Role of Endocannabinoid System in the Ventral Hippocampus of Rats in the Modulation of Anxiety-Like Behaviours

The effects of unilateral intra-ventral hippocampus injection of URB597, a fatty acid amid hydrolase inhibitor, and AM251, a selective CB1 receptor antagonist, on anxiety-related behaviours using elevated plus-maze test of anxiety were evaluated in the present study. Possible involvement of GABAergic system in those effects of URB597 was also evaluated. Injection of URB597 at the doses of 0.01, 0.1 and 1 mu g/rat showed significant anxiogenic-like effects at 0.1 and 1 mu g/rat. However, intra-ventral hippocampus injection of AM251 at the doses of 0.001, 0.01 and 0.1 mu g/rat did not produce any significant effect in the elevated plus-maze. The ineffective doses of selective GABA(A) receptor antagonist, bicuculline (2 mu g/rat) and selective GABA(B) receptor antagonist, phaclofen (1 mu g/rat) on anxiety-related behaviours were also injected with URB597 (0.1 mu g/rat). The present data showed that neither bicuculline nor phaclofen affected the anxiogenic-like effects of URB597. The results showed that injection of URB597 into the ventral hippocampus may be anxiogenic and GABAergic system may not be involved in its anxiogenic-like effects.