Journal of Andrology
HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
This Article
Right arrow Full Text (PDF)
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Eisenhauer, K. M.
Right arrow Articles by Roser, J. F.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Eisenhauer, K. M.
Right arrow Articles by Roser, J. F.

Journal of Andrology, Vol 16, Issue 1 18-27, Copyright © 1995 by The American Society of Andrology

JOURNAL ARTICLE

Effects of lipoprotein, equine luteinizing hormone, equine follicle-stimulating hormone, and equine prolactin on equine testicular steroidogenesis in vitro

K. M. Eisenhauer and J. F. Roser
Department of Animal Science, University of California, Davis 95616, USA.

A stallion testicular cell incubation system was developed and used to investigate the regulation of steroidogenesis in stallion testes. Cells isolated from testes of 2- to 4-year-old stallions (n = 6) were cultured for 12 hours in a defined medium with and without varying doses of lipoprotein, equine luteinizing hormone (eLH), human chorionic gonadotropin (hCG), equine follicle-stimulating hormone (eFSH), and/or equine prolactin (ePRL). Estrogen conjugate (EC), testosterone (T), and estradiol-17 beta (E2) production were determined by RIA. Increasing doses of lipoprotein significantly (P < 0.001) increased basal, hCG- and eLH-stimulated EC production, resulting in a maximal fourfold increase in each case. A maximal dose of lipoprotein (3 mg/ml) significantly (P < 0.001) increased basal T production threefold, whereas hCG- and eLH-stimulated T production were increased 76- and 30-fold, respectively. In the presence of 0.5 mg/ml of lipoprotein, increasing doses of eLH significantly (P < 0.001) stimulated EC, T, and E2 production. The increase in T production (5.6-fold) at a physiological dose of eLH (5 ng/ml) was significantly (P < 0.05) greater than the increase in EC or E2 production (2.1- and 2.3-fold, respectively). However, the total mass of EC produced was significantly greater (P < 0.05) than the total amount of T produced at both basal (15 ng vs. 148 pg) or hormone-stimulated (48 ng vs. 2,427 pg at 5 ng/ml eLH) levels. hCG significantly (P < 0.001) stimulated EC and T production and was 82-fold more active in stimulating EC production and 41-fold more active in stimulating T production than was eLH. FSH had no significant effect on steroidogenesis either alone or in the presence of eLH, except at the highest dose tested (50 ng/ml), which was above the physiological level of circulating FSH (4-7 ng/ml) in the stallion. PRL (1-50 ng/ml) had no significant effect on steroidogenesis either alone or in the presence of eLH. These data suggest that in the postpubertal stallion, both estrogen and T production are regulated by LH, and this regulation appears to be dependent on the availability of lipoprotein-derived cholesterol. Furthermore, the observation that testicular cells produced a larger mass of EC than T, but responded to eLH with a larger relative increase in T production, suggests that production of these two steroids may be independently regulated.


This article has been cited by other articles:


Home page
 Biol. Reprod.Home page
E.E. At-Taras, A.J. Conley, T. Berger, and J.F. Roser
Reducing Estrogen Synthesis Does Not Affect Gonadotropin Secretion in the Developing Boar
Biol Reprod, January 1, 2006; 74(1): 58 - 66.
[Abstract] [Full Text] [PDF]


HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
Copyright © 1995 by The American Society of Andrology.