ESTROGEN-INDUCED LH RELEASE IN PROGESTERONE-TREATED OVARIECTOMIZED EWES

1974 ◽  
Vol 54 (4) ◽  
pp. 565-572 ◽  
Author(s):  
P. YUTHASASTRAKOSOL ◽  
S. SIMARAKS ◽  
W. M. PALMER ◽  
B. E. HOWLAND
Keyword(s):  
Luteinizing Hormone ◽  
Intramuscular Injection ◽  
Time Course ◽  
Serum Concentrations ◽  
Serum Luteinizing Hormone ◽  
Lh Release ◽  
Estradiol 17Β

Ovariectomized ewes were injected with either 10 or 30 mg of progesterone, administered either intramuscularly (im) or subcutaneously (sc) at 24, 8, 4 h before, or at the same time, as im injections of 1, 2 or 4 mg of estradiol-17β. Determinations of serum luteinizing hormone (LH), estrogen, and progesterone by radioimmunoassay (RIA) were conducted to study the effects of the treatments on LH release, and the time course of estrogen and progesterone serum concentrations following injection. In the first experiment, progesterone failed to block the estrogen-induced LH release in four of six ewes, and in all three ewes of the second experiment. Intramuscular injection of progesterone resulted in higher circulating progesterone concentrations than sc injection and reached peak levels at 2–4 h postinjection. Estrogen reached peak values at 30 min–2 h postinjection. The results showed that progesterone injected at either 4, 8 and 24 h before, or simultaneously with, a pharmacological dosage of estrogen did not consistently block the LH release in ovariectomized ewes.

Androgenic and oestrogenic steroid participation in feedback control of luteinizing hormone secretion in male sheep

1983 ◽  
Vol 102 (4) ◽  
pp. 499-504 ◽  
Author(s):  
M. J. D'Occhio ◽  
B. D. Schanbacher ◽  
J. E. Kinder
Keyword(s):  
Luteinizing Hormone ◽  
Pulse Generator ◽  
Hormone Secretion ◽  
Pulse Interval ◽  
Serum Concentrations ◽  
Luteinizing Hormone Secretion ◽  
Lh Release ◽  
Lh Secretion ◽  
Additional Feedback ◽  
Male Sheep

Abstract. The acute castrate ram (wether) was used as an experimental model to investigate the site(s) of feedback on luteinizing hormone (LH) by testosterone, dihydrotestosterone and oestradiol. At the time of castration, wethers were implanted subdermally with Silastic capsules containing either crystalline testosterone (three 30 cm capsules), dihydrotestosterone (five 30 cm capsules) or oestradiol (one 6.5 cm capsule). Blood samples were taken at 10 min intervals for 6 h 2 weeks after implantation to determine serum steroid concentrations and to characterize the patterns of LH secretion. Pituitary LH response to exogenous LRH (5 ng/kg body weight) were also determined at the same time. The steroid implants produced serum concentrations of the respective hormones which were either one-third (testosterone) or two-to-four times (dihydrotestosterone, oestradiol) the levels measured in rams at the time of castration. Non-implanted wethers showed rhythmic pulses of LH (pulse interval 40–60 min) and had elevated LH levels (16.1 ± 1.6 ng/ml; mean ± se) 2 weeks after castration. All three steroids suppressed pulsatile LH release and reduced mean LH levels (to below 3 ng/ml) and pituitary LH responses to LRH. Inhibition of pulsatile LH secretion by all three steroids indicated that testosterone as well as its androgenic and oestrogenic metabolites can inhibit the LRH pulse generator in the hypothalamus. Additional feedback on the pituitary was indicated by the dampened LH responses to exogenous LRH.

