Colony-stimulating factor-1 plays a major role in the development of reproductive function in male mice

Colony-stimulating factor-1 (CSF-1) is the principal regulator of cells of the mononuclear phagocytic lineage that includes monocytes, tissue macrophages, microglia, and osteoclasts. Macrophages are found throughout the reproductive tract of both males and females and have been proposed to act as regulators of fertility at several levels. Mice homozygous for the osteopetrosis mutation (csfm[op]) lack CSF-1 and, consequently, have depleted macrophage numbers. Further analysis has revealed that male csfm(op)/csfm(op) mice have reduced mating ability, low sperm numbers, and 90% lower serum testosterone levels. The present studies show that this low serum testosterone is due to reduced testicular Leydig cell steroidogenesis associated with severe ultrastructural abnormalities characterized by disrupted intracellular membrane structures. In addition, the Leydig cells from csfm(op)/ csfm(op) males have diminished amounts of the steroidogenic enzyme proteins P450 side chain cleavage, 3beta-hydroxysteroid dehydrogenase, and P450 17alpha-hydroxylase-lyase, with associated reductions in the activity of all these steroidogenic enzymes, as well as in 17beta-hydroxysteroid dehydrogenase. The CSF-1-deficient males also have reduced serum LH and disruption of the normal testosterone negative feedback response of the hypothalamus, as demonstrated by the failure to increase LH secretion in castrated males and their lack of response to exogenous testosterone. However, these males are responsive to GnRH and LH treatment. These studies have identified a novel role for CSF-1 in the development and/or regulation of the male hypothalamic-pituitary-gonadal axis.

Luteinizing hormone on Leydig cell structure and function

The effects of luteinizing hormone (LH) and human chorionic gonadotrophic hormone (hCG) on Leydig cell structure and function are reviewed in this paper under two main headings; responses to LH and hCG stimulation and responses to LH deprivation. With acute LH stimulation, up to 2 hours following the LH injection, there was no change in the volume of a Leydig cell. However, Leydig cell peroxisomal volume and intraperoxisomal SCP2 content showed a rapid and transient change. These changes can be considered to be specific because: i) no other Leydig cell organelle including smooth endoplasmic reticulum (SER) showed such a change, and ii) only the intraperoxisomal SCP2 but not catalase (a marker enzyme for peroxisomes) showed such a change within 30 minutes of LH stimulation. As these changes occurred prior to the peak testosterone levels following this treatment, it is suggested that SCP2 and peroxisomes may have an association with testosterone biosynthesis prior to cholesterol transport into mitochondria. With LH or hCG stimulation for longer periods, i.e. one day or more, the same morphological changes are produced in Leydig cells irrespective of the age of the species, dosage of LH or hCG, and with single or multiple doses. These changes include, Leydig cells hypertrophy and/or hyperplasia, increase in the cellular organelle content (mostly SER and mitochondria) and depletion of lipid droplets. In addition, a recent study showed that Leydig cell peroxisomal volume, SCP2 content, the amount of intraperoxisomal SCP2 and testosterone secretory capacity were also significantly increased in response to chronic LH treatment. The effects of LH deprivation by whatever means (e.g. hypophysectomy, with testosterone and 17 beta-estradiol silastic implants, LH antisera) on Leydig cell structure and function is generally described as opposite to those observed following LH or hCG stimulation. These include Leydig cell hypotrophy and hypoplasia, reductions in the cytoplasmic organelle content in general and specific reductions in SER and peroxisomal volumes, reductions in total catalase and SCP2 in Leydig cells together with reductions in the intraperoxisomal SCP2 content in Leydig cells and their testosterone secretory capacity.

