Complete Sertoli cell proliferation induced by follicle-stimulating hormone (FSH) independently of luteinizing hormone activity: evidence from genetic models of isolated FSH action

Defining the gonadal effects of FSH distinct from those of LH remains difficult. We have characterized and compared the level of Sertoli and germ cell development in three mouse models recently created to isolate FSH activity from LH effects. Two models used LH-deficient hypogonadal (hpg) mice to selectively study either pituitary-independent transgenic (tg) FSH or ligand-independent activated tg FSH receptor (FSHR(+)) expression, and the third model used LH receptor (LHR)-deficient mice to isolate and examine endogenous mouse FSH effects. Stereological evaluation revealed tg-FSH or tg-FSHR(+) activity significantly increased total Sertoli cell numbers per testis in both hpg models relative to control hpg testes. Furthermore, tg-FSH dose-dependently restored hpg Sertoli cells to wild-type (wt) (non-hpg) levels, and LHR-/- testes also exhibited wt Sertoli numbers. Spermatogonial proliferation and meiotic development were enhanced by tg-FSHR(+) or tg-FSH. Despite producing normal Sertoli numbers, isolated tg-FSH activity only increased total spermatogonia and spermatocyte populations to 57 and 44% of wt, which was comparable to spermatogonia and spermatocyte numbers observed in LHR-null testes (45 and 34% of wt). Selective FSH activity initiated round spermatid formation in all three models. However, elongated spermatid formation was detected in tg-FSH and tg-FSHR(+) hpg testes but not in LHR-/- testes, which may reflect even lower intratesticular testosterone levels in LHR-null compared with hpg testes. FSH increased round and elongated spermatid numbers in hpg testes to 16 and 6% of wt without altering intratesticular testosterone levels, but failed to produce spermatozoa demonstrating the inability of FSH to complete spermatogenesis. These findings revealed that full Sertoli cell proliferation can be accomplished by FSH activity without LH requirement, and although postnatal mitotic and meiotic germ cell development can be promoted by FSH alone, LH-mediated effects remain a critical determinant for initiating the full complement of germ cells and final stages of postmeiotic development.     

Androgens and spermatogenesis

Male infertility contributes to 50% of all cases of infertility. The main cause is low quality and quantity of sperm. In humans, spermatogenesis starts at the beginning of puberty and lasts lifelong. It is under the control of FSH and testicular androgens, and mainly testosterone (T), and therefore requires a normal gonadotroph axis, intratesticular T production by Leydig cells and functional androgen receptors (ARs) within testicular Sertoli cells. Various clinical cases illustrate the roles of T in human spermatogenesis. Men with complete congenital hypogonadotropic hypogonadism (HH) are usually azoospermic. Treatment by exogenous testosterone injection and FSH is not able to produce sperm. However, combined treatment with FSH and hCG is effective. This example shows that intratesticular T plays a major role in spermatogenesis. Furthermore, testicular histology of men with LH receptor mutations shows Leydig cell hypoplasia/agenesis/dysplasia with conserved Sertoli cell count. The sperm count is reduced, as in males with partial inactivating mutation of the androgen receptor. Some protocols of hormonal male contraception or exogenous androgen abuse induce negative feedback in the hypothalamic pituitary axis, decreasing FSH, LH and T levels and inducing sperm defects and testicular atrophy. The time to recovery after cessation of drug abuse is around 14 months for sperm output and 38 months for sperm motility. In summary, abnormal androgen production and/or AR signaling impairs spermatogenesis in humans. The minimal level of intratesticular T for normal sperm production is a matter of debate. Interestingly, some animal models showed that completely T-independent spermatogenesis is possible, potentially through strong FSH activation. Finally, recent data suggest important roles of prenatal life and minipuberty in adult spermatogenesis.     

