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PubMed: 32061493 Background: Recent studies have been revealed that oxidative damage is the main cause of aging and age-related neurodegenerative diseases like Alzheimer's disease (AD). Melatonin is secreted from the pineal gland and its secretion has been found to be altered in AD. In the last decade the role of exosomes in spreading toxic proteins and inducing the propagation of diseases like AD has been discussed. However, it is not known how melatonin affects the amount of exosomes released from the cells and the content of the exosomes. Objective: Herein, we investigated the possible role of melatonin treatment in the releasing of exosomes and exosomal tau content in an in vitro A? toxicity model. Method: SH-SY5Y cell line was used. The optimum concentration of A? was determined by cell viability and cell proliferation tests. Melatonin (100 µM) was applied before and after A? application. Total exosomes isolated from cell culture media were immunoprecipitated. The amount of released exosomes and their tau content were analyzed by Western blots. Results: Our data demonstrated for the first time that melatonin treatment clearly affected the amount of released exosomes. It would decrease the amyloid beta load and toxicity by inhibiting exosome release. We also demonstated that melatonin also affected the level of tau carried by exosomes depending on whether melatonin was applied before or after A? application. Conclusion: It is considered that the effect of melatonin in the release of exosomes and exosomal tau content would contribute the development of therapeutic strategies in AD and related disorders. © 2019 Elsevier Ltd

The circadian rhythm is driven by a master clock within the suprachiasmatic nucleus which regulates the rhythmic secretion of melatonin. Bmal1 coordinates the rhythmic expression of transcriptome and regulates biological activities, involved in cell metabolism and aging. However, the role of Bmal1 in cellular- survival, signaling, its interaction with intracellular proteins, and how melatonin regulates its expression is largely unclear. Here we observed that melatonin increases the expression of Bmal1 and both melatonin and Bmal1 increase cellular survival after oxygen glucose deprivation (OGD) while the inhibition of Bmal1 resulted in the decreased cellular survival without affecting neuroprotective effects of melatonin. By using a planar surface immunoassay for PI3K/AKT signaling pathway components, we revealed that both melatonin and Bmal1 increased phosphorylation of AKT, ERK-1/2, PDK1, mTOR, PTEN, GSK-3αβ, and p70S6K. In contrast, inhibition of Bmal1 resulted in decreased phosphorylation of these proteins, which the effect of melatonin on these signaling molecules was not affected by the absence of Bmal1. Besides, the inhibition of PI3K/AKT decreased Bmal1 expression and the effect of melatonin on Bmal1 after both OGD in vitro and focal cerebral ischemia in vivo. Our data demonstrate that melatonin controls the expression of Bmal1 via PI3K/AKT signaling, and Bmal1 plays critical roles in cellular survival via activation of survival kinases.

Background/aim Glial cell-line derived neurotrophic factor (GDNF) is a well-known regulatory neurotrophic factor on dopaminergic neurons. Several pathologies have been documented so far in case of any impairment in the dopaminergic system. This study aimed to investigate the potential protective role of lentiviral GNDF delivery on the small population of tyrosine hydroxylase (TH) positive dopamine producing striatal neurons after ischemic stroke. Materials and methods Fourteen C57BL/6J male mice (8-10 weeks) were intracerebrally treated with lentiviral GDNF (Lv-GDNF) or vehicle. Ten days after injections, cerebral ischemia was induced by blockage of the middle cerebral artery. Animals were terminated 72 hours after ischemia, and their brains were taken for histological and molecular investigations. Following confirmation of GDNF overexpression, TH immunostaining and immunoblotting were used to evaluate the role of GDNF on dopaminergic neurons. Next, Fluro Jade C staining was implemented to examine the degree of neuronal degeneration at the damaged parenchyma. Results Neither the amount of TH positive dopaminergic neurons nor the expression of TH changed in the Lv-GDNF treated animals comparing to the vehicle group. On the other hand, GDNF exposure caused a significant increase in the expression of Nurr1, an essential transcription factor for dopaminergic neurons and Gap43, growth and plasticity promoting protein, in the ischemic striatum. Treatment with Lv-GDNF gave rise to a significant reduction in the number of degenerated neurons. Finally, enhanced GDNF expression also induced expression of an important stress related transcription factor NF-?B as well as the nitric oxide synthase enzymes iNOS and nNOS in the contralesional hemisphere. Conclusion Considering these results together, GDNF?s impact on the survival of striatal dopaminergic neurons is not outstanding for its neuroprotective role. However, it seems that GDNF conducts several signaling pathways by acting on key transcription factors and shows its protective feature by fine tuning the degeneration related processes.

WOS: 000471268100003 The clinical use of cisplatin, which is a first-line anticancer agent, is highly restricted due to its adverse effects on kidneys that lead to nephrotoxicity. Therefore, some potential reno-protective substances have been used in combination with cisplatin to cope with nephrotoxicity. Due to its high antitumor activity and oxygen-carrying capacity, we investigated the molecular effects of squalene against cisplatin-induced oxidative stress and kidney damage in mice. Single dose of cisplatin (7 mg/kg) was given to male Balb/c mice. Squalene (100 mg/kg/day) was administered orogastrically to mice for 10 days. Following sacrification, molecular alterations were investigated as analysis of the levels of oxidative stress index (OSI), inflammatory cytokines and cell survival-related proteins in addition to histopathological examinations in mice kidney tissue. The level OSI and Interferon-gamma (IFN-gamma) decreased in the cisplatin and squalene cotreated mice compared to cisplatin-treated mice. Squalene treatment also increased the activation of protein kinase B (AKT). Furthermore, cisplatin-induced inactivation of mammalian target of rapamycin (mTOR) and histopathological damages were reversed by squalene. It may be suggested that squalene ameliorated the cisplatin-induced histopathological damages in the kidney through activation of AKT/mTOR signaling pathway by regulating the balance of the redox system due to its antioxidative effect.

Minocycline, a semisynthetic tetracycline-derived antibiotic, has been shown to exert anti-apoptotic, anti-inflammatory, and antioxidant effects. Furthermore, there is rapidly growing evidence suggesting that minocycline may have some neuroprotective activity in various experimental models such as cerebral ischemia, traumatic brain injury, amyotrophic lateral sclerosis, Parkinson’s disease (PD), Huntington’s disease, and multiple sclerosis. In this perspective review, we summarize the preclinical and clinical findings suggesting the neuroprotective role of minocycline in PD.