Deconvolution analysis of bioassayable LH secretion and half-life in men with idiopathic oligoasthenospermia

To further investigate the nature of neuroendocrine disturbances of the hypothalamopituitary-gonadal axis in idiopathic male infertility, we studied 12 infertile men with oligoasthenozoospermia and 13 euspermic controls, matched for age and body mass index, by blood withdrawal at 10-min intervals for 8 h to analyse pulsatile release of bioactive LH (b-LH). The rat interstitial cell testosterone (RICT) bioassay was used in conjunction with a recently validated multiparameter deconvolution algorithm, to estimate the endogenous half-life of b-LH, its secretory burst frequency, amplitude, duration and mass. Oligoasthenospermic men exhibited significant (p < 0.05) alterations within the LH axis; namely: (1) a prolonged half-life of b-LH (92 min in euspermic men, 127 min in oligoasthenospermic men); (2) a reduced b-LH secretory burst amplitude (2.2 +/- 1.2 IU/l/min in euspermic men, 1.7 +/- 0.8 IU/l/min in oligoasthenospermic men); (3) a lower bioactive/immunoactive (b/i) ratio for LH secretory burst amplitude (14 in euspermic men, 4 in oligoasthenospermic men); (4) a reduced b/i ratio in the mass of LH secreted per burst (5.4 in euspermic men, 4.1 in oligoasthenospermic men) and (5) decreased coordinate release of b-LH and testosterone in infertile men, as assessed by cross-correlation analysis. These disturbances differ from the neuroendocrine dysregulation described in other states of male hypogonadotrophism.

Follicular development and oocyte maturation in hypogonadotrophic women employing recombinant follicle-stimulating hormone: the role of oestradiol

Both luteinizing hormone (LH) and follicle-stimulating hormone (FSH) are required for follicle development and oestrogen production. Moreover, under normal conditions a close association between dominant follicle size and serum and intrafollicular oestradiol levels is observed. With the recent availability of human recombinant FSH (recFSH), it was possible for the first time to study effects of FSH alone, in the complete absence of endogenous or exogenous LH, on ovarian function. Recent studies applying recFSH in hypogonadotrophic women have shown convincingly that normal growth of follicles up to the preovulatory stage occurs despite extremely low oestradiol levels, in keeping with previous observations using exogenous gonadotrophins in women incapable of synthesizing oestradiol due to steroid enzyme abnormalities. Insufficient data are presently available in humans to conclude whether or not oocyte quality is compromised under these circumstances. It should, however, be realized that sufficient oestradiol levels are required for fertilization in vivo. Therefore LH, or human chorionic gonadotrophin (HCG), should be added to stimulation protocols in hypogonadotrophic individuals. These observations may also be relevant for monitoring of ovarian response during recFSH therapy, especially when combined with gonadotrophin-releasing hormone agonists for ovarian hyperstimulation for in-vitro fertilization.

Clinical manifestations of genetic defects affecting gonadotrophins and their receptors

Raised activity of the LH axis caused by activating mutations of LH receptor gene presents with precocious puberty in boys, analogous to the presentation of LH secreting pituitary adenomas (Faggiano et al., 1983; Ambrosi et al., 1990). LH "hyperactivity' in females appears to have no effect. Hyperactivity of the FSH axis caused by activating mutations of the FSH receptor gene might parallel the presentation of FSH secreting pituitary adenomas with Sertoli cell hypertrophy in men (Heseltine et al., 1989) or reversible premature ovarian failure in women (Moses et al., 1986; Okuda et al., 1989). Indeed the first such case to be described is a male who maintained testicular volume and fertility in the absence of gonadotrophins (Gromoll et al., 1996). Female precocious puberty may require hyperactivity of both gonadotrophin axes because of the "two-cell' arrangement required for ovarian oestrogen production. Mutations of the Gs alpha-subunit gene can mimic this situation in some women with the McCune-Albright syndrome (Malchoff et al., 1994). Lack of LH activity caused by defects in the LH beta molecule causes infertility in men and that resulting from inactivating mutations of the LH receptor gene causes Leydig cell agenesis in men while ovarian development in females is relatively normal. Lack of FSH activity caused by defects in the FSH beta caused infertility in a female, and that caused by inactivating mutations of the FSH receptor gene causes ovarian dysgenesis in women but only variable depression of spermatogenesis in men. Incidentally, this categorization of reproductive disorders may also be applied to the TSH axis. Pituitary adenomas and activating mutations of the TSH receptor gene (Parma et al., 1993) cause hyperthyroidism and TSH beta gene defects (Hayashizaki et al., 1989) and inactivating mutations of the TSH receptor gene (Sunthornthepvarakul et al., 1995) cause hypothyroidism. To complete the analogy with thyroid disorders, it is curious that despite structural similarities with the TSH receptor, neither LH nor FSH receptor autoantibodies have a prominent role in ovarian pathophysiology (Moncayo et al., 1989; Van Weissenbruch et al., 1991; Simoni et al., 1993). Complete gonadotrophin resistance is likely to be very rare, however, so what are we likely to find in partial gonadotrophin resistance? Might the "resistant ovary syndrome' come right in the end, with corresponding minor FSH receptor mutations? Experience with insulin and androgen resistance syndromes suggests that such a scenario is unlikely. Insulin receptor gene mutations are found in extreme Type A insulin resistance but not in moderate forms of insulin resistance (O'Rahilly et al., 1991). Androgen receptor gene mutations are found in nearly all cases of complete androgen insensitivity but rarely in partial forms (Patterson et al., 1994). Mild resistance to hormone action is rarely detectable in relatives who are heterozygous for receptor mutations which are inherited in a recessive pattern. It seems unlikely therefore, that individuals heterozygous for inactivating receptor mutations will manifest symptoms of reproductive disorders and account for common conditions. Thus, while mutation analysis provides new insights into the gender specific role of the gonadotrophins the cause of early gonadal failure in the majority of individuals remains a mystery.

