Meal pattern of male rats maintained on histidine-, leucine-, or tyrosine-supplemented diet.
OBJECTIVE
Food intake is known to be affected by macronutrient composition of the diet, and protein manipulation has been reported to alter food intake, but the effect of individual amino acids on eating behavior has not been fully studied. This study investigated the effect of diet supplementation with three individual amino acids on meal pattern in male rats.


METHODS
Thirty-two Sprague-Dawley rats were randomly divided into four equal groups and fed control diet or histidine (5%)-, leucine (5%)-, or tyrosine (5%)-supplemented diet for 2 weeks and were monitored for their meal pattern.


RESULTS
Total food intake and feeding rate of the different groups were not affected, although other components of meal pattern were altered. Histidine supplementation reduced diurnal meal size by 42% (p < 0.05), whereas that of leucine increased nocturnal meal size by approximately 35% (p < 0.05). Tyrosine supplementation increased food intake of the nocturnal period and decreased that of the diurnal period. Both histidine and tyrosine supplementation elevated fasting plasma insulin levels and suppressed fasting glucose significantly.


CONCLUSIONS
Individual amino acids were found to alter meal pattern differently. Further investigations are required to dissect the involvement of central and peripheral factors in these alterations.
Bassil
Maya S
MS
Department of Nutrition and Food Sciences, Faculty of Agricultural and Food Sciences, American University of Beirut, P.O. Box 11-0236, Beirut, Lebanon.
Hwalla
Nahla
N
Obeid
Omar A
OA
D000818:Animals; D001786:Blood Glucose / Q000032:analysis; D001835:Body Weight; D004032:Diet; D019587:Dietary Supplements; D004435:Eating / Q000187:drug effects; D005247:Feeding Behavior / Q000502:physiology*; D006639:Histidine / Q000008:administration & dosage* / Q000097:blood; D007328:Insulin / Q000097:blood; D007930:Leucine / Q000008:administration & dosage* / Q000097:blood; D008297:Male; D051381:Rats; D017207:Rats, Sprague-Dawley; D014443:Tyrosine / Q000008:administration & dosage* / Q000097:blood
D001786:Blood Glucose; D007328:Insulin; D014443:Tyrosine; D006639:Histidine; D007930:Leucine