Negative feedback potency of estradiol is increased in orchidectomized sheep during chronic nutrient restriction

• Published in: Biology of reproduction 1997-08, Vol.57 (2), p.408-414
• Main Authors: Beckett, J.L, Sakurai, H, Famula, T.R, Adams, T.E
• Format: Article
• Language: English
• Subjects: Animal Nutritional Physiological Phenomena; Animals; AZUCAR EN SANGRE; Biological and medical sciences; Blood Glucose - metabolism; BLOOD LIPIDS; BLOOD SERUM; BLOOD SUGAR; BODY WEIGHT; CARNERO; Estradiol - blood; Estradiol - pharmacology; ESTRADIOL FEEDBACK; ESTROGENOS; Fatty Acids, Nonesterified - blood; Feedback; FEEDING LEVEL; Feeding. Feeding behavior; Follicle Stimulating Hormone - blood; Food Deprivation; FOOD RESTRICTION; FSH; Fundamental and applied biological sciences. Psychology; HEMOLIPIDOS; HFS; HORMONAS; HORMONE; HORMONES; INANICION; INANITION; LIPIDE SANGUIN; Luteinizing Hormone - blood; Luteinizing Hormone - metabolism; Male; MOUTON; NIVEAU D'ALIMENTATION; NIVEL ALIMENTICIO; OESTROGENE; OESTROGENS; Orchiectomy; OVIN; OVINOS; PERDIDA DE PESO; PERTE DE POIDS; PESO CORPORAL; PLANE OF NUTRITION; POIDS CORPOREL; SECRECION; SECRETION; SERUM SANGUIN; SHEEP; Sheep - physiology; STARVATION; SUCRE DU SANG; SUERO SANGUINEO; Vertebrates: anatomy and physiology, studies on body, several organs or systems; WEIGHT LOSSES; WETHERS
• ISSN: 0006-3363; 1529-7268
• DOI: 10.1095/biolreprod57.2.408

The effect of nutrient restriction on serum concentrations of the gonadotropins, on the pattern of LH secretion, and on sensitivity to estradiol (E2) was assessed in orchidectomized sheep (wethers). Thirty-six wethers (initial weight = 42.3 +/- 0.6 kg) were fed to gain, maintain, or lose body weight (feeding groups G, M, and L, respectively; n = 12 wethers/group). After 7 wk of controlled feeding, G, M, and L wethers weighed 57.0 +/- 1.7, 42.5 +/- 0.6, and 36.6 +/- 0.8 kg, respectively. At the end of controlled feeding, serum concentrations of LH and FSH in M and L wethers were significantly higher than levels in G wethers. During Days 51-54 of controlled feeding, six animals from each feeding group received E2 or vehicle as a continuous infusion. The pattern of LH secretion was assessed 48 h after initiation of infusion. Although E2 infusion did not affect (p > 0.05) LH pulse frequency in G and M wethers, pulse frequency was reduced (p < 0.05) in L wethers receiving E2. These data indicate that serum concentrations of gonadotropins are increased in wethers fed to maintain or lose body weight. In addition, the negative feedback potency of E2 is enhanced during prolonged weight loss.