Luteinizing hormone deficiency and female infertility in mice lacking the transcription factor NGFI-A (Egr-1)

The immediate-early transcription factor NGFI-A (also called Egr-1, zif/268, or Krox-24) is thought to couple extracellular signals to changes in gene expression. Although activins and inhibins regulate follicle-stimulating hormone (FSH) synthesis, no factor has been identified that exclusively regulates luteinizing hormone (LH) synthesis. An analysis of NGFI-A-deficient mice derived from embryonic stem cells demonstrated female infertility that was secondary to LH-beta deficiency. Ovariectomy led to increased amounts of FSH-beta but not LH-beta messenger RNA, which suggested a pituitary defect. A conserved, canonical NGFI-A site in the LH-beta promoter was required for synergistic activation by NGFI-A and steroidogenic factor-1 (SF-1). NGFI-A apparently influences female reproductive capacity through its regulation of LH-beta transcription.

Developmental potential of embryos produced by in-vitro fertilization from gonadotrophin-releasing hormone antagonist-treated macaques stimulated with recombinant human follicle stimulating hormone alone or in combination with luteinizing hormone

We previously demonstrated, in luteinizing hormone (LH)-deficient macaques, that follicular growth and maturation occurred with administration of exogenous (recombinant human) follicle stimulating hormone (r-hFSH) alone, and that the oocytes recovered fertilized at a notably higher rate than their counterparts from animals receiving both r-hFSH and r-hLH (Zelinski-Wooten et al., 1995). Here, the developmental potential of embryos produced from animals treated with r-hFSH alone or in combination with r-hLH was evaluated. Embryos (n = 127) were cryopreserved, thawed and either co-cultured on buffalo rat liver cells until the hatched blastocyst stage or transferred to synchronized recipients. Although embryos from each treatment group demonstrated a similar ability to develop to hatched blastocysts with a definitive inner cell mass, a significant difference was seen in cryosurvival (56 versus 78%) and in developmental rate to the hatched blastocyst (12 versus 10 days) between embryos from the r-hFSH alone and the combination group respectively. Pregnancies resulted following oviductal embryo transfers in both groups, with corpus luteum rescue occurring on days 12-16 of the luteal phase. In summary, r-hFSH alone during the pre-ovulatory interval is adequate for the gametogenic events required to produce embryos that develop either in vitro or in vivo; however, exposure to r-hLH may improve embryo viability and the rate of development.

Use of the gonadotropin-releasing hormone agonist triptorelin in the diagnosis of delayed puberty in boys

To differentiate gonadotropin deficiency from delayed puberty in teenage boys, 0.1 mg/m2 of triptorelin, a gonadotropin-releasing hormone agonist, was administered subcutaneously at 4 AM. Serum gonadotropins and testosterone levels were determined at baseline and 4 hours after the injection. The increase in blood gonadotropin and testosterone levels was significantly greater in patients with delayed puberty than in those with gonadotropin deficiency.

