Preconditioning with morphine protects hippocampal CA1 neurons from ischemia-reperfusion injury via activation of the mTOR pathway

Morphine Induced Neuroprotection in Ischemic Stroke by Activating Autophagy Via mTOR-Independent Activation of the JNK1/2 Pathway

Morphine (Mor) has exhibited efficacy in safeguarding neurons against ischemic injuries by simulating ischemic/hypoxic preconditioning (I/HPC). Concurrently, autophagy plays a pivotal role in neuronal survival during IPC against ischemic stroke. However, the involvement of autophagy in Mor-induced neuroprotection and the potential mechanisms remain elusive. Our experiments further confirmed the effect of Mor in cellular and animal models of ischemic stroke and explored its potential mechanism. The findings revealed that Mor enhanced cell viability in a dose-dependent manner by augmenting autophagy levels and autophagic flux in neurons subjected to oxygen-glucose deprivation/reoxygenation (OGD/R). Pretreatment of Mor improved neurological outcome and reduced infarct size in mice with middle cerebral artery occlusion/reperfusion (MCAO/R) at 1, 7 and 14 days. Moreover, the use of autophagy inhibitors nullified the protective effects of Mor, leading to reactive oxygen species (ROS) accumulation, increased loss of mitochondrial membrane potential (MMP) and neuronal apoptosis in OGD/R neurons. Results further demonstrated that Mor-induced autophagy activation was regulated by mTOR-independent activation of the c-Jun NH2- terminal kinase (JNK)1/2 Pathway, both in vitro and in vivo. Overall, these findings suggested Mor-induced neuroprotection by activating autophagy, which were regulated by JNK1/2 pathway in ischemic stroke.

Long-term administration of morphine specifically alters the level of protein expression in different brain regions and affects the redox state

We investigated the changes in redox state and protein expression in selected parts of the rat brain induced by a 4 week administration of morphine (10 mg/kg/day). We found a significant reduction in lipid peroxidation that mostly persisted for 1 week after morphine withdrawal. Morphine treatment led to a significant increase in complex II in the cerebral cortex (Crt), which was accompanied by increased protein carbonylation, in contrast to the other brain regions studied. Glutathione levels were altered differently in the different brain regions after morphine treatment. Using label-free quantitative proteomic analysis, we found some specific changes in protein expression profiles in the Crt, hippocampus, striatum, and cerebellum on the day after morphine withdrawal and 1 week later. A common feature was the upregulation of anti-apoptotic proteins and dysregulation of the extracellular matrix. Our results indicate that the tested protocol of morphine administration has no significant toxic effect on the rat brain. On the contrary, it led to a decrease in lipid peroxidation and activation of anti-apoptotic proteins. Furthermore, our data suggest that long-term treatment with morphine acts specifically on different brain regions and that a 1 week drug withdrawal is not sufficient to normalize cellular redox state and protein levels.

Dapoxetine prevents neuronal damage and improves functional outcomes in a model of ischemic stroke through the modulation of inflammation and oxidative stress

Stroke is a medical emergency that is associated with substantial mortality and functional disability in adults. The most popular class of antidepressants, selective serotonin reuptake inhibitors SSRIs, have recently been shown in studies to have positive effects on post-stroke motor and cognitive function. Thus, we hypothesized that dapoxetine (DAP), a short-acting SSRI, would be effective against cerebral ischemia/reperfusion injury. Adult male Wister rats (200-250 g) were subjected to a sham operation or bilateral common carotid artery occlusion (BCCAO) for 30 min followed by 24 h of reperfusion to induce global cerebral ischemia/reperfusion (I/R) injury. Rats were treated with vehicle or DAP (30 or 60 mg/kg, i.p.) 1 h before BCCAO. The neurobehavioral performance of rats was assessed. The infarct volume, histopathological changes, oxidative stress parameters, and apoptotic and inflammatory mediators were determined in the brain tissues of euthanized rats. Our results confirmed that DAP significantly ameliorated cerebral I/R-induced neurobehavioral deficits, reduced cerebral infarct volume, and histopathological damage. Moreover, DAP pretreatment reduced lipid peroxidation, caspase-3, and inflammatory mediators (TNF-α and iNOS) compared to I/R-injured rats. Thus, DAP pretreatment potentially improves neurological function, and cerebral damage in cerebral ischemic rats may be partly related to the reduction in the inflammatory response, preservation of oxidative balance, and suppression of cell apoptosis in brain tissues.

