FACTORS INFLUENCING OVARIAN SENSITIVITY TO GONADOTROPHINS

1957 ◽  
Vol 15 (4) ◽  
pp. 448-457 ◽  
Author(s):  
ANITA M. MANDL

SUMMARY 1. A study was made of the ovarian reaction to pregnant mares' serum (PMS) in adult thyroidectomized, thyroidectomized/adrenalectomized, adrenalectomized and intact rats. 2. Thyroidectomized animals responded more vigorously than did any other group. Adrenalectomized animals hardly responded at all. Animals that had been both thyroidectomized and adrenalectomized reacted almost as strongly as did non-adrenalectomized thyroidectomized animals, and slightly more than intact controls. 3. A histological analysis confirmed that thyroidectomy is associated with hypersensitivity to both follicle-stimulating hormone (FSH) and luteinizing hormone (LH), and that adrenalectomy in the adult is associated with an impaired response to FSH but not to LH. The ovaries of thyroidectomized/adrenalectomized animals contained more large Graafian follicles and more large corpora lutea than did those of adrenalectomized litter-mates. 4. The results appear to imply that the mechanisms mediating the changes in ovarian sensitivity to PMS after thyroidectomy and after adrenalectomy are independent of each other.

1977 ◽  
Vol 75 (1) ◽  
pp. 109-118 ◽  
Author(s):  
HILARY DOBSON ◽  
W. R. WARD

A radioimmunoassay system for the measurement of ovine follicle-stimulating hormone (FSH) was established. After the onset of normal oestrus, there were simultaneous surges of luteinizing hormone (LH) and FSH, and 24 h later, a surge of FSH alone. Administration of sodium pentobarbitone when the dual surge of LH and FSH was expected inhibited the release of LH, but prolonged that of FSH. Development of corpora lutea that took place immediately was normal in ewes treated with sodium pentobarbitone, but after the subsequent oestrus, the life-time of corpora lutea was abnormally short. When sodium pentobarbitone was administered at the time when the second surge of FSH was expected, no effect was observed on the level of LH or FSH. Subsequent development of corpora lutea was similar to that in the non-treated group. Administration of sodium pentobarbitone at the expected time of the dual surges of LH and FSH after infusion of oestradiol to anoestrous ewes blocked the release of both LH and FSH. Administration of sodium pentobarbitone at the expected time of the second surge of FSH after infusion of oestradiol delayed the increase in the level of FSH. In a pilot experiment after combined infusion of androstenedione and oestradiol, sodium pentobarbitone did not completely inhibit the release of FSH, but the release of LH was totally prevented.


1972 ◽  
Vol 54 (1) ◽  
pp. 25-NP ◽  
Author(s):  
J. DAVIES ◽  
L. H. HOFFMAN ◽  
G. R. DAVENPORT

SUMMARY Ovine luteinizing hormone (LH) (300 μg/day in divided subcutaneous doses) had a luteotrophic effect of limited duration in intact and hypophysectomized 10-day pseudopregnant rabbits (6–10 days in intact animals; 3–6 days in hypophysectomized animals). Higher dose levels caused reovulation in which case luteolysis occurred. Suppression of reovulation with anti-ovine follicle-stimulating hormone (FSH) serum permitted the daily dose of LH to be raised to 750 μg without causing luteolysis or reovulation. Anti-LH serum was luteolytic in the intact animals. A combination of ovine FSH (200 μg) and LH (300 μg) was indistinguishable from LH alone in terms of its luteotrophic effect in hypophysectomized 10-day pseudopregnant rabbits. Ovine FSH at large daily dose levels (1000 μg) was more effectively luteotrophic than LH alone in a significant number of animals for 10 days after hypophysectomy: endometrial changes in these animals resembled those only seen in normal pregnancy. The luteotrophic effect of 1000 μg FSH was believed to be dependent on a small but significant content of LH, estimated to be about 10 μg. Ovine FSH and anti-FSH serum in intact pseudopregnant rabbits had no detectable effect on luteal function. Animals hypophysectomized at the 7th day and treated with 300 or 500 μg LH/day showed no luteal maintenance for 6 days nor was reovulation induced. Sensitivity to the luteotrophic effect of LH was deemed, therefore, to be greater at 10 than at 7 days of pseudopregnancy. Endometrial criteria were found to be reliable indicators of luteal function. The appearance of ciliated cells was correlated with the decline of the corpora lutea. When reovulation occurred, a new progestational cycle was rapidly superimposed on the existing one.


1976 ◽  
Vol 70 (3) ◽  
pp. 465-471 ◽  
Author(s):  
W. J. DE GREEF ◽  
J. DULLAART ◽  
G. H. ZEILMAKER

SUMMARY Pseudopregnant rats were treated early in pseudopregnancy with 1 or 10 mg medroxyprogesterone acetate (MPA). Serum FSH, LH and progesterone concentrations were determined on days 2–20 of pseudopregnancy in treated and control rats. The mean duration of pseudopregnancy was 13·5 days in the control animals, but when animals were treated with 1 mg MPA a dioestrous period of 21·4 days was observed. A period with leucocytic vaginal smears of at least 2 months was observed after treatment with 10 mg MPA. Injection with MPA on day 3 of pseudopregnancy did not affect the serum FSH concentrations during the subsequent days. The progesterone pattern was alike in the three groups of animals, i.e. the duration of the activity of the corpora lutea was similar in all groups. However, 10 mg MPA slightly lowered progesterone concentrations on days 4–8 of pseudopregnancy. In the saline-treated rats, LH concentrations decreased from days 2–5, and remained low until they increased after day 11 of pseudopregnancy. This increase was delayed until day 20 in the animals treated with 1 mg MPA, and was not observed in the animals treated with 10 mg MPA. It is argued that the increase of LH concentration at the end of pseudopregnancy is not instrumental in the decrease of peripheral progesterone concentration but rather that the decrease in the progesterone concentration leads to the increase in the LH concentration.


