USE OF A PULSED INFUSION OF LUTEINIZING HORMONE RELEASING HORMONE TO MIMIC SEASONALLY INDUCED ENDOCRINE CHANGES IN THE RAM

1979 ◽  
Vol 83 (2) ◽  
pp. 251-260 ◽  
Author(s):  
G. A. LINCOLN
Keyword(s):  
Plasma Concentrations ◽  
Prolonged Treatment ◽  
Mating Season ◽  
Releasing Hormone ◽  
Natural Lighting ◽  
Sexual Skin ◽  
Gonadotrophin Secretion ◽  
The Individual ◽  
Lh Rh ◽  
Lh Releasing Hormone

Adult Soay rams were housed indoors under natural lighting during the spring non-mating season when gonadotrophin secretion was low. Four animals received small doses (100 ng or 500 ng) of synthetic LH releasing hormone (LH-RH) infused into the jugular vein by a mechanical device for 60 s every 2 h for 33–57 days: two other rams acted as controls. The prolonged treatment with LH-RH resulted in growth of the testes and the development of the sexual skin flush; these effects were lost when treatment stopped. The plasma concentrations of LH, FSH and testosterone were low at the beginning; each short infusion of LH-RH resulted in a transitory increase in the level of LH and testosterone while the concentration of FSH was only marginally affected. After prolonged treatment with 500 ng pulses of LH-RH the plasma concentrations of all three hormones were permanently raised. The response to the individual injections of LH-RH was also modified, the peak in LH being reduced in amplitude but more prolonged while the FSH and testosterone responses were both enhanced. When the pulsed infusion was stopped the concentration of LH and testosterone declined rapidly while the decline in FSH levels took many days. These endocrine changes induced by the pulsed infusion are comparable to those that occur naturally in the ram during testicular redevelopment before the mating season.

Effects of hyperprolactinaemia and testosterone on the release of LH-releasing hormone and the gonadotrophins in intact and castrated rats

1985 ◽  
Vol 104 (1) ◽  
pp. 35-43 ◽  
Author(s):  
A. K. Brar ◽  
A. S. McNeilly ◽  
G. Fink
Keyword(s):  
Plasma Concentrations ◽  
Inhibitory Effect ◽  
Male Rats ◽  
Pituitary Stalk ◽  
Male Rat ◽  
Female Rat ◽  
Kidney Capsule ◽  
Releasing Hormone ◽  
Gonadotrophin Secretion ◽  
Lh Releasing Hormone

ABSTRACT We have investigated the effect of hyperprolactinaemia on the secretion of LH-releasing hormone (LHRH), LH and FSH in male rats of the PVG strain which were left intact, castrated or castrated and then implanted with either a 10 or 30 mm silicone elastomer capsule containing testosterone (T10 and T30 respectively). Hyperprolactinaemia was produced by pituitary grafts under the kidney capsule. Pituitary stalk blood, for LHRH estimation, and peripheral blood, for LH, FSH and prolactin, were collected under alphaxalone anaesthesia. Pituitary stalk blood was collected during three consecutive periods of 30 min each before, during and after the application of an electrical stimulus to the median eminence (ME). Hyperprolactinaemia significantly reduced the plasma concentrations of FSH in intact rats and the post-castration increase in the plasma concentrations of both LH and FSH. Neither hyperprolactinaemia nor castration had any significant effect on the spontaneous output of LHRH, but castration alone or castration plus implantation of a T30 capsule did significantly reduce the increment in LHRH output produced by ME stimulation, an effect not seen in rats bearing pituitary grafts. The T30, but not the T10 capsules suppressed the post-castration increase in the gonadotrophins, and the inhibitory effect of testosterone was not significantly affected by hyperprolactinaemia. An incidental but important finding was that the presence of pituitary grafts under the kidney capsule reduced the anaesthetic dose of alphaxalone by 63%. These results show that (i) in the male rat the inhibitory effect of hyperprolactinaemia on gonadotrophin secretion is not due to a decrease in the spontaneous release of LHRH, (ii) in contrast to the female rat the post-castration increase in gonadotrophin secretion is not accompanied by an increase in the output of LHRH, (iii) the output of LHRH in response to ME stimulation is affected by castration and testosterone but not by hyperprolactinaemia and (iv) the anaesthetic effects of alphaxalone are potentiated by hyperprolactinaemia, and this may explain in part the potentiation of alphaxalone anaesthesia by oestrogen. J. Endocr. (1985) 104, 35–43

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.

GONADOTROPHIN REGULATION IN THE LACTATING RAT

1978 ◽  
Vol 88 (3) ◽  
pp. 668-675 ◽  
Author(s):  
R. W. Steger ◽  
J. J. Peluso
Keyword(s):  
Positive Feedback ◽  
Post Partum ◽  
Ovariectomized Rats ◽  
Releasing Hormone ◽  
Gonadotrophin Secretion ◽  
Lh Release ◽  
Lh Rh ◽  
Lh Releasing Hormone

ABSTRACT Post-partum lactation in the rat is associated with follicular quiescence and an attenuation of gonadotrophin secretion. The present study demonstrates that the lactating rat responds to exogenous LH-releasing hormone (LH-RH) in a manner similar to dioestrous rats. Oestrogen priming increases the LH and FSH response to LH-RH to a smaller degree in ovariectomized, lactating, than in non-lactating, ovariectomized rats. Pituitary LH levels throughout lactation did not seem to be related to LH-RH-induced LH release. A diminished post-castration rise in both LH and FSH, and a diminished positive feedback response to oestrogen administration were also observed and may indicate a disruption of gonadotrophin regulation at both the hypothalamic and the pituitary level.

