Abstract
Gustatory response of marbled rockfish Sebastiscus marmoratus was recorded from the facial nerve supplying the anterior palate. In amino acids, the lowest threshold was for L-proline at 10-6-10-5 M; in ATP-related substances, the value for inosine was approximately 10-5 M and in organic acids, the value for L-lactic acid was approximately 10-6 M. An almost complete self-adaptation was observed for stimulants after 5 s application. While a weak solution of L-lactic acid as adapting stimulus depressed the response to it completely, it did not appreciably affect the response to 10-times or more concentrated L-lactic acid solution. In contrast to a weak solution, a moderate solution caused a severe depression of the response to stronger solutions, resulting in a shift of the dose-response curve towards a high concentration range. Time for recovery from adaptation differed depending on chemicals and stimulus duration: for 10-4 M L-lactic acid, it took about 2.3 and 4.5 s for 1/2 recovery of response magnitude under unadapted condition from the adaptation after 1 s- and 5 s-stimulation, respectively. L-Lactic acid and L-alanine strongly depressed the response to each other, yielding a rightward shift of the dose-response curve. A similar profound cross-adaptation was also observed between inosine and 5'-inosinic acid. The possible role of gustation is discussed.
