Neurotransmitter antagonists block some odor responses in olfactory receptor neurons

The first step in olfactory transduction is the recognition of odor molecules by membrane bound receptors belonging to the superfamily of G-protein coupled receptors; other members of this family are involved in neurotransmission. Based on the considerable homology between individual members of this family, we have investigated the ability of well-known neurotransmitter antagonists to block the olfactory response. Adrenergic and muscarinic antagonists were found to block some odor induced currents (45-55%) with an IC50 between 15 and 75 microM. By contrast, antagonists of glutamate and GABA receptors, which do not belong to this receptor superfamily, were ineffective. These results suggest that further pharmacological analysis may be useful for characterizing and classifying the family of odor receptors.