scholarly journals Effect of Heat Stress on Plasma Concentrations of Prolactin and Luteinizing Hormone in Ewes

1979 ◽  
Vol 32 (2) ◽  
pp. 231 ◽  
Author(s):  
RD Hooley ◽  
JK Findlay ◽  
RGA Stephenson
Keyword(s):  
Heat Stress ◽  
Luteinizing Hormone ◽  
Plasma Concentrations ◽  
Oestrous Cycle ◽  
Thyrotrophin Releasing Hormone ◽  
Releasing Hormone ◽  
Hormone Responses ◽  
Gonadotrophin Releasing Hormone

Basal concentrations of prolactin but not luteinizing hormone were elevated in ewes by 8-10 h of heat stress given daily during the first 11 days of their oestrous cycle. However, the prolactin and luteinizing hormone responses to thyrotrophin releasing hormone and gonadotrophin releasing hormone were unaffected.

PROLONGED RELEASE BY DIOESTROUS RATS OF FOLLICLE-STIMULATING HORMONE DURING THE PERIOD OF OVULATION INDUCED BY LUTEINIZING HORMONE RELEASING HORMONE

1979 ◽  
Vol 81 (1) ◽  
pp. 109-118 ◽  
Author(s):  
SHUJI SASAMOTO ◽  
SHIGEO HARADA ◽  
KAZUYOSHI TAYA
Keyword(s):  
Luteinizing Hormone ◽  
Plasma Concentrations ◽  
High Plasma ◽  
Oestrous Cycle ◽  
Prolonged Release ◽  
Luteinizing Hormone Releasing Hormone ◽  
Releasing Hormone ◽  
Follicular Maturation ◽  
Lh Rh ◽  
Premature Ovulation

When 1·0 μg luteinizing hormone releasing hormone (LH-RH) was given i.v. three times at 1 h intervals from 17.00 to 19.00 h on the day of dioestrus (day 0) to regular 4 day cyclic rats, premature ovulation was induced the next morning (day 1) with the number of ova present comparable to normal spontaneous ovulation. The next spontaneous ovulation occurred on the morning of day 5, 4 days after premature ovulation induced by LH-RH. Plasma concentrations of FSH and LH showed transient rises and falls within 1 h of administration of LH-RH; concentrations of FSH in the plasma decreased from 20.00 h on day 0 but markedly increased again from 23.00 h on day 0 to 02.00 h on day 1 and these high levels persisted until 14.00 h on day 1, with only a small increase of plasma LH during this period. The duration of increased FSH release during premature ovulation induced by LH-RH treatment was 6 h longer than the FSH surge occurring after administration of HCG on day 0. Surges of gonadotrophin were absent on the afternoon of day 1 (the expected day of pro-oestrus) and the surges characteristic of pro-oestrus occurred on the afternoon of day 4 and ovulation followed the next morning. The pituitary content of FSH did not decrease despite persisting high plasma levels of FSH during premature ovulation induced by either LH-RH or HCG on day 0. The changes in uterine weight indicated that the pattern of oestrogen secretion from the day of premature ovulation induced by LH-RH to the day of the next spontaneous ovulation was similar to that of the normal 4 day oestrous cycle. When 10 i.u. HCG were given on day 0, an increase in oestrogen secretion occurred on day 2, 1 day earlier than in the group given LH-RH on day 0. This advancement of oestrogen secretion was assumed to be responsible for the gonadotrophin surges on day 3. Similar numbers of fully developed follicles were found by 17.00 h on day 2 after premature ovulation induced by either LH-RH or HCG, suggesting that the shorter surge of FSH during premature ovulation induced by HCG had no serious consequences on the initiation of follicular maturation for the succeeding oestrous cycle in these rats. Administration of LH-RH on day 0 had no direct effect on the FSH surge during premature ovulation. Secretory changes in the ovary during ovulation may be responsible for this prolonged selective release of FSH.