Activating mutations in the luteinizing hormone receptor gene: a human model of non-follicle-stimulating hormone-dependent inhibin production and germ cell maturation

CONTEXT: Familial male-limited precocious puberty is a dominant autosomal genetic disease caused by activating LH receptor gene mutations, clinically expressed only in males. In preliminary studies, in addition to the expected testosterone increase, we found high inhibin B levels before the age of normal puberty. OBJECTIVES: The objective of the study was to assess the cellular origin of serum inhibin thanks to testis section immunostaining. MAIN OUTCOME MEASURES: Serum testosterone, gonadotropin, inhibin B, pan-alphaC-inhibin, and anti-Mullerian hormone levels were measured. Immunostaining was performed using specific anti-alpha- and anti-beta-subunit antibodies. SUBJECTS AND METHODS: Five boys from three families (mutation M398T or I542L) were investigated at onset (2-6 yr), on ketoconazole treatment, and at adolescence. Testis biopsies were performed in three subjects before the disease was fully characterized. RESULTS: The high testosterone levels were suppressed by ketoconazole. Anti-Mullerian hormone levels were inversely related to testosterone: low at diagnosis, elevated after testosterone suppression. Despite FSH suppression, inhibin B and pan-alphaC-inhibin levels were high from clinical onset to adolescence. Biopsy specimens showed normal Sertoli cell complement and germ cell maturation until the spermatocyte II stage. Sertoli and Leydig cells displayed positive inhibin alpha-subunit immunostaining. Only Leydig cells and spermatogonia stained positively for the inhibin betaB-subunit. CONCLUSIONS: Familial male-limited precocious puberty is a unique model of inhibin B secretion, demonstrating that Leydig cells can produce significant amounts of the dimeric molecule. Our results also suggest that the pubertal FSH rise is not required for full expression of the two inhibin B genes and for the initiation of germ cell maturation.     

Hormonal control of spermatogenesis.

FSH and testosterone (T) secretion are essential for the successful completion of spermatogenesis. Because there are no receptors for FSH or testosterone on germ cells, there are intermediate steps in this action, the nature of which are unknown. However, as the Sertoli cell contains receptors for both FSH and T, it is likely that these hormones exert their influence on germ cells by modulating Sertoli cell function. Both FSH and T exert synergistic actions on germ cells, but T has a specific action on the later stages of spermatid maturation. FSH, by its ability to stimulate Sertoli cell mitosis during testicular development, can influence the spermatogenic capacity of the adult testis.     

Pituitary-testicular interrelationships during germinal involution in the vitamin A deficient rat

Pituitary-testicular relationships in mature male rats were investigated during the period of germinal involution after the induction of vitamin A deficiency (VAD). Vitamin A deficiency caused a decrease in testicular weight, a gradual increase in the incidence of delayed spermiation, increased phagocytosis of spermatids and pyknosis of germ cell nuclei in rats aged 80 to 110 days. Both basal and gonadotrophin releasing hormone (GnRH)-stimulated serum FSH concentrations were increased by 100 days of age. During the same period, the per cent increment in GnRH-stimulated FSH secretion, pituitary FSH concentration and LH secretion remained unchanged. These results suggest that the increased serum FSH may mark specifically an alteration in the germinal epithelium. By 140 days of age, spermatogenic activity in the rats with VAD was limited to the spermatogonial proliferations so that only Sertoli cells, spermatogonia and preleptotene spermatocytes remained. At this time hypersecretion of FSH persisted while the per cent increment of GnRH-stimulated FSH secretion decreased. Concomitantly, basal and GnRH-stimulated LH concentrations were also increased in the presence of normal serum testosterone. These results indicate that a complete cessation of spermatogenesis beyond preleptotene spermatocytes is associated with a change in the secretion of both FSH and LH. The relationship between serum LH and testosterone was normal until at least 110 days of age. By 140 days the ratio between basal LH and basal testosterone, and between total LH and total testosterone, after GnRH administration, increased in the rats with VAD.(ABSTRACT TRUNCATED AT 250 WORDS)     

Testosterone-induced inhibition of spermatogenesis is more closely related to suppression of FSH than to testicular androgen levels in the cynomolgus monkey model (Macaca fascicularis)

