK-801 reduced the brain oedema by 68% compared to the control group (P < 0.05), but rosiglitazone or combination did not show any significant effect. The drugs alone or in combination also demonstrated improved neurological function, but combination therapy was more effective on neurological deficits improving. Our data show that the combination of MK-801 and rosiglitazone is more neuroprotective in thromboembolic stroke than given alone; this effect perhaps represents a possible additive effect in the brain infarction.

Animal models of learning and memory have been the subject of considerable research. Rodents such as mice and rats are nocturnal animals with poor vision, and their survival depends on their sense of touch. Recent reports have shown that whisker somatosensation is the main channel through which rodents collect and process environmental information. This review describes tactile learning in rodents from a neurobiological and neuropharmacological perspective, and how this is involved in memory-related processes.

Many plants produce flavonoids as secondary metabolites. These organic compounds may be involved in the defense against plant-threatening factors, such as microbes and toxins. Certain flavonoids protect their origin source against plant pathogens, but they also exhibit potential healthy properties in human organisms. Hesperidin (Hsd) and its aglycone, hesperetin (Hst), are two flavonoids from the Citrus species that exhibit various biological properties, including antioxidant, antiinflammatory and anticancer effects. Recent studies indicated that Hst and Hsd possess antimicrobial activity. Although the exact mechanisms behind their antimicrobial properties are not fully understood, several mechanisms such as the activation of the host immune system, bacterial membrane disruption, and interference with microbial enzymes, have been proposed. Hsd and Hst may also have protective effects against toxicity induced by various agents. These natural substances may contribute to the protection of cells and tissues through their antioxidant and radical scavenging activities. This review discusses the protective activities of Hsd and Hst against microbes and several toxicities induced by oxidants, chemicals, toxins, chemotherapy and radiotherapy agents, which were reported in vitro and in vivo. Furthermore, the probable mechanisms behind these activities are discussed.

Inflammation and oxidative stress are two major causes of various life-threatening diseases. Hesperidin (Hsd) and its aglycone, hesperetin (Hst), are two flavonoids from citrus species that have numerous biological properties, particularly antioxidant and anti-inflammatory. New findings showed that the antioxidant activity of Hsd/Hst was not only limited to its radical scavenging activity, but it augmented the antioxidant cellular defenses via the ERK/Nrf2 signaling pathway as well. Various in vitro and in vivo studies have been conducted to evaluate Hsd, its metabolites, or its synthetic derivatives at reducing inflammatory targets including NF-κB, iNOS, and COX-2, and the markers of chronic inflammation. In this review, new findings regarding the molecular targets of Hsd and Hst in the reduction of oxidative stress are discussed. Also, in the anti-inflammatory section, we provide a summary of significant investigations concerning the mechanisms of action based on the studied inflammation models.

ObjectivesDopamine receptor-mediated 3′,5′-cyclic adenosine monophosphate (cAMP)-dependent intracellular signalling is important for reward-related learning. cAMP activates cAMP-dependent protein kinase (PKA) and exchange protein directly activated by cAMP (Epac). We tested the hypothesis that reward-related learning may be mediated by Epac.MethodsWe evaluated conditioned place preference (CPP) on the basis of nucleus accumbens (NAc) injections of amphetamine (20 μg/0.5 μl/side) plus Sp-adenosine 3′,5′-cyclic monophosphorothioate triethylamanine (Sp-cAMPS) (0.1, 1.0, 10, 15, 20 μg/0.5 μl/side), an activator of both PKA and Epac, or amphetamine (20 μg) plus 8-(4-chlorophenylthio)-2′-O-methyladenosine-3′,5′-cyclic monophosphate (8-pCPT) (0.73, 1.27, 1.45, 2.89, 5.78, 11.56 μg/0.5 μl/side), an activator of Epac.ResultsIn agreement with previous results, Sp-cAMPS dose-dependently impaired CPP. 8-pCPT impaired CPP at one dose (1.45 μg/0.5 μl/side) and we replicated this effect three times.ConclusionThe results implicate Epac in the acquisition of reward-related learning.

