A selective increase in circulating inhibin and inhibin pro-alphaC at the time of ovulation in the mare.
The relationship between a selective increase in circulating immunoreactive (ir)-inhibin and the time of ovulation was investigated in mares. Concentrations of plasma ir-inhibin were measured every 4 h during the periovulatory period. Inhibin pro-alphaC, a precursor protein of the inhibin alpha-subunit, was also measured. The changes in ir-inhibin and inhibin pro-alphaC in circulation were parallel. Concentrations of both ir-inhibin and inhibin pro-alphaC in the plasma increased at the same time when ovulatory follicles ruptured, and the peak levels of circulating ir-inhibin and inhibin pro-alphaC were maintained for 4-8 h. There was no selective increase in plasma concentrations of estradiol-17beta during the process of ovulation. These results suggest that the selective increase in ir-inhibin and inhibin pro-alphaC was caused by the absorption of follicular fluid after the rupture of ovulatory follicles. These results also suggest that the measuring of plasma concentrations of ir-inhibin or inhibin pro-alphaC in mares might be a useful method for detecting the time of ovulation.
Nagaoka
K
K
Laboratory of Veterinary Physiology, Tokyo University of Agriculture and Technology, Tokyo 183-8509, Japan.
Nambo
Y
Y
Nagamine
N
N
Nagata
S I
SI
Tanaka
Y
Y
Shinbo
H
H
Tsunoda
N
N
Taniyama
H
H
Watanabe
G
G
Groome
N P
NP
Taya
K
K
D000818:Animals; D015415:Biomarkers; D001947:Breeding; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods; D005260:Female; D005640:Follicle Stimulating Hormone / Q000097:blood; D006736:Horses / Q000502:physiology*; D007265:Inhibins / Q000032:analysis / Q000097:blood*; D007986:Luteinizing Hormone / Q000097:blood; D010060:Ovulation / Q000502:physiology*; D011374:Progesterone / Q000097:blood; D011498:Protein Precursors / Q000032:analysis / Q000097:blood*; D011863:Radioimmunoassay
D015415:Biomarkers; D011498:Protein Precursors; C095971:inhibin-alpha subunit precursor; D011374:Progesterone; D007265:Inhibins; D007986:Luteinizing Hormone; D005640:Follicle Stimulating Hormone