Effects of dietary protein alterations on circadian rhythms of gastrointestinal peptides in rats

• Published in: Digestive diseases and sciences Vol. 35; no. 10; p. 1265
• Main Authors: Pasley, J.N. (University of Arkansas for Medical Sciences, Little Rock, AR), Rayford, P.L
• Format: Journal Article
• Language: English
• Published: United States 01.10.1990
• Subjects: Animals; APPAREIL DIGESTIF; Cholecystokinin - blood; Circadian Rhythm - drug effects; Circadian Rhythm - physiology; DIETA; Dietary Proteins - pharmacology; Female; GASTRINA; GASTRINE; Gastrins - blood; HORMONAS GASTROINTESTINALES; HORMONE GASTROINTESTINALE; Male; PROTEINAS; PROTEINE; RAT; RATA; Rats; Rats, Inbred Strains; REGIME ALIMENTAIRE; RITMOS BIOLOGICOS; RYTHME BIOLOGIQUE; Sex Factors; SEXE; SEXO; SISTEMA DIGESTIVO
• ISSN: 0163-2116; 1573-2568
• DOI: 10.1007/BF01536417

Altered protein diets and circadian rhythms of gastrin and cholecystokinin (CCK) were investigated in 126 male and 126 female Sprague-Dawley rats acclimated for two weeks to a 12:12 hr light-dark cycle. Rats were divided equally and fed low-protein (8%), high-protein (64%) or normal protein (27%) diets for four weeks. All animals were fasted for 24 hr prior to blood collections. Blood samples were collected at 4-hr intervals for 24 hr for determination of plasma gastrin and CCK using specific radioimmunoassays. A significant rhythm for gastrin was detected in males on normal and low-protein diets (P 0.03) and in females on low-protein diets (P .02). A significant rhythm for CCK was detected (P 0.05) in rats of both sexes fed normal and high-protein diets. Mean plasma levels of both peptides were lower in females than males. In a separate study, food intake and body weight were monitored in male rats receiving the three diets over 21 days. Animals on the low-protein diet exhibited reduced food intake and body weight compared to rats fed the normal or high-protein diets