Differential effects of castration on LH and FSH secretion in male and female rats.

Serum levels of LH and of FSH have been measured using specific radioimmunological procedures in normal controls and in male and female rats submitted to castration 1, 2, 7, 14, 21, 28 and 35 days before. Gonadectomy is followed by a rapid increase of serum levels of LH in males, and by a delayed response in females. The responses of serum FSH to castration are quantitatively and qualitatively similar in the two sexes. Both in males and in females an elevation of serum FSH levels is already present 1 day after the operation. Serum FSH continues to rise, between post-castration days 1 and 7 with a rather rapid slope, and at later intervals with a smoother progression.     

Effects of pure FSH and LH preparations on the number and function of Leydig cells in immature hypophysectomized rats

The effects of pure FSH and/or LH preparations on the number of Leydig cells and their function in immature hypophysectomized rats have been investigated. As a result of hypophysectomy at the age of 17-18 days, the number of recognizable Leydig cells per testis decreased, as did the steroidogenic capacity in vivo and in vitro. Treatment with 64 micrograms FSH on both 22 and 23 days of age, did not affect the number of recognizable Leydig cells. In contrast, two injections of LH (10 micrograms) caused a sixfold increase in the number of Leydig cells, but had a negative effect on spermatogenesis. These stimulatory and inhibitory effects of LH diminished when FSH was added. Treatment with FSH for 7 days caused a twofold increase in the number of Leydig cells when compared with hypophysectomized controls. 3 beta-Hydroxysteroid dehydrogenase (3 beta-HSD) and esterase activity in Leydig cells also increased under the influence of FSH. The pregnenolone production per Leydig cell in the presence of 5-cholesten-3 beta,22(R)-diol (22R-hydroxycholesterol) as substrate showed a sevenfold increase. Plasma testosterone levels 2 h after injection of human chorionic gonadotrophin in intact rats and hypophysectomized FSH-treated rats were the same. Following LH treatment for 7 days, the number of Leydig cells proved to be 11 times higher, and 3 beta-HSD and esterase activity were not different from intact controls. The testicular pregnenolone production was four- to fivefold higher when compared with untreated hypophysectomized rats. However, pregnenolone production per Leydig cell in LH-treated rats was only slightly different from the hypophysectomized controls.(ABSTRACT TRUNCATED AT 250 WORDS)     

Biopotency of highly purified porcine FSH and human LH on gonadal function

The gonadotrophin preparations that have been used previously to study different aspects of testis function are of limited purity. We have, therefore, purified existing gonadotrophin preparations further. The demonstration of their purity and biological activity are reported as well as their suitability for in-vivo use. After separation of the subunits of the intact hormones by high-performance liquid chromatography followed by analytical sodium dodecylsulphate-polyacrylamide gel electrophoresis, no contaminating proteins could be detected in either the FSH or LH preparation. After immunoadsorption, contamination by other pituitary hormones (TSH, prolactin, FSH, LH and GH) was found to be less than 0.002% by weight for all the hormones tested. The biological activity of porcine FSH (pFSH) measured in a Steelman-Pohley assay was 150-170 times more potent than the NIH-FSH-P1 reference preparation. The biopotency of human LH (hLH) in the ovarian ascorbic acid depletion test was measured and appeared to be 8100-8300 IU/mg against the 68/40 International Standard. The dose-dependent effects of pFSH and hLH on testis weight and the number of FSH and LH receptors were measured in immature (22-day-old) hypophysectomized rats treated for 7 consecutive days. Treatment with FSH induced a dose-dependent increase in testis weight (threefold) when compared with the control. The concentration and total number of LH receptors were increased (two- to sixfold) in a dose-dependent manner. The number of FSH receptors per testis increased while the number of FSH receptors per mg of protein remained unchanged. Administration of human LH to immature hypophysectomized rats had no effect on either LH or FSH receptors, regardless of the dose administered.(ABSTRACT TRUNCATED AT 250 WORDS)     

Effects of hyper- and hypothyroidism on serum LH and FSH levels in intact and gonadectomized male and female rats.

The effects of hypo- and hyper-thyroidism on serum LH and FSH were determined in both intact and castrated male and female rats. Thyro-parathyroidectomy (Tx) for 30 days in rats with intact gonads resulted in a significant reduction in serum LH and FSH, and also in a decrease in serum testosterone in males. Administration of 2.5 mug thyroxine (T4)/100 g BW to Tx rats of both sexes returned serum LH and FSH levels to those of intact rats, and in males also restored normal serum testosterone levels. Tx superimposed upon castration resulted in a significantly greater increase in serum LH and FSH than produced by castration alone. Administration of 2.5 mug T4/100 g body weight to castrate-Tx rats reduced serum LH and FSH values to those of castrate rats, whereas 10 mug T4/100 g BW evoked a further decrease in serum LH but no additional reduction in serum FSH. When both 2.5 mug T4/100 g BW and 2 mug estradiol benzoate were injected into Tx-ovariectomized rats, the decrease in serum LH and FSH was much greater than produced by T4 alone. These observations indicate that hypothyroidism results in decreased release of LH and FSH in rats with intact gonads, and in increased release of LH and FSH in castrate rats of both sexes. Administration of a replacement dose of T4 can restore LH and FSH release to normal in Tx rats with intact gonads, and to castration levels in Tx-castrate rats.     

