Resveratrol dilates arterioles and protects against N-methyl-d-aspartic acid-induced excitotoxicity in the rat retina.

Resveratrol, a natural polyphenolic compound, reportedly possesses numerous biological activities, including anti-inflammatory and antioxidant effects. In the current study, we examined (1) the dilator effects of resveratrol on retinal arterioles, (2) the protective effects of resveratrol against excitotoxic retinal injury, and (3) whether these effects are mediated by the AMP-activated kinase (AMPK)-dependent pathway in rats. Male Wistar rats (7 to 10 weeks old) were used in this study. The diameters of the retinal arterioles, mean arterial pressure, and heart rate were measured in vivo. The retinal injury was assessed by histological examination. Intravenous injection of resveratrol (3 mg/kg) increased the diameter of the retinal arterioles without affecting the mean arterial pressure and heart rate. The AMPK inhibitor, compound C (5 mg/kg, intravenously), significantly attenuated the retinal vasodilator response to resveratrol. Seven days after intravitreal injection of N-methyl-d-aspartic acid (NMDA; 25, 50, and 100 nmol/eye), the number of cells located in the ganglion cell layer (GCL) was reduced, along with thinning of the inner plexiform layer. Intravitreal resveratrol injection (100 nmol/eye) reduced the NMDA (25 and 50 nmol/eye)-induced cell loss in the GCL. The neuroprotective effect of resveratrol was significantly but not completely reversed by compound C (10 nmol/eye). These results suggest that resveratrol dilates retinal arterioles and protects against NMDA-induced retinal neurodegeneration via an AMPK-dependent pathway in rats. Resveratrol may have the potential to slow the onset and progression of diseases associated with retinal ischemia by improving impaired retinal circulation and protecting retinal neuronal cells.

Urokinase-Type Plasminogen Activator Enhances the Neuroprotective Activity of Brain-Derived Neurotrophic Factor in a Model of Intracerebral Hemorrhage.

Brain-derived neurotrophic factor (BDNF) is a classic neuroprotective and pro-regenerative factor in peripheral and central nervous tissue. Its ability to stimulate the restoration of damaged nerve and brain tissue after ischemic stroke and intraventricular hemorrhage has been demonstrated. However, the current concept of regeneration allows us to assert that one factor, even if essential, cannot be the sole contributor to this complex biological process. We have previously shown that urokinase-type plasminogen activator (uPA) complements BDNF activity and stimulates restoration of nervous tissue. Using a model of intracerebral hemorrhage in rats, we investigated the neurotrophic and neuroprotective effect of BDNF combined with uPA. The local simultaneous administration of BDNF and uPA provided effective neuroprotection of brain tissue after intracerebral hemorrhage, promoted survival of experimental animals and their neurological recovery, and decreased lesion volume. The study of cellular mechanisms of the observed neurotrophic effect of BDNF and uPA combination revealed both known mechanisms (neuronal survival and neurite growth) and new ones (microglial activation) that had not been shown for BDNF and uPA. Our findings support the concept of using combinations of biological factors with diverse but complementary mechanisms of action as a promising regenerative approach.

MSC Secretome as a Promising Tool for Neuroprotection and Neuroregeneration in a Model of Intracerebral Hemorrhage.

Multipotent mesenchymal stromal cells (MSCs) are considered to be critical contributors to injured tissue repair and regeneration, and MSC-based therapeutic approaches have been applied to many peripheral and central neurologic disorders. It has been demonstrated that the beneficial effects of MSC are mainly mediated by the components of their secretome. In the current study, we have explored the neuroprotective potential of the MSC secretome in a rat model of intracerebral hemorrhage and shown that a 10-fold concentrated secretome of human MSC and its combination with the brain-derived neurotrophic factor (BDNF) provided a better survival and neurological outcome of rats within 14 days of intracerebral hemorrhage compared to the negative (non-treated) and positive (BDNF) control groups. We found that it was due to the ability of MSC secretome to stimulate neuron survival under conditions of glutamate-induced neurotoxicity. However, the lesion volume did not shrink in these rats, and this also correlated with prominent microglia activation. We hypothesize that this could be caused by the species-specificity of the used MSC secretome and provide evidence to confirm this. Thus, we have found that allogenic rat MSC secretome was more effective than xenogenic human MSC secretome in the rat intracerebral hemorrhage model: it reduced the volume of the lesion and promoted excellent survival and neurological outcome of the treated rats.

Synthesis and biological evaluation of isoliquiritigenin derivatives as a neuroprotective agent against glutamate mediated neurotoxicity in HT22 cells.

Glutamate-induced neurotoxicity is characterized by cellular Ca2+ uptake, which is upstream of reactive oxygen species (ROS)-induced apoptosis signaling and MAPKs activation. In the present study, we synthesized isoliquiritigenin analogs with electron-donating and electron-withdrawing functional groups. These analogs were evaluated for neuroprotective effect against glutamate-induced neurotoxicity in HT22 cells. Among these analogs, compound BS11 was selected as a potent neuroprotective agent. Cellular Ca2+ concentration, ROS level, MAPKs activation and AIF translocation to the nucleus were increased upon treatment with 5 mM glutamate. In contrast, we identified that compound BS11 reduced the cellular Ca2+ concentration and ROS level upon glutamate exposure. Western blot analysis showed that MAPK activation was decreased by treatment with compound BS11. We further identified that cotreatment of compound BS11 and glutamate inhibited translocation of AIF to the nucleus.

Effects of Dexmedetomidine Hydrochloride on Glutamate-induced Neurotoxicity in Rats / 中国医科大学学报

Objective To investigate the effects and mechanism of dexmedetomidine hydrochloride preconditioning against glutamate-induced neurotoxicity.Methods The model of glutamate-induced neurotoxicity was established by the injection of glutamate into lateral cerebral ventricle.Thirty-six SD rats were randomly divided into control group (C group),glutamate-induced neurotoxicity group (G group),Dex1 group and Dex2 group.Dex1 group and Dex2 group received intraperitoneal injection of dexmedetomidine respectively at a dose of 50 μg/kg or 100 μg/kg before glutamate application.Two hours later,the rats were sacrificed and hippocampus was separated to measure the level of SOD and MDA.The rest of each brain was used to measure the degree of brain edema.Pathological changes were observed under microscope with Nissl's staining.Results In contrast to G group,brain edema and MDA concentration in Dex1 group and Dex2 group were significant lower,while SOD concentrations were significantly increased and the pathological change in Dex1 group and Dex2 group were relieved obviously compared to glutamate-induced neurotoxicity group.Conclusion Dexmedetomidine preconditioning can significantly attenuate glutamate-induced neurotoxicity,which is properly related to the inhibition of oxidative-stress reaction.

Protective effects of cycloartane triterpenoides from Passiflora edulis Sims against glutamate-induced neurotoxicity in PC12 cell.

Four new cycloartane triterpenoids, 1α,3ß-dihydroxy-16-keto-24(31)-en-cycloartane (1), 31-methoxyl-passifloic acid (2), cyclopassifloside XIV (3), and cyclopassifloside XV (4), together with six known compounds (5-10) were isolated from Passiflora edulis Sims. Their structures were elucidated on the basis of extensive spectroscopic analysis. All the compounds were evaluated for protective effects against damage of PC12 cell induced by glutamate according to traditional usage of the herbal medicine, and the results indicated that cycloartane triterpenoids maybe one of the active compositions of P. edulis Sims for the treatment of neurodegenerative disease.