| Abstract: |
The effects of adenosine, and selective adenosine receptor agonists and antagonists on methylmercury (MeHg)-induced aspartate release were studied in neonatal rat primary astrocyte cultures. Whereas basal levels ofd-[3H]aspartate release were unchanged upon treatment with adenosine or selective A1 receptor agonists, N6-cyclopentyladenosine (CPA), cyclohexyladenosine (CHA), and R-phenylisopropyladenosine (R-PIA), all partially reversed the MeHg-induced release ofd-aspartate. Treatment of astrocytes with the xanthine derivative, theophylline, an adenosine antagonist, reversed the inhibitory effect of adenosine on MeHg-inducedd-[3H]aspartate release. Since the effect of MeHg ond-[3H]aspartate release is known to be associated with sulfhydryl (-SH) groups which are controlled by intracellular glutathione concentrations [GSH]i, we also evaluated the effects of adenosine, the A1 agonists CPA and CHP, and the adenosine antagonist, theophylline, on astrocytic [GSH]i. Attenuation of the stimulatory effect of MeHg ond-[3H]aspartate release by adenosine and its agonists occurred in the presence of reduced astrocytic [GSH]i, suggesting that other mechanisms must be invoked for this protective effect. Whilst the mechanism of MeHg-inducedd-[3H]aspartate release is not known, the data suggest a role for adenosine in its regulation. |
