Cyclic Nucleotide-Dependent Pathway Is One of Mechanisms of Olfactory Transduction of Amino Acid Signal in the Carp Cyprinus carpio

The mechanism of the amino acid signal transduction in the olfactory receptor cells (ORC) of the carp Cyprinus carpio was studied using extracellular recording of the electroolfactogram (EOG) under the conditions of action of various pharmacological substances affecting selectively individual chains of inositol- and cyclic nucleotide-dependent pathways of the transduction or inhibiting proteinkinase C. The amino acid signal transduction at low concentrations of the odorant serine (1–10 µM) has been shown to occur via the inositol-dependent pathway. At high concentrations of serine (1 mM), the proteinkinase C-mediated adenylyl cyclase pathway is involved in the transduction process. In some cases (10% of the fish), serine and cAMP evoke a biphasic EOG with the characteristic positive component following the negative wave. According to the results of pharmacological analysis, the transduction process in ORC generating such EOG uses only the cyclic nucleotide-dependent pathway.