Chronic neuroendocrinological sequelae of radiation therapy

A variety of neuroendocrine disturbances are observed following treatment with external radiation therapy when the hypothalamic-pituitary axis (HPA) is included in the treatment field. Radiation-induced abnormalities are generally dose dependent and may develop many years after irradiation. Growth hormone deficiency and premature sexual development can occur following doses as low as 18 Gy fractionated radiation and are the most common neuroendocrine problems noted in children. Deficiency of gonadotropins, thyroid stimulating hormone, and adrenocorticotropin are seen primarily in individuals treated with > 40 Gy HPA irradiation. Hyperprolactinemia can be seen following high-dose radiotherapy (> 40 Gy), especially among young women. Most neuroendocrine disturbances that develop as a result of HPA irradiation are treatable; patients at risk require long-term endocrine follow-up.

Hereditary abnormality of luteinizing hormone resulting in discrepant serum concentrations determined by different assays

We herein report familial defects in the molecular structure of luteinizing hormone (LH). The propositus was a 29-year-old women with repeated abortion in whom the serum LH concentration was extremely low determined by an immunoradiometric assay utilizing two monoclonal antibodies for the intact LH dimer and beta-subunit of LH (SPAC-S kit). Further studies on the serum LH concentration in this propositus by five different assay systems gave various results ranging from low to normal values. Bioassay of the propositus's LH using C57 black mice showed normal in biological activity. These data suggest that LH in the propositus is abnormal in terms of its molecular structure located in the bond region between alpha and beta subunits. A family study showed that the bioactivity of LH was normal in all family members. The serum LH was not detected in either the propositus or her brother with the SPAC-S kit even after the administration of LHRH, while the serum LH concentrations in the father, mother and sister were approximately half the normal range, indicating that the defect is hereditary and the mode of inheritance is autosomal dominant: the propositus and brother were homozygously affected, and the parents and sister heterozygously affected.

Four patients with polyendocrinopathy with associated pituitary hormone deficiency

Four cases of polyglandular endocrine disorders associated with pituitary hormone secretion failure are reported. Three of them had both insulin dependent diabetes mellitus (IDDM) and Hashimoto's disease. Each of these patients (cases 1-3) showed isolated deficiency of ACTH, TSH or gonadotropin, respectively. Another patient (case 4) had both Hashimoto's disease and isolated ACTH deficiency. Anti-pituitary antibody to AtT-20 cells was detected in case 1. Serum gamma-globulins from patients 1 and 4 attenuated corticotropin releasing hormone-induced ACTH release in monolayer cultured rat anterior pituitary cells. Gamma-globulins from patients 1 and 2 decreased baseline TSH release but stimulated baseline prolactin release in pituitary cell cultures. It is possible that pituitary hormone deficiency in these patients may be caused by autoimmune disorders.

Impaired growth hormone secretion in patients operated for pituitary adenomas

The frequency of growth hormone (GH) deficiency in patients operated for pituitary neoplasms of various size and type was investigated using the insulin tolerance test. 45 patients were included in the study. 20 of the patients had a non-hormone secreting pituitary neoplasm, 9 had GH-, 6 ACTH-, 7 prolactin secreting adenomas and 3 had a craniopharyngeoma. Complete endocrinological examination was obtained in all patients after pituitary surgery. Apart from patients operated for GH secreting adenomas, GH deficiency was very common after pituitary surgery (92%), even in patients operated for small lesions. Among the 45 patients LH/FSH deficiency was found in 33%, ACTH in 33%, TSH in 18% and ADH deficiency in 9% of the patients. In this study, impaired GH secretion was found to be independent of the size of the tumors and was present in nearly all patients after pituitary surgery (with exception of GH secreting adenomas). Deficiencies of other pituitary hormones were predominantly observed after surgery for large tumors.

