(1) Electro-olfactogram recording was used to determine whether the olfactory epithelium of adult sea lamprey is specifically sensitive to bile acids, some of which have been hypothesized to function as pheromones. Ten bile acids were selected from 38 which had already been pre-screened for olfactory activity. These compounds were first tested on their own, then as adapting stimuli, and finally as components of mixtures (2) The lamprey-specific bile acids, petromyzonol sulfate and allocholic acid, were the most potent compounds tested. Five other bile acids were also detectable at picomolar concentrations. Petromyzonol sulfate had a distinctive dose-response curve. (3) Cross-adaptation demonstrated that sensitivity to bile acids is attributable to at least four independent classes of olfactory receptor sites and that both the nature and position of conjugating group(s) are critical to receptor specificity. Notably, petromyzonol sulfate has its own highly specific and independent receptor site. The situation for unconjugated bile acids was more complex and there appeared to be several sub-classes of receptor sites for these compounds. (4) Mixture studies largely confirmed the cross-adaptation results, describing receptor site independence for the same four sets of odorants. Mixture enhancement was also seen when expected and there was no evidence of mixture suppression. (5) Together, these data demonstrate that conspecific bile acids are discriminated by the olfactory epithelium of the sea lamprey, supporting the possibility that these compounds may function as migratory pheromones.
|Original language||English (US)|
|Number of pages||10|
|Journal||Journal of Comparative Physiology - A Sensory, Neural, and Behavioral Physiology|
|State||Published - Apr 1997|
Bibliographical noteFunding Information:
Acknowledgements We thank Mr. Peter Maniak for his assistance in EOG recording, Dr. James Seelye of US National Biological Survey and Mr. Rodney MacDonald of Canada Department of Fisheries and Ocean for arranging the capture and shipping of animals used in the experiments, and Dr. William Elliott of St. Louis University Medical School for supplying authentic allo-cholic acid. Dan Gallaher and several anonymous reviewers provided helpful criticism. This study was founded by Minnesota Sea Grant, the Great Lakes Fishery Commission and the Minnesota Agricultural Experiment Station. It is the result of research sponsored by the NOAA office of Sea Grant, United States Department of Commerce, under grant no. NA46-RG 0101. Reprint number JR 427. The US Government is authorized to reproduce and distribute reprints for government purposes, not withstanding any copyright notation that may appear herein.
- Bile acid