Ovarian responses of anestrous ewes to the "ram effect"

2002 ◽  
Vol 82 (4) ◽  
pp. 599-602 ◽  
Author(s):  
R. Ungerfeld ◽  
A. Pinczak ◽  
M. Forsberg ◽  
E. Rubianes
Keyword(s):  
Luteinizing Hormone ◽  
Key Words ◽  
Luteal Phase ◽  
Follicle Stimulating Hormone ◽  
Lh Surge ◽  
Follicular Cyst ◽  
Ram Effect ◽  
Ovulatory Follicles ◽  
Follicular Dynamics ◽  
Stimulating Hormone

Ovarian responses to the "ram effect" were characterized in 11 anestrous Corriedale ewes. In seven ewes, there was a luteinizing hormone (LH) surge 36.7 ± 12.3 h (mean ± SEM) after ram introduction and a concurrent increase (P < 0.05) in serum follicle stimulating hormone (FSH). Ovarian responses (monitored ultrasonographically) were highly variable. One ewe had two luteal phases (short and normal, respectively), three had delayed ovulation (days 5–7), two had luteinization of non-ovulatory follicles, one developed a luteinized follicular cyst, and four had no luteal phase. Key words: Ram effect, ovarian follicular dynamics, seasonal anestrus, ultrasonography, gonadotropin

Antifolliculogenic action of progesterone despite hypersecretion of FSH in monkeys

1982 ◽  
Vol 243 (5) ◽  
pp. E387-E397 ◽  
Author(s):  
A. L. Goodman ◽  
G. D. Hodgen
Keyword(s):  
Luteinizing Hormone ◽  
Luteal Phase ◽  
Functional Role ◽  
Follicle Stimulating Hormone ◽  
Dominant Follicle ◽  
Follicle Growth ◽  
Lh Surge ◽  
The Face ◽  
Peripheral Conversion ◽  
Midluteal Phase

To learn how progesterone (P) inhibits follicle growth during the luteal phase, we determined whether P will inhibit follicle growth when follicle-stimulating hormone (FSH) is secreted in large amounts, namely, after luteectomy (CLX) in monkeys with only one ovary. Second, a functional role for 17 alpha-hydroxyprogesterone (17OHP) was examined as a common mediator of the inhibition of folliculogenesis by the dominant follicle and corpus luteum. To accomplish the first goal, nine chronically hemiovarectomized monkeys were lutectomized chronically hemiovariectomized monkeys were luteectomized at midluteal phase. In five monkeys that received no steroid, the next preovulatory luteinizing hormone (LH) surge occurred 14.0 +/- 0.8 days (mean +/- SE) after CLX. In contrast, the next LH surge was delayed in four monkeys implanted for 10 days with Silastic capsules containing P and occurred 25.0 +/- 2.7 days after CLX, i.e., 14.8 +/- 2.7 days after the capsule removal. In both groups, FSH levels increased markedly after CLX to a comparable degree and duration; yet, only a single follicle ovulated in each monkey. To examine a potential inhibitory role for 17OHP, monkeys with two ovaries were luteectomized and received 1) no steroid, 2) 17OHP via Silastic capsules, or 3) P for 10 days after CLX. Progesterone replacement after CLX appeared to maintain 17OHP levels, which showed a transient decrease after CLX alone. As above, P delayed the next LH surge (25.4 +/- 1.3 vs. 15.0 +/- 0.6 days) despite comparable increases in serum FSH after CLX alone. Replacement at two levels of 17OHP did not delay the onset of menses (2-3 days post-CLX) or significantly delay the next LH surge 18.3 +/!- 1.9 or 20.8 +/- 3.4 vs. 15.0 +/- 0.6 days (P greater than 0.2) in monkeys CLX only. Whatever may be the mode of action of P, it appears that it is not mediated by peripheral conversion to 17OHP. These findings demonstrate that P at luteal phase levels can inhibit follicle growth culminating in ovulation even in the face of sustained, elevated levels of endogenous FSH. Because single ovulations occurred despite unambiguous and prolonged increments in serum FSH after CLX, the precise regulation of the ovulatory quota in this primate appears to be accomplished by means other than FSH alone.