Monoclonal antibody targeting mu-opioid receptor attenuates morphine tolerance via enhancing morphine-induced receptor endocytosis

Morphine is a frequently used analgesic that activates the mu-opioid receptor (MOR), which has prominent side effects of tolerance. Although the inefficiency of morphine in inducing the endocytosis of MOR underlies the development of morphine tolerance, currently, there is no effective therapy to treat morphine tolerance. In the current study, we aimed to develop a monoclonal antibody (mAb) precisely targeting MOR and to determine its therapeutic efficacy on morphine tolerance and the underlying molecular mechanisms. We successfully prepared a mAb targeting MOR, named 3A5C7, by hybridoma technique using a strategy of deoxyribonucleic acid immunization combined with cell immunization, and identified it as an immunoglobulin G mAb with high specificity and affinity for MOR and binding ability to antigens with spatial conformation. Treatment of two cell lines, HEK293T and SH-SY5Y, with 3A5C7 enhanced morphine-induced MOR endocytosis via a G protein-coupled receptor kinase 2 (GRK2)/β-arrestin2-dependent mechanism, as demonstrated by immunofluorescence staining, flow cytometry, Western blotting, coimmunoprecipitation, and small interfering ribonucleic acid (siRNA)-based knockdown. This mAb also allowed MOR recycling from cytoplasm to plasma membrane and attenuated morphine-induced phosphorylation of MOR. We established an in vitro morphine tolerance model using differentiated SH-SY5Y cells induced by retinoic acid. Western blot, enzyme-linked immunosorbent assays, and siRNA-based knockdown revealed that 3A5C7 mAb diminished hyperactivation of adenylate cyclase, the in vitro biomarker of morphine tolerance, via the GRK2/β-arrestin2 pathway. Furthermore, in vivo hotplate test demonstrated that chronic intrathecal administration of 3A5C7 significantly alleviated morphine tolerance in mice, and withdrawal jumping test revealed that both chronic and acute 3A5C7 intrathecal administration attenuated morphine dependence. Finally, intrathecal electroporation of silencing short hairpin RNA illustrated that the in vivo anti-tolerance and anti-dependence efficacy of 3A5C7 was mediated by enhanced morphine-induced MOR endocytosis via GRK2/β-arrestin2 pathway. Collectively, our study provided a therapeutic mAb, 3A5C7, targeting MOR to treat morphine tolerance, mediated by enhancing morphine-induced MOR endocytosis. The mAb 3A5C7 demonstrates promising translational value to treat clinical morphine tolerance.

Remifentanil but not sufentanil induces cardioprotection in human ischemic heart muscle in vitro

BACKGROUND

Previous studies on animal models have suggested that δ-opioid receptor (OR) signaling is the primary pathway responsible for opioids' cardioprotective effect. We hypothesize that the μ-OR's activation protects the human heart muscle.

METHODS

We performed the experiments on muscular trabeculae obtained from the right atrial appendages of 104 consecutive patients subjected to coronary artery bypass surgery. Two trabeculae from each patient were studied simultaneously and exposed to 60 min of hypoxia with subsequent 60 min of reoxygenation. Remifentanil (5 μM or 50 μM) or sufentanil (40 μM or 400 μM) was used from the time of reoxygenation. Trabeculae contractility was assessed as the maximal amplitude of the contraction at baseline, after 60 min of hypoxia, during reoxygenation, and after norepinephrine application.

RESULTS

During reperfusion, the application of remifentanil improved cardiomyocytes' function as compared to the control group (time from reperfusion: 15 min: 39.8% vs. 21.7%, p = 0.01; 30 min: 41.4% vs. 21.8%, p = 0.01; 60 min: 42.7% vs. 26.9%, p = 0.04; after norepinephrine: 64.7% vs. 43.2%, p = 0.03). The application of sufentanil did not influence cardiomyocyte function as can be seen when comparing the results of the experimental and control group.

CONCLUSIONS

Remifentanil, but not sufentanil, induces a cardioprotective effect on human right atria muscle in in vitro conditions, manifested as the increased amplitude of their contraction during reperfusion after 60 min of ischemia.

