Guanosine 3',5'-cyclic monophosphate reduces the response of the Moth's olfactory receptor neuron to pheromone.

The effects of the membrane-permeable dibutyryl guanosine 3', 5'-cyclic monophosphate (db-cGMP) on the bombykol-elicited receptor current and nerve impulse activity were studied using the open sensillum recording technique. db-cGMP was applied to the outer dendritic membrane of the olfactory receptor neuron of the moth Bombyx mori. db-cGMP reduced the amplitude of the overall receptor current activated by a pulse of strong pheromone stimuli as well as diminished the nerve impulse frequency elicited by continuously applied weak pheromone stimuli. The observed inhibition of the response to pheromone was due to size reduction of an elementary receptor current that elicits the nerve impulses and underlies the overall receptor current. It is suggested that cGMP is a factor which may adjust cell sensitivity to odour and play a role in olfactory adaptation.