Independent ingestion and microstructure of feeding patterns in infant rats lacking CCK-1 receptors

• Published in: American journal of physiology. Regulatory, integrative and comparative physiology Vol. 290; no. 1; pp. R208 - R218
• Main Authors: Blumberg, S, Haba, D, Schroeder, M, Smith, G. P, Weller, A
• Format: Journal Article
• Language: English
• Published: United States 01.01.2006
• Subjects: Aging; Animals; Animals, Newborn; Diet; Feeding Behavior - physiology; Rats; Rats, Inbred OLETF; Rats, Long-Evans; Receptor, Cholecystokinin A - deficiency; Receptor, Cholecystokinin A - genetics; Receptor, Cholecystokinin A - metabolism; Time Factors; Weight Gain
• ISSN: 0363-6119; 1522-1490
• DOI: 10.1152/ajpregu.00379.2005

1 Developmental Psychobiology Laboratory, Department of Psychology and the Gonda (Goldschmeid) Brain Research Center, Bar Ilan University, Ramat-Gan, Israel; and 2 Department of Psychiatry, Joan and Sanford I. Weill Medical College of Cornell University and New York-Presbyterian Hospital, Westchester Division, White Plains, New York Submitted 31 May 2005 ; accepted in final form 26 July 2005 Otsuka Long-Evans Tokushima fatty (OLETF) rats are a strain of Long-Evans Tokushima Otsuka (LETO) rats that do not express CCK-1 receptors, developing in adulthood, hyperphagia, obesity, and non-insulin-dependent diabetes mellitus (NIDDM). We examined weight gain and meal patterns during a 30-min independent ingestion test on postnatal days 2–4 and again on days 9–11 in OLETF and LETO rat pups. OLETF pups were significantly heavier compared with their LETO controls at both ages, and they consumed significantly more of the sweet milk diet. The difference in intake can be attributed to a significant increase in meal size and duration. Number of clusters and bursts of licking within a meal were greater in OLETF rat pups, with no difference between strains in burst and cluster size. Interlick interval (ILI) was not significantly different between OLETF and LETO pups. This measure decreased on days 9–11 compared with days 2–4 in both strains. Latency to start feeding was significantly shorter on days 2–4 in OLETF vs. LETO pups, but this difference disappeared at the second test at the older age. Two- to four-day-old OLETF pups consumed a larger volume of milk during the first minute of feeding, and their initial lick rate and decay of lick rate were significantly larger compared with their LETO controls. Lack of CCK-1 receptors, or other OLETF-related abnormalities, therefore, resulted in a satiation deficit, leading to increased meal size, hyperphagia, and increased weight gain as early as 2–4 postnatal days. cholecystokinin; obesity; independent ingestion; meal-patterns; Otsuka Long-Evans Tokushima fatty rats; infant rats Address for reprint requests and other correspondence: A. Weller, Dept. of Psychology, Bar Ilan Univ., Ramat-Gan 52900, Israel (e-mail: weller{at}mail.biu.ac.il )