Dysregulation of mTOR Signaling after Brain Ischemia

In this review, we provide recent data on the role of mTOR kinase in the brain under physiological conditions and after damage, with a particular focus on cerebral ischemia. We cover the upstream and downstream pathways that regulate the activation state of mTOR complexes. Furthermore, we summarize recent advances in our understanding of mTORC1 and mTORC2 status in ischemia–hypoxia at tissue and cellular levels and analyze the existing evidence related to two types of neural cells, namely glia and neurons. Finally, we discuss the potential use of mTORC1 and mTORC2 as therapeutic targets after stroke.

Minocycline Improves Memory by Enhancing Hippocampal Synaptic Plasticity and Restoring Antioxidant Enzyme Activity in a Rat Model of Cerebral Ischemia-Reperfusion

INTRODUCTION

Oxidative stress plays a crucial role in the impairment of synaptic plasticity following cerebral ischemia, ultimately resulting in memory dysfunction. Hence, the applying antioxidant agents could be beneficial in managing memory deficits after brain ischemia. Minocycline is a tetracycline antibiotic with antioxidant effect. The main objective of this work was to assess the minocycline effect on the impairment of synaptic plasticity and memory after cerebral ischemia-reperfusion in rats.

METHODS

Transient occlusion of common carotid arteries was used to induce ischemiareperfusion injury in rats. Single or multiple (once daily for 7 days) dose(s) of minocycline were administered before (pretreatment) or after (treatment) brain ischemia. Seven days after ischemia-reperfusion, passive avoidance performance, long-term hippocampal potentiation, and the activity of antioxidant enzymes were assessed.

RESULTS

The passive avoidance test showed that minocycline (20 and 40 mg/kg) significantly increased step-through latency while reducing the duration of staying in a dark chamber in the treatment (but not pretreatment) group. In electrophysiological experiments, the rats treated (but not pretreated) with minocycline (40 mg/kg) showed a significant increase in the amplitude of the field excitatory postsynaptic potentials in the dentate gyrus area of the hippocampus. The treatment (but not pretreatment) with minocycline (20 and 40 mg/kg) resulted in a significant increase in the activity of catalase, glutathione peroxidase, and superoxide dismutase in the hippocampus.

CONCLUSION

It was determined that minocycline attenuates memory dysfunction after cerebral ischemia-reperfusion in rats by improving hippocampal synaptic plasticity and restoring antioxidant enzyme activity.

HIGHLIGHTS

Minocycline enhances passive avoidance memory after cerebral ischemia-reperfusion.Minocycline increases enzymatic antioxidant capacity in hippocampal formation.Minocycline improves synaptic plasticity in perforant path-granule cell synapse.

PLAIN LANGUAGE SUMMARY

Stroke is a common neurological disease with a relatively high mortality rate and disabilities worldwide. More than half of the patients who have had an episode of stroke suffer from the impairment of sensorimotor function and language problems as well as learning and memory disorders. Oxidative stress plays an important role in memory impairment following brain ischemia. Hence, the application of antioxidant agents could be beneficial in managing memory deficits after stroke. Minocycline is a tetracycline antibiotic that is used for the treatment of infectious diseases; it can also function as a potent antioxidant medication. Hence, we hypothesized that minocycline could attenuate memory impairment after brain ischemia. We examined this hypothesis in a rat model of brain ischemia. In this model, the main arteries that supply the brain with oxygenated blood were occluded to induce brain ischemia in the rats. Then, minocycline was administered to the rats, which were subjected to brain ischemia. Seven days later, memory function in the rats was evaluated. The results showed that minocycline could enhance the activity of antioxidant enzymes in the brain, which physiologically fight off oxidative stress. This property of minocycline protects brain cells against ischemic injury and thereby increases the transmission of neuronal signals from one cell to another cell in the memory centers in the brain. These effects ultimately increase the memory function of rats, which was evident in the behavioral memory test. Overall, the study results suggest that minocycline can be considered a memory enhancer drug in patients who suffer from learning and memory disorders following a stroke.

Experimental Study on the Central Mechanism of Penehyclidine Hydrochloride against Relapse Behavior in Morphine-Dependent Rats

OBJECTIVE

This article is mainly to study the central mechanism of penehyclidine hydrochloride against relapse behavior in morphine-dependent rats.

METHODS

The rats were randomly divided into the blank control group (k), PHC low-dose group (LP according to a body weight of 0.22 mg/kg), middle-dose group (MP according to a body weight of 0.55 mg/kg), high-dose group (HP according to a body weight of 1.38 mg/kg), and administration group, with 40 rats in each group. Each group was randomly divided into 5 subgroups (n = 10): 4 h after administration, 7 h after administration, 13 h after administration, 25 h after administration (K48, LP48, MP48, and HP48), and 37 h after administration, and then, Morris water maze experiment and immunohistochemical detection of the rat brain hippocampus were carried out.