Responses of luteinizing hormone (LH) and follicle-stimulating hormone levels to exogenous gonadotropin-releasing hormone during the estrogen-induced LH surge in the ovariectomized rhesus monkey

1989 ◽  
Vol 67 (2) ◽  
pp. 135-139 ◽  
Author(s):  
Richard F. Weick ◽  
Vaclav Pitelka ◽  
David L. Thompson
Keyword(s):  
Luteinizing Hormone ◽  
Rhesus Monkey ◽  
Negative Feedback ◽  
Follicle Stimulating Hormone ◽  
Gonadotropin Releasing Hormone ◽  
Gonadotropin Secretion ◽  
Lh Surge ◽  
Releasing Hormone ◽  
Acute Response ◽  
Stimulating Hormone

Experiments were performed to study the responsiveness of the pituitary to gonadotropin-releasing hormone (GnRH) during the dynamic changes in gonadotropin secretion associated with the estrogen-induced luteinizing hormone (LH) surge in the ovariectomized (OVX) rhesus monkey. Silastic capsules filled with estradiol-17-β were implanted subcutaneously in ovariectomized rhesus monkeys, resulting in an initial lowering of circulating LH and follicle-stimulating hormone (FSH) concentrations followed by an LH–FSH surge. GnRH was injected intravenously just before estrogen implantation, during the negative feedback response and during the rising, the peak, and the declining phases of the LH surge. The LH and FSH responses during the negative feedback phase were as large as those before estrogen treatment (control responses). During the rising phase of the LH surge, the acute response to GnRH injection did not differ significantly from the control response, but the responses 60 and 120 min after injection were somewhat increased. During the declining phase of the LH surge, the pituitary was not responsive to exogenous GnRH, although LH probably continued to be secreted at this time since the LH surge decreased more slowly than predicted by the normal rate of disappearance of LH in the monkey. We conclude that an increased duration of response to GnRH may be an important part of the mechanism by which estrogen induces the LH surge, but we do not see evidence of increased sensitivity of the pituitary to GnRH as an acute releasing factor at that time.Key words: LH surge, GnRH, FSH, ovariectomized monkey.

Normal Menstrual Cycle

2018 ◽  
Author(s):  
Rebecca Pierson ◽  
Kelly Pagidas
Keyword(s):  
Menstrual Cycle ◽  
Luteinizing Hormone ◽  
Luteal Phase ◽  
Follicle Stimulating Hormone ◽  
Follicular Phase ◽  
Gonadotropin Releasing Hormone ◽  
Hormonal Control ◽  
Releasing Hormone ◽  
Normal Menstrual Cycle ◽  
Stimulating Hormone

A normal menstrual cycle is the end result of a sequence of purposeful and coordinated events that occur from intact hypothalamic-pituitary-ovarian and uterine axes. The menstrual cycle is under hormonal control in the reproductively active female and is functionally divided into two phases: the proliferative or follicular phase and the secretory or luteal phase. This tight hormonal control is orchestrated by a series of negative and positive endocrine feedback loops that alter the frequency of the pulsatile secretion of gonadotropin-releasing hormone (GnRH), the pituitary response to GnRH, and the relative secretion of luteinizing hormone and follicle-stimulating hormone from the pituitary gonadotrope with subsequent direct effects on the ovary to produce a series of sex steroids and peptides that aid in the generation of a single mature oocyte and the preparation of a receptive endometrium for implantation to ensue. Any derailment along this programmed pathway can lead to an abnormal menstrual cycle with subsequent impact on the ability to conceive and maintain a pregnancy. This review contains 7 figures and 26 references Key words: follicle-stimulating hormone, follicular phase, gonadotropin-releasing hormone, luteal phase, luteinizing hormone, menstrual cycle, ovulation, progesterone, proliferative phase, secretory phase

