Activation of the sensory current in salamander olfactory receptor neurons depends on a G protein-mediated cAMP second messenger system.
Olfactory receptor neurons respond to odor stimulation with an inward cationic current. Under whole-cell patch clamp, individual, isolated olfactory receptors were exposed to pharmacological agents known to interact with distinct enzymes in a putative second messenger cascade, and their response to odors was measured. IBMX prolonged the odor-evoked current and also reduced its amplitude. cAMP and cGMP induced a current electrically identical to the odor current, but the current showed desensitization only with cAMP. GTP-gamma-s prolonged and GDP-beta-s interfered with the odor-evoked current. The long latency seen in the odor response appears to be mainly due to the loading of the G protein and secondarily to the requirement for cAMP accumulation. The main source of the response decay appears to be cyclic nucleotide hydrolysis.
Firestein
S
S
Section of Neurobiology, Yale University Medical School, New Haven, Connecticut 06510.
Darrow
B
B
Shepherd
G M
GM
D015056:1-Methyl-3-isobutylxanthine / Q000494:pharmacology; D000818:Animals; D000242:Cyclic AMP / Q000494:pharmacology / Q000502:physiology*; D006152:Cyclic GMP / Q000031:analogs & derivatives / Q000494:pharmacology / Q000502:physiology; D004594:Electrophysiology; D019204:GTP-Binding Proteins / Q000502:physiology*; D016244:Guanosine 5'-O-(3-Thiotriphosphate) / Q000031:analogs & derivatives / Q000494:pharmacology; D006868:Hydrolysis; D009474:Neurons / Q000502:physiology; D009812:Odorants; D010727:Phosphoric Diester Hydrolases / Q000502:physiology; D011494:Protein Kinases / Q000502:physiology*; D015290:Second Messenger Systems / Q000187:drug effects / Q000502:physiology*; D011984:Sensory Receptor Cells / Q000502:physiology*; D012903:Smell / Q000502:physiology*; D014562:Caudata / Q000502:physiology*
C034882:guanosine 5'-O-(1-thiotriphosphate); C034883:guanosine 5'-O-(2-thiotriphosphate); C016276:8-bromocyclic GMP; D016244:Guanosine 5'-O-(3-Thiotriphosphate); D000242:Cyclic AMP; D011494:Protein Kinases; D010727:Phosphoric Diester Hydrolases; D019204:GTP-Binding Proteins; D006152:Cyclic GMP; D015056:1-Methyl-3-isobutylxanthine