Endocrinology, Vol 131, 213-220, Copyright © 1992 by Endocrine Society

ARTICLES

Circulating bioactive follicle-stimulating hormone and less acidic follicle-stimulating hormone isoforms increase during experimental induction of puberty in the female lamb

V Padmanabhan, CD Mieher, M Borondy, H I'Anson, RI Wood, TD Landefeld, DL Foster and IZ Beitins
Department of Pediatrics, University of Michigan, Ann Arbor 48109.

The pubertal process with its multifaceted neuroendocrine control provides an excellent model for the study of the regulation of FSH heterogeneity. We tested the hypothesis that during the pubertal transition in the female lamb 1) an increase in both pituitary and circulating bioactive FSH concentrations occur and 2) that the increase in bioactivity is associated with a change in the distribution pattern of both pituitary and circulating FSH isoforms. Pituitary and serum immunoreactive (I), and bioactive (B, Sertoli cell bioassay) FSH concentrations were measured in six prepubertal lambs (18 +/- 1 weeks, 29.9 +/- 2.8 kg body weight; mean +/- SE) and compared to those of six others (24.2 +/- 2.2 weeks of age, 41.4 +/- 2.5 kg body weight) during the pubertal transition period. Puberty was synchronized by pulsatile iv administration of GnRH (2 ng/kg every 2 h for 24 h and then at hourly intervals for the next 12 h) in a manner mimicking the I-LH pulse patterns observed during the natural transition to adulthood. Blood samples were collected at 12-min intervals for 4 h from both groups of lambs; for the pubertal group this included the final 32-36 h of GnRH administration. At the end of the study, a 25 ml volume of peripheral blood was collected from both prepubertal and pubertal females for the determination of serum FSH distribution patterns; the lambs were then euthanised, and pituitaries were removed for determination of pituitary hormone content and FSH isoform distribution patterns. In addition, the distribution pattern of I-FSH isoforms in the pituitary and serum from both groups of lambs were compared. The pubertal stages of all lambs were verified by measuring the size of follicles, the circulating concentrations of estradiol (E2) and inhibin, and the I-LH pulse patterns. Prepubertal lambs had low frequency I-LH pulses, small (2-3 mm) size ovarian follicles and low circulating concentrations of E2 (4.1 +/- 0.4 pg/ml) and inhibin (38.0 +/- 2.9 U/ml WHO). By contrast, all the pubertal lambs had hourly I-LH pulse frequency (induced with exogenous GnRH), a large (5-6 mm) follicle (in one lamb a 4-mm follicle), follicular phase levels of E2 (7.1 +/- 0.8 pg/ml), and higher concentrations of inhibin (53.2 +/- 3.1 U/ml).(ABSTRACT TRUNCATED AT 400 WORDS)

This article has been cited by other articles:

				T. L. Steckler, J. S. Lee, W. Ye, E. K. Inskeep, and V. Padmanabhan Developmental Programming: Exogenous Gonadotropin Treatment Rescues Ovulatory Function But Does Not Completely Normalize Ovarian Function in Sheep Treated Prenatally with Testosterone Biol Reprod, October 1, 2008; 79(4): 686 - 695. [Abstract] [Full Text] [PDF]

				M Amstalden, D A Zieba, M R Garcia, R L Stanko, T H Welsh Jr, W H Hansel, and G L Williams Evidence that lamprey GnRH-III does not release FSH selectively in cattle Reproduction, January 1, 2004; 127(1): 35 - 43. [Abstract] [Full Text] [PDF]

				A. Ulloa-Aguirre, C. Timossi, J. Barrios-de-Tomasi, A. Maldonado, and P. Nayudu Impact of Carbohydrate Heterogeneity in Function of Follicle-Stimulating Hormone: Studies Derived from in Vitro and in Vivo Models Biol Reprod, August 1, 2003; 69(2): 379 - 389. [Abstract] [Full Text] [PDF]

				C. Wright, A.C.O. Evans, N.P. Evans, P. Duffy, J. Fox, M.P. Boland, J.F. Roche, and T. Sweeney Effect of Maternal Exposure to the Environmental Estrogen, Octylphenol, During Fetal and/or Postnatal Life on Onset of Puberty, Endocrine Status, and Ovarian Follicular Dynamics in Ewe Lambs Biol Reprod, December 1, 2002; 67(6): 1734 - 1740. [Abstract] [Full Text] [PDF]

				C. R. West, N. E. Carlson, J. S. Lee, A. S. McNeilly, T. P. Sharma, W. Ye, and V. Padmanabhan Acidic Mix of FSH Isoforms Are Better Facilitators of Ovarian Follicular Maturation and E2 Production than the Less Acidic Endocrinology, January 1, 2002; 143(1): 107 - 116. [Abstract] [Full Text] [PDF]

				A. Ulloa-Aguirre, C. Timossi, and J.P. Mendez Is there any physiological role for gonadotrophin oligosaccharide heterogeneity in humans?: I. Gondatrophins are synthesized and released in multiple molecular forms. A matter of fact Hum. Reprod., April 1, 2001; 16(4): 599 - 604. [Abstract] [Full Text] [PDF]

				M. D'Antonio, F. Borrelli, A. Datola, R. Bucci, M. Mascia, P. Polletta, D. Piscitelli, and R. Papoian Biological characterization of recombinant human follicle stimulating hormone isoforms Hum. Reprod., May 1, 1999; 14(5): 1160 - 1167. [Abstract] [Full Text] [PDF]

				V. Padmanabhan, K. McFadden, D. T. Mauger, F. J. Karsch, and A. R. Midgley Jr. Neuroendocrine Control of Follicle-Stimulating Hormone (FSH) Secretion. I. Direct Evidence for Separate Episodic and Basal Components of FSH Secretion Endocrinology, January 1, 1997; 138(1): 424 - 432. [Abstract] [Full Text] [PDF]