Objectives Post-ischemic inflammation leads to apoptosis as an indirect cause of functional disabilities after the stroke. Melatonin may be a good candidate for the stroke recovery because of its anti-inflammatory effects. Therefore, we investigated the effect of melatonin on inflammation in the functional recovery of brain by evaluating ipsilesional and contralesional alterations. Materials and Methods Melatonin (4 mg/kg/day) was intraperitoneally administered into the mice from the 3rd to the 55th day of the post-ischemia after 30 min of middle cerebral artery occlusion. Results Melatonin produced a functional recovery by reducing the emigration of the circulatory leukocytes and the local microglial activation within the ischemic brain. Overall, the expression of the inflammation-related genes reduced upon melatonin treatment in the ischemic hemisphere. On the other hand, the expression level of the inflammatory cytokine genes raised in the contralateral hemisphere at the 55th day of the post-ischemia. Furthermore, melatonin triggers an increase in the iNOS expression and a decrease in the nNOS expression in the ipsilateral hemisphere at the earlier times in the post-ischemic recovery. At the 55th day of the post-ischemic recovery, melatonin administration enhanced the eNOS and nNOS protein expressions. Conclusions The present molecular, biological, and histological data have revealed broad anti-inflammatory effects of melatonin in both hemispheres with distinct temporal and spatial patterns at different phases of post-stroke recovery. These outcomes also established that melatonin act recruitment of contralesional rather than of ipsilesional.

Successful functional recovery from stroke is crucial in the rehabilitation of patients and mainly depends on several ischemia-induced processes, including cell survival and apoptosis. Melatonin is an interesting candidate for secondary stroke prevention due to its effect on signaling pathways. Therefore, we investigated the coordination of ipsilateral and contralateral hemispheres to evaluate delayed post-acute effect of melatonin on recovery of the cell survival and apoptosis after stroke. Melatonin was administered (4 mg/kg/day) intraperitoneally for 45 days, starting 3-day after 30-min of middle cerebral artery occlusion. The genes and proteins related to the cell survival and apoptosis were investigated by immunofluorescence, western blotting and RT-PCR techniques after behavioral experiments. Melatonin produced delayed neurological recovery by improving motor coordination, which was also reflected by enhanced neuronal survival and reduced apoptosis in the post-acute phase of stroke in both contralateral and ipsilateral hemispheres. The increase of NGF, Nrp1, c-jun; activation of AKT; and dephosphorylation of ERK and JNK at the 55th day showed that cell survival and apoptosis signaling molecules compete to contribute to the remodeling of brain. Furthermore, an increase in the CREB and Atf-1 expressions suggested the melatonin's strong reformative effect on neuronal regeneration. The contralateral hemisphere was more active at the latter stages of the molecular and functional regeneration which provides a further proof of principle about melatonin's action on the promotion of brain plasticity and recovery after stroke.

BACKGROUND: The purpose of the present study was to examine the chemopreventive effect of Stampidine, an aryl phosphate derivative of stavudine, in side by side comparison with the standard anti-breast cancer drug paclitaxel in the well-established 7,12-dimethylbenz(a)anthracene (DMBA)-induced murine breast cancer model. METHODS: Groups of 20 female mice were challenged with the chemical carcinogen DMBA. DMBA-challenged mice were assigned to various chemoprevention treatments, including stampidine alone, paclitaxel alone, and stampidine plus paclitaxel according to the same treatment schedules for 25 weeks. RESULTS: Stampidine treatments resulted in substantially reduced numbers of mammary tumors, tumor weight as well as tumor size in DMBA-treated mice. Stampidine was as effective as paclitaxel in the model and their combination exhibited greater chemopreventive activity, as measured by reduced tumor incidence and improved tumor-free survival as well as overall survival of DMBA-treated mice. The length of time for the initial tumor to appear in DMBA-challenged mice treated with stampidine was longer than that of mice treated DMBA-challenged control mice. Tumors from mice treated with stampidine or stampidine plus paclitaxel displayed unique changes of a signature protein cassette comprised of BRCA1, p21, Bax, and Bcl-2. CONCLUSION: Stampidine has potent chemopreventive activity and is as effective as the standard chemotherapy drug paclitaxel in the chemical carcinogenesis model of DMBA-induced murine breast cancer.

Objective: Herein, we aimed to investigate the long-term effects of neonatal hypoxia and the potential protective role of melatonin and memantine on the learning and memory. Methods: Seven-day-old rat underwent right carotid ligation, followed by hypoxia. Rat received Melatonin (MLT) (4 mg/kg), Memantine (MEM) (20 mg/kg), and MLT+MEM combination after hypoxia. We tested these rats for anxiety by elevated O-maze and for spatial learning and memory by Morris water maze (MWM) at postnatal day 45. Results: Hypoxia increased the level of anxiety compared to the control group (p=0.05) while treatment of MLT, MEM, and MLT+MEM ameliorated this effect. In addition, hypoxia produced significant decrease in spatial learning of the rats on the fourth day of training (P=0.05) and the percent time spent in the platform quadrant and the entrance frequencies to the platform quadrant compared to the control group (P=0.049 and P=0.023). Treatment of MLT, MEM, and MLT+MEM after hypoxia improved the performance of the rats at the third (P=0.686, P=0.876, P=0.977, respectively) and fourth day (P=0.738, P=0.553, P=0.789, respectively) of MWM training. The decrease in the percent time spent was ameliorated by the treatment of MLT (P=0.239), MEM (P=0.289), and MLT+MEM (P=0.567) compared to the control group. In addition, MLT treatment significantly increased the entrance frequency to the platform quadrant compared to the hypoxia group (P=0.020). Conclusion: Our data suggested that the MLT was more effective in the release of memory deficits from hypoxia-related damage. MLT might have a therapeutic value in improving hypoxic damage in the developing brain. WOS:000640976900004

Background: Antibiotic therapies targeting multiple regenerative mechanisms have the potential for neuroprotective effects, but the diversity of experimental strategies and analyses of non-standardised therapeutic trials are challenging. In this respect, there are no cases of successful clinical application of such candidate molecules when it comes to human patients. Methods: After 24 hours of culturing, three different minocycline (Sigma-Aldrich, M9511, Germany) concentrations (1 μM, 10 μM and 100 μM) were added to the primary cortical neurons 15 minutes before laser axotomy procedure in order to observe protective effect of minocycline in these dosages. Results: Here, we have shown that minocycline exerted a significant neuroprotective effect at 1 and 100μM doses. Beyond confirming the neuroprotective effect of minocycline in a more standardised and advanced in-vitro trauma model, our findings could have important implications for future studies that concentrate on the translational block between animal and human studies. Conclusion: Such sophisticated approaches might also help to conquer the influence of humanmade variabilities in critical experimental injury models. To the best of our knowledge, this is the first study showing that minocycline increases in-vitro neuronal cell survival after laser-axotomy.