Effect of Long-Acting Thyroid Stimulator on Serum Concentration of Luteinizing Hormone in the Rat

1975 ◽  
Vol 48 (3) ◽  
pp. 231-233
Author(s):  
P. Dandona ◽  
D. J. El Kabir ◽  
F. Naftolin ◽  
P. C. B. MacKinnon
Keyword(s):  
Luteinizing Hormone ◽  
Serum Concentration ◽  
Pituitary Gland ◽  
Immunoglobulin G ◽  
Adrenocorticotrophic Hormone ◽  
Serum Concentrations ◽  
Serum Luteinizing Hormone ◽  
Serum Lh ◽  
Long Acting ◽  
Dexamethasone Suppression

1. The effect of long-acting thyroid stimulator (LATS) on the serum luteinizing hormone (LH) levels of the rat in pro-oestrus has been studied. 2. The injection of three out of four LATS-containing immunoglobulin G fractions caused an increase in amounts of serum LH. 3. Adrenalectomy and dexamethasone suppression did not alter this response. 4. Injection of large doses of adrenocorticotrophic hormone did not produce any increase in serum concentrations of LH. 5. It is postulated that LATS may have a direct effect on the release of LH from the pituitary gland.

RESTORATION OF OESTROGEN POSITIVE FEEDBACK EFFECT ON LH RELEASE BY BROMOCRIPTINE IN HYPERPROLACTINAEMIC PATIENTS WITH GALACTORRHOEA-AMENORRHOEA

1979 ◽  
Vol 91 (3) ◽  
pp. 591-600 ◽  
Author(s):  
Toshihiro Aono ◽  
Akira Miyake ◽  
Takenori Shioji Motoi Yasuda ◽  
Koji Koike ◽  
Keiichi Kurachi
Keyword(s):  
Luteinizing Hormone ◽  
Follicle Stimulating Hormone ◽  
Serum Prolactin ◽  
Serum Luteinizing Hormone ◽  
Serum Lh ◽  
Lh Release ◽  
The Mean ◽  
Lh Rh ◽  
Lh Releasing Hormone ◽  
Positive Feedback Effect

ABSTRACT Five mg of bromocriptine was administered for 3 weeks to 8 hyperprolactinaemic women with galactorrhoea-amernorrhoea, in whom the response of serum luteinizing hormone (LH) and follicle-stimulating hormone (FSH) to 100 μg of iv LH-releasing hormone (LH-RH) had been evaluated. Twenty mg of conjugated oestrogen (Premarin®) was injected iv any day between the 10th and 12th day from the initiation of the treatment, and serum LH levels were serially determined for 120 h. Hyperresponse of LH with normal FSH response to LH-RH was observed in most patients. Bromocriptine treatment for 10 to 12 days significantly suppressed mean (± se) serum prolactin (PRL) levels from 65.1 ± 23.0 to 10.4 ± 2.0 ng/ml, while LH (12.6 ± 2.1 to 24.8 ± 5.9 mIU/ml) and oestradiol (40.1 ± 7.6 to 111.4 ± 20.8 pg/ml) levels increased significantly. Patients on bromocriptine treatment showed LH release with a peak at 48 h after the injection of Premarin. The mean per cent increases in LH were significantly higher than those in untreated patients with galactorrhoea-amenorrhoea between 32 and 96 h after the injection. The present results seem to suggest that the restoration of LH-releasing response to oestrogen following suppression of PRL by bromocriptine may play an important role in induction of ovulation in hyperprolactinaemic patients with galactorrhoea-amenorrhoea.

Effects of age on the irregularity of LH and FSH serum concentrations in women and men

1997 ◽  
Vol 273 (5) ◽  
pp. E989-E995 ◽  
Author(s):  
Steven M. Pincus ◽  
Johannes D. Veldhuis ◽  
Thomas Mulligan ◽  
Ali Iranmanesh ◽  
William S. Evans
Keyword(s):  
Luteinizing Hormone ◽  
Follicle Stimulating Hormone ◽  
Approximate Entropy ◽  
Serum Concentrations ◽  
Serum Samples ◽  
Clinical Marker ◽  
Young Females ◽  
Healthy Humans ◽  
Lh Release ◽  
Model Independent