Blockade of LH and FSH secretion by LH-releasing hormone, by the LH-releasing hormone analogue, buserelin, and by combined treatment with LH-releasing hormone and oestradiol benzoate

1984 ◽  
Vol 103 (3) ◽  
pp. 301-309 ◽  
Author(s):  
G. A. Schuiling ◽  
N. Pols-Valkhof ◽  
G. C. J. van der Schaaf-Verdonk ◽  
T. R. Koiter
Keyword(s):  
Half Life ◽  
Combined Treatment ◽  
Plasma Concentrations ◽  
Blocking Agent ◽  
Releasing Hormone ◽  
Oestradiol Benzoate ◽  
Pituitary Glands ◽  
Lh Rh ◽  
Lh Releasing Hormone ◽  
Dose Levels

ABSTRACT The LH and FSH release-stimulating (experiment 1) and -blocking (experiment 2) effects of LH-releasing hormone (LHRH) and of the LHRH analogue d-Ser(But)6-des-Gly10-LHRH-ethylamide (buserelin), as well as the effect of combined treatment with LH RH and oestradiol benzoate (OB; experiment 3) on the 'supra-maximally' LHRH-stimulated release of LH and FSH were studied in rats ovariectomized for 2 weeks. Pretreatment with LHRH (250 or 500 ng/h) or buserelin (250 ng/h) for 6 days was effected by means of subcutaneously implanted Alzet osmotic minipumps; control rats received a 'sham pump', i.e. a piece of silicone elastomer with the dimensions of a minipump. Oestradiol benzoate (3 μg/injection) or solvent was injected subcutaneously 75 and 27 h before the induction of LH/FSH responses. Experiment 1 revealed that after infusion of LHRH and buserelin, both at the rate of 1 μg/h, plasma LHRH concentrations were established which were about twice as low as the plasma buserelin concentrations. This might suggest that buserelin has a longer half-life than LHRH. As an LH and FSH release-stimulating substance, however, it appeared that buserelin was about as effective as LHRH. Experiment 2, however, suggested that as an LH/FSH release-blocking agent buserelin was much more effective than LHRH. In addition, after buserelin pretreatment the pituitary glands contained much less LH and FSH than after LHRH pretreatment at both dose levels used. However, this may also (at least partly) be due to the fact that buserelin has a longer half-life so that after infusion of buserelin and LHRH at the same rate the plasma concentrations of buserelin are higher than those of LHRH; after buserelin infusion the pituitary gland is therefore stimulated at a higher intensity. Experiment 3 showed that in OB-injected, sham-implanted rats the LHRH-stimulated secretion of LH and FSH was significantly higher than in the oil-injected, sham-implanted rats. In the LHRH-pretreated rats (LHRH: 250 ng/h for 6 days), however, the already depressed LHRH-stimulated secretion of LH and FSH was still further depressed by OB treatment. These latter results suggest that the increase of the pituitary LHRH responsiveness during exposure to oestrogen requires a reduction of the LHRH stimulation, which is normally caused by the negative feedback of oestrogen on the hypothalamus. J. Endocr. (1984) 103, 301–309

RESPONSES OF SERUM GONADOTROPHINS TO LH-RELEASING HORMONE AND OESTROGENS IN JAPANESE WOMEN WITH POLYCYSTIC OVARIES

1977 ◽  
Vol 85 (4) ◽  
pp. 840-849 ◽  
Author(s):  
Toshihiro Aono ◽  
Masatoshi Miyazaki ◽  
Akira Miyake ◽  
Takayuki Kinugasa ◽  
Keiichi Kurachi ◽  
...  
Keyword(s):  
Ovarian Response ◽  
Japanese Patients ◽  
Japanese Women ◽  
Polycystic Ovaries ◽  
Releasing Hormone ◽  
Gonadotrophin Secretion ◽  
The Mean ◽  
Lh Rh ◽  
Lh Releasing Hormone ◽  
Normal Controls

ABSTRACT In order to define the abnormality in gonadotrophin secretion in Japanese women with polycystic ovaries (PCO) who rarely show virilization and markedly enlarged ovaries, basal levels of LH and FSH, and responses of serum gonadotrophins to LH-releasing hormone (LH-RH) or oestrogens were determined by radioimmunoassay. Eleven patients with PCO diagnosed by laparotomy or laparoscopy and 30 normal women in the follicular phase were studied. The mean (± sd) basal level of LH was significantly higher in patients with PCO than in normal controls (PCO 28.6 ± 2.4 vs. normal 10.9 ± 3.0 mIU/ml), while the mean FSH level in PCO patients was not significantly different from that in the normal controls (9.7 ± 0.7 vs. 11.4 ± 2.6 mIU/ml). The mean LH/FSH ratio in PCO patients was significantly higher than that in normal controls (3.2 ± 0.9 vs. 1.0 ± 0.3). Exaggerated response of LH to LH-RH was observed in PCO patients, while the FSH response was comparable with the normal controls. Ten out of 11 patients with PCO showed LH release exceeding the basal level after bolus iv injection of 20 mg conjugated oestrogens (Premarin®), and virtually the same mean net increase in LH from the basal level was obtained in both PCO patients and normal controls. Since the abnormalities in gonadotrophin secretion in Japanese women with PCO are not different from those reported in patients with PCO in Europe and USA, it seems likely that lower incidence of markedly enlarged ovaries and virilization in Japanese patients may be caused by the difference in ovarian response to gonadotrophin.

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.

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.

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