Dagdelen, Daghan/0000-0002-2523-9195 WOS:000542499100006 PubMed: 32617053 Objectives: Degloving hand injuries have generally been viewed as among the most difficult of injuries to manage due to the extensive nature of associated damage. The traditional approach to the circumferentially degloved segment of problematic flap viability has been to resuture the flap and to wait and see. However, the waiting period or the specific hemorheological protocol remains uncertain. This study aims to acknowledge if Sivelestat, known to ameliorate ischemia-reperfusion injury, enhances the survival of avulsed flaps in a hind limb degloving model of rats and to compare Sivelestat's effects to Pentoxifylline. Methods: In this study, total flap area (cm2), area of necrosis in the flap (cm(2)), and the ratio between the necrotic and total areas (percentage) were determined. Angiogenesis among the groups was documented with CD31, anti-PECAM staining. TUNEL assay was performed to allow the visualization of cell nuclei containing fragmented DNA, a typical feature of apoptosis. Results: The findings obtained in this study showed that Sivelestat administered at 10 mg/kg/hour dosage will inhibit the ischemia-reperfusion injury more pertinently than Pentoxifylline, which exerts only hemorheological effects. Conclusion: The anti-inflammatory effects of Sivelestat will be beneficial for decreasing the early complications of degloving injury, such as inflammation, sepsis, and edema, better than Pentoxifylline, which exerts only hemorheological effects.

Rifampicin exerts significant brain protective functions in multiple experimental models. Here we summarize the underlying mechanisms of the neuroprotective and pro-cognitive effects of rifampicin that are mediated by its anti-inflammatory, anti-tau, anti-amyloid, and cholinergic effects. Beyond suggesting that rifampicin shows strong brain protective effects in preclinical models of Alzheimer's disease, we also provide substantial clinical evidence for the neuroprotective and pro-cognitive effects of rifampicin. Future neuroimaging studies combined with clinical assessment scores are the following steps to be taken in this field of research.

Aim: The neuroprotective effects of clopidogrel have already been shown in various experimental models. Taking into account the fact that clopidogrel is well tolerated and approved for use in various clinical settings, it can be an attractive candidate for further clinical investigations, especially when the anti-oedema effect appears to be a reasonable adjuvant strategy, such as in brain injury (BI). Here we aimed to examine the neuroprotective role of clopidogrel in BI. Methods: To investigate the effects of clopidogrel, we induced BI in mice using a cold trauma model and evaluated the underlying cell survival/death mechanisms via cresyl violet, TUNEL staining and western blot analysis. Results: Clopidogrel at a dose of 3 mg/kg led to a significant reduction in brain swelling. Similar decreases were observed with 10 mg/kg and 30 mg/kg of clopidogrel. We also have shown that clopidogrel blocks the prominent inflammatory injury pathways and exerts a significant anti-apoptotic effect (3 and 30 mg/kg), which has boon associated with increased neuronal cell survival pathways. Clopidogrel (3, 10 and 30 mg/kg) dose-dependently altered the JNK, p-38, AKT, ERK and p53 levels. Conclusion: Our findings demonstrate that clopidogrel can be a novel candidate for the reduction of post-traumatic BI and oedema. We propose that it can be applied mainly in the acute phases of cerebral ischaemia, which is characterized by haemorrhagic transformation and brain oedema. Cíl: Neuroprotektivní účinky klopidogrelu již byly prokázány na různých experimentálních modelech. Vzhledem k tomu, že klopidogrel je dobře tolerován a schválen k používání v různých klinických podmínkách, může být atraktivním kandidátem pro další klinická zkoumání, zejména v situaci, kdy se antiedematický účinek jeví jako vhodná adjuvantní strategie, například při poranění mozku. Naším záměrem bylo prozkoumat neuroprotektivní roli klopidogrelu při poranění mozku. Metody: Pro zkoumání účinků klopidogrelu jsme navodili poranění mozku s použitím modelu chladového traumatu u myší a zkoumali jsme základní mechanizmus přežití/odumírání buněk s použitím kresolové violeti, barvení TUNEL a analýzy western blot. Výsledky: Klopidogrel v dávce 3 mg/kg vedl k signifi kantnímu snížení otoku mozku. Podobný pokles byl pozorován při dávce klopidogrelu 10 mg/kg a 30 mg/kg. Rovněž jsme prokázali, že klopidogrel blokoval prominentní cesty poškození zánětem a vykazoval silný antiaptotický účinek (3 a 30 mg/kg), který byl spojen se zvýšenou možností přežití neuronových buněk. Klopidogrel (3, 10 a 30 mg/kg) měnil dávkově dependentním způsobem hladiny JNK, p-38, AKT, ERK a p53. Závěr: Naše nálezy prokazují, že klopidogrel může být novým kandidátem pro zmírnění posttraumatického poranění mozku a edému. Domníváme se, že může být aplikován hlavně v akutních fázích cerebrální ischemie, která je charakterizována hemoragickou transformací a edémem mozku.

WOS: 000369471900016 PubMed ID: 26639427 The tissue damage that emerges during traumatic brain injury (TBI) is a consequence of a variety of pathophysiological events, including free radical generation and over-activation of N-methyl-D-aspartate-type glutamate receptors (NMDAR). Considering the complex pathophysiology of TBI, we hypothesized that combination of neuroprotective compounds, targeting different events which appear during injury, may be a more promising approach for patients. In this context, both NMDAR antagonist memantine and free radical scavenger melatonin are safe in humans and promising agents for the treatment of TBI. Herein, we examined the effects of melatonin administered alone or in combination with memantine on the activation of signaling pathways, injury development and DNA fragmentation. Both compounds reduced brain injury moderately and the density of DNA fragmentation significantly. Notably, melatonin/memantine combination decreased brain injury and DNA fragmentation significantly, which was associated with reduced p38 and ERK-1/2 phosphorylation. As compared with melatonin and memantine groups, SAM/INK-1/2 phosphorylation was also reduced in melatonin/memantine combined animals. In addition, melatonin, memantine and their combination decreased iNOS activity significantly. Here, we provide evidence that melatonin/memantine combination protects brain from traumatic injury, which was associated with decreased DNA fragmentation, p38 phosphorylation and iNOS activity. EMBO (European Molecular Biology Organization); Turkish Academy of Sciences (TUBA) This work was supported by EMBO (European Molecular Biology Organization) installation grant and Turkish Academy of Sciences (TUBA).