Usefulness of sequential urinary follicle-stimulating hormone and luteinizing hormone measurements in the diagnosis of adolescent hypogonadotropism in males

FSH and/or LH deficiency in the second decade of life remains difficult to diagnose with testing at a single point in time because of the partial lack of hormone as well as the dynamic and inherently variable aspects of the pubertal process. A longitudinal study of gonadotropin excretion, therefore, was carried out in 78 normal boys and 157 male patients, aged 10-28 yr, with relative or absolute deficiencies of FSH and/or LH. Seven hundred and fifty-five timed urine samples were extracted with acetone, concentrated, and subjected to RIA. The results from patient groups with multiple tropic hormone deficiencies or isolated gonadotropin deficiency were clearly different from those of normal boys and individuals with constitutional delay in puberty. However, multiple samples obtained over a 2-yr period and, in selected cases, until the late teenage years may be required to diagnose gonadotropin deficiency in some patients, even using stringent predictive modeling criteria.

Chromosomal translocation t(13;16) in a patient with idiopathic hypogonadotropic hypogonadism

A patient with idiopathic hypogonadotropic hypogonadism (IHH) had an apparently balanced reciprocal translocation involving chromosomes 13 and 16 [t(13;16)(q14.11;q24)]. The patient's father has the same chromosomal translocation with no apparent physical abnormalities. The role of the chromosomal translocation in this patient is discussed.

[Back pain]

This 54 year old male patient complained of upper back pain for four months, which increased on physical exertion. An X-ray examination of the spine showed compression fractures of the anterior aspects of the thoracic vertebrae VI and XI as well as anterior aspects of the thoracic vertebrae VI and XI and signs of osteoporosis. Physical examination revealed signs of hypogonadism as well as eunuchoid disproportions of the skeleton. Serum tests gave evidence of a hypogonadotropic hypogonadism due to isolated LH-secretion deficiency (Pasqualini syndrome) with secondary osteoporosis.

Estimation error of Leydig cell numbers in atrophied rat testes due to the assumption of spherical nuclei

In this study, Leydig cell numbers in control and atrophied testes (induced via subcutaneous implants of testosterone plus 17 beta estradiol for 16 weeks; TE-implanted) of rats, estimated via the fractionator method (independent of any assumptions) were compared to those estimated via the disector (unbiased, but dependent on shrinkage) and Floderus (assumes spherical particles, dependent on shrinkage) methods. Estimates of Leydig cell numbers in control rats produced by all three stereological methods were similar. In rats with atrophied testes, both the fractionator and the disector methods produced significantly lower (P < 0.01; 47% and 41% with fractionator and disector, respectively) Leydig cell number estimates per testis than in the controls. By contrast, the estimates of Leydig cell number in atrophied testes derived via the Floderus equation were not significantly different from those of controls, but larger than those obtained via the fractionator and the disector methods. These results suggested that the assumptions of the Floderus method were violated in the atrophied rat testes. Why was the Floderus method of estimating Leydig cell number applicable to control rats but not to the TE-implanted rats? In an attempt to answer this question the diameter measurement together with its correction factor used in the Floderus equation (i.e. D+t - 2H) was also derived from the data collected for the disector method. The values for D+t - 2H used in the Floderus method and also calculated via the disector method were found to be identical in controls, but for the TE-implanted rats a 32% lower value was obtained with the Floderus equation when compared to the disector. These findings suggested that this estimation error caused an overestimation of Leydig cell numbers in the TE-implanted rat testes.

Evaluation of gonadotropin responses to synthetic gonadotropin-releasing hormone in girls with idiopathic hypopituitarism

