Effects of alpha-kainic acid, domoic acid and their derivatives on a molluscan giant neuron sensitive to beta-hydroxy-L-glutamic acid.
No identifiable giant neuron of an African giant snail (Achatina fulica Férussac) was found to be sensitive to L-glutamic acid (L-Glu). However, some of them, including the RAPN (right anterior pallial neuron), were sensitive to beta-hydroxy-L-glutamic acid (L-BHGA). The effects on RAPN of alpha-kainic acid (alpha-KA), domoic acid (DMA) and their derivatives, which are structurally related to L-Glu and L-BHGA, were examined in order to elucidate the chemical structures necessary to produce the effects under study. Erythro- and threo-L-BHGA showed similar excitatory effects on RAPN (the minimal effective concentration (M.E.C.): 10(-4)M). alpha-KA, alpha-KA methylketone and DMA also showed marked excitatory effects on the same neuron (M.E.C.: 3 X 10(-5)-10(-4)M). The two derivatives of alpha-KA, (2S, 3S, 4S)-2-carboxy-4-(1-methyl-5(R)-hydroxymethyl-l(Z),3(Z)-hexadienyl) pyrrolidine-3-acetic acid and (2S,3S,4S)-2-carboxy-4-(1-methyl-5(R)-hydroxymethyl-1(Z),3(E)-hexadie nyl) pyrrolidine-3-acetic acid, also had excitatory effects (M.E.C.: about 3 X 10(-4)M) which were somewhat less potent than those of L-BHGA, alpha-KA etc. However, alpha-allo-KA, alpha-allo-KA methylketone and dihydro-alpha-KA even at a high concentration of 4.7 X 10(-4)M, had no effect on RAPN. From the results obtained, it appears likely that the seven excitatory compounds mentioned above act on the common receptors of the RAPN neuromembrane, due to similarities in their structures and in the type of excitation caused by these compounds.
D000818:Animals; D005971:Glutamates / Q000494:pharmacology*; D018698:Glutamic Acid; D066298:In Vitro Techniques; D007608:Kainic Acid / Q000031:analogs & derivatives / Q000494:pharmacology*; D008564:Membrane Potentials / Q000187:drug effects; D009474:Neurons / Q000187:drug effects*; D011759:Pyrrolidines / Q000494:pharmacology*; D012908:Snails; D013237:Stereoisomerism
D005971:Glutamates; D011759:Pyrrolidines; D018698:Glutamic Acid; C011859:hydroxyglutamic acid; C012301:domoic acid; D007608:Kainic Acid