DIFFERENCE IN BEHAVIOR BETWEEN RESPONSES TO FORSKOLIN AND GENERAL ODORANTS IN TURTLE VOMERONASAL ORGAN

To elucidate the signal transduction mechanisms in the turtle vomerona sal receptor neurons, the effects of forskolin, changes in mucosal Ca2 + concentrations and ruthenium red on the responses of the accessory o lfactory bulb to general odorants were examined. Forskolin elicited a large response, suggesting that there are cAMP-gated channels in the v omeronasal neurons. On the other hand, the dependence of the responses to general odorants on Ca2+ concentrations was different from that of the response to forskolin. A large response to an odorant (n-amyl ace tate) appeared after the cAMP-mediated pathway was fully desensitized by application of 50 mu M forskolin. These results suggest that the cA MP-mediated pathway does not contribute significantly to generation of the response to general odorants. A concentration of 50 mu M rutheniu m red significantly reduced the responses to n-amyl acetate alone and after 50 mu M forskolin desensitization, suggesting that the inositol triphosphate-mediated pathway contributes partly to generation of the responses to general odorants in the vomeronasal neurons.