citralva and isovaleric-acid

The ability of the turtle olfactory system to discriminate between various odorants that increase levels of adenosine 3',5'-cyclic monophosphate (cAMP) and inositol trisphosphate (IP3) in the olfactory bulb was examined by the cross-adaptation technique and analyzed by multidimensional scaling. The mean values of the degree of discrimination among the IP3-increasing odorants were higher than those among the cAMP-increasing odorants, and were similar to those between cAMP- and IP3-increasing odorants, suggesting that the features of the receptors of cAMP-increasing odorants are different from those which respond to IP3-increasing odorants. Analysis by multidimensional scaling suggested that differences in second messenger pathways are not related to detecting odor quality in the turtle olfactory system.

Topics: Acyclic Monoterpenes; Animals; Cyclic AMP; Discrimination, Psychological; Hemiterpenes; Inositol 1,4,5-Trisphosphate; Nitriles; Odorants; Olfactory Bulb; Pentanoic Acids; Pyrrolidines; Receptors, Odorant; Terpenes; Turtles

Odorant responses of isolated olfactory neurons from the toad Caudiverbera caudiverbera were monitored by using patch-clamp techniques. Depending on the stimulus, the same neuron responded with an increase or a decrease in action potential firing. Odorants that activate the cAMP cascade in olfactory cilia increased electrical activity, caused membrane depolarization, and triggered inward currents. In contrast, odorants that do not activate the cAMP cascade inhibited electrical activity, produced membrane hyperpolarization, and activated outward currents in a dose-dependent fashion. Such currents were carried by K+ and blocked by tetraethylammonium. Similar currents were recorded from Xenopus laevis. Our results suggest that this K+ current is responsible for odorant-induced inhibition of action potential firing in olfactory neurons.

Topics: Acyclic Monoterpenes; Animals; Anura; Dose-Response Relationship, Drug; Electric Stimulation; Ethylamines; Hemiterpenes; In Vitro Techniques; Membrane Potentials; Nitriles; Odorants; Olfactory Receptor Neurons; Pentanoic Acids; Potassium Channels; Pyrazines; Terpenes; Xenopus laevis

Using primary olfactory neuronal cultures, we have demonstrated rapid, potent increases in cAMP levels and adenylate cyclase [AC; ATP pyrophosphate-lyase (cyclizing), EC 4.6.1.1] activity in response to odorants. Isobutyl-methoxypyrazine is active at 1 nM. Odorant enhancement is dependent on Ca2+ concentration with maximal effects at 10-100 microM. Biphasic temporal and concentration-related effects occur with all odorants. All odorants examined elicit desensitization with AC responses abolished when odorants are reapplied immediately after removal. When reapplied 1 min after removal, odorants elicit an AC response greater than on first exposure, implying a cellular "memory" for odorants.

Topics: Adenylyl Cyclases; Animals; Cells, Cultured; Cyclohexane Monoterpenes; Cyclohexanols; Enzyme Activation; Hemiterpenes; Kinetics; Monoterpenes; Neurons; Nitriles; Odorants; Olfactory Bulb; Pentanoic Acids; Pyrazines; Rats; Terpenes