Use of spironolactone to investigate the role of testosterone secretion during luteolysis in the goat

Summary. In non-pregnant goats, appreciable amounts of testosterone (2\m=.\1ng/g) and 5\g=a\-dihydrotestosterone(DHT, 0\m=.\8ng/g) were present in the corpus luteum on Day 12 of the oestrous cycle. Significant (P < 0\m=.\01,N = 18) veno-arterial concentration dif-ferences of testosterone were found across ovaries bearing corpora lutea. No such dif-ference in testosterone concentration occurred across ovaries without corpora lutea (P> 0\m=.\5,N = 12). Increased peripheral plasma concentrations of testosterone and DHT occurred at the start of luteal regression, as monitored by progesterone con-centration, and before the day of oestrus. Subcutaneous injections of spironolactone (10mg/kg/day) in peanut oil between Days 10 and 20 of the oestrous cycle inhibited the increase in testosterone and DHT concentrations and delayed luteolysis and oestrus. It is suggested that aromatization of testosterone to oestrogens is needed for luteal regression and expression of oestrus in goats