Ontogeny of sex differences in LH and FSH levels 48 h after castration in the rat

1981 ◽  
Vol 241 (6) ◽  
pp. E460-E464
Author(s):  
J. R. Lorenzen ◽  
J. A. Ramaley
Keyword(s):  
Follicle Stimulating Hormone ◽  
Female Rats ◽  
Hormonal Changes ◽  
Vaginal Opening ◽  
Immature Female ◽  
Immature Male ◽  
Male And Female Rats ◽  
Serum Lh ◽  
Pituitary Secretion ◽  
Serum Gonadotropin

Serum gonadotropin levels were measured 12, 24, and 48 h after gonadectomy in male and female rats (ages, 22--60 days) to assess when during development the rate of rise of luteinizing hormone (LH) and follicle-stimulating hormone (FSH) after castration approximates that seen in the gonadectomized adult. In females serum LH levels 48 h after ovariectomy were increased above sham levels only when the ovaries were removed prior to vaginal opening. Ovariectomy on the day of vaginal opening or at older ages resulted in no increase in LH levels by 48 h after surgery. Serum FSH levels at 24 and 48 h after ovariectomy declined with increasing age at the time of ovariectomy. In males serum LH levels at 48 h after castration increased with increasing age at the time of gonadectomy. Serum FSH levels at either 12, 24, or 48 h after orchidectomy did not change appreciably with age at the time of surgery. It is concluded that the acute pituitary secretion of gonadotropins after removal of testes in the immature male resembles that seen in the mature male early in the course of the development of sexual maturity. In contrast, the acute pituitary secretion of gonadotropins after removal of the ovaries in the immature female does not resemble that seen in the ovariectomized adult until she is mature and capable of ovulating. Thus, the observed delay in the rise of LH seen in ovariectomized adults may be a function of some aspect of the hormonal changes associated with the estrous cycle.

THE EFFECT OF PINEAL METHOXYINDOLES ON RAT VAGINAL OPENING TIME

1971 ◽  
Vol 50 (4) ◽  
pp. 679-683 ◽  
Author(s):  
R. COLLU ◽  
F. FRASCHINI ◽  
L. MARTINI
Keyword(s):  
Luteinizing Hormone ◽  
Sexual Maturation ◽  
Lateral Ventricle ◽  
Follicle Stimulating Hormone ◽  
Female Rats ◽  
Vaginal Opening ◽  
Significant Delay ◽  
Immature Female ◽  
The Brain ◽  
Stimulating Hormone

SUMMARY Melatonin and 5-methoxytryptophol, the two methoxyindoles of pineal origin, were injected into a lateral ventricle of the brain of immature female rats. Treatment was started on the 25th day of age and terminated when the vagina opened. The injection of both methoxyindoles resulted in a statistically significant delay in vaginal opening. Since previous experiments had shown that melatonin specifically inhibits secretion of luteinizing hormone and that 5-methoxytryptophol specifically blocks release of follicle-stimulating hormone, the present results support the hypothesis that the onset of sexual maturation needs a balanced secretion of both gonadotrophins.

INVOLVEMENT OF INHIBIN IN THE REGULATION OF FOLLICLE-STIMULATING HORMONE CONCENTRATIONS IN PREPUBERTAL AND ADULT, MALE AND FEMALE RATS

1980 ◽  
Vol 86 (1) ◽  
pp. 79-92 ◽  
Author(s):  
W. P. HERMANS ◽  
E. C. M. VAN LEEUWEN ◽  
M. H. M. DEBETS ◽  
F. H. DE JONG
Keyword(s):  
Follicle Stimulating Hormone ◽  
Female Rats ◽  
Male Rats ◽  
Intact Male ◽  
Adult Rats ◽  
Physiological Factor ◽  
Male And Female ◽  
Male And Female Rats ◽  
Pituitary Secretion ◽  
Fast Acting

Administration of steroid-free bovine follicular fluid (bFF), containing inhibin-like activity, depressed levels of FSH measured 4 h after injection in intact adult and 35-day-old female rats, but not in younger females. Suppression of FSH was also observed in intact male rats, aged 55 days, but not in older and younger male rats. Eight hours after injection of bFF, FSH levels were depressed in 15-day-old and older immature and adult rats of both sexes. Male and female rats, gonadectomized 2 days earlier, responded similarly to bFF treatment as did the intact animals. In a second experiment it was found that the rise of FSH levels, occurring within 8 h of gonadectomy, decreased with age in male and increased with age in female rats. Steroid treatment was found to prevent the rise in FSH levels partially in 15-day-old male and completely in 25-day-old female rats, whereas treatment with bFF was fully effective in blocking the FSH rise in both immature and adult rats of both sexes. It is concluded that inhibin might be a major physiological factor in a fast-acting control of FSH concentrations from at least the age of 25 days onwards in female rats. In male rats its physiological significance might be limited to the prepubertal period, despite the fact that pituitary secretion of FSH is suppressed by exogenous inhibin-like activity at all ages studied.

