Initiation of spermatogenesis and testicular growth in oestradiol-17β-implanted bull calves with pulsatile infusion of luteinizing hormone releasing hormone

1982 ◽  
Vol 93 (2) ◽  
pp. 183-NP ◽  
Author(s):  
B. D. Schanbacher ◽  
M. J. D'Occhio ◽  
J. E. Kinder
Keyword(s):  
Pubertal Development ◽  
Serum Testosterone ◽  
Sperm Production ◽  
Releasing Hormone ◽  
Testicular Growth ◽  
Bull Calves ◽  
Testicular Weight ◽  
Additional Support ◽  
Lh Rh ◽  
Lh Releasing Hormone

Testicular growth and secretory profiles of LH and testosterone were monitored in three bull calves implanted with oestradiol-17β and three bull calves implanted with oestradiol-17β and infused intravenously with LH releasing hormone (LH-RH; 500 ng/pulse per h, 30-s pulse) continuously between 34 and 42 weeks of age. Oestradiol-17β implants restricted testicular growth and spermatogenesis by interfering with the hypothalamo-pituitary-testicular endocrine axis. Initiation of pulsatile LH release by LH-RH pulse infusion was accompanied by a twofold increase in mean circulating levels of LH (3·4 v. 1·8 μg/l) and a marked increase in serum testosterone (13·0 v. 0·4 μg/l). Testicular diameter was enhanced significantly by week 4 of infusion and increased in a linear fashion up to and including week 8. Testicular weight (g) and total daily sperm production (× 109) at 42 weeks of age were decreased in calves implanted with oestradiol-17β (105 ± 14 (s.e.m.); 0·0) when compared with calves implanted with oestradiol-17β and infused with LH-RH (254 ± 12; 1·2 ± 0·3). Differences in testicular size and sperm production rates between LH-RH-infused and control bulls without implants (352 ± 26; 3·3 ± 0·9) were attributed to the 2-month delay between oestradiol-17β treatment and the initiation of LH-RH treatment. These results (1) confirm our earlier conclusion that oestradiol-17β can interfere with normal pubertal development in beef bulls and (2) provide additional support that pulsatile LH secretion is important for the initiation of testicular growth and spermatogenesis in pubertal bulls.

IMPORTANCE OF THE EPISODIC NATURE OF LUTEINIZING HORMONE SECRETION FOR NORMAL DEVELOPMENT OF THE BOVINE TESTIS DURING PUBERTY: INTERFERENCE WITH OESTRADIOL-17β

1981 ◽  
Vol 88 (3) ◽  
pp. 393-400 ◽  
Author(s):  
B. D. SCHANBACHER
Keyword(s):  
Normal Development ◽  
Pubertal Development ◽  
Hormone Secretion ◽  
Serum Testosterone ◽  
Luteinizing Hormone Secretion ◽  
Testicular Growth ◽  
Serum Lh ◽  
Beef Bulls ◽  
Lh Releasing Hormone ◽  
Lh Secretion

An experiment was conducted to determine the importance of episodic LH secretion during pubertal development in beef bulls. Testicular growth, LH secretory patterns and serum testosterone concentrations were monitored in control bulls, and bulls implanted with one or two oestradiol-filled capsules from 26 to 38 weeks of age. Control but not oestradiol-treated bulls showed normal testicular growth and episodic LH secretory patterns. Serum LH and testosterone responses of 38-week-old control and oestradiol-treated bulls to an intravenous challenge of 5 μg LH releasing hormone indicated normal pituitary responsiveness, but steroidogenic responsiveness had not yet developed in oestradiol-treated bulls. Removal of the capsules at 38 weeks of age resulted in a normal episodic release pattern for LH, with concomitant growth of the underdeveloped testes up to 44 weeks of age. Serum concentrations of LH and testosterone were within the range of normal, adult values by 42 weeks of age. These results suggest that oestradiol can interfere with episodic LH secretion and normal pubertal development in beef bulls, and furthermore that episodic LH secretion is commensurate with the establishment of normal development of the bovine testis during puberty.