We evaluated an apparent distinction between follicle-stimulating hormone (FSH) and luteinizing hormone (LH) dynamics: visually, it appears that the pattern of serum concentrations of FSH is more irregular than that of LH in younger human females. We studied healthy humans, with LH and FSH serum samples obtained every 10 min for 24 h. Three groups were studied: 24 young females [8 early follicular (EFol), 8 late follicular (LFol), and 8 midluteal (MLut)]; 8 postmenopausal females; and 17 males 21–79 yr of age. To quantify serial irregularity, we utilized approximate entropy (ApEn), a scale- and model-independent statistic. For young females, FSH was consistently more irregular than LH per subject: among the younger subjects, ApEn(FSH) − ApEn(LH) = 0.342 ± 0.270; ApEn(FSH) > ApEn(LH), P < 0.00001; ApEn(FSH) > ApEn(LH) for 23 of 24 subjects. For each cycle stage, pairwise ApEn(FSH) > ApEn(LH): P < 0.005 for both LFol and MLut, P < 0.01 for EFol. Notably, for the postmenopausal women, the irregularity difference vanished: ApEn(FSH) − ApEn(LH) = 0.008 ± 0.205. Males exhibited qualitatively similar results: ApEn(FSH) − ApEn(LH) was significantly and negatively correlated with age ( r = −0.75, P = 0.0006). The capability to quantify (the extent of) differences between FSH and LH release, beyond the general 1:1 correspondence between primary LH and FSH pulses, suggests a means to assess bihormonal changes as a clinical marker of altered reproductive status in a variety of settings, e.g., a perimenopausal milieu. Mechanistically, the erosion of unequal FSH-LH regularity with age is consistent with a loss of synchrony control within the integrated hypothalamo-pituitary-gonadal axis.

EFFECTS OF AN ANTI-OESTROGEN, TAMOXIFEN (ICI 46,474), ON LUTEINIZING HORMONE RELEASE AND OVULATION IN THE HEN

1981 ◽  
Vol 88 (2) ◽  
pp. 309-316 ◽  
Author(s):  
SUSAN C. WILSON ◽  
F. J. CUNNINGHAM
Keyword(s):  
Luteinizing Hormone ◽  
Pituitary Gland ◽  
Intramuscular Injection ◽  
Hormone Release ◽  
Luteinizing Hormone Release ◽  
Facilitative Role ◽  
Lh Release ◽  
Lh Rh ◽  
Lh Releasing Hormone

The role of oestradiol in the regulation of LH release in the hen was studied by use of the anti-oestrogen, tamoxifen (ICI 46,474). Intramuscular injection of laying hens with 2 or 4 mg tamoxifen on 2 successive days delayed or prevented the occurrence of the preovulatory release of LH and ovulation expected on day 3. Ovulation could be restored by i.v. injection of 20 pg LH releasing hormone (LH-RH). Tamoxifen at a dose of 1 mg affected neither the timing of the preovulatory release of LH nor ovulation. Treatment with 2 or 4 mg tamoxifen on 2 successive days reduced the effectiveness of an i.m. injection of progesterone to stimulate a release of LH. Injection of 1, 2 or 4 mg tamoxifen on 2 successive days significantly raised basal levels of LH in the blood at 24 h after the last injection. This was associated with an increase in the capacity of the pituitary gland to respond to an injection of synthetic LH-RH by a release of LH. These studies suggest that oestradiol has at least two roles in the regulation of LH release in the hen. First, it maintains a low basal level of LH in the blood by reducing the responsiveness of the pituitary gland to LH-RH. Secondly, oestradiol has a facilitative role in the mechanism by which progesterone stimulates the preovulatory release of LH.