We have investigated the antigonadotropic and antispermatogenic effects of exposure to a long-acting testosterone ester in the cynomolgus monkey model. Groups of five adult animals were exposed either to vehicle or to 10 mg/kg or 20 mg/kg testosterone buciclate (TB) over a 26-week period with injections given in weeks 0, 11 and 18. In week 26, testicular biopsy tissue was collected. Serum testosterone levels were in the upper normal range with 10 mg/kg TB and were approximately twofold higher with 20 mg/kg TB. The estradiol pattern followed that of testosterone and body weights increased in a testosterone-dependent manner. TB completely abolished serum LH bioactivity. Serum concentrations of FSH and inhibin-alpha were suppressed in a TB dose-dependent manner. During weeks 4-8 after the first injection, a rebound of FSH and inhibin but not bioactive LH secretion occurred. This rebound was followed immediately by a restimulation of testis size and sperm numbers. After the next TB injections these parameters were once again suppressed. Nadir testis size was 30-40% of baseline and animals were severely oligozoospermic or transiently azoospermic. Consistent azoospermia was not achieved. Quantitation of serum inhibin B, proliferating cell-nuclear antigen staining and flow cytometric analysis of germ cell populations revealed pronounced suppression of spermatogenesis in both TB-treated groups whereas androgen receptor expression remained unchanged. Testicular androgens levels, determined in week 26, did not differ among all three groups and did not correlate with sperm numbers, histological and immunocytochemical findings. All suppressive effects were fully reversed during the recovery period. We have concluded that pronounced suppression of primate spermatogenesis seemingly requires inhibition of FSH rather than testicular androgen levels, at least in this preclinical non-human primate model. For the purpose of male contraception, FSH inhibition appears mandatory.     

Follicle-stimulating hormone-independent functions of primate Sertoli cells: potential implications in the diagnosis and management of male infertility

CONTEXT: FSH is known to augment the production of essential germ cell (Gc) survival factors, lactate and estradiol, by Sertoli cells (Sc) of 18-d-old pubertal rats. However, the failure of gonadotropin and androgen treatment to initiate spermatogenesis in testis of some infertile men bearing Sc and Gc is intriguing. The role of FSH in regulation of lactate and estradiol production by primate Sc is currently unknown. OBJECTIVE: The objective of the study was to determine the role of FSH in regulating lactate and estradiol production by primate Sc. METHODS: Gc differentiation was initiated in male juvenile rhesus monkeys by pulsatile administration of GnRH for 4-5 wk. Sc from these pseudopubertal monkeys and pubertal rats were cultured. Production of lactate and estradiol in response to FSH and 8-bromoadenosine-cAMP was evaluated. Inhibin-betaB expression, cAMP production, and cell proliferation were also assayed. RESULTS: Unlike Sc from pubertal rats, Sc from pseudopubertal monkeys constitutively aromatized testosterone to estradiol and produced large amounts of lactate without FSH stimulation. Increasing doses of recombinant monkey FSH or 8-bromoadenosine-cAMP failed to augment lactate production, although they significantly augmented proliferation of Sc. Production of cAMP and expression of inhibin-betaB mRNA were also remarkably augmented by recombinant monkey FSH. CONCLUSIONS: These results suggest that lactate and estradiol production by monkey Sc is not governed by FSH, as previously thought based on studies of rat Sc. Thus, in a clinical situation, assessment of such gonadotropin-independent functions of Sc may be obligatory for the diagnosis and management of certain forms of idiopathic male infertility.     

Inhibin B in male reproduction: pathophysiology and clinical relevance.

