INDUCTION OF HYPERTREHALOSEMIA BY EXCITATION IN PERIPLANETA-AMERICANA

An excitation-induced hypertrehalosemic (EXIT) response has been demostrated in the American cockroach, Periplaneta americana. The response occurs in normal insects and in insects that were ligated at the neck 24 hr prior to experimentation. Several known and putative insect neurotransmitters were tested for their ability to elicit rapidly a hypertrehalosemic state in the cockroach. Octopamine was the most effective hypertrehalosemic agent, and produced a 100% increase in haemolymph trehalose levels within 15 min of being injected into the haemocoel. Less pronounced hypertrehalosemic responses were obtained with dopamine and tyramine, but not with synephrine or 5-hydroxytryptamine. Hypertrehalosemia was observed also with normetanephrine, but not with isoproterenol. A slight inhibition of the EXIT response occurred with the β-blocking agents, propranolol and dichloroisoproterenol, but the monoamine oxidase inhibitors, iproniazid phosphate and nialamide, were without effect. It is suggested that the EXIT-response may be one of several octopamine-mediated responses to excitation in the insect. © 1979.