RESULTS

4 and 7 hours after administration, compared with group 1, the TchE activity increased and Ach level decreased in groups 2, 3, and 4 and the difference was significant (P < 0.05), so the principle of penehyclidine hydrochloride against morphine-dependent rats is that penehyclidine hydrochloride causes cognitive impairment in the brain of mice, thereby achieving antimorphine effects.

Morphine pretreatment protects against cerebral ischemic injury via a cPKCγ-mediated anti-apoptosis pathway

It has been reported that morphine pretreatment (MP) can exert neuroprotective effects, and that protein kinase C (PKC) participates in the initiation and development of ischemic/hypoxic preconditioning in the brain. However, it remains unknown whether PKC is involved in MP-induced neuroprotection. The aim of the present study, which included in vivo and in vitro experiments, was to determine whether the conventional γ isoform of PKC (cPKCγ) was involved in the protective effects of MP against cerebral ischemic injury. The present study included an in vivo experiment using a mouse model of middle cerebral artery occlusion and an in vitro experiment using neuroblastoma N2a cells with oxygen-glucose deprivation (OGD). Furthermore, a cPKCγ antagonist, Go6983, was used to determine the involvement of cPKCγ in the protective effects of MP against cerebral ischemic injury. In the in vivo experiment, neurological deficits, ischemic infarct volume, neural cell damage, apoptosis and caspase-3 activation were evaluated. In the in vitro experiment, flow cytometry was used to determine the activation of caspase-3 in N2a cells with OGD. It was found that MP protected against cerebral ischemic injury. However, intracerebroventricular injection of the cPKCγ antagonist before MP attenuated the neuroprotective effect of MP and increased the activation of cleaved caspase-3. These findings suggested that MP may provide protection against cerebral ischemic injury via a cPKCγ-mediated anti-apoptosis pathway.

Morphine Deteriorates Cisplatin-Induced Cardiotoxicity in Rats and Induces Dose-Dependent Cisplatin Chemoresistance in MCF-7 Human Breast Cancer Cells

Morphine (MOR) is a strong analgesic that is often used in treatment of severe pains during cancer treatment, and thus might be concomitantly used with anticancer drugs as cisplatin (CP). The aim of the current study was to investigate the mechanisms by which MOR can affect CP-induced cardiotoxicity and to explore effects of MOR on the cytotoxic efficacy of CP. MOR (10 mg/kg/day i.p.) was administered to rats for 10 days, with or without 7.5 mg/kg CP single i.p. dose at day 5 of the experiment. In addition, MOR and/or CP were administered to MCF-7 cells to test their cytotoxicity. Compared to control, CP caused cardiotoxic effects manifested by significant increase in serum enzymatic markers; creatine kinase-MB and lactate dehydrogenase, with histopathological cardiac damage. In addition, CP caused cardiac oxidative stress, manifested by significant increased tissue lipid peroxidation product; malondialdehyde and nitric oxide, with significant decrease in tissue antioxidants as reduced glutathione, superoxide dismutase and catalase compared to control. Furthermore, CP significantly increased tissue proinflammatory cytokines; TNF-α and IL-6, as well as upregulated the apoptotic marker; caspase 3 compared to control. MOR/CP combination significantly deteriorated all tested parameters compared to CP alone. In MCF-7 breast cancer cells, administration of MOR in concentrations of 0.1, 1, 10 or 30 μM concomitantly with 1 or 10 μM CP caused dose-dependent reduction in CP-induced cytotoxicity in vitro. In conclusion, MOR administration might deteriorate CP-induced cardiotoxicity during cancer chemotherapy through oxidant, pro-inflammatory and apoptotic mechanisms, and might reduce CP chemotherapeutic efficacy.