Luteinizing hormone releasing hormone prevents testicular atrophy in golden hamsters exposed to a short photoperiod: temporal difference in effectiveness of administration of luteinizing hormone releasing hormone

1983 ◽  
Vol 96 (1) ◽  
pp. 147-154 ◽  
Author(s):  
H. J. Chen
Keyword(s):  
Luteinizing Hormone ◽  
Serum Testosterone ◽  
Testicular Atrophy ◽  
Temporal Difference ◽  
Luteinizing Hormone Releasing Hormone ◽  
Testosterone Concentration ◽  
Releasing Hormone ◽  
Golden Hamsters ◽  
Testicular Weight ◽  
Lh Rh

Exposure of male golden hamsters to short photoperiods of 6 h light: 18 h darkness led to testicular and accessory sex organ atrophy in 5 weeks. Short photoperiods also significantly depressed serum levels of LH, FSH, prolactin and testosterone in samples obtained by decapitation, but not in samples collected on the preceding day under ether anaesthesia. Injections of luteinizing hormone releasing hormone (LH-RH) at 09.00 h (lights on) or at 15.00 h (lights off) prevented testicular regression when compared with hamsters receiving injection vehicle only. However, the hamsters receiving LH-RH injections at lights on had significantly greater testicular weight and accessory sex organ (seminal vesicles and coagulating glands) weight and testosterone concentration than those receiving LH-RH at lights off. No increase in testicular weight was observed in hypophysectomized male hamsters given the same LH-RH injections and the same lighting regimen. These results indicate that LH-RH alone can prevent, at least partially, testicular and sex organ atrophy and increase serum testosterone concentration by stimulating release of LH and FSH in hamsters exposed to short photoperiods, involving temporal difference of LH-RH action. Further implications of the results are discussed.

EFFECT OF CORTISOL OR ADRENOCORTICOTROPHIN ON RELEASE OF LUTEINIZING HORMONE INDUCED BY LUTEINIZING HORMONE RELEASING HORMONE IN THE DAIRY HEIFER

1982 ◽  
Vol 92 (1) ◽  
pp. 141-146 ◽  
Author(s):  
R. L. MATTERI ◽  
G. P. MOBERG
Keyword(s):  
Luteinizing Hormone ◽  
Luteinizing Hormone Releasing Hormone ◽  
Releasing Hormone ◽  
Dairy Heifers ◽  
Significant Difference ◽  
Significant Depression ◽  
Lh Rh ◽  
Lh Releasing Hormone ◽  
And Control ◽  
Slight Depression

During treatment with cortisol or ACTH, dairy heifers were given two doses of LH releasing hormone (LH-RH) spaced 1·5 h apart. Serum concentrations of cortisol and LH were monitored during each treatment. Treatment with both ACTH and cortisol raised plasma cortisol levels above the respective saline controls (P<0·001). Neither treatment affected basal LH concentrations. A slight depression in LH response was seen in the cortisol-treated animals after the first LH-RH injection, as shown by a statistically significant depression at three of the sample times. There was no significant difference between treated and control LH values after the second LH-RH administration. Treatment with ACTH resulted in significantly reduced LH values at all sample times after both injections of LH-RH.

Relative Insensitivity of Rhesus Monkeys to the LH-Releasing Hormone (LH-RH)

1973 ◽  
Vol 36 (2) ◽  
pp. 372-374 ◽  
Author(s):  
AKIRA ARIMURA ◽  
HAROLD G. SPIES ◽  
ANDREW V. SCHALLY
Keyword(s):  
Rhesus Monkeys ◽  
Releasing Hormone ◽  
Lh Rh ◽  
Lh Releasing Hormone

DIAGNOSTIC VALUE OF THE LH-RELEASING HORMONE STIMULATION TEST IN FUNCTIONAL AMENORRHEA

1975 ◽  
Vol 78 (4) ◽  
pp. 625-633 ◽  
Author(s):  
D. Vandekerckhove ◽  
M. Dhont ◽  
J. Van Eyck
Keyword(s):  
Anorexia Nervosa ◽  
Diagnostic Value ◽  
Base Line ◽  
List Type ◽  
Releasing Hormone ◽  
The Absolute ◽  
Lh Rh ◽  
Lh Releasing Hormone ◽  
Circulating Levels ◽  
Secretory Capacity

