Effect of Castration on Serum Gonadotropin Levels in Androgenized Male and Female Rats

Abstract

The changes in LH and FSH secretion 12, 18 h and 1, 3, 5, 20 and 30 days following castration in adult rats of both sexes neonatally androgenized were studied. After castration, serum LH concentration rose slowly in the female and rapidly in male rats. Orchidectomy induced an increase of LH that was significantly slower in the androgenized rats than in the controls until 20 days after the postcastration period, reaching similar values at 30 days. In the female rats the increase in the LH levels from 48 h to 30 days after castration was significantly lower in the androgenized than in the control rats. Basal levels of FSH were higher in the androgenized males than in the controls. The concentration of the hormone increased in both groups 12 h after orchidectomy, the basal differences disappearing. These groups of rats showed similar values from 48 h up to 30 days after castration. As in the males, FSH basal levels were higher in androgenized rats than in control female rats and the difference disappeared 12 h after castration. The increase in the FSH concentration postgonadectomy was significantly lower in androgenized rats than in the control rats from 48 h to 20 days. At this time, both groups reach a plateau with similar values. These results indicate that androgenized male and female rats showed, at different times of the postcastration period, lower levels of FSH and LH than the controls and that these differences disappear after 30 days of castration. On the other hand, the differences in the basal levels of FSH concentration between controls and androgenized male and female rats also disappear in the first few hours postgonadectomy.

Neuroendocrine consequences of androgen excess in female rodents

“…Basal LH levels in neonatally androgenized females have been reported to be decreased (Korenbrot et al, 1975) or unchanged (Kubo et al, 1975) in the ovary-intact state. Following ovariectomy, LH levels rise at a significantly slower rate and remain chronically lower in neonatally androgenized females compared to their control counterparts (Moguilevsky et al, 1979). We have recently assessed the characteristics of LH pulsatility in long-term ovariectomized females that received neonatal testosterone or control treatments (Figure 9) (Foecking, unpublished).…”

Responses of Serum LH and FSH to the Removal of Steroid Feedback Inhibition

“…'masculinize') the positive feedback effects of gonadal ste roids on gonadotropin secretion and induce, in adulthood, chronic anovulatory sterility and persistent estrus. Al though doses in the range of 1 mg of TP per rat are com monly used,a single injection of as little as 10 pg of TP ad ministered on or before postnatal day 4, will induce persis tent estrus in the majority of females [17], Previous studies of the effects of neonatal TP treatment on the postcastration LH rise in females have used high doses of TP (1.0-1.25 mg TP/rat), and found that the LH response was not 'masculinized' but, in fact, was even somewhat slower than in normal female controls [11,26,32], In the present study, we have found that this inhibitory effect of high-dose neonatal androgen treatment on the 'postcastration' LH response is not simply a result of altered sex steroid production in persistent estrous females. Fe males which were treated neonataliy with a high dose of TP (500 pg/rat), and then gonadectomized and implanted with T capsules for 3 weeks as adults, also showed a slower LH response following removal of the T capsule than did the similarly treated, oil-injected controls.…”

“…Females injected with the androgen, testosterone propionate (TP) during the 1st week of postnatal life exhibited serum LH responses to ovariectomy which were as slow or even slower than those shown by diestrous females [11,26,32]. However, in these studies, females were androgenized with doses of TP which were at least 100-fold greater than those required to block the cyclic release of gonadotropins [18].…”