VARIATIONS IN STORED AND PLASMA CONCENTRATIONS OF ANDROGENS AND LUTEINIZING HORMONE DURING SEXUAL DEVELOPMENT IN THE COCKEREL

1977 ◽  
Vol 74 (3) ◽  
pp. 467-476 ◽  
Author(s):  
P. J. SHARP ◽  
J. CULBERT ◽  
J. W. WELLS
Keyword(s):  
Luteinizing Hormone ◽  
Pituitary Gland ◽  
Sexual Development ◽  
Rapid Growth ◽  
Plasma Concentrations ◽  
Body Growth ◽  
Initial Increase ◽  
Temporary Reduction ◽  
Testicular Growth ◽  
Rate Of Growth

SUMMARY The concentrations of luteinizing hormone (LH) and testosterone in the plasma and the stored levels of LH, testosterone and androstenedione were measured in cockerels aged 8–29 weeks. The onset of puberty occurred between 16 and 24 weeks of age, when the testes entered a phase of rapid growth and spermatogenesis was completed. The following sequence of endocrine events was found to be associated with the onset of puberty: a fall in the amount of androstenedione in the testes before any evidence of increased testicular growth; an increase in the total amount of LH in the pituitary gland as the testes started to enlarge; an increase in the total amount of testosterone in the testes and in the concentration of LH in the plasma; an increase in the concentration of testosterone in the plasma. An increase in the rate of growth of the comb and testes preceded a detectable increase in the levels of LH and testosterone in the plasma. The increase in the amount of testosterone in the plasma which occurred after the initial increase in the concentration of LH was associated with the final stages of spermatogenesis, a decrease in the rate of body growth and a temporary reduction in the amount of LH secreted.

Concentrations of luteinizing hormone and progesterone in plasma during sexual development of the Khaki Campbell duck

1982 ◽  
Vol 93 (1) ◽  
pp. 47-53 ◽  
Author(s):  
Susan C. Wilson ◽  
T. R. Morris
Keyword(s):  
Plasma Concentration ◽  
Luteinizing Hormone ◽  
Negative Correlation ◽  
Sexual Development ◽  
Plasma Concentrations ◽  
Winter Solstice ◽  
Pronounced Increase ◽  
Threefold Increase ◽  
Lh Release

Concentrations of LH and progesterone were measured in the plasma of ducks which were, from 3 weeks of age, raised on either a constant photoperiod of 16 h light: 8 h darkness or a lighting schedule which simulated natural changes in daylength. In ducks raised on a constant photoperiod of 16 h light: 8 h darkness the plasma concentration of LH increased steeply between 7 and 3·5 weeks before the onset of lay. Concentrations of LH then declined, gradually at first, but then rapidly during the 7 days before the first oviposition in association with a pronounced increase in the plasma concentration of progesterone. During the 18 days before the first egg was laid there was a significant (P < 0·01) negative correlation between the plasma concentrations of LH and progesterone. The patterns of LH release during sexual development of ducks raised on a schedule which simulated natural changes in daylength were variable but could be categorized according to the daylength at which each duck came into lay. In ducks coming into lay soon after the winter solstice when daylength was short (8·0–8·5 h light/day) there was a pronounced 15-fold prepubertal increase in the plasma concentration of LH although in some ducks high LH levels were not maintained until 3–4 weeks before the first oviposition and were not always followed by a rise in the plasma concentration of progesterone. In contrast, in ducks coming into lay when daylength had increased to 11·0–11·5 h light/day there were only minor fluctuations in the plasma concentration of LH until a small two- to threefold increase in LH was observed during the 2 weeks before the first oviposition.

Priming effect of luteinizing hormone releasing hormone in the hypogonadal mouse

1982 ◽  
Vol 94 (2) ◽  
pp. 283-287 ◽  
Author(s):  
G. Fink ◽  
W. J. Sheward ◽  
H. M. Charlton
Keyword(s):  
Luteinizing Hormone ◽  
Pituitary Gland ◽  
Priming Effect ◽  
Plasma Concentrations ◽  
Luteinizing Hormone Releasing Hormone ◽  
Releasing Hormone ◽  
Lh Rh ◽  
Lh Releasing Hormone

We have investigated the LH response to LH releasing hormone (LH-RH) in female hypogonadal (hpg) mice in which the hypothalamus contains no LH-RH and the pituitary gland contains significantly less LH than in normal mice. Both the releasing action and the priming effect of LH-RH were not significantly different in hpg compared with normal mice. Raised plasma concentrations of oestradiol-17β reduced pituitary responsiveness to LH-RH in normal but not in hpg mice. These results show that in the mouse neither longterm exposure to normal levels of LH-RH nor a normal pituitary content of LH are necessary for either the releasing or the priming action of LH-RH.

