Differences in response to corticotropin-releasing factor after short- and long-term consumption of a high-fat diet.
We previously reported an exaggerated endocrine and weight loss response to stress in rats fed a high-fat (HF) diet for 5 days. Others report blunted stress-induced anxiety in rats made obese on a HF diet. Experiments described here tested whether sensitivity to stress-related peptides was changed in obese and nonobese HF-fed rats. Third ventricle infusion of corticotropin-releasing factor (CRF) in rats made obese on HF diet (40% kcal fat) produced an exaggerated hypophagia, which is thought to be mediated by CRF(2) receptors. Obese rats responded to a lower dose of CRF for a longer time than rats fed a low-fat (LF) diet (12% kcal fat). CRF-induced release of corticosterone, which is thought to be mediated by CRF(1) receptors, was not exaggerated in obese HF-fed rats. In contrast, rats fed HF diet for 5 days showed the same food intake and corticosterone response to CRF as LF-fed rats. CRF mRNA expression in the paraventricular nucleus of the hypothalamus was stimulated by mild stress (ip saline injection and placement in a novel cage) in LF-fed rats but not in rats fed HF diet for 5 days because of a nonsignificant increase in expression in nonstressed HF-fed rats. In addition, nonstressed levels of urocortin (UCN) I mRNA expression in the Edinger-Westphal nucleus were significantly inhibited in HF-fed rats. These data suggest that rats that have become obese on a HF diet show a change in responsiveness to stress peptides, whereas the increased stress response in nonobese HF-fed rats may be associated with changes in basal CRF and UCN I mRNA expression.
Legendre
Ariadne
A
Department of Foods and Nutrition, University of Georgia, Athens, GA 30602, USA. harrisrb@uga.edu
Papakonstantinou
Emilia
E
Roy
Marie-Claude
MC
Richard
Denis
D
Harris
Ruth B S
RB
D000273:Adipose Tissue / Q000502:physiology; D050154:Adiposity / Q000502:physiology; D000818:Animals; D019540:Area Under Curve; D001823:Body Composition / Q000187:drug effects / Q000502:physiology; D001835:Body Weight / Q000502:physiology; D001923:Brain Chemistry / Q000187:drug effects / Q000502:physiology; D003345:Corticosterone / Q000378:metabolism; D003346:Corticotropin-Releasing Hormone / Q000008:administration & dosage / Q000096:biosynthesis / Q000235:genetics / Q000494:pharmacology*; D018076:DNA, Complementary / Q000096:biosynthesis / Q000235:genetics; D004032:Diet; D018752:Diet, Fat-Restricted; D004041:Dietary Fats / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D004435:Eating / Q000187:drug effects; D002149:Energy Intake / Q000187:drug effects; D008297:Male; D009929:Organ Size / Q000502:physiology; D012333:RNA, Messenger / Q000096:biosynthesis / Q000235:genetics; D051381:Rats; D017207:Rats, Sprague-Dawley; D013315:Stress, Psychological / Q000523:psychology; D013997:Time Factors; D054832:Urocortins
D018076:DNA, Complementary; D004041:Dietary Fats; D012333:RNA, Messenger; D054832:Urocortins; D003346:Corticotropin-Releasing Hormone; D003345:Corticosterone