ABSTRACT LH-releasing hormone (25 μg, iv.) was administered to 37 women with functional amenorrhea. In addition to the clinical classification, these patients were divided into three groups according to the basal level of serum LH. A significant correlation was found between the base-line levels of LH and the serum concentration of oestradiol plus oestrone. The absolute increment of LH after the injection of LH-RH was found to be dependent only on the base-line level of LH. Except for the patients with anorexia nervosa, the base-line levels and the response pattern of FSH were almost the same for all three groups. From the results of this study, it was concluded that: The circulating levels of oestradiol and oestrone, where derived from ovarian secretion, actually depend on the gonadotrophic stimulus. In patients with functional amenorrhea, the oestrogens do not make an independent contribution to the pituitary response to LH-RH. Dysregulation of releasing hormones, whether located at the hypothalamic or suprahypothalamic level, necessarily influences the secretory capacity of the pituitary gland; long-standing deficiency of LH-RH may finally lead to a state of pituitary "functional" unresponsiveness to releasing hormones. In view of the excellent correlation between the base-line levels of LH and the absolute increment of LH following stimulation with LH-RH, this test only accentuates the existing pituitary secretory capacity, which can be roughly estimated from the circulating levels of LH and FSH. This test may be useful in distinguishing the milder cases of psychogenic amenorrhea from extreme gonadotrophic dysfunction in patients with anorexia nervosa.

EFFECT OF LONG-TERM INFUSION OF AN LH-RELEASING HORMONE AGONIST ON TESTICULAR FUNCTION IN BULLS

1986 ◽  
Vol 109 (2) ◽  
pp. R9-R11 ◽  
Author(s):  
W. v. Rechenberg ◽  
J. Sandow ◽  
P. Klatt
Keyword(s):  
Treatment Period ◽  
Serum Testosterone ◽  
Constant Infusion ◽  
Continuous Administration ◽  
Entire Treatment Period ◽  
Releasing Hormone ◽  
Testosterone Secretion ◽  
Lhrh Agonists ◽  
Lh Releasing Hormone

ABSTRACT Continuous administration of LH-releasing hormone (LHRH) agonists is an effective method of suppressing testosterone secretion in the male. The effect of the LH-releasing hormone (LHRH) agonist, buserelin, administered to bulls by constant infusion from osmotic minipumps was studied. In one experiment with four treated and one control bull, 109 pg buserelin/day were administered for 22 days. Immediately after implantation, serum testosterone concentrations rose from below 35 nmol/l to 35-105 nmol/l, and all four buserelin-infused bulls showed increased testosterone secretion during the treatment period. After removal of the minipumps, testosterone concentrations decreased to pretreatment levels. In a second experiment bulls were infused for 42 days (four treated and one control), and identical results were obtained. Testosterone secretion was stimulated (52-87 nmol/l serum) during the entire treatment period. These results demonstrate that conditions for stimulation of the pituitary-testicular axis may vary between species. Infusion of low doses of LHRH-agonists in bulls has an extended stimulatory effect without immediate desensitization of gonadotrophin release.

EFFECTS OF MATING AND INJECTION OF LUTEINIZING HORMONE RELEASING HORMONE ON SERUM LUTEINIZING HORMONE AND TESTOSTERONE CONCENTRATIONS IN RABBITS

1978 ◽  
Vol 76 (3) ◽  
pp. 417-425 ◽  
Author(s):  
C. A. BLAKE ◽  
PATRICIA K. BLAKE ◽  
NANCY K. THORNEYCROFT ◽  
I. H. THORNEYCROFT
Keyword(s):  
Luteinizing Hormone ◽  
Serum Testosterone ◽  
Serum Levels ◽  
Transient Increase ◽  
Marked Rise ◽  
Luteinizing Hormone Releasing Hormone ◽  
Releasing Hormone ◽  
Serum Lh ◽  
Before And After ◽  
Lh Rh

The effects of coitus and injection of luteinizing hormone releasing hormone (LH-RH) on serum concentrations of LH, testosterone and dihydrotestosterone (17β-hydroxy-5α-androstan-3-one; DHT) were tested in male rabbits. Before experimentation, male and female rabbits were housed in individual cages in the same room. Male rabbits were then bled by cardiac puncture before and after placement with female rabbits or intravenous injection of LH-RH. Serum LH, testosterone and DHT were measured by radioimmunoassay. Sexual excitement (sniffing, chasing and mounting), with or without intromission, caused a marked rise in serum testosterone and DHT concentrations in only some of the bucks. These increases were accompanied or preceded by a small, transient increase in serum LH. In the rest of the bucks, sexual excitement with or without intromission had either no effect on serum levels of all three hormones, or only serum testosterone and DHT decreased during the collection period. Similar responses were measured in bucks which were housed in a room without does for 2–4 weeks before experimentation. Injection of 10, 30 or 100 ng or 50 μg LH-RH caused serum LH, testosterone and DHT to rise in all bucks tested, but the magnitude of the rises in serum testosterone and DHT were not related to the magnitude of the LH rise. In both mated and LH-RH-injected bucks, the rises in serum testosterone and DHT were greatest in animals with low initial testosterone and DHT values. Under the conditions of this study, the data suggest that: (1) serum testosterone and DHT rise in only some male rabbits after sexual excitement (with or without intromission), (2) the rises in serum testosterone and DHT are dependent on a small transient increase in serum LH and (3) sexual excitement is less likely to cause release of LH-RH in bucks with raised serum testosterone and DHT concentrations.

