Testicular and serum testosterone variations in squirrel monkeys during seasonal cyclicity

The seasonal testicular maturation of squirrel monkeys (Saimiri sciureus) was used as a model of maturational hormonal regulation of the testis. Testicular testosterone and serum testosterone concentrations were determined during the circannual variations of body weight and testicular volume. These data have been correlated with changes in the germinal epithelium. According to individual weight curves and time of the year, the monkeys were divided into five groups: group A1, maximal weight, April-May; A2, July; A3, November; A4, minimal weight, February-March; and A5, March-April. Variations in testicular volume followed very closely variations in body weight. Sexual activity started at A1 and persisted in A2. A marked drop in the mean width of the germinal epithelium and the diameters of the seminiferous tubules was observed in A3, followed by a recovery during A4 and A5. Testicular testosterone showed two annual elevations. The first peak, 3.91 +/- 0.31 micrograms/g (mean +/- SE), coincided with the serum testosterone peak when body weight and testicular volume were high and the trophic response of the germinal epithelium was complete. The second peak reached levels of 5.21 +/- 1.48 micrograms/g and was observed before the reinitiation of spermatogenesis. This was accompanied by a moderate increase in serum testosterone. The second peak of testicular testosterone, which has been reported to occur in the rat and in humans, might represent a local androgen need for initiation of spermatogenesis, while the first peak might represent the androgen need for full stimulation of spermatogenesis.

Progressive decrease in serum sex hormone-binding globulin from infancy to late prepuberty in boys

Serum Sex hormone-binding globulin (SHBG) levels and affinity constant (Ka) of SHBG-dihydrotestosterone association were determined in 91 boys, aged 3 months to 15 yr, all at Tanner stage I of pubertal development. A gradual decrease in serum SHBG as a function of age was found in spite of unchanged serum testosterone levels. Ka values at different ages were not significantly different. Since steroids bound to SHBG are not transported into most tissues, particularly brain, a decrease in SHBG will have the effect of increasing tissue entrance of non-SHBG-bound sex hormones despite unchanged plasma concentrations. We speculate that the gradually increasing androgen and estrogen milieu of the brain created by this mechanism might be of physiological significance in triggering the onset of puberty.

Stimulation of ribonucleic acid and deoxyribonucleic acid synthesis in spermatogenic cells by their coculture with Sertoli cells

Germ cells were isolated from 30-day-old rat testes and purified by a Percoll gradient. Germ cells were cultured for 24 h to eliminate contaminant cells by utilizing the property of many nongerm cells of attaching to plastic surfaces. Germ cells were subsequently seeded on top of 7-day-old Sertoli cell monolayers. RNA and DNA synthetic activities were estimated by the rate of incorporation of [3H]uridine and [3H] thymidine into trichloroacetic acid-precipitable material. Germ cells increased RNA synthesis from 54,053 +/- 22,824 to 168,019 +/- 57,137 dpm/2 h X 10(6) cells (mean +/- SD) between 4 and 24 h of coculture, respectively (P less than 0.01), while they decreased this activity from 32,150 +/- 6,800 to 6,014 +/- 5,243 dpm when they were cultured alone for the same periods. Coculture of germ cells with either a cell derived from the adult bovine aortic endothelial cells (ABAE), or rat fibroblasts in primary culture prevented the fall in RNA synthesis but did not stimulate it. Addition of high concentrations of lactate to the culture medium did not have any affect in germ cells cultured alone but produced a slight stimulation in germ cells cocultured with ABAE cells, which was much smaller than the effect observed during coculture with Sertoli cells. Germ cells in coculture with Sertoli cells also increased their DNA synthesis from 2,186 +/- 765 at 4 h to 9,679 +/- 4,057 dpm [3H]thymidine/2 h X 10(6) cells at 24 h (P less than 0.05). When Sertoli cells were treated with FSH (1 microgram/ml), the synthesis of both RNA and DNA of germ cells cocultured with these cells was significantly higher than for germ cells cocultured with nontreated Sertoli cells. The system of coculture of Sertoli cells and germ cells consisted of the reassociation of the two previously isolated cells in a coculture, followed by their separation which permitted the effect of the coculture on the individual cell type to be assessed. By using this technique is was possible to obtain evidence suggesting that a chemical messenger other than lactate might be involved in the stimulatory effect of Sertoli cells on germ cells and that FSH increased this putative chemical messenger.

