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The present study compared the metabolic response to acute feed deprivation in ovariectomized prepuberal (P; n = 6), 62 +/- 2 kg BW, and mature (M; n = 6) gilts, 124 +/- 4 kg BW. Blood was collected at 1, 2, 3, 4, 6, 8, 12, 16, 20, 24, 28, 32, 40, and 48 h after initiation of feeding. Samples were quantified for glucose, insulin, free fatty acids (FFA),(More)
This study describes the distribution of catecholaminergic neurons in the hypothalamus and the pituitary gland of the domestic pig, Sus scrofa, an animal that is widely used as an experimental model of human physiology in addition to its worldwide agricultural importance. Hypothalamic catecholamine neurons were identified by immunocytochemical staining for(More)
Much effort has focused recently on understanding the role of leptin, the obese gene product secreted by adipocytes, in regulating growth and reproduction in rodents, humans and domestic animals. We previously demonstrated that leptin inhibited feed intake and stimulated growth hormone (GH) and luteinizing hormone (LH) secretion in the pig. This study was(More)
The goal of this study was to pharmacologically block central nervous system (CNS) input to gonadotropes in mature ovariectomized gilts to determine the direct actions of estradiol (E2) on pituitary LH release when given at a dose sufficient to elicit a gonadotropin surge. Feeding AIMAX [N-methyl-N'-(1-methyl-2-propenyl)1,2-hydrazinedicarbothioamide; 125(More)
Two experiments (EXP) were conducted to test the hypothesis that porcine leptin affects GH, insulin-like growth factor-I (IGF-I), insulin, thyroxine (T4) secretion, and feed intake. In EXP I, prepuberal gilts received intracerebroventricular (i.c.v.) leptin injections. Blood was collected every 15 min for 4 hr before and 3 hr after i.c.v. injections of 0.9%(More)
Treatment with ACTH (100 i.u.) or hydrocortisone acetate (250 mg) twice daily for 12 days to increase cortisol concentrations blocked ovulation in all gilts. The preovulatory surge of LH was also blocked in the treated gilts. Oestrous cycle length and number of days in oestrus were similar for all treatments except that in one of the 2 experiments ACTH(More)
Two experiments were conducted to determine 1) the effect of acute feed deprivation on leptin secretion and 2) if the effect of metabolic fuel restriction on LH and GH secretion is associated with changes in serum leptin concentrations. Experiment (EXP) I, seven crossbred prepuberal gilts, 66 +/- 1 kg body weight (BW) and 130 d of age were used. All pigs(More)
The influence of glucose and free fatty acids (FFA) on LH and GH secretion from porcine pituitary cells was examined in culture. Cells were challenged with 10(-9), 10(-8), or 10(-7) M GnRH; 10(-9), 10(-8), or 10(-7) M [Ala15]-h growth hormone-releasing factor-(1-29)NH2 (GRF); 10(-3) or 10(-5) M forskolin; glucose (100, 300, or 600 mg/dL); and oleic or(More)
Seven sows were placed into one of two environmental chambers at 22 C, 5 d prior to farrowing. On day 9 of lactation, one chamber was changed to 30 C (n = 4) and the other remained at 22 C (n = 3). On days 24 and 25, blood samples were collected every 15 min for 9 hr and 7 hr, respectively. On day 24, thyrotropin releasing hormone (TRH) and gonadotropin(More)