Difference in behavior between responses to forskolin and general odorants in turtle vomeronasal organ.

To elucidate the signal transduction mechanisms in the turtle vomeronasal receptor neurons, the effects of forskolin, changes in mucosal Ca2+ concentrations and ruthenium red on the responses of the accessory olfactory bulb to general odorants were examined. Forskolin elicited a large response, suggesting that there are cAMP-gated channels in the vomeronasal 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 acetate) appeared after the cAMP-mediated pathway was fully desensitized by application of 50 microM forskolin. These results suggest that the cAMP-mediated pathway does not contribute significantly to generation of the response to general odorants. A concentration of 50 microM ruthenium red significantly reduced the responses to n-amyl acetate alone and after 50 microM forskolin desensitization, suggesting that the inositol triphosphate-mediated pathway contributes partly to generation of the responses to general odorants in the vomeronasal neurons.