Effects of 2-chloroadenosine on hippocampal GABA content and turnover.

The effects of 2-Chloroadenosine (CADO), a stable analog of adenosine, on GABA turnover rate and GABA content in the rat hippocampus in vivo have been studied. The intracerebroventricular injection of CADO reduced the GABA turnover rate in the hippocampus, as estimated from the rate of GABA accumulation after inhibition of GABA transaminase (GABA-T) by aminooxyacetic acid (AOAA). The effect of CADO on AOAA-induced accumulation of GABA in the hippocampus was blocked by the intraperitoneal injection of the adenosine receptor antagonist caffeine. Furthermore, CADO at the dose of 5 micrograms per ventricle produced a significant decrease in GABA content in the hippocampus. Our results support the hypothesis that adenosine exerts inhibitory effects on GABAergic circuits in the hippocampus.