Attenuating effect of paroxetine on memory impairment following cerebral ischemia-reperfusion injury in rat: The involvement of BDNF and antioxidant capacity

Memory impairments are frequently reported in patients suffering from brain ischemic diseases. Oxidative/nitrosative stress, synaptic plasticity, and brain-derived neurotrophic factor (BDNF) are involved in the physiopathology of brain ischemia-induced memory disorders. In the present study, the effect of paroxetine as an efficacious antidepressant medication with antioxidant properties was evaluated on passive avoidance memory deficit following cerebral ischemia in rats. Transient occlusion of common carotid arteries was applied to induce ischemia-reperfusion injury in male Wistar rats. Paroxetine (5, 10, 20 mg/kg) was administered intraperitoneally once daily before (for 3 days) or after (for 7 days) the induction of ischemia. A week after ischemia-reperfusion injury, passive avoidance memory, long-term potentiation (LTP), BDNF levels, total antioxidant capacity, the activity of antioxidant enzymes (including catalase, glutathione peroxidase, and superoxide dismutase), the concentration of malondialdehyde (MDA), and nitric oxide (NO) were investigated in the hippocampus. In the passive avoidance test, paroxetine significantly increased the step-through latency and decreased the time spent in the dark compartment. This affirmative function of paroxetine on the passive avoidance memory was accompanied by the improvement of hippocampal LTP and an obvious augmentation in the BDNF contents. Besides, paroxetine caused a significant rise in the total antioxidant capacity and antioxidant enzyme activity; while decreased the hippocampal levels of NO and MDA. It was ultimately attained that paroxetine attenuates cerebral ischemia-induced passive avoidance memory dysfunction in rats by the enhancement of hippocampal synaptic plasticity and BDNF content together with the suppression of oxidative/nitrosative stress.

Endogenous Opiates and Behavior: 2018

This paper is the forty-first consecutive installment of the annual anthological review of research concerning the endogenous opioid system, summarizing articles published during 2018 that studied the behavioral effects of molecular, pharmacological and genetic manipulation of opioid peptides and receptors as well as effects of opioid/opiate agonists and antagonists. The review is subdivided into the following specific topics: molecular-biochemical effects and neurochemical localization studies of endogenous opioids and their receptors (2), the roles of these opioid peptides and receptors in pain and analgesia in animals (3) and humans (4), opioid-sensitive and opioid-insensitive effects of nonopioid analgesics (5), opioid peptide and receptor involvement in tolerance and dependence (6), stress and social status (7), learning and memory (8), eating and drinking (9), drug abuse and alcohol (10), sexual activity and hormones, pregnancy, development and endocrinology (11), mental illness and mood (12), seizures and neurologic disorders (13), electrical-related activity and neurophysiology (14), general activity and locomotion (15), gastrointestinal, renal and hepatic functions (16), cardiovascular responses (17), respiration and thermoregulation (18), and immunological responses (19).

Nanomaterial integration into the scaffolding materials for nerve tissue engineering: a review

The nervous system, which consists of a complex network of millions of neurons, is one of the most highly intricate systems in the body. This complex network is responsible for the physiological and cognitive functions of the human body. Following injuries or degenerative diseases, damage to the nervous system is overwhelming because of its complexity and its limited regeneration capacity. However, neural tissue engineering currently has some capacities for repairing nerve deficits and promoting neural regeneration, with more developments in the future. Nevertheless, controlling the guidance of stem cell proliferation and differentiation is a challenging step towards this goal. Nanomaterials have the potential for the guidance of the stem cells towards the neural lineage which can overcome the pitfalls of the classical methods since they provide a unique microenvironment that facilitates cell-matrix and cell-cell interaction, and they can manipulate the cell signaling mechanisms to control stem cells' fate. In this article, the suitable cell sources and microenvironment cues for neuronal tissue engineering were examined. Afterward, the nanomaterials that impact stem cell proliferation and differentiation towards neuronal lineage were reviewed.

Injection of minocycline into the periaqueductal gray attenuates morphine withdrawal signs

This study investigated the effects of minocycline microinjections, into the midbrain periaqueductal gray (PAG), on morphine withdrawal and the expression of pannexin-1 (panx1), phosphorylated mammalian target of rapamycin (p-mTOR), protein kinase A (PKA), and cAMP response element-binding protein (CREB). Rats were injected with morphine, intraperitoneally, at increasing doses, twice per day, to establish animal models of morphine exposure. Minocycline was administered into the PAG before the first intraperitoneal (i.p.) injection of morphine each day, on days 1-4. On the last day of the experiment, all rats were injected with naloxone, and morphine withdrawal was observed, and then changes in the expression levels of ionized calcium-binding adaptor molecule 1 (Iba1) and its downstream factors, panx1, p-mTOR, PKA, and CREB were evaluated by western blot and immunohistochemistry analyses. Morphine withdrawal increased microglial activation, whereas minocycline could inhibit microglial activation and withdrawal and the downregulation of panx1, p-mTOR, PKA, and CREB expression, reducing the effects of morphine withdrawal.

