Neonatal hypothyroidism permanently alters follicle-stimulating hormone and luteinizing hormone production in the male rat
| Autor: | Gary L. Jackson, Tarja Porkka-Heiskanen, Amy E. Jetton, Gary A. Iwamoto, Yvonne K. Kirby, Hiroaki Nitta, Fred W. Turek, Paul S. Cooke, Marsha L. Rhoads, John D. Kirby, Niromi K. Arambepola |
|---|---|
| Rok vydání: | 1997 |
| Předmět: |
Male
endocrine system medicine.medical_specialty medicine.drug_class Thyroid Gland 030209 endocrinology & metabolism Gonadotropin-releasing hormone Biology Gonadotropic cell Gonadotropin-Releasing Hormone Rats Sprague-Dawley 03 medical and health sciences Follicle-stimulating hormone chemistry.chemical_compound 0302 clinical medicine Endocrinology Hypothyroidism Pituitary Gland Anterior Pregnancy Internal medicine Testis medicine Animals Castration RNA Messenger Testosterone 030304 developmental biology 0303 health sciences Organ Size Luteinizing Hormone Rats chemistry Animals Newborn Propylthiouracil Female Gonadotropin Follicle Stimulating Hormone Luteinizing hormone hormones hormone substitutes and hormone antagonists Hormone |
| Zdroj: | Endocrinology. 138(7) |
| ISSN: | 0013-7227 |
| Popis: | 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 beta-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. |
| Databáze: | OpenAIRE |
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