Beta-endorphin and dynorphin abnormalities in rats subjected to exercise and restricted feeding: relationship to anorexia nervosa?
Exercise and the endogenous opioids have been linked to anorexia nervosa. This investigation determined the effects of the weight-loss syndrome induced by voluntary exercise (22.5 h/day) in food-restricted rats (1.5 h/day food access) on the endogenous opioids. The animals were tested under resting-fed and 2-deoxy-D-glucose (2DG) stimulated conditions. Weight-matched, freely fed exercised and ad libitum fed unexercised groups served as controls. Specific opioid abnormalities were found in the syndrome. These included a basal elevation in plasma beta-endorphin, which was abnormally suppressed by 2DG, and 2DG-induced elevations in arcuate hypothalamic beta-endorphin content and supraoptic hypothalamic dynorphin-A content. None of these changes occurred in controls. Finally, it was found that short-term moderate exercise itself chronically reduced adenohypophysial beta-endorphin content and elevated supraoptic dynorphin-A content. The relationship of the syndrome's hyperendorphinism to the hypothalamo-pituitary-adrenal axis and the auto-addiction hypothesis of anorexia nervosa was considered, as was the significance of the supraoptic dynorphin-A abnormality to the hypothalamo-neurohypophysial system. The differential sensitivity of the supraoptic dynorphin-A system compared to the arcuate hypothalamic beta-endorphin system to moderate exercise was also discussed.
Aravich
P F
PF
Department of Anatomy and Neurobiology, Eastern Virginia Medical School, Norfolk 23501.
Rieg
T S
TS
Lauterio
T J
TJ
Doerries
L E
LE
D000818:Animals; D000856:Anorexia Nervosa / Q000378:metabolism*; D001111:Arcuate Nucleus of Hypothalamus / Q000503:physiopathology; D003847:Deoxyglucose / Q000494:pharmacology; D004399:Dynorphins / Q000378:metabolism*; D005508:Food Deprivation / Q000502:physiology*; D008297:Male; D010805:Physical Conditioning, Animal / Q000502:physiology*; D010903:Pituitary Gland, Anterior / Q000187:drug effects / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D013495:Supraoptic Nucleus / Q000503:physiopathology; D001615:beta-Endorphin / Q000378:metabolism*
D001615:beta-Endorphin; D004399:Dynorphins; D003847:Deoxyglucose