Hesperidin (Hsd) and its aglycone, hesperetin (Hst), are two flavonoids from citrus species that have various biological properties. Over the past decade, a large number of papers have been published regarding the biological activities of these compounds and their molecular mechanisms. In this paper, we reviewed the neuropharmacology of Hsd and Hst as a recently emerged topic that has not been addressed in the past. Some of molecular targets and signaling pathways for neuropharmacological effects of Hst and Hsd, including antidepressant, neuroprotective and the effects of Hsd/Hst on memory, have also been included in the review. We also discussed the mechanisms of actions for antidepressant activities of Hsd and Hst. In addition, pharmacokinetics of Hsd and Hst, their interaction with some drugs such as atenolol, diltiazem, felodipine and verapamil, as well as related underlying mechanisms have been discussed.

A large body of evidence suggests that the cannabinoid CB1 receptor plays a key role in the regulation of emotional behaviors. The present study was designed to evaluate the effects of CB1 agonist and antagonist on anxiety-like behaviors in the lateral septum (LS) region of the rat brain using elevated plus maze test.Rats were anesthetized with ketamine and xylazine and special cannulas were inserted stereotaxically into the LS region. After 1 week of recovery, the effects of intra-LS administration of the CB1 receptor agonist, WIN 55,212-2 and CB1 receptor antagonist, AM251, on %OAT and %OAE were measured. Moreover, the effects of pretreatment with AM251 on the response induced by intra-LS administration of WIN 55,212-2 were also assessed.Intra-LS administration of WIN 55,212-2 (0.001, 0.005 and 0.5μg/rat) decreased the %OAT and %OAE but not locomotor activity, showing an anxiogenic-like response. Intra-LS injection of different doses of AM251 (0.001, 0.01 and 0.1 µg/rat) did not significantly alter the anxiety-like parameters on the plus-maze test. However, intra-LS injections of AM251 (0.01 µg/rat) significantly reversed WIN 55,212-2-induced anxiogenic-like effects.The results suggest that the cannabinoid system of the lateral septum modulates anxiety-like behavior through CB1 receptor.

There is evidence that exercise decreases ischemia/reperfusion injury in rats. Since behavioral deficits are the main outcome in patients after stroke, our study was designed to investigate whether exercise preconditioning improves the acute behavioral functions and also brain inflammatory injury following cerebral ischemia.Male rats weighing 250-300 g were randomly allocated into five experimental groups. Exercise was performed on a treadmill 30min/day for 3 weeks. Ischemia was induced by 4-vessel occlusion method. Recognition memory was assessed by novel object recognition task (NORT) and step-through passive avoidance task. Sensorimotor function and motor movements were evaluated by adhesive removal test and ledged beam-walking test, respectively. Brain inflammatory injury was evaluated by histological assessment.In NORT, the discrimination ratio was decreased after ischemia (P0.05) and exercise preconditioning improved it in ischemic animals. In the passive avoidance test, a significant reduction in response latency was observed in the ischemic group. Exercise preconditioning significantly decreased the response latency in the ischemic rats (P0.001). In the adhesive removal test, latency to touch and remove the sticky labels from forepaw was increased following induction of ischemia (all P0.001) and exercise preconditioning decreased these indices compared to the ischemic group (all P0.001). In the ledged beam-walking test, the slip ratio was increased following ischemia (P0.05). In the ischemia group, marked neuronal injury in hippocampus was observed. These neuropathological changes were attenuated by exercise preconditioning (P0.001).Our results showed that exercise preconditioning improves behavioral functions and maintains more viable cells in the dorsal hippocampus of the ischemic brain.

Opiates are traditionally used for treatment of some acute heart disorders. There are only few reports on the effects of long-term treatment of cardiovascular diseases with morphine. This study aimed to investigate the effects of chronic low-dose morphine use on the cardiovascular system in two-kidney one-clip (2K1C) hypertensive rats.Male Wistar rats were divided into two groups as the sham and 2K1C groups and each group was further subdivided into saline and morphine treatment subgroups. Blood pressure, heart rate, plasma rennin activity, serum nitric oxide concentration, and baroreflex sensitivity were measured.Morphine significantly attenuated systolic blood pressure, diastolic blood pressure, and mean arterial pressure in the 2K1C animals. In addition, morphine decreased plasma rennin activity in the 2K1C group. Serum concentrations of nitric oxide were also decreased, and morphine prevented the reduction of nitric oxide. The baroreflex sensitivity was also improved following morphine administration in the 2K1C group.According to the results presented in this study, chronic administration of low-dose morphine reduces regulated hypertension in the 2K1C rats, probably via a nitric oxide-dependent pathway.