Objective: Besides its hematopoietic function, erythropoietin (EPO) may protect tissues from degenerative disorders. As such, EPO and its receptors were revealed in nonhematopoietic cells, including stromal and endometrial epithelial cells. However, the role of EPO in endometrial disorders is still unknown. Here, we aimed to examine the role of EPO and its receptor activation in the development of endometriosis in rats. Material and Methods: Animals were treated with EPO, darbepoietin (the synthetic form of EPO) or EPO’s receptor activator, methoxy polyethylene glycol-epoetin beta (MIRCERA), after development of endometriosis. Endometriosis was induced by estrogen-administration following surgical attachment of endometrial surface on the inner abdominal wall. Treatments were started 3 weeks after induction of endometriosis and continued for the following 3 weeks. For the analysis of recurrence of endometriosis, additional analyses were conducted 3 weeks after cessation of treatments. Results: As compared with vehicle-treated animals, lesion size was reduced significantly and recurrence of endometriosis was not observed in all treatment groups. Histopathologic examination revealed that EPO and darbepoietin were more effective than MIRCERA- and vehicle-treated animals. Conclusion: Here we provide evidence that EPO is a promising candidate for the treatment of endometriosis. Our histopathologic results in particular indicate that EPO is more effective than its receptor activator MIRCERA in the development endometriosis. © 2019 by the Turkish-German Gynecological Education and Research Foundation. Türkiye Bilimler Akademisi Acknowledgements: This work was funded by Turkish Academy of Sciences (TUBA). We would like to thank to Laboratory Technician Nurhayat Dönek from Bezmialem University for help throughout this research.

WOS: 000439906200002 PubMed ID: 30035652 Objective: To investigate the molecular mechanisms of colistimethate sodium-induced nephrotoxicity and the protective effect of N-acetylcysteine (NAC) against nephrotoxicity.Methods: Twenty-eight Wistar rats were divided into four groups comprised of control, colistin, NAC, and colistin-NAC co-treatment, respectively. Serum creatinine and urine N-acetyl--d-glucosaminidase (NAG) levels were measured at different time intervals. Histological changes, apoptosis, total oxidant and antioxidant status, and the expression levels of endothelial nitric oxide synthase (eNOS), superoxide dismutase 2 (SOD2), and matrix metalloproteinase 3 (MMP3) were evaluated in renal tissue.Results: In the colistin group, post-treatment creatinine levels were higher than pretreatment levels (p=.001). There was a significant increase in urine NAG level following colistin treatment on day 10, compared to the baseline value and the first day of treatment (p=.001 and .0001, respectively). Urine NAG levels were higher in the colistin group on the 10th day of treatment than in the other groups (p

WOS: 000346243100032 PubMed ID: 25453767 Apart from its repressing effect on plasma lipid levels, 3-hydroxy-3-methyl glutaryl coenzyme A (HMG-CoA) reductase inhibitors exert neuroprotective functions in animal models of neurodegenerative disorders. In view of these promising observations, we were interested in whether HMG-CoA reductase inhibition would affect epileptiform activity in the brain. To elucidate this issue, atorvastatin, simvastatin and rosuvastatin were administered orally at a dose of 20 mg/kg each for 3 days and their anti-epileptic activities were tested and compared in rats. Epileptiform activity in the brain was induced by an intracortical penicillin G injection. Among HMG-CoA reductase inhibitors, simvastatin-treatment was less effective in terms of spike frequency as compared with atorvastatin- and rosuvastatin-treated animals. Atorvastatin treatment reduced spike frequencies and amplitudes significantly throughout the experiment. However, the most pronounced anti-epileptic effect was observed in rosuvastatin-treated animals, which was associated with improved blood-brain barrier (BBB) integrity, increased expression of endothelial nitric oxide synthase (eNOS) mRNA and decreased expressions of pro-apoptotic p53, Bax and caspase-3 mRNAs. Inhibition of eNOS activity with L-NG-Nitroarginine Methyl Ester (L-NAME) reversed the anti-epileptic effect of rosuvastatin significantly. However, L-NAME did not alter the effect of rosuvastatin on the levels of p53, Bax and caspase-3 mRNA expression. Here, we provide evidence that among HMG-CoA reductase inhibitors, rosuvastatin was the most effective statin on the reduction of epileptiform activity, which was associated with improved BBB permeability, increased expression of eNOS and decreased expressions of pro-apoptotic p53, Bax and caspase-3. Our observation also revealed that the anti-epileptic effect of rosuvastatin was dependent on the increased expression level of eNOS. The robust anti-epileptic effect encourages proof-of-concept studies with rosuvastatin in human epilepsy patients with hypercholesterolemia. European Molecular Biology Organization (EMBO); Turkish Academy of Sciences (TUBA/GEBIP) This work was supported by European Molecular Biology Organization (EMBO) (installation grant) and Turkish Academy of Sciences (TUBA/GEBIP).

Apart from its potent antioxidant property, recent studies have revealed that melatonin promotes PI3K/Akt phosphorylation following focal cerebral ischemia (FCI) in mice. However, it is not clear (i) whether increased PI3K/Akt phosphorylation is a concomitant event or it directly contributes to melatonin's neuroprotective effect, and (ii) how melatonin regulates PI3K/Akt signaling pathway after FCI. In this study, we showed that Akt was intensively phosphorylated at the Thr308 activation loop as compared with Ser473 by melatonin after FCI. Melatonin treatment reduced infarct volume, which was reversed by PI3K/Akt inhibition. However, PI3K/Akt inhibition did not inhibit melatonin's positive effect on brain swelling and IgG extravasation. Additionally, phosphorylation of mTOR, PTEN, AMPKα, PDK1 and RSK1 were increased, while phosphorylation of 4E-BP1, GSK-3α/β, S6 ribosomal protein were decreased in melatonin treated animals. In addition, melatonin decreased apoptosis through reduced p53 phosphorylation by the PI3K/Akt pathway. In conclusion, we demonstrated the activation profiles of PI3K/Akt signaling pathway components in the pathophysiological aspect of ischemic stroke and melatonin's neuroprotective activity. Our data suggest that Akt phosphorylation, preferably at the Thr308 site of the activation loop via PDK1 and PTEN, mediates melatonin's neuroprotective activity and increased Akt phosphorylation leads to reduced apoptosis., Graphical abstract fx1