Effects of high levels of body condition and food intake on plasma follicle stimulating hormone, luteinizing hormone, prolactin and progesterone profiles around mating in Greyface ewes

1986 ◽  
Vol 43 (1) ◽  
pp. 101-107 ◽  
Author(s):  
S. M. Rhind ◽  
I. D. Leslie ◽  
R. G. Gunn ◽  
J. M. Doney
Keyword(s):  
Luteinizing Hormone ◽  
Body Condition ◽  
Luteal Phase ◽  
Weight Maintenance ◽  
Follicle Stimulating Hormone ◽  
Live Weight ◽  
Follicular Phase ◽  
High Group ◽  
High Level ◽  
Stimulating Hormone

ABSTRACTTwo groups of 19 Border Leicester cf × Scottish Blackface 9 ewes were fed so that ewes of one group were in a very high level of body condition at mating (mean score 3·35) and had a high level of intake. Ewes of the second group were in moderately high condition (mean score 2·74) and were given a live-weight maintenance ration. Ewes in the high group had a higher ovulation rate than those of the moderate group (3·36 v. 2·33) but a lower number of embryos per ewe mated (1·16 v. 1·42). Mean follicle stimulating hormone profiles were similar for ewes of the two groups during the luteal and follicular phases of the cycle before mating and during the subsequent oestrus. Mean prolactin concentrations were higher in ewes of the high group during the follicular phase and oestrus but not during the luteal phase. Mean luteinizing hormone (LH) concentrations were higher in ewes of the high group during the follicular phase and oestrus but not during the luteal phase. Mean LH concentrations were similar for the two groups at all times but the frequency of LH pulses was higher in the high group during the follicular phase.Ewes that were not pregnant at slaughter had abnormal progesterone profiles following mating, abnormal pre-ovulatory LH surges or failed to show oestrus. These abnormalities were not related to gonadotrophin profiles prior to oestrus.

CHANGES IN THE BINDING OF HUMAN CHORIONIC GONADOTROPHIN/LUTEINIZING HORMONE, FOLLICLE-STIMULATING HORMONE AND PROLACTIN TO HUMAN CORPORA LUTEA DURING THE MENSTRUAL CYCLE AND PREGNANCY

1980 ◽  
Vol 87 (3) ◽  
pp. 315-325 ◽  
Author(s):  
A. S. McNEILLY ◽  
J. KERIN ◽  
I. A. SWANSTON ◽  
T. A. BRAMLEY ◽  
D. T. BAIRD
Keyword(s):  
Menstrual Cycle ◽  
Luteinizing Hormone ◽  
Luteal Phase ◽  
Follicle Stimulating Hormone ◽  
Chorionic Gonadotrophin ◽  
Human Chorionic Gonadotrophin ◽  
Corpora Lutea ◽  
Maximum Serum ◽  
Human Menstrual Cycle ◽  
Stimulating Hormone

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.

Ovarian follicular dynamics and concentrations of oestradiol-17 beta, progesterone, luteinizing hormone and follicle stimulating hormone during the periovulatory phase of the oestrous cycle in the cow

1991 ◽  
Vol 3 (5) ◽  
pp. 529 ◽  
Author(s):  
H Kaneko ◽  
T Terada ◽  
K Taya ◽  
G Watanabe ◽  
S Sasamoto ◽  
...  
Keyword(s):  
Plasma Concentration ◽  
Luteinizing Hormone ◽  
Follicle Stimulating Hormone ◽  
Follicular Phase ◽  
Corpora Lutea ◽  
Dominant Follicle ◽  
Follicular Wave ◽  
Ovulatory Follicle ◽  
Follicular Dynamics ◽  
Stimulating Hormone

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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