Anti-fertility effects of oral medroxyprogesterone acetate in rabbits

1996 ◽  
Vol 8 (8) ◽  
pp. 1185 ◽  
Author(s):  
NO Oguge ◽  
GK Barrell
Keyword(s):  
Single Dose ◽  
Luteinizing Hormone ◽  
Medroxyprogesterone Acetate ◽  
Plasma Concentrations ◽  
Inhibitory Effect ◽  
Multiple Dosing ◽  
Releasing Hormone ◽  
Single Meal ◽  
Gonadotrophin Releasing Hormone ◽  
Hypothalamic Level

Studies on the anti-fertility effects of medroxyprogesterone acetate (MPA) were conducted in rabbits. The bioavailability of MPA and plasma concentrations of progesterone and luteinizing hormone (LH) after mating were monitored following a single meal containing MPA (1000 mg) in entire does (n = 4); the response to gonadotrophin-releasing hormone (GnRH; 250 ng) was also observed in MPA-treated, ovariectomized does (n = 6). The reproductive tracts of rabbits mated following MPA treatment were examined 28-30 h after mating. Another group of rabbits (n = 4) received a single dose of MPA on Days 1, 10 or 19 after mating or daily for five days from Day 24. After dosage with 1000 mg MPA, plasma concentrations of MPA were detectable for eight days. However, following multiple dosing (10 mg, 5 days) MPA was detectable in the plasma for two days. MPA reduced the rate of ovulation and suppressed the increase in plasma concentrations of progesterone and LH observed after mating for four days, but had no effect on the response to GnRH. When administered late in gestation, MPA caused the death of fetuses. These results demonstrate an inhibitory effect of MPA on ovulation, probably at the hypothalamic level, and impairment of gestation or parturition.

Luteinizing hormone responses to luteinizing hormone releasing hormone (LHRH) in acute mania and the effects of lithium on LHRH and thyrotrophin releasing hormone tests in volunteers

1989 ◽  
Vol 19 (1) ◽  
pp. 69-77 ◽  
Author(s):  
R. Hunter ◽  
J. E. Christie ◽  
L. J. Whalley ◽  
J. Bennie ◽  
S. Carroll ◽  
...  
Keyword(s):  
Luteinizing Hormone ◽  
Thyroid Stimulating Hormone ◽  
Thyrotrophin Releasing Hormone ◽  
Luteinizing Hormone Releasing Hormone ◽  
Releasing Hormone ◽  
Trh Stimulation ◽  
The Status ◽  
Hormone Responses ◽  
Independent Features ◽  
Stimulating Hormone

SynopsisThe endocrine responses to Luteinizing Hormone Releasing Hormone (LHRH) of eight drug-free males with mania were determined. Basal levels of Luteinizing Hormone (LH) and the plasma levels following injection of LHRH were elevated in patients compared with controls; Follicle Stimulating Hormone (FSH) and testosterone were not different. Elevated levels of LH have been described previously in recovered manic patients and have been suggested to be state-independent features of mania. In order to clarify the status of this finding, the effects of lithium administration upon hormone responses to LHRH in six male volunteers were also investigated, together with the effects upon Thyrotrophin Releasing Hormone (TRH) stimulation of Thyroid Stimulating Hormone (TSH) and prolactin release. Lithium increased the basal levels of LH and levels after injection of LHRH without effect upon FSH and testosterone. Lithium also increased basal and TRH stimulated release of TSH and basal prolactin levels. Lithium was without effect upon prolactin responses to TRH. The results are discussed in relation to current information on the mechanism of lithium's action. The implications for neuroendocrine work on recovered patients taking lithium are also explored.