Background The role of transient receptor potential vanilloid 1 (TRPV1) in peripheral nervous system has been studied well but its role in the central nervous system remains to be studied in detail. The expression of TRPV1 receptors in hippocampus is suggesting that they may play an important role in higher cognitive functions such as learning and memory. Methods In the present study, the role of TRPV1 receptors in acquisition and retrieval of spatial memory of male Wistar rats was evaluated by intra-ventral hippocampus administration of TRPV1 selective agonist (OLDA) and antagonist (AMG9810) using Morris water maze. Results The results demonstrated that administration of either OLDA (0.001, 0.01 and 0.1 μg/rat) or AMG9810 (0.003, 0.03 and 0.3 μg/rat) did not influence memory acquisition or retrieval. Conclusions These data suggest that ventral-hippocampal TRPV1 receptors possibly are not involved in spatial learning and memory.

In this study, the effects of aqueous extracts of Carum copticum seeds (CCS) were evaluated in kindling models of epilepsy. Additionally, the sedative and anxiolytic effects of the extract were assessed. For pentylenetetrazole (PTZ) kindling, rats received a subconvulsant dose of PTZ (40 mg/kg, ip) every second day and seizure stages were recorded. CCS aqueous extract (200, 400, or 600 mg/kg, ip) was injected 30 minutes prior to each PTZ injection. In electrical kindling, bipolar stimulating and monopolar recording electrodes were implanted stereotaxically in the right basolateral amygdala of male Sprague–Dawley rats. After kindling, the effect of aqueous extracts of CCS (200, 400, or 600 mg/kg, ip) on afterdischarge duration, duration of rearing, forelimb clonus, and loss of equilibrium (stage 5 seizure), and latency to the onset of bilateral forelimb clonus were measured. The sedative and the anxiolytic effects of CCS extracts were evaluated in an open-field apparatus and elevated plus maze, respectively. The results indicate that aqueous extracts of CCS have a significant anticonvulsant effect. Different doses of extract significantly delayed the incidence of every seizure stage in the PTZ model of kindling. Moreover, CCS extract (400 and 600 mg/kg, ip) suppressed afterdischarge duration, latency to the onset of bilateral forelimb clonus, and stage 5 seizure in the electrical kindling model. These results suggest that CCS extract has remarkable antiepileptic and central depressant effects.

The effects of unilateral intra-ventral hippocampus injection of URB597, a fatty acid amid hydrolase inhibitor, and AM251, a selective CB(1) receptor antagonist, on anxiety-related behaviours using elevated plus-maze test of anxiety were evaluated in the present study. Possible involvement of GABAergic system in those effects of URB597 was also evaluated. Injection of URB597 at the doses of 0.01, 0.1 and 1 microg/rat showed significant anxiogenic-like effects at 0.1 and 1 microg/rat. However, intra-ventral hippocampus injection of AM251 at the doses of 0.001, 0.01 and 0.1 microg/rat did not produce any significant effect in the elevated plus-maze. The ineffective doses of selective GABA(A) receptor antagonist, bicuculline (2 microg/rat) and selective GABA(B) receptor antagonist, phaclofen (1 microg/rat) on anxiety-related behaviours were also injected with URB597 (0.1 microg/rat). The present data showed that neither bicuculline nor phaclofen affected the anxiogenic-like effects of URB597. The results showed that injection of URB597 into the ventral hippocampus may be anxiogenic and GABAergic system may not be involved in its anxiogenic-like effects.