Indolamine melatonin structurally resembles non-covalent proteasome inhibitors; however, the role of ubiquitin proteasome system (UPS) in neuronal survival and how melatonin carries out UPS inhibition remain largely unknown. With the use of melatonin treated cells, we evaluated the expression of Nedd4-1, an E3 ligase, how melatonin regulates its activity and its relationship with neuronal survival. Nedd4-1 was upregulated in the hypoxic condition in both control and Nedd4-1 overexpressed cells and melatonin treatment reversed its expression in both normoxic and hypoxic conditions, which was associated with increased cellular survival. Melatonin had no effect on the expression of Nedd4-1 at mRNA level. However, when melatonin was administered along with protein synthesis inhibitor cycloheximide, protein level of Nedd4-1 was further reduced, indicating that melatonin possibly downregulates Nedd4-1 after its synthesis. Notably, co-immunoprecipitation analyses followed by Liquid chromatography-Mass Spectrometry (LC-MS/MS) revealed that melatonin may dissociate ribosomal proteins, such as RS19, RL23A, and nucleophosmin from Nedd4-1, while 40S ribosomal protein S7 and 60S ribosomal protein L35 came into contact with Nedd4-1 upon melatonin treatment. By using IPA analyses, we obtained further data indicated novel target molecules of melatonin in hypoxic conditions, including OTOF, SF3B2, IPO5, ST13, FGFR3, Mx1/Mx2, playing roles in RNA splicing and trafficking, growth factor and interferon signaling. Here, we described a new insight into the role of melatonin in UPS functioning by proposing a molecular mechanism through which melatonin regulates Nedd4-1.

Cervical cancer is among the top causes of death from cancer in women. Cisplatin-based chemotherapy has been shown to improve survival; however, cisplatin treatment is associated with toxicity to healthy cells. Genistein has been used as an adjunct to chemotherapy to enhance the activity of chemotherapeutic agents without causing increased toxicity. The present study was designed to investigate the effect of genistein (25 μM) on antitumor activity of cisplatin (250 nM) on HeLa cervical cancer cells. We have examined the alterations in expression of NF-B, p-mTOR, p-p70S6K1, p-4E-BP1, and p-Akt protein levels in response to treatment. The combination of 25 μM genistein with 250 nM cisplatin resulted in significantly greater growth inhibition (). Genistein enhanced the antitumor activity of cisplatin and reduced the expression of NF-B, p-mTOR, p-p70S6K1, p-4E-BP1, and p-Akt. The results in the present study suggest that genistein could enhance the activity of cisplatin via inhibition of NF-κB and Akt/mTOR pathways. Genistein is a promising nontoxic nutritional agent that may enhance treatment outcome in cervical cancer patients when given concomitantly with cisplatin. Clinical trials of genistein and cisplatin combination are warranted to test this hypothesis.

Melatonin is synthesized and released by the pineal gland in a circadian rhythm, and many of its peripheral actions are mediated via membrane MT1 and MT2 receptors. Apart from its metabolic functions, melatonin is a potent neuroprotective molecule owing to its antioxidative actions. The roles of MT1 and MT2 in the neuroprotective effects of melatonin and cell signaling after cerebral ischemia remain unknown. With the use of MT1 and MT2 knockout (mt1/2(-/-) ) mice treated with melatonin, we evaluated brain injury, edema formation, inducible nitric oxide synthase (iNOS) activity, and signaling pathways, including CREB, ATF-1, p21, Jun kinase (JNK)1/2, p38 phosphorylation, resulting from ischemia/reperfusion injury. We show that the infarct volume and brain edema do not differ between mt1/2(-/-) and wild-type (WT) animals, but melatonin treatment decreases infarct volume in both groups and brain edema in WT animals after middle cerebral artery occlusion. Notably, melatonin's neuroprotective effect was even more pronounced in mt1/2(-/-) animals compared to that in WT animals. We also demonstrate that melatonin treatment decreased CREB, ATF-1, and p38 phosphorylation in both mt1/2(-/-) and WT mice, while p21 and JNK1/2 were reduced only in melatonin-treated WT animals in the ischemic hemisphere. Furthermore, melatonin treatment lowered iNOS activity only in WT animals. We provide evidence that the absence of MT1 and MT2 has no unfavorable effect on ischemic brain injury. In addition, the neuroprotective effects of melatonin appear to be mediated through a mechanism independent of its membrane receptors. The underlying mechanism(s) should be further studied using selective melatonin receptor agonists and antagonists.

Cisplatin is one of the effective chemotherapeutics in the treatment of several types of cancers. However, in addition to the efforts against to its toxicity, the amelioration of cisplatin sensitivity is an important point in treatment of cervical cancer. To do so, additional substances such as epigallocatechin gallate (EGCG), a polyphenol in green tea, have been used in combination with chemotherapeutics. We aimed to investigate the possible molecular pathways to potentiate cervical cancer cell (HeLa) growth inhibition by combination therapy of cisplatin and EGCG. HeLa cells were treated with EGCG (25 μM), cisplatin (250 nM), and their combination for 24 hours. Cell viability was determined by MTS Assay. We analyzed the expressions of NF-κB p65, COX-2, Nrf2, HO-1, p-mTOR, p-p70S6K1, p-4EBP1 and p-Akt by Western blot analysis. Herein, we have demonstrated that EGCG works synergistic with cisplatin in inhibiting growth of cervical cancer cells. EGCG improved efficacy of cisplatin treatment in HeLa cells by regulating NFκB p65, COX-2, p-Akt, and p-mTOR pathways, whereas it increased the expression levels of Nrf2/HO-1 in combined therapy. Our observations revealed that EGCG increases the sensitization of cisplatin to cervical cancer cells by inhibiting cell survival and inducing apoptosis.

WOS: 000363185200028 PubMed ID: 26416428 In order to protect the brain before an irreversible injury occurs, penumbral oxygenation is the primary goal of current acute ischemic stroke treatment. However, hyperoxia treatment remains controversial due to the risk of free radical generation and vasoconstriction. Melatonin is a highly potent free radical scavenger that protects against ischemic stroke. Considering its anti-oxidant activity, we hypothesized that melatonin may augment the survival-promoting action of normobaric oxygen (NBO) and prevent brain infarction. Herein, we exposed mice to 30 or 90 min of intraluminal middle cerebral artery occlusion (MCAo) and evaluated the effects of NBO (70% or 100% over 90 min), administered either alone or in combination with melatonin (4 mg/ kg, i.p.), on disseminate neuronal injury, neurological deficits, infarct volume, blood-brain barrier (BBB) permeability, cerebral blood flow (CBF) and cell signaling. Both NBO and particularly melatonin alone reduced neuronal injury, neurological deficits, infarct volume and BBB permeability, and increased post-ischemic CBF, evaluated by laser speckle imaging (LSI). They also improved CBF significantly in the ischemic-core and penumbra, which was associated with reduced IgG extravasation, DNA fragmentation, infarct volume, brain swelling and neurological scores. Levels of phosphorylated Akt, anti-apoptotic Bcl-xL, pro-apoptotic Bax and endothelial nitric oxide synthase (NOS) were re-regulated after combined oxygen and melatonin delivery, whereas neuronal and inducible NOS, which were increased by oxygen treatment, were not influenced by melatonin. Our present data suggest that melatonin and NBO are promising approaches for the treatment of acute-ischemic stroke, which encourage proof-of-concept studies in human stroke patients. TUBITAK (The Scientific and Technological Research Council of Turkey) [111S418, 114S402]; Turkish Academy of Sciences (TUBA); EMBO (European Molecular Biology Organization) installation grant This work was supported by TUBITAK (The Scientific and Technological Research Council of Turkey/111S418; 114S402), Turkish Academy of Sciences (TUBA) and EMBO (European Molecular Biology Organization) installation grant.