Plasma LH and testosterone responses to gonadotrophin-releasing hormone in adult red deer (Cervus elaphus) stags during the annual antler cycle

1988 ◽  
Vol 117 (1) ◽  
pp. 35-41 ◽  
Author(s):  
P. F. Fennessy ◽  
J. M. Suttie ◽  
S. F. Crosbie ◽  
I. D. Corson ◽  
H. J. Elgar ◽  
...  
Keyword(s):  
Red Deer ◽  
Plasma Concentrations ◽  
Reproductive Hormones ◽  
Sexual Cycle ◽  
Late Winter ◽  
Releasing Hormone ◽  
Antler Growth ◽  
Velvet Antler ◽  
Antler Cycle ◽  
Gonadotrophin Releasing Hormone

ABSTRACT Eight adult red deer stags were given an i.v. injection of synthetic gonadotrophin-releasing hormone (GnRH) on seven occasions at various stages of the antler cycle, namely hard antler in late winter, casting, mid-velvet growth, full velvet growth, antler cleaning and hard antler both during the rut and in mid-winter. The stags were allocated at random on each occasion to one of four doses, i.e. 1, 3, 10 or 95 μg GnRH. Blood samples were taken before GnRH injection and for up to 2 h after injection. Pituitary and testicular responses were recorded in terms of plasma LH and testosterone concentrations. There was an increase in plasma concentration of LH after the GnRH injection in all stags at all stages of the antler cycle. Dose-dependent responses of LH to GnRH in terms of area under the curve were apparent at all stages of the antler cycle. The lowest responses were recorded at casting, during velvet antler growth and at the rut sampling. The pattern of testosterone response reflected the inter-relationship of the antler and sexual cycles with very low testosterone responses occurring at casting and during velvet antler growth. The responses were higher at antler cleaning and then increased to a maximum at the rut before declining to reach their nadir at casting. The results are consistent with a hypothesis that the antler cycle, as a male secondary sexual characteristic, is closely linked to the sexual cycle and its timing is controlled by reproductive hormones. Low plasma concentrations of testosterone, even after LH stimulation, are consistent with the hypothesis that testosterone is unnecessary as an antler growth stimulant during growth. J. Endocr. (1988) 117, 35–41

PLASMA CONCENTRATIONS OF PROLACTIN AND THYROTROPHIN DURING SUCKLING: EFFECTS OF STIMULATION OF THE MEDIAN EMINENCE

1978 ◽  
Vol 76 (3) ◽  
pp. 557-558 ◽  
Author(s):  
J. B. WAKERLEY ◽  
M. B. TER HAAR
Keyword(s):  
Direct Effect ◽  
Median Eminence ◽  
Plasma Concentrations ◽  
Prolactin Release ◽  
Thyrotrophin Releasing Hormone ◽  
Releasing Hormone ◽  
Animal Physiology ◽  
Inhibiting Factor ◽  
Hypothalamic Level ◽  
Stimulation Of

A.R.C. Institute of Animal Physiology, Babraham, Cambridge, CB2 4AT (Received 1 November 1977) Thyrotrophin releasing hormone (TRH) can have a stimulatory effect on the release of both prolactin and thyrotrophin (TSH; Deis & Alonso, 1973), although in the rat, supraphysiological doses of TRH are required to affect the secretion of prolactin (Burnet & Wakerley, 1976). A more important factor in the control of the release of prolactin is considered to be prolactin release inhibiting factor (PIF), which is thought to act through the catecholamine, dopamine (MacLeod, 1976). Stimuli which cause the concomitant release of TSH and prolactin are thought to have a direct effect at the hypothalamic level such that neurones releasing TRH are excited, whereas those releasing PIF are inhibited. In the present work, we have tested this hypothesis using the suckling stimulus to elicit the simultaneous release of prolactin and TSH (Blake, 1974; Burnet & Wakerley, 1976). If

Decreased serum testosterone and free triiodothyronine levels in healthy middle-aged men indicate an age effect at the pituitary level

1995 ◽  
Vol 132 (6) ◽  
pp. 663-667 ◽  
Author(s):  
Eva Marie T Erfurth ◽  
Lars E Hagmar
Keyword(s):  
Luteinizing Hormone ◽  
Young Men ◽  
Serum Testosterone ◽  
Free Testosterone ◽  
Age Effect ◽  
Hormone Response ◽  
Middle Aged ◽  
Free Triiodothyronine ◽  
Thyrotrophin Releasing Hormone ◽  
Releasing Hormone