Diabetic rats display increased pain responses after injection of formalin into the paw or thermal stimulation of the tail, suggesting the presence of hyperalgesia. In this study, we investigated the efficacy of URB597 (0.1, 0.3, and 0.5 mg/kg, i.p.), an inhibitor of endocannabinoids metabolism, on 2 models of experimental hyperalgesia in streptozotocin (STZ)-induced diabetic rats. Animals were divided into control, URB597-treated control (0.1, 0.3, and 0.5 mg/kg), diabetic, and URB597-treated diabetic (0.1, 0.3, and 0.5 mg/kg) groups. Formalin and tail-flick tests were performed 4 and 8 weeks after the onset of hyperglycemia, respectively. Diabetes caused significant hyperalgesia during these tests. URB597 (0.3 and 0.5 mg/kg) reversed chemical and thermal hyperalgesia in diabetic rats. Administration of URB597 at a dose of 0.1 mg/kg did not alter pain-related behaviors in control and diabetic groups compared with those of the respective control groups. URB597 treatment did not affect body weight or plasma glucose level of treated animals compared with nontreated animals. This study shows that increasing endocannabinoid neurotransmission with URB597 displays efficacy in chemical and thermal models of diabetic hyperalgesia. It also suggests that URB597 is a promising tool for treatment of painful diabetic neuropathy.

In the present study, we have investigated the effects and the interaction of the GABAergic and histaminergic systems in the basolateral amygdala (BLA) of rats using the plus-maze test of anxiety-like behaviors. Unilateral injection of different doses of muscimol (GABAA receptor selective agonist; 0.01, 0.05 and 0.1 µg/rat) into the BLA (intra-BLA) increased the percentage of open arm time (%OAT) and open arm entries (%OAE) at the doses of 0.05 and 0.1 µg/rat that are representative of an anxiolytic response. Intra-BLA injection of bicuculline (GABAA receptor selective antagonist; 0.05, 0.1 and 0.5 µg/rat) decreased %OAT and %OAE at the doses of 0.1 and 0.5 µg/rat showing an anxiogenic-like effect. Intra-BLA administration of histamine (0.05, 0.1 and 0.5 µg/rat) also showed anxiogenic-like effects at the doses of 0.1 and 0.5 µg/rat while intra-BLA administration of pyrilamine (an H1 receptor selective antagonist; 5, 10 and 20 µg/rat) induced anxiolytic effects at the dose of 20 µg/rat. Coadministration of histamine (0.1 µg/rat) with muscimol reversed the anxiolytic effect of muscimol at the dose of 0.1 µg/rat while coadministration of histamine (0.1 µg/rat) with bicuculline increased the anxiogenic effect of bicuculline at the dose of 0.05 µg/rat. On the other hand, coadministration of pyrilamine (10 µg/rat) with bicuculline decreased anxiety-like behaviors of bicuculline at the dose of 0.5 µg/rat while pyrilamine could not affect the anxiolytic effect of muscimol. In conclusion, it seems that both GABAergic and histaminergic systems not only play a part in the modulation of anxiety-like behaviors in the BLA of rats but may also have opposite effects in this brain region.

1. The important role of the cannabinoid system in the modulation of anxiety like behaviours in clinical and experimental studies has been proposed. However, investigations into this effect of cannabinoids has produced contradictory results. It has been reported that different neurotransmitters, such as nitric oxide (NO), are involved in the behavioural effects of cannabinoids. The hippocampus is also an important brain region in the modulation of anxiety in which CB1 receptors are densely expressed. The present study was designed to evaluate the interactions between cannabinoid and NO systems in the CA1 brain region of the rats using the plus-maze test. 2. Rats were anaesthetized with ketamine and xylazine and special cannulas were inserted stereotaxically into the CA1 region of the dorsal hippocampus. After 1 week recovery, the effects of intra-CA1 administration of WIN55212-2 (1, 2.5 and 5 microg/rat), AM251 (2, 10 and 50 ng/rat), L-arginine (0.01, 0.1 and 1 microg/rat) and N(G)-nitro-L-arginine methyl ester (L-NAME; 1, 10 and 100 ng/rat) on percentage open arm time (%OAT) and percentage open arm entries (%OAE) were determined. Moreover, the effects of pretreatment with AM251 (2 ng/rat), L-arginine (0.01 microg/rat) and L-NAME (1 ng/rat) on the response induced by intra-CA1 administration of WIN55212-2 were also assessed. 3. The administration of either L-arginine or L-NAME into the CA1 region produced significant anxiogenic-like responses, whereas administration of AM251 induced anxiolytic effects. Intra-CA1 injection of WIN55212-2 produced a significant anxiogenic-like effect that was reversed by AM251 and was also altered by L-NAME, but not by L-arginine. 4. These data imply that cannabinoids may have anxiogenic-like effects in the CA1 region of the hippocampus in which CB1 receptors and NO may be involved.