Blockage of gonadotropin-induced first ovulation caused by thyroidectomy and its possible mechanisms in rats

1998 ◽  
Vol 275 (3) ◽  
pp. E380-E385 ◽  
Author(s):  
Kazuhiro Tamura ◽  
Minoru Hatsuta ◽  
Gen Watanabe ◽  
Kazuyoshi Taya ◽  
Hiroshi Kogo
Keyword(s):  
Chorionic Gonadotropin ◽  
Follicle Stimulating Hormone ◽  
Female Rats ◽  
Inhibitory Effects ◽  
Immature Female ◽  
Serum Lh ◽  
Equine Chorionic Gonadotropin ◽  
Lh Releasing Hormone ◽  
Significant Increment

To determine the role of the thyroid gland on the ovarian functions during the initiation process of puberty, we examined the effects and its mechanisms of hypothyroidism on the first ovulation induced by equine chorionic gonadotropin (eCG) in immature female rats. Animals were thyroidectomized on day 22 and were injected with 5 IU of eCG on day 26 to induce the first ovulation on day 29. The number of antral follicles that secrete inhibin and the ovarian weight were significantly increased in thyroidectomized rats (Tx rats) 48 h after eCG treatment compared with those in non-Tx rats. However, thyroidectomy (Tx) significantly suppressed the rates of ovulating animals on day 29. The blockage of ovulation in Tx rats was recovered by administration of human chorionic gonadotropin or luteinizing hormone (LH)-releasing hormone (LHRH) on day 28. Inhibition of serum LH (not follicle-stimulating hormone) levels induced by Tx was almost restored to control levels by injection of LHRH. A significant increment in prolactin levels in Tx rats was also observed on day 28. The present data indicate that Tx before puberty in female rats causes the blockage of the first ovulation and that the inhibitory effects on ovulation are mainly due to the reduction in the preovulatory LH surge, which is partially mediated through an inhibition of LHRH action on the secretion of LH.

Administration of a GnRH-antagonist to immature rats affects subsequent female and male pubertal development differently

1989 ◽  
Vol 120 (6) ◽  
pp. 778-784 ◽  
Author(s):  
H. M. van den Dungen ◽  
J. A. M. J. van Dieten ◽  
F. J. H. Tilders ◽  
G. P. van Rees ◽  
J. Schoemaker
Keyword(s):  
Gnrh Antagonist ◽  
Pubertal Development ◽  
Female Rats ◽  
Female Rat ◽  
Vaginal Opening ◽  
Gonadotropin Secretion ◽  
Adult Age ◽  
Immature Male ◽  
Male And Female Rats ◽  
Testicular Weight

Abstract. Gonadotropin secretion was inhibited in immature male and female rats by sc administration of the GnRH-antagonist ORG30276 (GnRH-A) on days 6, 9, 12 and 15. In GnRH-A-treated females this resulted in suppression of the temporarily increased plasma LH and FSH levels, which normally occur in prepubertal female rats. Ovarian weight was decreased. Although vaginal opening in GnRH-A-treated rats occurred earlier, the age of 1st estrus and the number of ova shed at first ovulation were not affected. Fertility at 4 months of age was normal. After initial suppression of gonadotropin levels, the FSH levels in GnRH-A-treated males, however, sharply increased to about twice the control levels. Plasma FSH remained elevated at least until 4 months of age. The LH levels at adult age were not affected by antagonist treatment and neither were testosterone levels. Testicular weight was decreased by GnRH-A from about 50% on day 15 to about 30% at 4 months of age. Pubertal development as measured by balano-preputial separation was delayed by about 7–10 days. At 4 months of age fertility was decreased. Thus, suppression of early gonadotropin secretion by GnRH-A treatment had dramatic effects on subsequent pubertal development in the male, but not in the female rat.

