Relative sensitivity of the corpus luteum of different days of pregnancy to LH-deprivation in the rat and hamster

Deprivation of endogenous LH by LH antiserum (LH A/S) in 6-day pregnant rats did not affect the luteal or serum progesterone within 24 h. LH A/S treatment on day 7 or 8 of pregnancy, however, caused a 70 and 92% reduction in luteal progesterone, respectively, within 24 h. Serum levels of progesterone showed a similar reduction. In the case of pregnant hamster, unlike the rat, there was a significant decrease in progesterone in the serum, luteal and non-luteal compartments whether the A/S was administered on day 4, 5 or 6. There was more than a 10-fold increase in the luteal cholesterol esters within 24 h whether the A/S was given on day 6, 7 or 8 of pregnancy in the rat. Rat corpora lutea of days 6 and 8 of pregnancy reacted in a like manner to LH-deprivation, showing an increased utilization of [U-14C]glucose to form 14CO2 in vitro. In the rat, LH (25 μg NIH-S19) administration in vivo either on day 6 or day 8 of pregnancy, caused within 2 h an increase in serum and non-luteal progesterone, but luteal progesterone was unchanged. On the other hand, LH administration to hamsters on day 8 of pregnancy caused an increase in progesterone levels in serum, luteal and non-luteal tissue. Incubation of corpora lutea isolated from untreated 6- and 8-day pregnant rats with LH brought about an increase in progesterone secretion into the medium in both cases. The results show that, even though LH-deprivation does not apparently affect progesterone concentration in the corpus luteum of 6-day pregnant rats, it does affect other metabolic parameters such as glucose utilization and cholesterol turnover, suggesting that the corpus luteum of early pregnancy exhibits a continuous dependency on LH for the maintainence of metabolic functions

Relative sensitivity of the corpus luteum of different days of pregnancy to LH-deprivation in the rat and hamster

Deprivation of endogenous LH by LH antiserum (LH A/S) in 6-day pregnant rats did not affect the luteal or serum progesterone within 24 h. LH A/S treatment on day 7 or 8 of pregnancy, however, caused a 70 and 92% reduction in luteal progesterone, respectively, within 24 h. Serum levels of progesterone showed a similar reduction. In the case of pregnant hamster, unlike the rat, there was a significant decrease in progesterone in the serum, luteal and non-luteal compartments whether the A/S was administered on day 4, 5 or 6. There was more than a 10-fold increase in the luteal cholesterol esters within 24 h whether the A/S was given on day 6, 7 or 8 of pregnancy in the rat. Rat corpora lutea of days 6 and 8 of pregnancy reacted in a like manner to LH-deprivation, showing an increased utilization of [U-14C]glucose to form 14CO2 in vitro. In the rat, LH (25 μg NIH-S19) administration in vivo either on day 6 or day 8 of pregnancy, caused within 2 h an increase in serum and non-luteal progesterone, but luteal progesterone was unchanged. On the other hand, LH administration to hamsters on day 8 of pregnancy caused an increase in progesterone levels in serum, luteal and non-luteal tissue. Incubation of corpora lutea isolated from untreated 6- and 8-day pregnant rats with LH brought about an increase in progesterone secretion into the medium in both cases. The results show that, even though LH-deprivation does not apparently affect progesterone concentration in the corpus luteum of 6-day pregnant rats, it does affect other metabolic parameters such as glucose utilization and cholesterol turnover, suggesting that the corpus luteum of early pregnancy exhibits a continuous dependency on LH for the maintainence of metabolic functions

Studies on luteolysis: effect of antiserum to luteinizing hormone on sterols and steroid levels in pregnant hamsters

The effect of luteinizing hormone antiserum (LH A/S) on sterol and steroid levels in luteal and non-luteal ovarian compartments, and on serum steroid levels of pregnant hamsters, was studied. Injection (ip) of 0.1 ml of LH A/S on day 7 caused termination of pregnancy and morphological regression of the corpus luteum (CL) within 18-20 h of treatment, whereas LH-free non-immune serum had no effect. Within 3 h of administration of LH A/S the luteal progesterone levels fell from a control value of 36.0 ± 2.4 to 15.6 ± 3.4 ng/mg, and estrogen from a control value of 20.8 ± 3.4 to 12.2 ± 1.5 pg/mg. By 12 h progesterone had dropped to 7.3 ± 0.3 ng/mg whereas estrogen was undetectable by radioimmunoassay. Serum progesterone fell in 3 h from 5.53 ± 0.39 to 3.15 ± 0.26 ng/ml whereas estrogen fell from 172 ± 26 to 123 ± 9 pg/ml. The progesterone content of non-luteal ovarian tissue dropped in 3 h from 1.06 ± 0.01 to 0.47 ± 0.06 ng/mg and estrogen from 115.0 ± 1.5 to 11.0 ± 0.65 pg/mg. Both progesterone and estrogen were undetectable at 24 h. In the CL, free cholesterol concentration did not change significantly after A/S treatment, while esterified cholesterol increased from 2.82 ± 0.14 to 4.14 ± 0.25 μg/mg within 6 hand 5.52 ± 0.17μg/mgby 12 h. The results suggest that LH plays a critical role in the maintenance of CL of early pregnancy in the hamster and that deprivation of LH, even for periods as short as 3 h, significantly influences steroid production. The accumulation of cholesterol esters following LH-deprivation suggests that loss of cholesteryl esterase activity could be one of the events leading to luteolysis

Termination of pregnancy in macaques (Macaca radiata) using monkey antiserum to ovine luteinizing hormone

The ability of a monkey antiserum to ovine LH to interrupt gestation in monkeys has been established. The antiserum has been shown to neutralize monkey pituitary LH by a number of criteria. The significant increase in serum progesterone level on day 23 of the cycle shown by mated monkeys has been used as an index of pregnancy. Injection of LH antiserum during the first week of missed menses (day 29-31 of cycle or day 18-20 of gestation) causes significant reduction in serum levels of progesterone followed by onset of bleeding which is interpreted as the termination of gestation. The same dose of non-immune serum given to monkeys during the same period does not have any deleterious effect on the progress of pregnancy. The antiserum-treated animals after the termination of gestation, resume cyclicity. Injection of antiserum after day 25 of gestation does not bring about termination of pregnancy. It is suggested that by using antisera raised in humans to ovine LH, this method may be developed as a fertility control measure in humans