In vivo studies showed that tissue-plasminogen activator (t-PA) may aggravate neuronal injury after focal cerebral ischemia. We hypothesized that t-PA impairs survival-promoting cell signaling in the ischemic brain, which may be reversed by a neuroprotectant, i.e. melatonin. We examined the effects of t-PA (10 mg/kg, i.v.), administered alone or in combination with melatonin (4 mg/kg, i.p.), on ischemic injury, inducible nitric oxide synthase (iNOS) expression as well as Akt, Bcl-X(L) and caspase-3 signaling following 90 min of intraluminal middle cerebral artery (MCA) occlusion in mice. t-PA, delivered immediately after reperfusion onset, increased infarct volume at 24 hr after MCA occlusion, in accordance with previous findings. Melatonin reduced infarct size when administered alone and reversed the t-PA-induced brain injury. Immunohistochemical studies showed that t-PA treatment was associated with an accumulation of iNOS positive cells in ischemic brain areas, which was abolished after co-delivery of melatonin. Western blots revealed that t-PA decreased phosphorylated Akt levels, but did not influence Bcl-X(L) expression and caspase-3 activity in ischemic brain lysates. Co-treatment with melatonin restored phosphorylated Akt levels, increased Bcl-X(L) expression and reduced caspase-3 activity. We provide evidence that t-PA-induced brain injury is accompanied by an activation of iNOS and inhibition of phosphatidylinositol-3 kinase/Akt. That melatonin reversed these signaling changes and the t-PA-induced brain injury makes this indole attractive as an add-on treatment with thrombolytics.

This article summarizes the evidence that endogenously produced and exogenously administered melatonin reduces the degree of tissue damage and limits the biobehavioral deficits associated with experimental models of ischemia/reperfusion injury in the brain (i.e., stroke). Melatonin's efficacy in curtailing neural damage under conditions of transitory interruption of the blood supply to the brain has been documented in models of both focal and global ischemia. In these studies many indices have been shown to be improved as a consequence of melatonin treatment. For example, when given at the time of ischemia or reperfusion onset, melatonin reduces neurophysio-logical deficits, infarct volume, the degree of neural edema, lipid peroxidation, protein carbonyls, DNA damage, neuron and glial loss, and death of the animals. Melatonin's protective actions against these adverse changes are believed to stem from its direct free radical scavenging and indirect antioxidant activities, possibly from its ability to limit free radical generation at the mitochondrial level and because of yet-undefined functions. Considering its high efficacy in overcoming much of the damage associated with ischemia/reperfusion injury, not only in the brain but in other organs as well, its use in clinical trials for the purpose of improving stroke outcome should be seriously considered.

Background and Purpose— It has repeatedly been reported that the thrombolytic tissue plasminogen activator (tPA) may aggravate ischemic injury after stroke. The underlying mechanisms, however, remain unknown. We hypothesized that tPA induces an inhibition of endothelial NO synthase (eNOS) after focal ischemia that is responsible for ischemic damage and may be restored by 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors. Methods— We examined the effects of tPA, administered either alone or in combination with rosuvastatin, on ischemic injury, on eNOS expression, and cell signaling after 90 minutes of intraluminal middle cerebral artery occlusion. Results— In wild-type mice, tPA delivered immediately after ischemia significantly increased infarct volume 24 hours after reperfusion. Coadministration of rosuvastatin completely reversed the tPA-induced brain damage. Western blots of ischemic brain lysates showed that tPA markedly diminished eNOS levels, increased extracellular regulated kinase (ERK)-2, and decreased MAP kinase/p38 activity. Cotreatment with rosuvastatin prevented the decrease in eNOS, reduced ERK-1/-2 and normalized p38 levels. To elucidate the role of eNOS in tPA-induced ischemic injury, we also evaluated tPA effects in eNOS knockout mice. In eNOS knockout animals, tPA again significantly increased infarct size after transient focal ischemia. Conclusions— In a mouse model of focal cerebral ischemia, tPA induces eNOS inhibition, ERK-2 activation, and p38 inhibition, possibly as part of a more complex signaling response exacerbating brain injury. 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibition reverses the effects of tPA by a mechanism independent of eNOS.

Because of its favorable action profile in humans, melatonin is a particularly interesting candidate as a neuroprotectant in acute ischemic stroke. Until now, the signaling mechanisms mediating melatonin's neuroprotective actions remained essentially uninvestigated. Herein, we examined the effects of melatonin, administered either orally for 9 wk as a stroke prophylactic (4 mg/kg/day) or intraperitoneally immediately after reperfusion onset (4 mg/kg), on the activation of signal transduction pathways in mice submitted to 90 min of intraluminal middle cerebral artery occlusion, followed by 24 hr of reperfusion. In these studies, melatonin significantly reduced ischemic infarct size by approximately 30-35%, as compared with animals receiving diluent (sham) treatment, independent of whether the indole was administered prior to or after ischemia. Under both conditions, animals receiving melatonin exhibited elevated phosphorylated Akt levels in their brains, as determined by Western blots. Additionally, phosphorylation levels of mitogen-activated protein kinase/extracellular-regulated kinase (ERK)-1/-2 and Jun kinase (JNK)-1/-2 were increased following prophylactic, but not acute, melatonin treatment. Our data suggest a role of phosphatidyl inositol-3 kinase/Akt signaling in acute melatonin-induced neuroprotection, while ERK-1/-2 and/or JNK-1/-2 rather appear to be involved in melatonin's long-term effects.