scholarly journals Studies on the Measurements of LH-releasing Hormone (LH-RH) by Radioimmunoassay (RIA)

1976 ◽  
Vol 52 (1) ◽  
pp. 62-71
Author(s):  
Takayuki KTNUGASA ◽  
Osamu TANIZAWA ◽  
Kenji YAMAJI ◽  
Keiichi KURACHI
Keyword(s):  
Releasing Hormone ◽  
Lh Rh ◽  
Lh Releasing Hormone

LUTEINIZING HORMONE RELEASING HORMONE-INDUCED RELEASE OF LUTEINIZING HORMONE FROM PITUITARY EXPLANTS OF COWS KILLED BEFORE OR AFTER OESTRADIOL TREATMENT

1981 ◽  
Vol 88 (1) ◽  
pp. 17-25 ◽  
Author(s):  
E. M. CONVEY ◽  
J. S. KESNER ◽  
V. PADMANABHAN ◽  
T. D. CARRUTHERS ◽  
T. W. BECK
Keyword(s):  
Luteinizing Hormone ◽  
Pituitary Gland ◽  
Lh Surge ◽  
Releasing Hormone ◽  
Oestradiol Treatment ◽  
Readily Releasable Pool ◽  
Serum Lh ◽  
Pituitary Glands ◽  
Lh Rh ◽  
Lh Releasing Hormone

In ovariectomized heifers, oestradiol decreases concentrations of LH in serum for approximately 12 h after which LH is released in a surge comparable in size and duration to the preovulatory surge. Using this model, we measured LH release induced by LH releasing hormone (LH-RH) from pituitary explants taken from ovariectomized heifers before or after an oestradiol-induced LH surge. These changes were related to changes in LH concentrations in serum and pituitary glands and hypothalamic LH-RH content. Twenty Holstein heifers were randomly assigned to one of four treatment groups to be killed 0, 6, 12, or 24 h after the injection of 500 μg oestradiol-17β. Jugular blood was collected at −2, −1 and 0 h then at intervals of 2 h until slaughter. Pituitary glands were collected and ≃2 mm3 explants were exposed to 4 ng LH-RH/ml medium for 30 min (superfusion) or 4 ng LH-RH/ml medium for 2 h in Erlenmeyer flasks. Levels of LH were measured in the medium. Hypothalami, collected at autopsy, were assayed for LH-RH content. To determine pituitary LH content, an additional 15 ovariectomized heifers were killed, five each at 0, 12 and 24 h after the injection of 500 μg oestradiol. In both groups of heifers, oestradiol reduced serum LH concentrations to ≃ 1 ng/ml, a level which persisted for 12 h, when LH was released in a surge. Pituitary sensitivity to LH-RH was increased at 6 and 12 h after the injection of oestradiol, but was markedly decreased at 24 h, i.e. after the LH surge. Despite this twofold increase in capacity of the pituitary gland to release LH in response to LH-RH, pituitary LH content did not change during 12 h after oestradiol treatment. However, LH content decreased after the LH surge and this decrease was associated with a decrease in pituitary responsiveness to LH-RH. Hypothalamic LH-RH content was not altered by these treatments. We have interpreted our results as evidence that oestradiol exerts a positive feedback effect on the pituitary gland of ovariectomized heifers such that pituitary sensitivity to LH-RH is increased twofold by the time the LH surge is initiated. In addition, oestradiol causes a transitory inhibition of LH-RH release as shown by the fact that serum LH concentrations remained low during the interval from injection of oestradiol until the beginning of the LH surge despite the fact that pituitary sensitivity to LH-RH is increased at this time. Depletion of a readily releasable pool of pituitary LH may be the mechanism by which the LH surge is terminated.

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