1980 ◽  
Vol 87 (3) ◽  
pp. 315-325 ◽  
Author(s):  
A. S. McNEILLY ◽  
J. KERIN ◽  
I. A. SWANSTON ◽  
T. A. BRAMLEY ◽  
D. T. BAIRD

The changes in the binding of human chorionic gonadotrophin/luteinizing hormone (HCG/LH), follicle-stimulating hormone (FSH) and prolactin to 44 corpora lutea have been assessed during the luteal phase of the human menstrual cycle and early pregnancy. All corpora lutea bound HCG but out of 32 only ten bound FSH and only seven bound prolactin specifically. While binding of HCG increased to maximal levels in the mid-luteal phase, binding of FSH and prolactin was most often found in the early luteal phase. Maximum binding of HCG was associated with maximum serum levels of progesterone. Luteal regression was associated with a decrease in the binding of HCG but a causal relationship could not be established. Very low binding of HCG was found to corpora lutea of pregnancy. These results show that (1) the changes in binding of HCG during the luteal phase of the human menstrual cycle are similar to those in other species and (2) there are specific binding sites for prolactin and FSH in the human corpus luteum.


1981 ◽  
Vol 88 (1) ◽  
pp. 103-113 ◽  
Author(s):  
O. A. ASHIRU ◽  
M. E. RUSH ◽  
C. A. BLAKE

The effects of exogenous rat LH or FSH on the release of endogenous FSH in the cyclic rat have been investigated. Rats were administered phenobarbitone to block the spontaneous increases in gonadotrophins in plasma during pro-oestrus and oestrus and then cannulated through the jugular vein or cannulated and hypophysectomized during the late morning or early afternoon of pro-oestrus. Comparison of patterns of plasma FSH in hypophysectomized and intact rats after i.v. injection of 0·5 μg FSH at 17.00 h suggested that exogenous FSH stimulated the release of endogenous FSH in less than 5 h. Intravenous LH (2 μg at 16.00 and at 18.00 h) raised the level of FSH in plasma between 2 and 6 h after the first injection of LH. Both gonadotrophins stimulated FSH release by the pituitary gland during the morning of oestrus. Comparison of patterns of plasma FSH in hypophysectomized and intact rats after i.v. injection of 0·25 or 0·05 μg FSH at 14.00 h suggested that the latency between FSH injection and stimulation of some FSH release by the pituitary gland is as short as 2 h. Intravenous LH (3,4 or 9 μg) at 14.00 h did not increase the level of FSH in plasma within 2 h and was only minimally effective in raising the level within 4 h. Intravenous LH (2 μg at 16.00 and at 18.00 h) on the afternoon of dioestrus day 2 was nearly as effective in increasing the levels of FSH in plasma as it was when administered to pro-oestrous rats. This procedure did not raise the plasma levels of FSH in rats used on dioestrus day 1. The results suggest that in the phenobarbitone-blocked, pro-oestrous rat (1) a small increase (less than that observed spontaneously) in plasma rat FSH during pro-oestrus is effective in stimulating FSH release by the pituitary gland, (2) an increase in plasma rat FSH can exert positive feedback on its own secretion within 2 h and (3) a large increase in plasma rat LH is not very effective in increasing the plasma level of FSH over a period of 4 h. The results also suggest that the spontaneous increase in plasma levels of FSH and, to a lesser extent, of LH is involved in causing the selective phase of FSH release which occurs during late pro-oestrus and the morning of oestrus, and that LH and FSH act differently, but not necessarily by way of a different mechanism, to stimulate release of FSH by the pituitary gland.


1991 ◽  
Vol 3 (5) ◽  
pp. 529 ◽  
Author(s):  
H Kaneko ◽  
T Terada ◽  
K Taya ◽  
G Watanabe ◽  
S Sasamoto ◽  
...  

Changes in the plasma concentration of oestradiol-17 beta, progesterone, luteinizing hormone (LH) and follicle stimulating hormone (FSH) were characterized during the transition from the luteal to the follicular phase, the periovulatory period and the early luteal phase in five cycling cows. The pattern of growth and the regression of follicles and corpora lutea in the ovary of the same animals were also assessed by daily ultrasonographic examinations. Two waves of follicular growth (ovulatory and non-ovulatory) occurred in all animals. The ovulatory follicular wave started from 4 days before the preovulatory surges of LH and FSH and the wave of next growth of a dominant follicle (non-ovulatory follicle) started within one day after ovulation. Changes in plasma levels of oestradiol-17 beta correlated well with the growth of both ovulatory and non-ovulatory dominant follicles. Suppression of FSH concentration during the follicular phase was inversely related to the increase in plasma concentration of oestradiol-17 beta. These results suggest that, in the cow, ovulatory dominant follicles suppress FSH secretion by increasing the concentration of oestradiol-17 beta (and probably also inhibin) during the follicular phase.


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