Interactions of cannabinoidergic system and H1 receptor in the dorsal hippocampus of mice on the anxiety-like behavior

Cannabinoids are a class of psychoactive compound that produce a wide array of effects in a large number of species. In the present study، the effects of cannabinoidergic systems and H1 receptor agents on anxiety-related behaviors and their interactions were investigated، using hole-board test in mice. Bilateral intra-CA1 administration of CB1/CB2 receptor agonist، WIN55، 212-2 (0. 1- 0. 5μg/mice) did not modify exploratory behaviors in mice. On the other hand، intra-CA1 administration of CB1 receptor antagonist، AM251 (25 and 50 ng/mice) or histamine، pyrilamine (5- 10μg/mice) decreased the number of head-dipping and increased the first head-dip، suggesting anxiogenic-like response. Furthermore، our present data indicated that co-administration of WIN55، 212-2 (0. 25μg/mice) with histaminergic agents، decreased the anxiogenic-like response of an effective dose (5μg/mice) of histamine and pyrilamine. In addition، the results demonstrated that co-administration of an ineffective dose of AM251 (25 ng/mice) with histaminergic drugs did not alter the response induced by an ineffective dose (2. 5μg/mice) of either histamine or pyrilamine. In all experiments in doses used، locomotor activity was not significantly changed. Our results showed that there may be a partial interaction between the cannabinoidergic and the histaminergic systems of the dorsal hippocampus on anxiogenic/anxiolytic-like behaviors in hole-board test.