Sex hormone binding globulin response to testosterone. An androgen sensitivity test

Adequate distinction between an abnormality in androgen secretion or in target cell response is important in the diagnosis and management of male pseudohermaphroditism. Hormone serum levels give reasonable information on steroid secretion, but there are no simple methods, in clinical practice, to evaluate target cell response to androgens. In this work, we have evaluated the validity of the acute decrease in serum (SHBG) after administration of hCG or exogenous testosterone, as an indicator of androgen sensitivity in prepubertal subjects. The results were expressed as percentage of basal values. In control subjects, after hCG, SHBG dropped below 85% of basal, mean 55 +/- 17, and, after exogenous testosterone, below 80%, mean 62.18 +/- 8.85. In 23 patients studied with the hCG test, 10 positive and 13 negative results were found, but most of the negative responses became positive after exogenous testosterone. Of 25 patients studied with the exogenous testosterone test, 19 positive and 6 negative results were found. Clinical analysis of these 6 patients with negative responses showed that 4 subjects had a confirmed androgen insensitivity syndrome, while clinical information was compatible with this diagnosis in the other 2 patients. Furthermore, in 4 additional patients with the androgen insensitivity syndrome, but with high basal serum testosterone, this test was also negative. It is concluded that determination of serum SHBG after hCG is not reliable as an androgen sensitivity test, but the detection of the decrease in serum SHBG after exogenous testosterone is a useful and simple test of androgen sensitivity.

Response to acute hCG stimulation and steroidogenic potential of Leydig cell fibroblastic precursors in humans

The process of early testosterone (T) secretion and Leydig cell differentiation in humans was studied to explore the steroidogenic capacity of Leydig cell fibroblastic precursors. Seven cryptorchid boys received hCG prior to orchidopexy. Patients CP, PB, and MR received one injection of 1000 IU; patients JR and GG, three daily injections of 1000 IU, and patients MP and MM, five daily injections of 1000 IU. A testicular biopsy was obtained at the time of operation, 24 hours after the last injection. Serum T (ng/dl) before and after hCG stimulation and testicular T (ng/g) were determined by RIA. A control prepubertal testis (tumoral orchidectomy) was incubated in vitro and showed a time-dependent accumulation of T both in the medium and the testicular tissue. Testosterone released into the medium at 1, 2, and 4 hours was 0.76, 1.43, and 4.03 ng/ml, respectively. Tissue T at 0, 1, 2, and 4 hours was 9, 11, 16, and 24 ng/g, respectively. This indicates synthesis and secretion of T into the medium. Control testes showed abundant fibroblastic precursors with scanty cytoplasm, few organelles, heterochromatic nuclei, and minute nucleoli. No Leydig cells were present. After 1 day of hCG stimulation, numerous fibroblasts were activated, displaying enlarged cytoplasms with increased numbers of organelles, nuclei rich in euchromatin, and bigger nucleoli. No Leydig cells were present. Basal serum testosterone was 58.2 +/- 45.3 ng/dl and 87.3 +/- 42.0 after hCG administration, while testicular T was 974.0 +/- 686.0 ng/g (control prepubertal testicular T is 10-50 ng/g). After 3 days of hCG, activated fibroblasts increased and immature Leydig cells appeared. Basal serum T was 35.5 +/- 7.8 ng/dl and 394.0 +/- 24.0 after hCG stimulation, while testicular T rose to 2797.5 +/- 1222.6 ng/g. After 5 days, mature Leydig cells appeared for the first time. Serum T was 58 +/- 59.3 ng/dl (basal) and 641.5 +/- 390 ng/dl (after hCG); testicular T was 789 ng/g (patient MM did not have a value for testicular T). HCG induced numerous coated pits and endocytic vesicles in activated fibroblasts and young Leydig cells, suggesting receptor aggregation and internalization of hormone-receptor complexes. Peroxidase-antiperoxidase (PAP) localization of T was positive in peritubular fibroblasts and Leydig cells.(ABSTRACT TRUNCATED AT 400 WORDS)