Erfurth EMT, Hagmar LE. Decreased serum testosterone and free triidothyronine levels in healthy middle-aged men indicate an age effect at the pituitary level. Eur J Endocrinol 1995;132:663–7. ISSN 0804–4643 In an attempt to study further the age-specific influence on the hypothalamo-pituitary–gonadal axis as well as the hypothalamo–pituitary–thyroid axis, we have now investigated young and middle-aged men, considering possible confounding factors. Both serum total testosterone, free testosterone and the total ratio of testosterone to sex-hormone binding globulin were significantly lower among middle-aged men as compared with young men (p = 0.02, p = 0.002 and p = 0.0003, respectively). In accordance with these findings there was also a decrease in the luteinizing hormone response to gonadotrophin-releasing hormone in the middle-aged men (p= 0.02). Free testosterone was correlated significantly with the luteinizing hormone response (r = 0.32, p = 0.02). Serum free triiodothyronine was significantly higher among young men as compared with middle-aged men (p = 0.002) and the thyrotrophin-releasing hormone-stimulated thyrotrophin response was also higher in the young group compared with the middle-aged group. The present results may indicate that the age effect on serum levels of testosterone and free triidothyronine is mediated at the pituitary level. Eva Marie Erfurth, Dept. of Internal Medicine, University of Lund, S-221 85 Lund, Sweden

Infertility

2013 ◽  
pp. 551-566
Author(s):  
John Reynard ◽  
Simon Brewster ◽  
Suzanne Biers
Keyword(s):  
Luteinizing Hormone ◽  
Male Infertility ◽  
Anterior Pituitary ◽  
Treatment Options ◽  
Follicle Stimulating Hormone ◽  
Reproductive Physiology ◽  
Seminiferous Tubules ◽  
Luteinizing Hormone Releasing Hormone ◽  
Releasing Hormone ◽  
Gonadotrophin Releasing Hormone

Male reproductive physiology 552 Aetiology and evaluation of male infertility 554 Investigation of male infertility 556 Oligozoospermia and azoospermia 560 Varicocele 562 Treatment options for male infertility 564 The hypothalamus secretes luteinizing hormone-releasing hormone (LHRH), also known as gonadotrophin-releasing hormone (GnRH). This causes the pulsatile release of anterior pituitary gonadotrophins called follicle-stimulating hormone (FSH) and luteinizing hormone (LH), which act on the testis. FSH stimulates the seminiferous tubules to secrete inhibin and produce sperm; LH acts on Leydig cells to produce testosterone (...

Stimulatory effect of thyrotrophin-releasing hormone (TRH) on the release of luteinizing hormone (LH) from rat anterior pituitary cells in vitro

1983 ◽  
Vol 61 (2) ◽  
pp. 186-189 ◽  
Author(s):  
Noboru Fujihara ◽  
Masataka Shiino
Keyword(s):  
Luteinizing Hormone ◽  
Anterior Pituitary ◽  
Pituitary Cells ◽  
Thyrotrophin Releasing Hormone ◽  
Releasing Hormone ◽  
Anterior Pituitary Cells ◽  
Lh Release ◽  
Lh Rh

The effect of thyrotrophin-releasing hormone (TRH, 10−7 M) on luteinizing hormone (LH) release from rat anterior pituitary cells was examined using organ and primary cell culture. The addition of TRH to the culture medium resulted in a slightly enhanced release of LH from the cultured pituitary tissues. However, the amount of LH release stimulated by TRH was not greater than that produced by luteinizing hormone – releasing hormone (LH–RH, 10−7 M). Actinomycin D (2 × 10−5 M) and cycloheximide (10−4 M) had an inhibitory effect on the action of TRH on LH release. The inability of TRH to elicit gonadotrophin release from the anterior pituitary glands in vivo may partly be due to physiological inhibition of its action by other hypothalamic factor(s).

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