A receptor-like testosterone-binding protein in ovaries from estrogen-stimulated hypophysectomized immature female rats.

A soluble thermolabile protein with many characteristics of an androgen receptor has been demonstrated for the first time in the cytosol (100,000 X g supernatant) of estrogen-stimulated ovaries from hypophysectomized immature female rats (HIFR) treated with diethylstilbestrol in Silastic capsules (DESC). This binding protein is organ-specific and androgen-specific, has a high affinity with a Kd of 2.4 X 10(-9)M for testosterone, and is saturable with 2.1 X 10(-13) moles of binding sites per mg cytosol protein. The number of binding sites is linear with cytosol protein concentration and the binding protein sediments at 7-8 S on sucrose gradients. Estradiol is an effective inhibitor of testosterone binding. A role for this testosterone-binding protein as an effector of ovarian morphologic change is hypothesized.     

Effects of treatment of neonatal rats with highly purified FSH alone and in combination with LH on testicular function and endogenous hormone levels at various ages

Factors which play a role in the regulation of testicular size in rats were investigated using neonatal animals treated with exogenous gonadotrophins for 2 or 3 weeks, starting on the day after birth. Effects on testis weight and various aspects of the pituitary-testicular axis were evaluated up to the age of 9 weeks. Daily treatment with human FSH (Metrodin; 0.15 U/g body wt) for 2 or 3 weeks, starting on the first day or 1 week after birth, resulted in enlargement of the testes, increased testicular content of inhibin and a suppression of pituitary and plasma FSH. The relative increase of testis weight decreased after cessation of treatment. Injections of human FSH combined with administration of human LH (Pergonal) for 3 weeks, starting on the first day after birth, resulted in larger testes immediately after treatment. In addition, an increased amount of interstitial tissue was observed in these animals. Pituitary and plasma FSH and LH were suppressed after this treatment, while the growth of the accessory sex organs was significantly stimulated. In animals treated with human FSH during the first 2 or 3 weeks of life, levels of rat FSH in blood samples collected at weekly intervals were significantly suppressed until the animals were killed at the age of 9 weeks. In the animals treated with human FSH and human LH, both FSH and testosterone concentrations were significantly lower than those in control animals between the ages of 4 and 9 weeks. At the age of 9 weeks testicular weights were still higher than those in control animals after these treatments.(ABSTRACT TRUNCATED AT 250 WORDS)     

Crystalline dihydrotestosterone implants in the lateral septum of male rats. A positive effect on LH and FSH.

Previous investigations in our laboratory have shown that testosterone implanted into the lateral septum in male rats increases LH and FSH secretion. However, it was unclear whether the effect of testosterone was direct via androgen receptor, or indirect via the estrogen receptor after conversion by aromatization to estradiol. To answer this question, we implanted either testosterone or the non-aromatizable androgen 5 alpha-dihydrotestosterone (DHT), into the lateral septum of adult male rats and measured plasma levels of LH and FSH by radioimmunoassay 2 days after implantation. Both testosterone and DHT significantly increased the plasma LH and FSH concentrations. Mean concentration of LH in control animals was 0.21 +/- 0.06 ng/ml, a figure that increased to 0.7 +/- 0.12 and 0.55 +/- 0.1 ng/ml after DHT or testosterone implantation respectively. Mean concentration of FSH in control animals was 1.5 +/- 0.3 ng/ml; this figure increased to 3 +/- 0.3 and 2.9 +/- 0.3 ng/ml after DHT or testosterone implantation. Neither plasma DHT (64.0 +/- 5.6 vs. 52 +/- 5 ng/100ml) nor plasma testosterone levels (4.1 +/- 0.38 vs. 3.3 +/- 0.18 ng/ml) were significantly affected by the implants. We conclude that androgens independently of conversion to estrogen acting in the lateral septum facilitates the release of LH and FSH.     

Effect of stress on the release of LH and FSH in female rat plasma. Critical study

The aim of this work was to study the effects of different procedures of blood removal on blood LH and FSH concentration at different stages of the diestrous period in 4-day cyclic female rats. Cardiac puncture, abdominal cava venipuncture both under ether anaesthesia and trunk blood collection were performed on diestrus 1 morning and diestrus 2 morning and afternoon. Non operated, adrenalectomized, sham adrenalectomized cyclic females and ovariectomized females were used. No changes in blood LH and FSH concentrations were observed on either diestrus 1 or diestrus 2 in the non operated and adrenalectomized cyclic females and in ovariectomized females following blood removal by heart puncture and bleeding from the abdominal vena cava, both under ether anaesthesia, as compared to decapitated animals. By contrast, these two procedures of blood removal caused an increase in blood LH concentration in sham adrenalectomized females as compared to their decapitated counterparts. Only heart puncture evoked an augmentation of blood FSH concentration under this experimental schedule. In accordance with previous studies blood LH and FSH concentrations appeared to be greater in ovariectomized than in intact cyclic females.