Brain levels of amines and amino acids in taste aversion-prone and -resistant rats.
Possible biological contributions to taste aversion (TA) conditionability were explored by comparing whole-brain levels of five neurotransmitter amines and 14 common amino acids within TA-prone (TAP) and TA-resistant (TAR) rats. The selectively bred strains had been developed via 22 generations of bidirectional nonsibling matings based on susceptibility to cyclophosphamide-induced conditioned TAs. The target substances were separated by HPLC and were measured by electrochemical or fluorometric procedures. The TAP brains had higher levels of serotonin (5-HT) and lower levels of norepinephrine (NE) than TAR brains. No strain differences were found with respect to dihydroxyphenylalanine (DOPAC), dopamine (DA), or 5-hydroxyindoleacetic acid (5-HIAA). Among amino acids, TAP rats had lower levels of lysine than TARs: no other differences were detected. Therefore, higher levels of 5-HT and lower levels of NE and lysine were associated with enhanced TA conditionability. The 5-HT and NE results extend prior indications of their central neurotransmitter TA involvements. The functional role of lysine in TA or other brain functions remains obscure.
Orr
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Psychology and Neurology Research Department, Veterans Affairs Medical Center, Augusta, GA 30910.
Walters
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Carl
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Elkins
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D000588:Amines / Q000378:metabolism*; D000596:Amino Acids / Q000378:metabolism*; D000818:Animals; D001362:Avoidance Learning / Q000502:physiology*; D001921:Brain / Q000502:physiology*; D003214:Conditioning, Classical / Q000502:physiology*; D005260:Female; D008297:Male; D051381:Rats; D011919:Rats, Inbred Strains; D012641:Selection, Genetic; D013045:Species Specificity; D013649:Taste / Q000235:genetics / Q000502:physiology*
D000588:Amines; D000596:Amino Acids