The neuroprotective effect of NeuroAid on morphine-induced amnesia with respect to the expression of TFAM, PGC-1α, ΔfosB and CART genes in the hippocampus of male Wistar rats

Morphine is a natural alkaloid which derived from the opium poppy Papaver somniferum. Many studies have reported the effect of morphine on learning, memory and gene expression. CART (cocaine-amphetamine regulated transcript)is an important neuropeptide which has a critical role in physiological processes including drug dependence and antioxidant activity. ΔfosB is a transcription factor which modulates synaptic plasticity and affects learning and memory. TFAM (the mitochondrial transcription factor A) and PGC-1α (Peroxisome proliferator-activated receptor γ coactivator-1α) are critically involved in mitochondrial biogenesis and antioxidant pathways. NeuroAid is a Chinese medicine that induces neuroprotective and anti-apoptotic effects. In this research, we aimed to investigate the effect of NeuroAid on morphine-induced amnesia with respect to the expression of TFAM, PGC-1α, ΔfosB and CART in the rat's hippocampus. In this study, Morphine sulfate (at increasing doses), Naloxone hydrochloride (2.5 mg/kg) and NeuroAid (2.5 mg/kg) were administered intraperitoneal and real-time PCR reactions were done to assess gene expression. The results showed, morphine impaired memory of step-through passive avoidance, while NeuroAid had no effect. NeuroAid attenuated (but not reversed) morphine-induced memory impairment in morphine-addicted rats. Morphine increased the expression of PGC-1α and decreased the expression of CART. However, NeuroAid increased the expression of TFAM, PGC-1α, ΔfosB and CART. NeuroAid restored the effect of morphine on the expression of CART and PGC-1α. In conclusion, morphine impaired memory of step-through passive avoidance and NeuroAid attenuated this effect. The effect of NeuroAid on morphine-induced memory impairment/gene expression may be related to its anti-apoptotic and neuroprotective effects.

Morphine Addiction and Oxidative Stress: The Potential Effects of Thioredoxin-1

Long-term administration of morphine for the management of chronic pain will result in tolerance to its analgesic effect and could even cause drug dependence. Numerous studies have demonstrated significant redox alteration in morphine dependence and addiction. Thioredoxin-1 (Trx-1) play important roles in controlling the cellular redox balance. In recent years, several recent studies have demonstrated that Trx-1 may be a promising novel therapeutic target for morphine addiction. In this article, we firstly review the redox alteration in morphine addiction. We also summarize the expression and the protective roles of Trx-1 in morphine dependence. We further highlight the protection of geranylgeranylacetone (GGA), a noncytotoxic pharmacological inducer of Trx-1, in morphine-induced conditioned place preference. In conclusion, Trx-1 may be very promising for clinical therapy of morphine addiction in the future.

Evaluation of the effects of metformin administration on morphine tolerance in mice

Opioids are used in clinical practice to relieve moderate to severe pain. Prolonged use of opioids can lead to a situation of analgesic tolerance and dependence. Several mechanisms are involved in the tolerance to analgesic opioids, including desensitization or internalization of the opioid receptor, elevation of cAMP levels, microglial activation and neuroinflammation, elevation of spinal mTOR activity and change in the expression of some proteins involved in tolerance, such as nNOS. Activation of the AMPK pathway inhibits mTOR and p38 MAPK ameliorating neuroinflammation and tolerance induced by morphine. Metformin, a potent antidiabetic agent, can also activate AMPK. Morphine tolerance was induced in mice by intraperitoneal administration three times daily at 08:00, 11.00 and 16.00 h of 50, 50 and 75 mg/kg morphine, respectively during four days. On the fifth day mice received a single injection of morphine 50 mg/kg. To evaluate the effects of metformin in development of morphine-induced analgesic tolerance a group of mice received metformin (10 mg/kg) 45 min before each morphine administration. Tail flick and hot plate tests were performed to estimate analgesic latency on days 1, 3 and 5. At five days, the animals were sacrificed, the brain dissected and nitrite levels determined. Chronic metformin administration significantly increased the analgesic latency on days 3 and 5 compared to the morphine group in hot plate test and in tail flick test. Chronic and acute metformin administration significantly decreased nitric oxide level compare to morphine group. The present results revealed that metformin attenuated analgesic tolerance induced by repeated intraperitoneal injections of morphine in mice.