EFFECT OF MESENCEPHALIC STIMULATION ON THE RELEASE OF GONADOTROPHINS

1970 ◽  
Vol 48 (4) ◽  
pp. 527-539 ◽  
Author(s):  
H. F. CARRER ◽  
S. TALEISNIK
Keyword(s):  
Follicle Stimulating Hormone ◽  
Elevated Serum ◽  
Serum Levels ◽  
Female Rats ◽  
Continuous Illumination ◽  
Electrolytic Deposition ◽  
Inhibitory Effects ◽  
Male And Female Rats ◽  
Serum Lh ◽  
Stimulation Of

SUMMARY Different regions of the midbrain were stimulated by electrolytic deposition of iron from stainless steel unipolar electrodes. Electrochemical stimulation of the ventral tegmental area (VTA), the raphe nuclei or the peri-aqueductal grey in rats in pro-oestrus was effective in preventing spontaneous ovulation. No blockade of ovulation was observed by stimulating other mesencephalic structures. After stimulation in the VTA there was a significant decrease of the elevated serum levels of luteinizing hormone (LH) found after an injection of progesterone into pro-oestrous rats or into ovariectomized—oestrogen-primed animals. In contrast, electrochemical stimulation of the dorsal mesencephalic tegmentum, lateral and inferior to the peri-aqueductal grey, in rats in which spontaneous ovulation had been blocked by continuous illumination, resulted in an ovulatory response. Serum LH was found to increase in gonadectomized—oestrogen-treated male and female rats after stimulating this area. No significant changes in serum follicle-stimulating hormone were found after stimulation in the ventral or dorsal tegmentum. It is concluded that both stimulatory and inhibitory influences on the release of gonadotrophin can be evoked by stimulating mesencephalic structures. The stimulatory and inhibitory effects could depend on the activation of noradrenergic and serotoninergic systems, respectively.

PITUITARY HORMONE SECRETION IN THE GENETICALLY MALE RAT PSEUDOHERMAPHRODITE

1975 ◽  
Vol 64 (2) ◽  
pp. 249-255 ◽  
Author(s):  
A. S. GOLDMAN ◽  
A. W. ROOT ◽  
G. DUCKETT ◽  
B. H. SHAPIRO
Keyword(s):  
Growth Hormone ◽  
Follicle Stimulating Hormone ◽  
Hormone Secretion ◽  
Female Rats ◽  
Male Rat ◽  
Normal Male ◽  
Pituitary Hormone ◽  
Male And Female ◽  
Male And Female Rats ◽  
Serum Lh

SUMMARY Pituitary content or concentration of follicle-stimulating hormone (FSH), prolactin and growth hormone in the genetically androgen insensitive male rat pseudohermaphrodite is intermediate between normal male and female rats, while pituitary luteinizing hormone (LH) concentration and serum FSH levels are the same as in the normal male. The concentration of serum LH, prolactin and growth hormone indicates no sexual dimorphism. Although the pseudohermaphrodite is genetically male with a female phenotype, our results suggest some degree of masculinization of the hypothalamicpituitary system.

The Fine Structure of Rat Granulosa Cell Cultures Correlated with Progestin Secretion

1973 ◽  
Vol 31 ◽  
pp. 552-553
Author(s):  
T. M. Crisp ◽  
F.R. Denys
Keyword(s):  
Fine Structure ◽  
Granulosa Cell ◽  
Cell Cultures ◽  
Single Injection ◽  
Surrounding Medium ◽  
Petri Dish ◽  
Female Rats ◽  
Vaginal Smear ◽  
Immature Female ◽  
Serum Gonadotropin

The purpose of this paper is to present observations on the fine structure of rat granulosa cell cultures grown in the presence of an adenohypophyseal explant and to correlate the morphology of these cells with progestin secretion. Twenty-six day old immature female rats were given a single injection of 5 IU pregnant mares serum gonadotropin (PMS) in order to obtain ovaries with large vesicular follicles. At 66 hrs. post-PMS administration (estrus indicated by vaginal smear cytology), the ovaries were removed and placed in a petri dish containing medium 199 and 100 U penicillin/streptomycin (P/S)/ml. Under a 20X magnification dissecting microscope, some 5-8 vesicular follicles/ovary were punctured and the granulosa cells were expressed into the surrounding medium. The cells were transferred to centrifuge tubes and spun down at 1000 rpm for 5 mins.

Effect of low doses of continuously administered catecholoestrogens on peripheral and central target organs

1981 ◽  
Vol 96 (4) ◽  
pp. 470-474 ◽  
Author(s):  
Peter Ball ◽  
Günter Emons ◽  
Ulrich Gethmann
Keyword(s):  
Serum Levels ◽  
Female Rats ◽  
Low Doses ◽  
Vaginal Opening ◽  
Uterine Weight ◽  
Central Target ◽  
Male And Female Rats ◽  
Target Organs ◽  
Uterine Growth ◽  
Lh Release