Induced hypoprolactinemia and testicular steroidogenesis in man

The effects of short-term hypoprolactinemia on the pituitary-gonadal axis were evaluated in a group of patients with untreated prostatic carcinoma. Each patient was studied prior to and during 7-day oral administrations of bromocriptine (2.5 mg q.i.d.). Serum LH, prolactin (PRL), androst-4-ene-3,17 dione (androstenedione), testosterone, and 5 alpha-androstane-3 alpha, 17 beta-diol (5 alpha-Diol) levels, as well as intra-testicular testosterone, dihydrotestosterone (DHT), 5 alpha-Diol and zinc (Zn) concentrations, were determined. Daily administration of bromocriptine caused a marked suppression of serum PRL (mean +/- SEM, 23.8 +/- 2.5 vs. 6.4 +/- 1.0 ng/ml) without concomitant changes in serum LH levels (mean +/- SEM, 8.3 +/- 1.6 vs. 8.9 +/- 2.1 ng/ml). Hypoprolactinemia induced a significant decrease (P less than 0.05) in the mean peripheral testosterone levels; but 5 alpha-Diol and androstenedione remained unchanged. However, in testicular tissues, bromocriptine treatment resulted in significant increases in mean concentrations of total androgens (P less than 0.001), testosterone (P less than 0.001) and DHT (P less than 0.02). Testicular levels of 5 alpha-Diol were not significantly altered. There was no change in Zn levels in basal conditions and during bromocriptine administration. These results indicate that short-term suppression of serum PRL levels in man affects basal testicular function without altering serum LH. However, a direct action of bromocriptine on the human gonad cannot be excluded.

Relative cellular distribution of particulate androgen binding between sertoli and germ cells in rat testis

An androgen binding activity with characteristics similar to ABP is present in a particulate fraction (105,000 g pellet) obtained by differential centrifugation of seminiferous tubules, impure Sertoli cells and impure germ cells homogenates. Purification of germ cells through albumin gradients, results in almost a complete loss of androgen binding activity in the purified germ cell suspensions. Furthermore, Sertoli cell enriched testes from 22-, 32- and 40-day old rats showed increases in particulate androgen binding, when compared to matched controls, parallel to increments in the activity of a Sertoli cell marker enzyme (beta-glucuronidase). These results suggest that particulate androgen binding activity is only present in Sertoli cells and this protein may play a role in the compartmentalization of androgens in the testis.

Phenotypic heterogeneity in familial isolated growth hormone deficiency type I-A

We studied an Argentinian family of Spanish ancestry in which the parents are of normal height and three of their four children have isolated GH deficiency type I-A. Restriction endonuclease analysis of DNA isolated from leukocytes was done using 32P-labeled human GH (hGH) cDNA sequences as a probe. The three siblings were homozygous, while their parents and the remaining sibling were heterozygous for a deletion of about 7.5 kilobases DNA, which included the normal hGH gene. The phenotype of the affected subjects differed in several respects. There was variation between the homozygotes in birth length and height before hGH treatment and growth responses during long term hGH treatment. Furthermore, heterozygotes in this family had normal height despite their diminished hGH responses to provocative tests.

Testicular testosterone and dihydrotestosterone during sexual development in humans

The concentrations of testosterone and dihydrotestosterone was determined in the human testis at different stages of sexual development, in patients with undescended testis or in subjects who had been treated for acute lymphoblastic leukemia. Patients were divided in three groups, prepubertal (Tanner's stage I), early puberty (Tanner's stages 2 + 3) and late puberty (Tanner's stages 4 + 5). Even though tubular diameter and serum testosterone followed the expected gradual rise during sexual maturation, testicular testosterone increased abruptly at early puberty, resulting in a high testicular: serum testosterone ratio at this stage. The testicular dihydrotestosterone:testosterone ratio was also high at early puberty. These data suggest that, at initiation of sexual development, seminiferous tubules receive a high androgen load, at a time when other androgen target organs are barely stimulated.