Acute and Chronic Estradiol-17β Inhibition of LH Release in Prepubertal Female Pigs: Time Course and Site of Action1

Endocrinology ◽  
1975 ◽  
Vol 96 (3) ◽  
pp. 558-563 ◽  
Author(s):  
D. K. POMERANTZ ◽  
G. R. FOXCROFT ◽  
A. V. NALBANDOV
Keyword(s):  
Time Course ◽  
Lh Release ◽  
Estradiol 17Β

Effect of 17 beta-estradiol on pituitary cAMP binding and responses to DBcAMP

1981 ◽  
Vol 240 (3) ◽  
pp. E297-E301
Author(s):  
L. K. Tang ◽  
F. Y. Tang
Keyword(s):  
Luteinizing Hormone ◽  
Priming Effect ◽  
Time Course ◽  
Time Dependent ◽  
Female Rats ◽  
Maximal Effect ◽  
Dibutyryl Camp ◽  
Hormone Synthesis ◽  
Monolayer Cultures ◽  
Lh Release

Effects of 17 beta-estradiol (E2) on adenosine 3',5'-cyclic monophosphate (cAMP) binding and luteinizing hormone (LH) and prolactin (PRL) responses to N6-O-2'-dibutyryl cAMP (DBcAMP) were examined in pituitary monolayer cultures prepared from female rats. Incubation with 8 mM DBcAMP for 4 h significantly (P less than 0.05) increased both LH and PRL release into medium by two- to threefold. E2 pretreatment augmented the DBcAMP-induced LH release but not PRL release to 160% of the non-E2-treated controls. However, the cellular and total accumulation of both LH and PRL were significantly increased in cultures pretreated with E2. The effect of E2 was time dependent, and the maximal effect was observed after 3 days of treatment. Furthermore, E2 treatment significantly increased cAMP-binding activities to 254% of the non-E2-treated controls. The time course of the E2 effect on cAMP-binding activities closely resembled the time course of the E2 effect on LH and PRL accumulation as well as the DBcAMP-induced LH release. These results suggest that the priming effect of E2 on pituitary LH and PRL responses to DBcAMP is associated with increased hormone synthesis and cAMP binding stimulated by E2 pretreatment.

scholarly journals Estradiol-17β Pharmacokinetics and Histological Assessment of the Ovaries and Uterine Horns following Intramuscular Administration of Estradiol Cypionate in Feral Cats

Animals ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 1708
Author(s):  
Timothy H. Hyndman ◽  
Kelly L. Algar ◽  
Andrew P. Woodward ◽  
Flaminia Coiacetto ◽  
Jordan O. Hampton ◽  
...  
Keyword(s):  
Time Course ◽  
Mixed Effects ◽  
Felis Catus ◽  
Serum Concentrations ◽  
Feral Cats ◽  
Linear Mixed Effects ◽  
Artificial Induction ◽  
Long Acting ◽  
Estrous Behavior ◽  
Estradiol 17Β

The control of feral cats (Felis catus) in Australia is a key biological conservation issue. Male cats are more difficult to control than female cats. Collared and tagged female cats displaying estrous behavior have been considered as a way to lure male cats and reveal their locations. As female cats are seasonal breeders, artificial induction of estrous behavior following the administration of a long-acting estrogen could improve their use for this purpose. Estradiol cypionate was intramuscularly administered to nine entire non-pregnant female feral cats, of unknown estrous status, at 0.1, 0.3, or 0.5 mg/kg. Mean peak serum concentrations of estradiol-17β were 365 pg/mL (0.1 mg/kg), 1281 pg/mL (0.3 mg/kg), and 1447 pg/mL (0.5 mg/kg). The time-course of estradiol-17β concentrations after various doses of estradiol cypionate was assessed using non-compartmental and non-linear mixed-effects methods. At the highest-studied dose (0.5 mg/kg), the 50th percentile of estradiol-17β concentrations exceeded 0.1 ng/mL for 11.8 days, and 0.05 ng/mL for 14.6 days. The duration increased with increasing dose. No signs of toxicity were noticed in any cat during the study. This information will be useful to ongoing studies that are investigating ways to reduce the abundance of feral cats in Australia, especially adult male cats.

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