Comparison of the olfactory responses to amino acids obtained from receptor and bulbar levels in a marine teleost

Abstract

Comparison of the olfactory responses to amino acids was made between electro-olfactogram (EOG) and induced bulbar electroencephalogram (EEG) in a marine teleost, red sea bream (Pargus major). The increase of the magnitude of EOG responses to five amino acids (L-glutamine, L-alanine, L-methionine, L-phenylalanine and L-aspartic acid) was shown to have exponential functions against logarithmic increase of the stimulus concentration within the range tested (10(-5) to 10(-2) M), and were found to have similar exponents ranging from 0.21 to 0.25. In EEG, dose-response curves for six amino acids (L-glutamine, L-alanine, L-arginine, L-methionine, L-serine and glycine) showed two different functions within the range tested (10(-5) to 10(-2) M). Against logarithmic increase of the stimulus concentration, responses increased exponentially for L-glutamine and L-arginine, and sigmoidally for L-alanine, L-methionine, L-serine and glycine, and even in the exponential functions exponents showed considerable diversity (0.12 to 0.21). Comparison of relative stimulatory effectiveness of amino acids between the two responses (EOG vs. EEG) revealed that in general they are similar. But a considerable difference was also found in L-glutamic acid which was more effective in producing EOG than EEG.