Sex hormone binding globulin in arterial, and in peripheral, hepatic, renal and spermatic venous blood of children and adults

Human sex hormone binding globulin (SHBG) was measured in arterial serum and in serum obtained from different venous territories. In 6 children, SHBG ranged from 44.4 +/- 4.8 (mean +/- SD) in arterial blood to 55.3 +/- 5.3 in the hepatic vein (P less than 0.01), while it did not change significantly in renal or peripheral tissue venous blood. In 6 male adults, no significant arteriovenous differences were found either in the peripheral tissues or in the splanchnic circulation. In the spermatic vein of 8 subjects, SHGB was significantly lower (17.1 +/- 5.7) than in the arterial blood (22.8 +/- 7.5), P less than 0.025. The arterio-venous difference found in the splanchnic circulation of children supports the hepatic origin of SHBG, and also suggests extra-hepatic clearance of the binding globulin. Testicular uptake of SHBG might be necessary to regulate delivery of androgens to Sertoli cells in the seminiferous tubules.

Dynamics of SHBG response to testosterone. Implications upon the immediate biological effect of sex hormones

The dynamics of the changes in serum concentrations of SHBG to variations in serum testosterone was studied in rabbits. Castration of male rabbits failed to produce changes in SHBG within 2 days but induced a significant increment 2 months later. Administration of 15 mg of testosterone to 5 male castrates produced a rapid decrease in SHBG concentrations from 215 +/- 121 nmol/l before, to 114 +/- 15, 6 h after (mean +/- SD), while 25 mg of the androgen barely changed SHBG levels in 5 females (from 81 +/- 26 to 72 +/- 22). Three of the males and the 5 females showed a tendency to recover basal levels at 24 and 48 h. Since SHBG is a major regulator of the availability of sex hormones to be transported into tissue cells for both biological action and degradation, the rapid changes in serum SHBG induced by testosterone might play a role in controlling its own biological effect. A decrease in SHBG will result in a more effective stimulation in androgen-responsive tissues, but it will also favor a faster interruption of the effect by increasing the rate of degradation. These androgen induced changes in SHBG are apparently different in male and females.

Inhibition of follicle-stimulating hormone receptor binding by circulating immunoglobulins

We have characterized a circulating inhibitor of FSH receptor binding found in two patients with hypergonadotropic amenorrhea and myasthenia gravis. The inhibitor behaves as an immunoglobulin according to several criteria, including precipitation by 30% ammonium sulfate, migration on DEAE-cellulose chromatography, specific binding to protein A-Sepharose, characterization as a 7S protein in sucrose density gradients, and immunoprecipitation with specific antihuman immunoglobulin G. Evidence suggests that these antibodies are directed at determinants on or near the FSH receptor, and they may be responsible for the observed clinical FSH resistance.

Sex hormone-binding globulin response to human chorionic gonadotropin stimulation in children with cryptorchidism, anorchia, male pseudohermaphroditism, and micropenis

Sex hormone-binding globulin serum concentrations (SHBG) were measured before and after a 5-day hCG stimulation test in 11 prepubertal boys with cryptorchidism, 6 with anorchia, 5 with male pseudohermaphroditism, and 5 with micropenis. Cryptorchid boys had decreased SHBG levels after hCG, by 55 +/- 17% (mean +/- SE) of the basal concentration. Patients with anorchia, who did not show an elevation in serum androgens, did not have decreased SHBG concentrations. Four of the 5 patients with male pseudohermaphroditism had an adequate elevation of serum androgens, did not have decreased SHBG concentrations. Four of the 5 patients with male pseudohermaphroditism had an adequate elevation of serum androgens after hCG, but in only 3 of them did SHBG decrease. None of the 5 patients with micropenis had decreased serum SHBG levels despite normal increments in serum androgens. The administration of a long-acting preparation of testosterone to sexually infantile subjects produce a similar decrease in the SHBG concentration. This change in SHBG concentration after hCG or testosterone in prepubertal boys could be used as a convenient test of biological response to androgens.