Reports indicate that histamine and histaminergic agents can change anxiety-related behaviours in both animals and humans. The amygdala is an important brain site in the modulation of fear or anxiety. In the present study, we investigated the effects of intracentral amygdala microinjection of histaminergic agents on anxiety-related behaviours in rats, using the elevated plus-maze test of anxiety. Intracentral amygdala administration of histamine (0.01-0.5 microg/0.5 microl bilateral) decreased %open armtime and % open arm entries, but not locomotor activity, showing an anxiogenic response. Intracentral amygdala microinjection of pyrilamine (H1 receptor antagonist) and ranitidine (H2 receptor antagonist) (both at 1-20 microg/0.5 microl bilateral) did not change anxiety-related parameters in our experiments. In another series of experiments, histamine (0.5 microg/0.5 microl bilateral) was coadministrated with pyrilamine and ranitidine (both at 1-20 mg/0.5 microl bilateral). The results showed that pyrilamine but not ranitidine could significantly reverse the anxiogenic effect of histamine at doses of 10 and 20 microg/0.5 microl bilateral. The results suggest that histamine may modulate anxiety via H1 but not H2 receptors in the rat central amygdala.

Some reports indicate that morphine can induce anxiolytic effects both in animal and in man. It has also been reported that histaminergic system can interfere with some pharmacological effects of morphine. The effects of histaminergic agents on morphine-induced anxiolysis in rats, using elevated plus-maze were investigated in the present study. Intraperitoneal injection of morphine (3, 6 and 9 mg/kg) induced antianxiety effects. Intracerebroventricular administration of histamine at the doses of (5, 10 and 20 microg/rat) also increased anxiety-related behaviours. Intracerebroventricular injection of pyrilamine, a H1 receptor antagonist (25, 50 and 100 microg/rat), increased anxiety whereas injection of ranitidine, a H2 receptor antagonist (5, 10 and 20 microg/rat) at the same site, decreased anxiety. Therefore, it seems that histamine induces anxiogenic response through activation of H2 receptors, while the response of H1 blocker may be due to release of histamine. We also evaluated the interactions between morphine and histaminergic agents. Our data show that histamine (10 microg/rat), pyrilamine (50 microg/rat) and ranitidine (5 microg/rat) did not alter the response induced by different doses of morphine (3, 6 and 9 mg/kg). Similarly, a single dose of morphine did not alter the response induced by different doses of histamine (5, 10 and 20 microg/rat), pyrilamine (25, 50 and 100 microg/rat) or ranitidine (5, 10 and 20 microg/rat). In conclusion, the histaminergic system plays an important role in the modulation of anxiety, although in our experiments, no interaction was found between the effects of histaminergic agents and morphine on anxiety-related indices in the elevated plus-maze. This may imply that morphine-induced anxiolysis probably is independent of the histaminergic system.

In the present study, we have investigated the effects and interaction of CCK and GABAergic systems in the dorsal hippocampus of rats using the elevated plus-maze test of anxiety. Bilateral injection of different doses of CCK(8s) (0.01, 0.05 and 0.1 microg/rat) into the dorsal hippocampus (intra-CA1) decreased percentage of open arm time (%OAT) and open arm entries (%OAE) that are representative of anxiogenic-like behavior. The bilateral injection of three doses of LY225910, a selective CCK2 receptor antagonist (0.01, 0.1 and 0.5 microg/rat) produced significant anxiolytic behavior. Although muscimol (GABA(A+)) (0.1, 0.5 and 1 microg/rat, intra-CA1) produced dose dependent increase in %OAT and a slight increase in %OAE, bicuculline (GABA(A-)), (1, 2 and 4 microg/rat, intra-CA1) failed to change the anxiety profile. Both muscimol (0.1 microg/rat) and bicuculline (1 microg/rat), when co-administered with LY225910, reversed the effect of latter drug on anxiety but when co-administered with CCK8s (0.05 microg/rat) showed no effect on anxiety profile. In conclusion, it seems that both CCK and GABAergic systems not only play a part in the modulation of anxiety in the dorsal hippocampus of rats but also have demonstrated a complex interaction as well.