5-HT6 RECEPTORS POSITIVELY COUPLED TO ADENYLYL-CYCLASE IN STRIATAL NEURONS IN CULTURE

5-HT receptor positively coupled to adenylyl cyclase in striatal neuro nes in culture does not correspond to the 5-HT4 receptor. 5-HT induces an increase in cAMP level with an EC(50) of 125 nM. 5-HT agonists dis played the following rank order of potencies 5-HT > LSD > 5-MeOT > 5-C T. 8-OH-DPAT, RU 24969 and cisapride were inactive. The most efficacio us antagonists were methiothepin and tricyclic antipsychotic drugs (cl ozapine, amitriptyline and nortryptyline). The pharmacological profile defined by both functional studies (cAMP level) and binding experimen ts ([I-125]-LSD binding), and its localization in striatal neurones ar e in favour of the presence of the recently cloned 5-HT6 receptor in t hese cells.