Steroid metabolism by a tumour of the specific gonadal stroma in a child

A study of steroid metabolism by a tumour of the specific gonadal stroma was carried out in a 10 year old boy. Tumours developed in the two testes from multiple foci, and clinically, no signs of sexual development were evident. Four testicular enzymes necessary for testosterone biosynthesis were estimated in the child, in two adult controls, and in three pre-pubertal boys with male pseudohermaphroditism but normal tests of Leydig cell function. 17 alpha-Hydroxylase and 17 beta-hydroxysteroid dehydrogenase were similar in the five controls and in the gonad with the tumour, while 17,20-desmolase and 3 beta-hydroxysteroid dehydrogenase were grossly deficient in the child with the tumour. These enzyme deficiencies might explain the absence of peripheral virilization in a boy with a tumour of Leydig and Sertoli cells.

Development of the gonadotrophic resistant ovary syndrome in myasthenia gravis: suggestion of similar autoimmune mechanisms

A woman with myasthenia gravis who developed hypergonadotrophic amenorrhoea was studied. This patient fulfilled all accepted criteria for the diagnosis of the gonadotrophin resistant ovary syndrome: high levels of serum LH and FSH by radioimmunoassay and urinary gonadotrophin excretion by bioassay, low serum oestradiol, lack of response to exogenous gonadotrophin and ovaries with multiple non-stimulated primordial follicles. The serum of this patient contained a substance which behaving like a gamma globulin, inhibited FSH specific binding to receptors in an in vitro system. This inhibitor was looked for in further patients with hypergonadotrophic amenorrhoea, other immunological diseases or myasthenia gravis with normal menses. Ovarian biopsy was not available in these patients. In all except one who also had the association of myasthenia gravis and hypergonadotrophic amenorrhoea, the inhibitor was not detected. It is suggested that development of antibodies directed against gonadotrophin receptors or a receptor related membrane domain may play a role in the mechanism of failure of gonadotrophin stimulation in some patients with the gonadotrophin resistant ovary syndrome.

Testosterone, dihydrotestosterone, and zinc concentrations in human testis and epididymis

Tissue testosterone, dihydrotestosterone, and zinc concentrations have been determined in testis and epididymis of 13 patients with carcinoma of the prostate, 1 patient with carcinoma of the penis, and 3 patients with carcinoma of the prostate on estrogens. The 13 patients not receiving estrogens had the following testicular levels: testosterone, of 529 +/- 63.1 ng/g (mean +/- SE); dihydrotestosterone, 23.7 +/- 2.58 ng/g; and zinc 62.2 +/- 7.6 micrograms/g. The epididymal levels were as follows: testosterone, 40.6 +/- 3.4 ng/g; dihydrotestosterone, 20.5 +/- 2.36 ng/g; and zinc, 67.2 +/- 11.1 micrograms/g. Patients on estrogen therapy showed much lower androgen values in the two organs but zinc was not changed significantly. Concentrations of androgens were not significantly different in the epididymal fractions of caput, corpus, and cauda. In testis, there was a positive correlation between zinc and androgens contents, while the opposite was suggested by the data in the epididymis. Even though these patients were not normal, there was no evidence of testicular or epididymal disturbances.

Testicular function in varicocele

Testicular testosterone concentration serum testosterone, LH and FSH, sperm count and testicular histology were evaluated in 17 patients with varicocele. Testicular testosterone was either normal or high (mean 906 +/- 723 ng/g of tissue), and serum testosterone was within the normal range in most patients. Serum LH was elevated in half of the patients. The degree of testicular damage observed was extremely variable and correlated with sperm analysis. Testicular testosterone tended to be higher in patients with severe microscopic lesions of the testis. It is concluded that even though Leydig cell function is partially altered, this deficiency is compensated by LH stimulation and therefore, failure of spermatogenesis is not secondary to low testosterone levels.