A PRIMING EFFECT OF LUTEINIZING HORMONE RELEASING FACTOR ON THE ANTERIOR PITUITARY GLAND IN THE FEMALE RAT

1974 ◽  
Vol 62 (3) ◽  
pp. 573-588 ◽  
Author(s):  
M. S. AIYER ◽  
SHARON A. CHIAPPA ◽  
G. FINK
Keyword(s):  
Luteinizing Hormone ◽  
Pituitary Gland ◽  
Anterior Pituitary ◽  
Priming Effect ◽  
Plasma Concentrations ◽  
External Jugular Vein ◽  
Anterior Pituitary Gland ◽  
Female Rat ◽  
Oestradiol Benzoate ◽  
Plasma Oestradiol

SUMMARY The possibility that luteinizing hormone releasing factor (LH-RF) not only stimulates the secretion of luteinizing hormone (LH) but also has the ability to prime the anterior pituitary gland so that further exposure to LH-RF enhances the responsiveness of the gonadotrophs has been investigated. The effect of two successive i.v. injections of the same dose of LH-RF (50 ng/100 g body weight) on the concentration of LH in plasma was determined in rats anaesthetized with sodium pentobarbitone. Blood samples were collected from the external jugular vein immediately before and at frequent intervals after the injections of LH-RF, and plasma concentrations of LH and, in some samples, follicle-stimulating hormone (FSH) were measured by radioimmunoassay. In rats anaesthetized with sodium pentobarbitone at 13.30 h of pro-oestrus and injected i.v. with two successive doses of LH-RF, separated by an interval of 30, 60, 120 or 240 min, the LH response to the second injection was significantly greater than that to the first. The LH response was greatest when the two doses were separated by an interval of 60 min. The FSH response to the second injection of LH-RF given 60 min after the first was not significantly different from that to the first injection. Compared with pro-oestrus, the priming effect of LH-RF was much less at metoestrus and dioestrus, and could not be demonstrated at oestrus. Ovariectomy on the morning of dioestrus reduced the LH responses to the first and second injections of LH-RF given 60 min apart on the afternoon of pro-oestrus, an effect which was partially reversed by administration of oestradiol benzoate shortly after ovariectomy. These findings together with the fact that administration of oestradiol benzoate at metoestrus increased the magnitude of the priming effect of LH-RF at dioestrus suggest that the response at pro-oestrus is dependent upon the rise in plasma oestradiol-17β which reaches a peak on the morning of pro-oestrus. Although oestrogen plays an important role in determining the magnitude of the priming effect of LH-RF, it appears that none of the steroids secreted by either the ovaries or the adrenal glands mediates this effect since the profile and magnitude of the LH responses to the two doses of LH-RF injected at pro-oestrus into rats adrenalectomized and ovariectomized before the first injection of LH-RF were comparable to those in control animals. The possible role which the priming effect of LH-RF may play in the development of the preovulatory surge of LH in the rat and man is discussed.

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.

PLASMA CONCENTRATIONS OF LUTEINIZING HORMONE, TESTOSTERONE AND ANDROSTENEDIONE IN CASTRATED AND ADRENALECTOMIZED BULL CALVES

1978 ◽  
Vol 79 (1) ◽  
pp. 137-138 ◽  
Author(s):  
J. J. BASS ◽  
A. J. PETERSON ◽  
E. PAYNE
Keyword(s):  
New Zealand ◽  
Plasma Concentration ◽  
Luteinizing Hormone ◽  
Agricultural Research ◽  
Plasma Concentrations ◽  
Young Male ◽  
Research Centre ◽  
Similar Magnitude ◽  
Research Division ◽  
Bull Calves

Ministry of Agriculture and Fisheries, Research Division, Ruakura Agricultural Research Centre, Hamilton, New Zealand (Received 17 April 1978) An increase in the plasma concentration of luteinizing hormone (LH) occurs in response to castration in bull calves aged 1–4 months; this response is of similar magnitude to that seen in cattle castrated as adults (Odell, Hescox & Kiddy, 1970). In bull calves castrated at birth, however, there is no increase in the plasma concentration of LH until after 28 days of age (Bass, Peterson, Payne & Jarnet, 1977). In other species a range of responses to castration has been reported. Gonadectomy of male guinea-pigs 0–35 days after birth produces an increase in the plasma concentration of LH similar to that observed in guineapigs castrated as adults (Donovan, ter Haar, Lockhart, MacKinnon, Mattock & Peddie, 1975). In contrast, the castration of young male macaques does not cause an immediate increase in the

Effect of Starvation on Pituitary and Serum Follicle-Stimulating Hormone and Luteinizing Hormone Following Ovariectomy in the Rat

1972 ◽  
Vol 50 (8) ◽  
pp. 768-773 ◽  
Author(s):  
E. A. Ibrahim ◽  
B. E. Howland
Keyword(s):  
Luteinizing Hormone ◽  
Pituitary Gland ◽  
Follicle Stimulating Hormone ◽  
Female Rats ◽  
Intact Female ◽  
Pituitary Glands ◽  
Ad Libitum ◽  
Stimulating Hormone

The concentration of follicle-stimulating hormone (FSH) and luteinizing hormone (LH) in serum and pituitary glands was studied in intact female rats and rats that were ovariectomized on day 0 of the experiment and then starved or fed for 2, 4, 7, or 9 days. Ovariectomy resulted in enhanced rates of synthesis and release of FSH and LH as indicated by the significant (P < 0.01) rises in the concentration of both hormones in the pituitary gland and serum.Starvation resulted in a decrease in body and pituitary weight. The concentration of FSH and LH in pituitary glands of starved rats was higher (P < 0.05) than that in fed rats on days 7 and 9. The concentration of FSH and LH in serum of starved rats was increased after ovariectomy but the levels on days 7 and 9 were lower than those of fed rats.These results suggest that the synthesis of FSH and LH was enhanced in both starved and fed rats following ovariectomy while the rate of release of both hormones was decreased at 7 and 9 days of starvation in comparison with rats fed ad libitum.

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