After recent clinical trials, statins have gained increasing significance in secondary stroke prevention. From experimental studies, it is well established that statins have beneficial action when delivered prophylactically prior to a stroke. Conversely, much less is known about the effects of statins on injury development when delivered after ischemia. We here examined the effects of a post-ischemic delivery of rosuvastatin (0.5, 5 or 20 mg/kg, administered i.p. immediately after reperfusion onset), a potent 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitor, on brain injury and cell signaling after focal cerebral ischemia, induced by 90 min of intraluminal middle cerebral artery occlusion in mice. In animals receiving normal saline, 0.5 or 5 mg/kg rosuvastatin, middle cerebral artery occlusions resulted in reproducible brain infarcts at 24 h after reperfusion onset, which did not differ in size. However, rosuvastatin, administered at higher doses (20 mg/kg), reduced infarct volume at 24 and 48 h after ischemia (by 34+/-16% and 18+/-3%, respectively, P

The effects of i.p. melatonin (4 + 4 mg/kg, after induction of ischemia and at reperfusion onset) administered either alone or in combination with the thrombolytic tissue-plasminogen activator (t-PA, 10 mg/kg), on cerebral laser Doppler flow (LDF) and ischemic injury were studied after 30 min of middle cerebral artery (MCA) thread occlusion in male C57BL/6 mice. Thread occlusions resulted in reproducible focal ischemias, followed by hyperperfusion reactions immediately after thread withdrawal, as revealed by LDF measurements. Compared with animals receiving normal saline (peak LDF after reperfusion: 172.0 +/- 24.2%), postischemic LDF was significantly attenuated in animals treated with melatonin (105.1 +/- 6.7%, P < 0.05). Delivery of t-PA (132.8 +/- 22.3%) or t-PA plus melatonin (164.7 +/- 36.7%), on the contrary, did not influence postischemic LDF recordings. Twenty-four hours after reperfusion, melatonin treated mice had significantly increased neuronal survival and decreased disseminate cell injury in the ischemia-vulnerable striatum, as investigated by cresyl violet and terminal transferase biotinylated-dUTP nick end labeling stainings. The protective effects were associated with inhibition of caspase-3 activity. Melatonin administration also increased neuronal survival after 30 min MCA occlusion in animals treated with t-PA, although t-PA itself already decreased the degree of injury in a significant manner. Our data demonstrate that melatonin reduces disseminated neuronal injury in the striatum after mild focal ischemia. Brain protection is independent of hemodynamic changes and involves inhibition of caspase-3.

This study aimed to demonstrate the presence of erythropoietin (EPO) receptor on spermatozoa. Whole ejaculates of four healthy volunteers were incubated with polyclonal rabbit anti-EPO receptor and subsequently stained with a Cy-3 labelled secondary antibody. Four slides per subject were analysed, no staining was observed in slides incubated with either primary or secondary antibody alone. EPO receptor staining was positive in 92 ± 8% of EPO pre-treated and 91 ± 4% of non-treated sperm cells. The results suggest that spermatozoa express EPO receptor on plasma membrane, which might act to protect these cells from damage after ejaculation. © 2010, Reproductive Healthcare Ltd. Published by Elsevier Ltd. All rights reserved.

WOS: 000317537800026 PubMed ID: 23396088 Because of their favorable action profiles in humans, both memantine and melatonin are particularly interesting candidates as neuroprotectants in acute ischemic stroke. Until now, the signaling mechanisms mediating memantine's neuroprotective actions remained essentially uninvestigated. In addition, we have combined memantine with melatonin, which is a well-known neuroprotective molecule. Herein, we examined the effects of memantine (20 mg/kg, i.p.) administered alone or in combination with melatonin (4 mg/kg, i.p.) on the activation of signaling transduction pathways, IgG extravasation and ischemic injury in mice submitted to 90 min of intraluminal middle cerebral artery occlusion, followed by 24 h of reperfusion. In these studies, both agents reduced ischemic injury and the density of DNA-fragmentation. Notably, melatonin/memantine combination reduced ischemic injury further as compared with memantine treatment, which was associated with reduced IgG extravasation, indicating vascular leakage in the brain. Animals receiving memantine exhibited elevated ERK-1/2 and decreased p21 and p38/MAPK activations, while it had no significant effect on phosphorylated Akt and SAPK/JNK1/2 in the ischemic brain. However, melatonin increased the activation of Akt and reduced the activations of ERK-1/2, p21, p38/MAPK and SAPK/JNK1/2 significantly. Synergistic effects of memantine and melatonin were observed in the inactivation of p21, p38/MAPK and SAPK/JNK1/2 pathways. Moreover, memantine reversed the effects of melatonin on the activation of ERK-1/2 pathway. Here, we provide evidence that free radical scavenger melatonin potentiates the effects of memantine on ischemic brain injury via inactivations of p21 and stress kinases p38/MAPK and SAPK/JNK1/2 pathways. EMBO (European Molecular Biology Organization); Turkish Academy of Sciences (TUBA/GEBIP) We thank M. Ugur and S. Eyuboglu for technical assistance. This work was supported by EMBO (European Molecular Biology Organization) installation Grant and The Turkish Academy of Sciences (TUBA/GEBIP).

Recombinant tissue-plasminogen activator (t-PA) increases brain injury after focal ischemias leading to overt tissue infarcts. The question arose, whether t-PA may also be detrimental after mild ischemias. To clarify this issue, we submitted mice to 30 min intraluminal thread occlusions and administered normal saline or t-PA (10 mg/kg, i.v.) after reperfusion onset. Thread occlusions resulted in reproducible ischemias, followed by hyperperfusion reactions immediately after thread withdrawal. Post-ischemic LDF did not differ between saline- and t-PA-treated animals. In contrast to earlier studies, where t-PA exacerbated injury, t-PA treatment did not increase, but attenuated disseminate neuronal death in the striatum, as shown by cresyl violet, TUNEL and activated caspase-3 staining 1 and 3 days after the ischemic event (p < 0.05). Our data argue against major detrimental actions of t-PA after mild focal ischemia.

The promotion of post-ischaemic motor recovery remains a major challenge in clinical neurology. Recently, plasticity-promoting effects have been described for the growth factor erythropoietin in animal models of neurodegenerative diseases. To elucidate erythropoietin's effects in the post-acute ischaemic brain, we examined how this growth factor influences functional neurological recovery, perilesional tissue remodelling and axonal sprouting of the corticorubral and corticobulbar tracts, when administered intra-cerebroventricularly starting 3 days after 30 min of middle cerebral artery occlusion. Erythropoietin administered at 10 IU/day (but not at 1 IU/day), increased grip strength of the contralesional paretic forelimb and improved motor coordination without influencing spontaneous locomotor activity and exploration behaviour. Neurological recovery by erythropoietin was associated with structural remodelling of ischaemic brain tissue, reflected by enhanced neuronal survival, increased angiogenesis and decreased reactive astrogliosis that resulted in reduced scar formation. Enhanced axonal sprouting from the ipsilesional pyramidal tract into the brainstem was observed in vehicle-treated ischaemic compared with non-ischaemic animals, as shown by injection of dextran amines into both motor cortices. Despite successful remodelling of the perilesional tissue, erythropoietin enhanced axonal sprouting of the contralesional, but not ipsilesional pyramidal tract at the level of the red and facial nuclei. Moreover, molecular biological and histochemical studies revealed broad anti-inflammatory effects of erythropoietin in both hemispheres together with expression changes of plasticity-related molecules that facilitated contralesional axonal growth. Our study establishes a plasticity-promoting effect of erythropoietin after stroke, indicating that erythropoietin acts via recruitment of contralesional rather than of ipsilesional pyramidal tract projections.

