Type

Journal Article

Authors

J J Ireland
A.C.O. Evans
P. Lonergan
G W Smith
J L H Ireland
J K Folger
F Jimenez-Krassel
F Mossa

Subjects

Biochemistry

Topics
biosynthesis reverse transcriptase polymerase chain reaction cytology blood veterinary steroid 17 alpha hydroxylase physiology theca cells follicular fluid enzymology progesterone estrous cycle rna messenger ultrasonography estradiol androstenedione female cattle genetics chemistry testosterone animals ovarian follicle

Evidence that high variation in antral follicle count during follicular waves is linked to alterations in ovarian androgen production in cattle. (2010)

Abstract Androgens have an important role in ovarian follicular growth and function, but circulating androgen concentrations are also associated with ovarian dysfunction, cardiovascular disease, and metabolic disorders in women. The extent and causes of the variation in androgen production in individuals, however, are unknown. Because thecal cells of follicles synthesize androstenedione and testosterone, variation in production of these androgens is hypothesized to be directly related to the inherently high variation in number of healthy growing follicles in ovaries of individuals. To test this hypothesis, we determined whether thecal CYP17A1 mRNA (codes for a cytochrome P450 enzyme involved in androgen synthesis), LH-induced thecal androstenedione production, androstenedione concentrations in follicular fluid, and circulating testosterone concentrations were lower in cattle with relatively low versus high number of follicles growing during follicular waves and whether ovariectomy reduced serum testosterone concentrations. Results demonstrated that cattle with a low follicle number had lower (P<0.05) abundance of CYP17A1 mRNA in thecal cells, reduced (P<0.01) capacity of thecal cells to produce androstenedione in response to LH, lower (P<0.01) androstenedione concentrations in ovulatory follicles, and lower (P<0.02) circulating testosterone concentrations during estrous cycles compared with animals with high follicle number. Also, serum testosterone in cattle with low or high follicle number was reduced by 63 and 70%, respectively, following ovariectomy. In conclusion, circulating androgen concentrations are lower in cattle with low versus high number of follicles growing during follicular waves, possibly because of a reduced responsiveness of thecal cells to LH.
Collections Ireland -> University College Dublin -> PubMed

Full list of authors on original publication

J J Ireland, A.C.O. Evans, P. Lonergan, G W Smith, J L H Ireland, J K Folger, F Jimenez-Krassel, F Mossa

Experts in our system

1
A.C.O. Evans
University College Dublin
Total Publications: 92
 
2
P. Lonergan
University College Dublin
Total Publications: 190