Amino acid imbalance, a nutritional model: serotonin3 mediation of aversive responses.
The feeding responses to essential dietary amino acid (AA) disproportion have been useful in nutritional studies. These responses involve first: recognition of the imbalance and second: rejection of the diet, likely via development of a learned aversion. In the rat, we have studied the role of the limiting AA and protein synthesis in the recognition phase by replacement of the limiting AA into a brain area essential for the initial depressed feeding response. We have also reported a reciprocal relationship between serotonin (5HT) activity and intake of imbalanced diets. High doses of the 5HT3 receptor antagonist, ICS 205-930 (ICS; 9 mg/kg IP), restored food intake to 85% or more of control intake. In the present experiments, similar treatment with ICS blocked the classical conditioned taste aversion to a saccharin solution paired with lithium chloride. These results suggest that the increased intake of AA imbalanced diets after ICS may be due to 5HT-mediated blockade of a learned aversion.
Gietzen
D W
DW
Department of Physiological Science, School of Veterinary Medicine, University of California, Davis 95616.
Duke
C M
CM
Hammer
V A
VA
D000596:Amino Acids / Q000502:physiology*; D000818:Animals; D001070:Appetitive Behavior / Q000502:physiology; D001362:Avoidance Learning / Q000502:physiology*; D001921:Brain / Q000502:physiology; D003214:Conditioning, Classical / Q000502:physiology*; D005518:Food Preferences / Q000502:physiology*; D008297:Male; D009752:Nutritional Status / Q000502:physiology*; D009753:Nutritive Value; D051381:Rats; D011919:Rats, Inbred Strains; D017459:Receptors, Amino Acid; D011956:Receptors, Cell Surface / Q000502:physiology; D011985:Receptors, Serotonin / Q000502:physiology*; D012701:Serotonin / Q000502:physiology*; D013649:Taste / Q000502:physiology*
D000596:Amino Acids; D017459:Receptors, Amino Acid; D011956:Receptors, Cell Surface; D011985:Receptors, Serotonin; D012701:Serotonin