Introduction Erythropoietin, which is a hematopoietic growth factor, has been found to play a role in various physiologic processes within the body including testicular steroidogenesis and spermatogenesis. However, it is not known whether erythropoietin is also essential for the normal physiology of mature sperm cells. In this study, the effects of recombinant human erythropoietin beta (rEPO) on sperm motility were investigated. Materials and methods Samples of 37 volunteers (with total motile sperm count >5 × 106/ml and a total motility of >50% according to WHO criteria) were collected by masturbation following a 3–5 days period of abstinence. After morphometric analysis before and just after washing, samples were either used as control or treated with rEPO at concentrations of 0.1, 1, 10 or 100 mIU/ml, respectively. Control and treated tubes were incubated for 4 h at 37°C. Results Total motility, total progressive motility, slow forward and nonmotile sperm counts of 1, 10 and 100 mIU/ml rEPO groups were significantly improved. This effect was dose independent. Conclusion No significant effect was found at 0.1 mIU/ml concentration. These results suggest that supplementation of media used for sperm preparation techniques with erythropoietin might be beneficial. Further studies are needed to clarify the mechanism of action of erythropoietin on mature sperm cells.

Hypoxic exposure of cells or organisms induces expression of a number of hypoxia responsive genes through the activation of the hypoxia-inducible factor-1 (HIF-1). One of the most prominent HIF-1 targets is erythropoietin that has beneficial effects on ischemia-related injury in the brain. Exposure to low environmental oxygen concentrations can be used as a preconditioning paradigm to protect cells or tissues against a variety of harmful conditions. Here, we summarize recent work on neuroprotection of retinal photoreceptors and ganglion cells induced by hypoxic preconditioning or by systemically elevated levels of Epo in mouse plasma.

Apart from its hematopoietic function, erythropoietin (Epo) exerts neuroprotective activity upon reduced oxygenation or ischemia of brain, retina, and spinal cord. To examine whether Epo has an impact on the retrograde degeneration of retinal ganglion cells (RGCs) following optic nerve transection in vivo, we made use of our transgenic mouse line tg21 that constitutively expresses human Epo preferentially in neuronal cells without inducing polycythemia. We show that the tg21 retina expresses human Epo and that RGCs in this mouse line carry the Epo receptor. Upon axotomy, the RGCs of Epo transgenic tg21 mice were protected against degeneration, as compared with wild-type control animals. Western blot analysis revealed decreased phosphorylation levels of STAT-5 and reduced expression of Bcl-XL in RGCs of axotomized tg21 animals, suggesting that the corresponding pathways are not crucial for Epo's neuroprotective activity. Increased phosphorylation levels of ERK-1/-2 and Akt, as well as decreased caspase-3 activity, however, were observed in injured tg21 retinae. Injection of selective inhibitors of ERK-1/-2 (PD98059) or Akt (Wortmannin) pathways into the vitreous space revealed that transgenic Epo protected the RGCs by a pathway involving ERK-1/-2 but not Akt. In view that axotomy-induced degeneration of RGC occurs slowly, and considering the earlier data on the safety and efficacy of Epo in human stroke patients, we predict the clinical implementation of recombinant human Epo not only in patients with acute ischemic stroke, but also with more delayed degenerative neurological diseases.

Melatonin has previously been shown to be neuroprotective in rodent models of ischemic stroke. Herein, we tested whether this antioxidant may also be suitable for prophylactic use against stroke. To clarify this issue, melatonin was administrated orally for 9 wk (4 mg/kg/day) in mice and its effects on subsequent injury development after 90 min of intraluminal middle cerebral artery (MCA) occlusion were tested. To evaluate its neuroprotective properties, the protective actions of prophylactic melatonin were compared with both acute melatonin (4 mg/kg, i.p.) administration and with a diluent (sham)-treated control condition. MCA occlusion resulted in reproducible ischemia, as revealed by laser Doppler flowmetry; this was followed by a rapid restoration of blood flow immediately after reperfusion onset. Laser Doppler flow values after reperfusion onset were moderately elevated by melatonin, both when the indole was given prophylactically and when acutely administrated after stroke. In control animals, reproducible brain infarcts were observed 24 hr after reperfusion onset. Treatment with melatonin significantly reduced the infarct size by approximately 30-35%, independent of whether the indole was given prophylactically before or acutely after ischemia. To test whether brain protection involved vascular mechanisms, as suggested earlier, the effects of melatonin on endothelin converting enzyme-1 (ECE-1) levels were studied using Western blots. Interestingly, delivery of melatonin was accompanied by a marked inhibition of ECE-1 levels, which was similarly seen after both acute and chronic melatonin treatment. Our data suggest that melatonin, given at pharmacological doses, may be suitable as a prophylaxis against stroke. Tissue protection may involve an inhibition of ECE-1, which improves vasodilation, after ischemia.

Rifampicin is an antibacterial agent that is widely used in tuberculosis and leprosy therapy. Interestingly, some experimental studies indicate that rifampicin acts as a hydroxyl radical scavenger and a glucocorticoid receptor activator. In this study, the neuroprotective effect of rifampicin was evaluated after transient and permanent focal cerebral ischemia. Anaesthetized mate C57BL/6j mice were submitted to permanent or transient thread occlusion of the middle cerebral artery (MCA). Reperfusion in transient ischemia was initiated 30 min later by thread retraction. Rifampicin or vehicle were applied intraperitoneally before permanent or immediately after 30 min of transient ischemia . Later, 24 It after permanent or transient ischemia, animals were re-anesthetized and decapitated. Brain injury was evaluated by triphenyltetrazolium chloride staining (TTC), terminal transferase biotinylated-dUTP nick end labeling TUNEL and cresyl violet staining. A 20-mg/kg sample of rifampicin showed a significant neuroprotection after cerebral ischemia. The number of TUNEL-positive cells in the striatum, where disseminated tissue injury was observed, was also reduced by application of rifampicin as compared with vehicle-treated animals. The present report shows that administration of rifampicin efficiently reduces brain injury after permanent and transient focal cerebral ischemia in mice. (C) 2003 Elsevier B.V. All rights reserved.