We hypothesized that prepubertal girls with gonadotropin deficiency would produce less follicle-stimulating hormone (FSH) in response to synthetic gonadotropin-releasing hormone (GnRH) than would gonadotropin-sufficient children. To test this hypothesis, we performed 103 GnRH tests serially in 21 children who had idiopathic hypopituitarism with growth hormone deficiency. We tried to predict whether puberty would occur in the 17 girls with bone ages of 8 years or less. Of these 17 girls, 4 failed to have spontaneous secondary sexual characteristics by age 16 1/2 years, and 12 had spontaneous complete pubertal development. One girl had incomplete pubertal maturation with partial gonadotropin deficiency; her results were combined with those of the girls who had no spontaneous pubertal development. With increasing bone age, the girls with complete pubertal development had a decrease in the increment of FSH released in response to GnRH, although basal gonadotropin concentrations did not change. For GnRH tests performed at bone ages of 8 years or less, basal luteinizing hormone (LH) values did not differ between girls with complete puberty and those with absent or incomplete puberty. However, basal FSH and the incremental response of LH and FSH to GnRH were greater in those with complete puberty. Only two girls with prepubertal bone ages at the time of testing, who subsequently had complete puberty, had incremental FSH responses to GnRH that were less than 5 IU/L. Individual incremental LH responses to GnRH did not discriminate well between groups. None of the girls with adrenocorticotropic hormone deficiency, either originally or subsequently, had spontaneous puberty, but 4 of 12 girls with thyrotropin deficiency, either originally or subsequently, had complete puberty. We conclude that a significant increase in GnRH-stimulated FSH suggests that spontaneous pubertal development will occur in girls with idiopathic hypopituitarism. However, a low FSH response to GnRH may not be diagnostic of gonadotropin deficiency.

Human recombinant follicle-stimulating hormone induces growth of preovulatory follicles without concomitant increase in androgen and estrogen biosynthesis in a woman with isolated gonadotropin deficiency

To evaluate the importance of luteinizing hormone (LH) for normal estrogen production and subsequent development of ovarian follicles, a woman with isolated gonadotropin deficiency (LH; 0.37 IU/L, FSH 1.2 IU/L) was monitored during recombinant human follicle-stimulating hormone (hFSHrec) administration with respect to ovarian follicular growth and steroid production. During the first week (75 IU/day hFSHrec im) a significant rise in serum FSH (4.9 IU/L) was observed in the absence of changes in serum estradiol (E2) concentrations (36-76 pmol/L). During the following five days 150 IU/day hFSHrec was administered resulting in a further increase of serum FSH levels (maximum 8.5 IU/L). Development of multiple follicles--maximum diameter 22 mm as observed by transvaginal sonography--emerged together with a minor rise in E2 levels (from 76 to 236 pmol/L) and with a minimal increase in endometrial thickness (below 6 mm). Six days following the last injection of hFSHrec, aspiration of 3 follicles (13, 15 and 18 mm) was performed and low intrafollicular androstenedione (AD) (less than 675 nmol/L) and E2 (less than 9400 pmol/L) concentrations as compared to normal follicles were found. These first data on hFSHrec administration in the human suggest that; a) FSH alone can induce growth of preovulatory follicles, b) follicle growth does occur in the presence of subnormal E2 levels, c) LH is needed for adequate AD biosynthesis as substrate for aromatase activity. This indicates that growth and steroidogenic granulosa cell activity may be differentially regulated.

[Male sterility through hormonal insufficiency in Cameroon]

At the Gyneco-obstetric service of the Yaounde CHU, we have studied 361 cases of couple sterility. In 38%, the man was responsible. Among these patients, less than 50% had a complete hormonal checkup. The hormonal cause of sterility was confirmed in 63 patients by static tests using the radio-immunologic method. These hormonal abnormalities were most the result of a primary testicular insufficiency (23.8%) and seminifer tube abnormalities (38.5%).

