Abstracts

Rationale: Previous studies in our lab showed that sst2 and sst3 receptors are implicated in the anticonvulsant actions of somatostatin-14 and cortistatin-14. These findings suggest a possible functional coupling between these two receptors. To confirm this intracellular interaction, we used L-779,976, a selective sst2 agonist, cyanamid154806, a selective sst2 antagonist, L-796,778, a selective sst3 agonist and SST3-ODN-8, a selective sst3 antagonist as pharmacological tools. Methods: In vivo microdialysis was applied for intrahippocampal drug administration and as a neurotransmitter sampling tool. Seizures were evoked by intrahippocampal pilocarpine perfusion (10 mM, 40 min) and seizure severity was assessed, using a behavioural scoring system. Results: Our results showed that anticonvulsant effects of L-796,778, a selective sst3 agonist, were reversed in the presence of cyanamid154806, a selective sst2 antagonist. Interestingly, sst3 antagonism was not able to block sst2 mediated anticonvulsant actions. Conclusions: These observations indicate a functional interaction between sst2 and sst3 receptors. Yet, under these circumstances, this interaction could only be demonstrated in one direction.