Pair feeding-mediated changes in metabolism: stress response and pathophysiology in insulin-resistant, atherosclerosis-prone JCR:LA-cp rats

• Published in: American journal of physiology: endocrinology and metabolism Vol. 294; no. 6; pp. E1078 - E1087
• Main Authors: Russell, James C, Proctor, Spencer D, Kelly, Sandra E, Brindley, David N
• Format: Journal Article
• Language: English
• Published: United States American Physiological Society 01.06.2008
• Subjects: Animals; Aorta, Thoracic - physiology; Blood Glucose - metabolism; Body Weight - physiology; Disease Models, Animal; Eating - physiology; Endocrinology; Fatty Acids, Nonesterified - blood; Fatty Acids, Nonesterified - metabolism; Food Deprivation - physiology; Genes; Histocytochemistry; Insulin; Insulin - blood; Insulin - metabolism; Insulin Resistance - physiology; Male; Metabolic Syndrome - metabolism; Metabolism; Muscle Contraction - drug effects; Muscle Contraction - physiology; Myocardium - pathology; Pathology; Phenylephrine - pharmacology; Rats; Restraint, Physical - physiology; Rodents; Stress, Physiological - metabolism; Triglycerides - blood; Triglycerides - metabolism; Vasoconstrictor Agents - pharmacology
• ISSN: 0193-1849; 1522-1555
• DOI: 10.1152/ajpendo.90257.2008

1 Metabolic and Cardiovascular Diseases Laboratory, Alberta Institute for Human Nutrition; and 2 Department of Biochemistry (Signal Transduction Research Group), University of Alberta, Edmonton, Alberta, Canada Submitted 27 February 2008 ; accepted in final form 3 April 2008 Rats of the JCR:LA-cp strain, which are homozygous for the cp gene ( cp / cp ), are obese, insulin-resistant, and hyperinsulinemic. They exhibit associated micro- and macrovascular disease and end-stage ischemic myocardial lesions and are highly stress sensitive. We subjected male cp / cp rats to pair feeding (providing the rats each day with the amount of food eaten by matched freely fed animals), a procedure that alters the diurnal feeding pattern, leading to a state of intermittent caloric restriction. Effects on insulin, glucose, and lipid metabolism, response to restraint stress, aortic contractile/relaxant response, and myocardial lesion frequency were investigated. Pair-fed young (12-wk-old) cp / cp rats had lower insulin and glucose levels (basal and following restraint), consistent with increased insulin sensitivity, but a greater increase in plasma nonesterified fatty acids in response to restraint. These effects were unrelated to lipolytic rates in adipose tissue but may be related to reduced fatty acid oxidation in skeletal muscle. Older (24-wk-old) pair-fed cp / cp rats had significantly reduced plasma triglyceride levels, improved micro- and macrovascular function, and reduced severity of ischemic myocardial lesions. These changes indicate a significant amelioration of end-stage disease processes in this animal model and the complexity of metabolic/physiological responses in studies involving alterations in food intake. The effects illustrate the sensitivity of the JCR:LA-cp rat, an animal model for the metabolic syndrome and associated cardiovascular disease, to the environmental and experimental milieu. Similar stress-related mechanisms may play a role in metabolically induced cardiovascular disease in susceptible human beings. metabolic syndrome; stress; fatty acids; vascular function; myocardial lesions Address for reprint requests and other correspondence: J. C. Russell, Alberta Institute for Human Nutrition, 4-10 Agriculture Forestry Centre, Univ. of Alberta, Edmonton, Alberta, T6G 2P5, Canada (e-mail: Jim.Russell{at}ualberta.ca )