This Article Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Request Copyright Permission Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Kirby, J. D. Articles by Cooke, P. S. Search for Related Content PubMed PubMed Citation Articles by Kirby, J. D. Articles by Cooke, P. S.

Neonatal Hypothyroidism Permanently Alters Follicle-Stimulating Hormone and Luteinizing Hormone Production in the Male Rat¹

Department of Poultry Science, University of Arkansas (J.D.K. Y.K.K., M.L.R.), Fayetteville, Arkansas 72701; the Departments of Veterinary Biosciences (N.A., G.I., G.L.J., P.S.C.) and Animal Science (H.N.), University of Illinois, Urbana, Illinois 61801; and the Department of Neurobiology and Physiology, Northwestern University (T.P.-H., F.W.T.), Evanston, Illinois 60208; and the Department of Biological Sciences, Middle Tennessee State University (A.E.J.), Murfreesboro, Tennessee 37132

Address all correspondence and requests for reprints to: Dr. John D. Kirby, Department of Poultry Science, John Tyson Building, Room O114, University of Arkansas, Fayetteville, Arkansas 72701. E-mail: jkirby{at}comp.uark.edu

Transient neonatal hypothyroidism, induced with the goitrogen 6-n-propyl-2-thiouracil (PTU), results in dramatic increases in both testis size and sperm production in the adult rat. The observed increases in testis size and function occur in the presence of normal circulating testosterone levels. However, circulating gonadotropin levels are chronically reduced by 30–50% at all times in treated males. To better understand the permanent reduction in serum gonadotropin levels following transient neonatal hypothyroidism, we conducted a series of experiments to evaluate pituitary and hypothalamic function in the adult male PTU-treated rat. PTU treatment led to a significant reduction in GnRH-stimulated LH production. Castration resulted in 3.9- to 8.5-fold increases in circulating gonadotropin levels in both treated and control males; however, the absolute increases were significantly reduced in treated males. In contrast to circulating levels, pituitary gonadotropin contents did not increase in treated males after castration. PTU treatment did not lead to a reduction in the density of either luteotropes or folliculotropes, and both cell types increased in size and density after castration. The relative concentrations of both gonadotropin ß-subunit messenger RNAs increased more slowly in treated males than in controls after castration. Thus, although treated rats have the intrinsic ability to produce normal circulating levels of LH and FSH, gonadal feedback and an overall reduction in gonadotrope synthetic ability combine to produce the chronically reduced circulating levels of these hormones.

This article has been cited by other articles:

				L. M. Zorrilla, E. K. Gibson, S. C. Jeffay, K. M. Crofton, W. R. Setzer, R. L. Cooper, and T. E. Stoker The Effects of Triclosan on Puberty and Thyroid Hormones in Male Wistar Rats Toxicol. Sci., January 1, 2009; 107(1): 56 - 64. [Abstract] [Full Text] [PDF]

				M. S. Wagner, S. M. Wajner, and A. L. Maia The role of thyroid hormone in testicular development and function J. Endocrinol., December 1, 2008; 199(3): 351 - 365. [Abstract] [Full Text] [PDF]

				D. Nonneman, G. A. Rohrer, T. H. Wise, D. D. Lunstra, and J. J. Ford A Variant of Porcine Thyroxine-Binding Globulin Has Reduced Affinity for Thyroxine and Is Associated with Testis Size Biol Reprod, January 1, 2005; 72(1): 214 - 220. [Abstract] [Full Text] [PDF]

				M.M. Ben Saad and D.L. Maurel Reciprocal Interaction Between Seasonal Testis and Thyroid Activity in Zembra Island Wild Rabbits (Oryctolagus cuniculus): Effects of Castration, Thyroidectomy, Temperature, and Photoperiod Biol Reprod, April 1, 2004; 70(4): 1001 - 1009. [Abstract] [Full Text] [PDF]

				N. St-Pierre, J. Dufresne, A. A. Rooney, and D. G. Cyr Neonatal Hypothyroidism Alters the Localization of Gap Junctional Protein Connexin 43 in the Testis and Messenger RNA Levels in the Epididymis of the Rat Biol Reprod, April 1, 2003; 68(4): 1232 - 1240. [Abstract] [Full Text] [PDF]

				N. Vasudevan, S. Ogawa, and D. Pfaff Estrogen and Thyroid Hormone Receptor Interactions: Physiological Flexibility by Molecular Specificity Physiol Rev, October 1, 2002; 82(4): 923 - 944. [Abstract] [Full Text] [PDF]