Modulatory Role of SIRT1 and Resistin as Therapeutic Targets in Patients with Aortic Valve Stenosis

BACKGROUND

Inflammatory is one of the main cause of aortic valve stenosis (AS), so discovering novel biomarkers for the targeted therapy of inflammation could be an attractive strategy in AS prevention. The objectives of our study were to clarify the modulatory role of resistin and silent information regulator 1 (SIRT1) before and after surgery and also to evaluate the therapeutic effects of resveratrol.

METHODS

Nineteen AS patients and 15 healthy subjects were studied as the case and control groups, respectively. Peripheral blood mononuclear cells (PBMCs) were isolated and cultured to determine the levels of resistin and SIRT1 and the effects of resveratrol on them.

RESULTS

Significant increase in resistin expression was observed in the patients compare to the control (p ≤0.01), and this upregulation was augmented 72 h following surgery (p ≤0.01). The SIRT1 expression decreased in the AS group compare to the control but this reduction was not significant. Aortic valve replacement caused a higher decrease in the protein (p ≤0.01) and mRNA level (p ≤0.05) of SIRT1. Resveratrol in the AS group significantly diminished the resistin level (p ≤0.05) but increased the SIRT1 level (p ≤0.001).

CONCLUSIONS

In our patients with AS, the resistin level was increased, whereas the expression of SIRT1 was reduced and surgery augmented these alterations. Resveratrol improved inflammation in the PBMCs of the patients through the SIRT1/resistin pathway. These findings suggest that pharmacological therapy with resveratrol might be a novel approach to alleviating inflammation in patients with AS.

Conditioned medium obtained from human amniotic mesenchymal stem cells attenuates focal cerebral ischemia/reperfusion injury in rats by targeting mTOR pathway

Conditioned medium obtained from human amniotic mesenchymal stem cells (hAMSC-CM) was recently shown to have many antioxidant, antiapoptotic and proangiogenic growth factors. The present study was performed to investigate whether protective effects of hAMSC-CM against focal cerebral ischemia/ reperfusion (I/R) injury is associated with modulation of the mammalian target of rapamycin (mTOR) pathway. A rat model of middle cerebral artery occlusion (MCAO) was created and the animals were divided into three groups including sham, MCAO and MCAO + hAMSC-CM. Drug was administrated immediately after cerebral reperfusion (i.v). The expressions of mTOR, p-mTOR and LC3 were measured using Western blotting and real time-PCR, respectively. Apoptosis and neuronal loss were determined using TUNEL and Nissl staining, respectively. Infarct volume and the blood-brain barrier (BBB) damage were evaluated using 2,3,5-triphenyltetrazolium chloride (TTC) staining and Evans Blue (EB) uptake, respectively. Compared with sham, significant infarct volume, apoptotic cell death, and neuronal loss were found in MCAO rats that reversed by hAMSC-CM (P < 0.05). Likewise, MCAO rats exhibited increased mRNA level of light-chain 3 (LC3) and the LC3II/LC3I ratio as well as decreased expression level of p-mTOR that reversed by hAMSC-CM (P < 0.05). There were no significant differences in the expression of total mTOR among the experimental groups. In summary, our results demonstrate that hAMSC-CM gives rise to neuroprotection following ischemic stroke by restoring mTOR activity and inhibiting autophagy.

Opioids Preconditioning Upon Renal Function and Ischemia-Reperfusion Injury: A Narrative Review

Kidneys have an important role in regulating water volume, blood pressure, secretion of hormones and acid-base and electrolyte balance. Kidney dysfunction derived from acute injury can, under certain conditions, progress to chronic kidney disease. In the late stages of kidney disease, treatment is limited to replacement therapy: Dialysis and transplantation. After renal transplant, grafts suffer from activation of immune cells and generation of oxidant molecules. Anesthetic preconditioning has emerged as a promising strategy to ameliorate ischemia reperfusion injury. This review compiles some significant aspects of renal physiology and discusses current understanding of the effects of anesthetic preconditioning upon renal function and ischemia reperfusion injury, focusing on opioids and its properties ameliorating renal injury. According to the available evidence, opioid preconditioning appears to reduce inflammation and reactive oxygen species generation after ischemia reperfusion. Therefore, opioid preconditioning represents a promising strategy to reduce renal ischemia reperfusion injury and, its application on current clinical practice could be beneficial in events such as acute renal injury and kidney transplantation.

