Resveratrol, a polyphenol presents in grapes and wine, displays antioxidant and anti-inflammatory properties and cytoprotective effect in brain pathologies associated to oxidative stress and neurodegeneration. In previous work, we demonstrated that resveratrol exerts neuroglial modulation, improving glial functions, mainly related to glutamate metabolism. Astrocytes are a major class of glial cells and regulate neurotransmitter systems, synaptic processing, energy metabolism and defense against oxidative stress. This study sought to determine the protective effect of resveratrol against hydrogen peroxide (H2O2)-induced cytotoxicity in C6 astrocyte cell line, an astrocytic lineage, on neurochemical parameters and their cellular and biochemical mechanisms. H2O2 exposure increased oxidative-nitrosative stress, iNOS expression, cytokine proinflammatory release (TNFα levels) and mitochondrial membrane potential dysfunction and decreased antioxidant defenses, such as SOD, CAT and creatine kinase activity. Resveratrol strongly prevented C6 cells from H2O2-induced toxicity by modulating glial, oxidative and inflammatory responses. Resveratrol per se increased heme oxygenase 1 (HO1) expression and extracellular GSH content. In addition, HO1 signaling pathway is involved in the protective effect of resveratrol against H2O2-induced oxidative damage in astroglial cells. Taken together, these results show that resveratrol represents an important mechanism for protection of glial cells against oxidative stress.

Background and PurposeStroke is a devastating disease. Both excitotoxicity and oxidative stress play important roles in ischemic brain injury, along with harmful impacts on ischemic cerebral tissue. As guanosine plays an important neuroprotective role in the central nervous system, the purpose of this study was to evaluate the neuroprotective effects of guanosine and putative cerebral events following the onset of permanent focal cerebral ischemia.MethodsPermanent focal cerebral ischemia was induced in rats by thermocoagulation. Guanosine was administered immediately, 1 h, 3 h and 6 h after surgery. Behavioral performance was evaluated by cylinder testing for a period of 15 days after surgery. Brain oxidative stress parameters, including levels of ROS/RNS, lipid peroxidation, antioxidant non-enzymatic levels (GSH, vitamin C) and enzymatic parameters (SOD expression and activity and CAT activity), as well as glutamatergic parameters (EAAC1, GLAST and GLT1, glutamine synthetase) were analyzed.ResultsAfter 24 h, ischemic injury resulted in impaired function of the forelimb, caused brain infarct and increased lipid peroxidation. Treatment with guanosine restored these parameters. Oxidative stress markers were affected by ischemic insult, demonstrated by increased ROS/RNS levels, increased SOD expression with reduced SOD activity and decreased non-enzymatic (GSH and vitamin C) antioxidant defenses. Guanosine prevented increased ROS/RNS levels, decreased SOD activity, further increased SOD expression, increased CAT activity and restored vitamin C levels. Ischemia also affected glutamatergic parameters, illustrated by increased EAAC1 levels and decreased GLT1 levels; guanosine reversed the decreased GLT1 levels and did not affect the EAAC1 levels.ConclusionThe effects of brain ischemia were strongly attenuated by guanosine administration. The cellular mechanisms involved in redox and glutamatergic homeostasis, which were both affected by the ischemic insult, were also modulated by guanosine. These observations reveal that guanosine may represent a potential therapeutic agent in cerebral ischemia by preventing oxidative stress and excitotoxicity.

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Astrocytes are responsible for modulating neurotransmitter systems and synaptic information processing, ionic homeostasis, energy metabolism, maintenance of the blood-brain barrier, and antioxidant and inflammatory responses. Our group recently published a culture model of cortical astrocytes obtained from adult Wistar rats. In this study, we established an in vitro model for hippocampal astrocyte cultures from adult (90 days old) and aged (180 days old) Wistar rats. Resveratrol, a polyphenol found in grapes and red wine, exhibits antioxidant, anti-inflammatory, anti-aging and neuroprotective effects that modulate glial functions. Here, we evaluated the effects of resveratrol on GSH content, GS activity, TNF-α and IL-1β levels in hippocampal astrocytes from newborn, adult and aged Wistar rats. We observed a decrease in antioxidant defenses and an increase in the inflammatory response in hippocampal astrocytes from adult and aged rats compared to classical astrocyte cultures from newborn rats. Resveratrol prevented these effects. These findings reinforce the neuroprotective effects of resveratrol, which are mainly associated with antioxidant and anti-inflammatory activities.

Astrocytes, a major class of glial cells, regulate neurotransmitter systems, synaptic processing, ion homeostasis, antioxidant defenses and energy metabolism. Astrocyte cultures derived from rodent brains have been extensively used to characterize astrocytes' biochemical, pharmacological and morphological properties. The aims of this study were to develop a protocol for routine preparation and to characterize a primary astrocyte culture from the brains of adult (90 days old) Wistar rats. For this we used enzymatic digestion (trypsin and papain) and mechanical dissociation. Medium exchange occurred from 24 h after obtaining a culture and after, twice a week up to reach the confluence (around the 4th to 5th week). Under basal conditions, adult astrocytes presented a polygonal to fusiform and flat morphology. Furthermore, approximately 95% the cells were positive for the main glial markers, including GFAP, glutamate transporters, glutamine synthetase and S100B. Moreover, the astrocytes were able to take up glucose and glutamate. Adult astrocytes were also able to respond to acute H2O2 exposure, which led to an increase in reactive oxygen species (ROS) levels and a decrease in glutamate uptake. The antioxidant compound resveratrol was able to protect adult astrocytes from oxidative damage. A response of adult astrocytes to an inflammatory stimulus with LPS was also observed. Changes in the actin cytoskeleton were induced in stimulated astrocytes, most likely by a mechanism dependent on MAPK and Rho A signaling pathways. Taken together, these findings indicate that the culture model described in this study exhibits the biochemical and physiological properties of astrocytes and may be useful for elucidating the mechanisms related to the adult brain, exploring changes between neonatal and adult astrocytes, as well as investigating compounds involved in cytotoxicity and cytoprotection.