Abstract. Osmotic minipumps containing low doses of either 4-hydroxyoestradiol or 2-hydroxyoestradiol2) were sc implanted for 152 h (6⅓ day) into immature male and female rats. At the end of the test period the animals were killed and the uterine weight, the vaginal opening, the gonadotrophin serum levels and the gonadal weight monitored. The following results were obtained: 1) a significant increase in the uterine weight and a consistent vaginal opening were observed after 4-hydroxyoestradiol but not after 2-hydroxyoestradiol treatment, 2) LH-levels increased after 2-hydroxyoestradiol but not after 4-hydroxyoestradiol; the increase was, however, not significant, 3) FSH-levels and gonadal weights were lowered by 4-hydroxyoestradiol treatment in male animals only; 2-hydroxyoestradiol had no effect on FSH-levels in both sexes, 4) in no instance an antioestrogenic effect of either catecholoestrogen was observed. It is concluded that 4-hydroxyoestrogens — using the above paradigm — have a significant importance on uterine growth and vaginal opening but (on day 6) no role on LH-release, whereas 2-hydroxyoestrogens may increase LH levels (on day 6) but are nearly ineffective with respect to peripheral parameters.

The development of the hypothalamo–pituitary axis in the neonatal rat: sexual maturation in male and female rats as assessed by hypothalamic LHRH and pituitary and serum LH and FSH concentrations

1977 ◽  
Vol 55 (5) ◽  
pp. 1091-1097 ◽  
Author(s):  
J. H. Dussault ◽  
P. Walker ◽  
J. D. Dubois ◽  
F. Labrie
Keyword(s):  
Developmental Process ◽  
Neonatal Period ◽  
Neonatal Rat ◽  
Female Rats ◽  
Human Foetus ◽  
Marked Rise ◽  
Male And Female Rats ◽  
Specific Radioimmunoassay ◽  
Serum Lh ◽  
And Control

Using specific radioimmunoassay techniques, we have measured hypothalamic LHRH concentration and pituitary and serum LH and FSH concentrations in neonatal rats from 0 to 60 days after birth. There were no sex differences demonstrable for hypothalamic LHRH concentration, which rose from minimal values at 2 days to peak concentrations at 22–28 days and declined significantly with the approach of puberty. Pituitary LH concentration in the two sexes rose to peak values at 19–25 days, with significantly higher values observed in females (p < 0.01). Serum LH concentration was high in both sexes at birth, the values in females being significantly higher than those observed in males (p < 0.01). While the serum LH concentration remained relatively stable throughout the study period in males, it declined rapidly to a nadir at 28 days in females. Pituitary FSH concentration was low at birth in both sexes. Females demonstrated a marked rise to peak concentrations at 16 days while males achieved significantly lower peak prepuberal values (p < 0.01) at 28 days. Serum FSH concentration was significantly higher in females (p < 0.01) at birth and rose further to peak values at 16 days. Males attained peak serum FSH concentrations at 35 days. These data demonstrate that the maturation of the hypothalamo–pituitary–gonadal axis develops in the neonatal period in the rat and confirm the presence of significant differences in hypothalamic sexual differentiation and control. The possibility of this developmental process in the neonatal rat as a model for the study of the midgestational hypothalamic maturation of the human foetus is discussed.

SERUM LUTEINIZING HORMONE AND FOLLICLE-STIMULATING HORMONE CONCENTRATIONS IN IMMATURE FEMALE RATS TREATED WITH MULTIPLE INJECTIONS AND VARIOUS AMOUNTS OF LUTEINIZING HORMONE RELEASING HORMONE

1975 ◽  
Vol 66 (1) ◽  
pp. 13-20 ◽  
Author(s):  
D. C. JOHNSON ◽  
R. S. MALLAMPATI
Keyword(s):  
Luteinizing Hormone ◽  
Constant Stimulus ◽  
Female Rats ◽  
Intact Female ◽  
Immature Female ◽  
Luteinizing Hormone Releasing Hormone ◽  
Releasing Hormone ◽  
Serum Luteinizing Hormone ◽  
Serum Lh ◽  
Lh Rh

SUMMARY Release of immunoreactive LH and FSH was induced in immature intact female rats by repeated injections of synthetic luteinizing hormone releasing hormone (LH-RH). Altering the dose of LH-RH (5, 10, 20, 50 ng) and the frequency of administration (every 10, 20, 30 or 60 min) over a period of 2 h produced a variety of serum LH and FSH concentrations and ratios. When the dose was a constant 20 ng but the frequency of injections was either 20 or 30 min, a steady state in serum gonadotrophin concentrations was reached within 1 h and the level remained the same during the second hour. When given every 10 min, 20 ng LH-RH produced a much higher concentration of both LH and FSH during the second hour of stimulation. Examination of the gonadotrophin levels after each injection of LH-RH showed that the pituitary response was variable in spite of a constant stimulus.

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