Combination therapy profoundly improved skin flap survival by modulating KATP channels and nitric oxide

PURPOSE

A potential therapeutic approach on skin flap necrosis is to target parallel pathways involved in necrosis. Azelaic Acid, Minoxidil and Caffeine combination was tried on skin flap survival by their possible interaction with ATP sensitive potassium (KATP) channels and nitric oxide pathway.

MATERIAL AND METHODS

Sprauge-Dawley rats were divided into 8 groups for skin flap surgery. Azelaic acid, minoxidil, caffeine, or their combination were applied topically in different groups. Two additional groups were treated with L-NAME or glibenclamide in addition to the combination therapy. Percentage of flap necrosis was calculated and flap samples were removed to measure tissue malondialdehyde (MDA) and nitric oxide (NO) and expression of inducible nitric oxide synthase (iNOS), Bcl-2 and Bax proteins.

RESULTS

Combination therapy profoundly decreased skin flap necrosis, tissue MDA contents, and expression of the pro-apoptotic protein Bax (p < 0.05 vs. single treatments). These effects were reversed by L-NAME and glibenclamide pre-treatments. Further evaluations showed combination therapy increases flap tissue NO content and iNOS expression (p < 0.05 vs. single treatments).

CONCLUSION

Beneficial effect of the combination therapy with azelaic acid, minoxidil and caffeine therapy on rescuing the flap from necrosis by targeting parallel signaling pathways suggested potential applications in clinical practice.

Capsaicin protects against testicular torsion injury through mTOR-dependent mechanism

SCOPE

Testicular torsion and subsequent release of reactive oxygen species (ROS) can cause infertility in adults. Oxidative stress following testicular torsion plays an important role in the ýonset and development of apoptotic cell death through dysregulation of the cellular signaling pathways. Anti-inflammatory and antioxidant properties of capsaicin, a bioactive composition present in red peppers, has already been exploited for treatment of the cancer and pain relief. In present work, we evaluated the role of the mammalian target of rapamycin (mTOR) in antioxidant effect of capsaicin against reperfusion injury following testicular torsion.

METHODS

Male Wistar rats weighing 200-220 g were randomly assigned into four major groups: (i) a sham operated group, (ii) a testicular torsion (TT) group, (iii) three groups treated with different doses of capsaicin (TT + 100, 500 and 1000 μg/ml Cap), and (iv) three groups of healthy rats treated with different doses of capsaicin (100, 500 and 1000 μg/ml). Western blotting assay was used to examine the anti-apoptotic effects of capsaicin in testicular cells following torsion. H&E and TUNEL methods were used to evaluate testicular morphology and apoptosis activity.

RESULTS

Compared to control group, phosphorylation of mTOR was significantly increased in the TT groups. Capsaicin administration remarkably decreased the phosphorylation of mTOR at the highest dose (P < 0.05). Capsaicin decreased apoptosis and preserved tubular morphology in testes.

CONCLUSION

Our results showed that antioxidant properties of capsaicin minimizes cell death and reperfusion injury following testicular torsion.

FOXO1 targeting by capsaicin reduces tissue damage after testicular torsion

Testicular torsion-related oxidative stress causes a sequential chain of DNA damage, lipid peroxidation and cell death that leads to the derangement in the sperm functions and infertility. Capsaicin that has been applied for pain relief and cancer prevention possesses antioxidant properties which can be exploited to confer cell survival under ischaemic testis damage. Wistar male rats weighing 150-200 g were randomly divided into four groups: (i) sham group (all procedures except torsion of testis), (ii) ischaemia group (TT group), (iii) three TT groups treated with different dose of capsaicin (TT + different doses of Cap) and (iv) three control groups treated with different doses of capsaicin (100, 500 and 1000 ug/ml). Capsaicin administration significantly decreased the expression of pro-apoptotic factors and increased the expression of anti-apoptotic factors. Likewise, the expression of FOXO1 is significantly increased by higher doses of the capsaicin. Histological assessment by H&E and TUNEL method also exhibited an improved testicular morphology and decreased apoptosis in testes. These results suggested clinical potential for capsaicin in treatment of testicular torsion by targeting FOXO1 and apoptotic pathways.