PHARMACOLOGICAL PROFILE OF OCTOPAMINE AND 5HT RECEPTORS ON THE LATERAL OVIDUCTS OF THE COCKROACH, PERIPLANETA-AMERICANA

The effects of the amines 5HT and octopamine on the myogenic activity of Periplaneta americana (L.) oviducts and the pharmacological profile of octopamine and 5HT receptors on the lateral oviducts have been det ermined. Application of 5HT to the oviducts resulted in a dose-depende nt increase in basal tonus and amplitude of contractions. Antagonist s tudies revealed that the 5HT receptor on the cockroach oviduct most re sembles the mammalian 5HT(2) receptor. Application of octopamine resul ted in a decrease in basal tonus and had a biphasic effect on the ampl itude of contractions, being stimulatory at low doses and inhibitory a t higher ones. The inhibitory effects of octopamine appear to be media ted via cAMP and are blocked by antagonists which indicate that the oc topamine receptor is of the octopamine-2 type. (C) 1995 Wiley-Liss, In c.