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Titolo:
Serum leptin concentrations, luteinizing hormone and growth hormone secretion during feed and metabolic fuel restriction in the prepuberal gilt
Autore:
Barb, CR; Barrett, JB; Kraeling, RR; Rampacek, GB;
Indirizzi:
ARS, USDA, Russell Agr Res Ctr, Athens, GA 30604 USA ARS Athens GA USA 30604 , USDA, Russell Agr Res Ctr, Athens, GA 30604 USA Univ Georgia, Athens, GA 30602 USA Univ Georgia Athens GA USA 30602Univ Georgia, Athens, GA 30602 USA
Titolo Testata:
DOMESTIC ANIMAL ENDOCRINOLOGY
fascicolo: 1, volume: 20, anno: 2001,
pagine: 47 - 63
SICI:
0739-7240(200101)20:1<47:SLCLHA>2.0.ZU;2-Z
Fonte:
ISI
Lingua:
ENG
Soggetto:
IGF-BINDING-PROTEINS; CENTRAL NEURAL NETWORKS; OB GENE-EXPRESSION; FREE FATTY-ACIDS; FACTOR-I; ADIPOSE-TISSUE; SOMATOMEDIN-C; MESSENGER-RNA; OBESE GENE; ANTERIOR-PITUITARY;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Agriculture,Biology & Environmental Sciences
Life Sciences
Citazioni:
71
Recensione:
Indirizzi per estratti:
Indirizzo: Barb, CR ARS, USDA, Russell Agr Res Ctr, Athens, GA 30604 USA ARS Athens GA USA 30604 ussell Agr Res Ctr, Athens, GA 30604 USA
Citazione:
C.R. Barb et al., "Serum leptin concentrations, luteinizing hormone and growth hormone secretion during feed and metabolic fuel restriction in the prepuberal gilt", DOM ANIM EN, 20(1), 2001, pp. 47-63

Abstract

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 +/- 1kg body weight (BW) and 130 d of age were used. All pigs were fed ad libitum. On the day of the EXP, feed was removed from four of the pigs at 0800 (time = 0) and pigs remained without feed for 28 hr. Blood samples were collected every 10 min from zero to 4 hr = Period (P) 1, 12 to 16 hr = P 2, and24 to 28 hr = P 3 after feed removal. At hr 28 fasted animals were presented with feed and blood samples collected for an additional 2 hr = P 4. EXP II, gilts, averaging 140 d of age (n = 15) and which had been ovariectomized, were individually penned in an environmentally controlled building and exposed to a constant ambient temperature of 22 C and 12:12 hr light: dark photoperiod. Pigs were fed daily at 0700 hr. Gilts were randomly assigned tothe following treatments: saline (S, n = 7), 100 (n = 4), or 300 (rr = 4) mg/kg BW of 2-deoxy-D-glucose (2DG), a competitive inhibitor of glycolysis,in saline iv. Blood samples were collected every 15 min for 2 hr before and 5 hr after treatment. Blood samples from EXP I and II were assayed for LH, GH and leptin by RTA. Selected samples were quantified for glucose, insulin and free fatty acids (FFA). In EXP I, fasting reduced (P < 0.04) leptin pulse frequency by P 3. Plasma glucose concentrations were reduced (P < 0.02) throughout the fast compared to fed animals, where as serum insulin concentrations did not decrease (P < 0.02) until P 3. Serum FFA concentrations increased (P < 0.02) by P 2 and remained elevated. Subcutaneous back fat thickness was similar among pigs. Serum IGF-I concentration decreased (P < 0.01) by P 2 in fasted animals compared to fed animals and remained lower through periods 3 and 4. Serum LH and GH concentrations were not effected by fast. Realimentation resulted in a marked increase in serum glucose (P < 0.02), insulin (P < 0.02), serum GH (P < 0.01) concentrations and leptin pulsefrequency (P < 0.01). EXP II treatment did not alter serum insulin levels but increased (P < 0.01) plasma glucose concentrations in the 300 mg 2DG group. Serum leptin concentrations were 4.0 +/- 0.1, 2.8 +/- 0.2, and 4.9 +/-0.2 ng/ml for S, 100 and 300 mg 2DG pigs respectively, prior to treatment and remained unchanged following treatment. Serum IGF-I concentrations werenot effected by treatment. The 300 mg dose of 2DG increased (P < 0.0001) mean CH concentrations (2.0 +/- 0.2 ng/ml) compared to S (0.8 +/- 0.2 ng/ml)and 100 mg 2DG (0.7 +/- 0.2 ng/ml). Frequency and amplitude of GH pulses were unaffected. However, number of LH pulses/5 hr were decreased (P < 0.01)by the 300 mg dose of 2DG (1.8 +/- 0.5) compared to S (4.0 +/- 0.4) and the 100 mg dose of 2DG (4.5 +/- 0.5). Mean serum LH concentrations and amplitude of LH pulses were unaffected. These results suggest that acute effects of energy deprivation on LH and GH secretion are independent of changes in serum leptin concentrations. (C) 2001 Elsevier Science Inc. All rights reserved.

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Documento generato il 25/01/20 alle ore 16:14:42