Effect of specific FSH or LH deprivation on testicular function of the adult rat

While the need for FSH in initiating spermatogenesis in the immature rat is well accepted, its requirement for maintenance of spermatogenesis in adulthood is questioned. In the current study, using gonadotropin antisera to neutralize specifically either endogenous FSH or LH, we have investigated the effect of either FSH or LH deprivation for a 10-day period on (i) testicular macromolecular synthesis in vitro, (ii) the activities of testicular germ cell specific LDH-X and hyaluronidase enzymes, and finally (iii) on the concentration of sulphated glycoprotein (SGP-2), one of the Sertoli cell marker proteins. Both immature (35-day-old) and adult (100-day-old) rats have been used in this study. Since LH deprivation leads to a near total blockade of testosterone production, the ability of exogenous testosterone supplementation to override the effects of LH deficiency has also been evaluated. Deprivation of either of the gonadotropins significantly affected in vitro RNA and protein synthesis by both testicular minces as well as single cell preparations. Fractionation of dispersed testicular cells preincubated with labelled precursors of RNA and protein on Percoll density gradient revealed that FSH deprivation affected specifically the rate of RNA and protein synthesis of germ cell and not Leydig cell fraction. LH but not FSH deprivation inhibited [3H]thymidine incorporation into DNA. The inhibitory effect of LH could mostly be overriden by testosterone supplementation. LDH-X and hyaluronidase activities of testicular homogenates of adult rats showed significant reduction (50%; P less than .05) following either FSH or LH deprivation. Again testosterone supplementation was able to reverse the LH inhibitory effect.(ABSTRACT TRUNCATED AT 250 WORDS)

Reversal of long-term LH deprivation on testosterone secretion and Leydig cell volume, number and proliferation in adult rats

The purpose of this study was to determine whether Leydig cell volume and function could recover fully from long-term LH deprivation upon restoration of endogenous LH secretion, and whether the restoration of LH would elicit a mitogenic response, i.e. stimulate Leydig cell proliferation or affect Leydig cell number per testis. LH secretion was inhibited by treating adult rats with testosterone and oestradiol-filled (TO) silicone elastomer implants (16 weeks), and was restored by removing the implants. Changes in serum concentrations of LH and FSH, LH-stimulated testosterone secretion by testes perfused in vitro, Leydig cell volume and number per testis, average Leydig cell volume and Leydig cell [3H]thymidine incorporation were measured at weekly intervals following implant removal. The TO implants inhibited (P less than 0.01) LH secretion, but serum concentrations of FSH were not significantly different (P greater than 0.10) from control values. After implant removal, serum LH returned to control values within 1 week, whereas serum FSH increased twofold (P less than 0.01) and returned to control values at 4 weeks. LH-stimulated in-vitro testosterone secretion was inhibited by more than 99% in TO-implanted rats, but increased (P less than 0.01) to 80% of control values by 8 weeks after implant removal. The total volume of Leydig cells per testis and the volume of an average Leydig cell were 14 and 19% of control values respectively, after 16 weeks of TO implantation (P less than 0.01), but returned to 83 and 86% of controls (P greater than 0.10) respectively, by 6 weeks after implant removal. Leydig cell proliferation ([3H]thymidine labelling index) was low (less than 0.1%) in both control and TO-implanted rats, increased (P less than 0.01) fivefold from 1 to 4 weeks after implant removal and then declined to control values at 6 weeks. The increase in Leydig cell [3H]thymidine incorporation was mimicked by treating TO-implanted rats with exogenous LH, but not FSH. Leydig cells were identified in both the interstitium and the lamina propria of the seminiferous epithelium. The proportion of Leydig cell nuclei in the lamina propria was 30-fold greater (P less than 0.01) at 1 and 3 weeks after implant removal (3%) compared with that for control and TO-implanted rats (0.1%). Total Leydig cell number per testis was marginally but not significantly (P = 0.06) decreased in rats treated with TO implants for 16 weeks when compared with controls (18.4 +/- 2.2 vs 25.4 +/- 1.2 x 10(6)).(ABSTRACT TRUNCATED AT 400 WORDS)

Syndrome of cerebellar ataxia and hypogonadotrophic hypogonadism: evidence for pituitary gonadotrophin deficiency

Familial cerebellar ataxia with hypogonadotrophic hypogonadism is a rare condition. Two affected siblings in a sibship of three were studied and found to have low plasma gonadotrophin levels. No rise in gonadotrophin levels was demonstrable after repeated stimulation with LHRH. The pattern of TSH and prolactin responses to TRH stimulation suggest hypothalamic dysfunction. The results clearly identify the cause of hypogonadism to be due to a defect in production or release of gonadotrophins by the pituitary gland and suggest that hypogonadism is part of a greater endocrine disturbance involving both the hypothalamus and pituitary.