The recent availability of specific inhibin assays has demonstrated that inhibin B is the relevant circulating inhibin form in the human male. Inhibin B is a dimer of an alpha and a betaB subunit. It is produced exclusively by the testis, predominantly by the Sertoli cells in the prepubertal testis, while the site of production in the adult is still controversial. Inhibin B controls FSH secretion via a negative feedback mechanism. In the adult, inhibin B production depends both on FSH and on spermatogenic status, but it is not known in which way germ cells contribute to inhibin B production. The regulation of inhibin B production changes during life. There is an inhibin B peak in serum shortly after birth only partly correlated with an increase in serum FSH, probably reflecting the proliferating activity of the Sertoli cells during this phase of life. Afterwards, inhibin B levels decrease and remain low until puberty, when they rise again, first as a consequence of FSH stimulation and then as a result of the combined regulation by FSH and the ongoing spermatogenesis. In the adult, serum inhibin B shows a clear diurnal variation closely related to that of testosterone. The administration of FSH increases the secretion of inhibin B in normal men, but is much more pronounced in males with secondary hypogonadism. The treatment of infertile men with FSH, however, does not result in an unequivocal inhibin B increase. There is a clear inverse relationship between serum inhibin B and FSH in the adult. Serum inhibin B levels are strongly positively correlated with testicular volume and sperm counts. In infertile patients, inhibin B decreases and FSH increases. In general, there is very good correlation with the degree of spermatogenetic damage, with the arrest at the earlier stages having the lowest inhibin B levels. However, for unknown reasons, there are cases of Sertoli-cell-only syndrome with normal inhibin B levels. Inhibin B and FSH together are a more sensitive and specific marker for spermatogenesis than either one alone. However, the inhibin B concentrations are not a reliable predictor of the presence of sperm in biopsy samples for testicular sperm extraction. Suppression of spermatogenesis with testosterone and gestagens leads to a partial reduction of inhibin B in serum but it is never completely suppressed. In contrast, testicular irradiation in monkeys or humans leads to a rapid and dramatic decrease of inhibin B, which becomes undetectable when germ cells are completely absent. In summary, although inhibin B is a valuable index of spermatogenesis, the measurement of serum inhibin B levels is still of limited clinical relevance for individual patients.     

New perspectives in the diagnosis of pediatric male hypogonadism: the importance of AMH as a Sertoli cell marker

Sertoli cells are the most active cell population in the testis during infancy and childhood. In these periods of life, hypogonadism can only be evidenced without stimulation tests, if Sertoli cell function is assessed. AMH is a useful marker of prepubertal Sertoli cell activity and number. Serum AMH is high from fetal life until mid-puberty. Testicular AMH production increases in response to FSH and is potently inhibited by androgens. Serum AMH is undetectable in anorchidic patients. In primary or central hypogonadism affecting the whole gonad and established in fetal life or childhood, serum AMH is low. Conversely, when hypogonadism affects only Leydig cells (e.g. LHβ mutations, LH/CG receptor or steroidogenic enzyme defects), serum AMH is normal or high. In pubertal males with central hypogonadism, AMH is low for Tanner stage (reflecting lack of FSH stimulus), but high for the age (indicating lack of testosterone inhibitory effect). Treatment with FSH provokes an increase in serum AMH, whereas hCG administration increases testosterone levels, which downregulate AMH. In conclusion, assessment of serum AMH is helpful to evaluate gonadal function, without the need for stimulation tests, and guides etiological diagnosis of pediatric male hypogonadism. Furthermore, serum AMH is an excellent marker of FSH and androgen action on the testis.     

Investigations upon the mechanism of inhibition of spermatogenesis in the rat by a dimeric ethynodiol-testosterone ester

The combination of androgens and progestogens has been shown to be a suitable male contraceptive. Previous experiments revealed that injection of a dimeric testosterone-ethynodiol ester into rats and monkeys induces azoospermia for several weeks. In order to investigate the mechanism of action, we compared the endocrine effects of a single injection of 10 mg of the dimeric ester into intact male rats with that of 6 mg of norethisterone enanthate + 6 mg of testosterone enanthate. After the injection of the dimer there was a transitory reduction of serum FSH and a strong suppression of serum LH and testosterone, of testicular testosterone and of androgen-binding protein (ABP) in the testis and epididymis for at least 8 weeks, whereas spermatogenesis was totally depressed between the 4th and 8th week. Contrary to this, the enanthates caused only a slight suppression of spermatogenesis, although serum LH, testicular testosterone and ABP were profoundly reduced. The only conspicuous difference in the endocrine pattern of both groups during the first 4 weeks was in the serum testosterone level which remained normal in the rats treated with the enanthates. The results suggest that testicular testosterone and ABP concentrations are of minor significance for an intact spermatogenesis, and that some other factors produced by Sertoli cells might be involved and possibly maintained by normal serum testosterone levels.     

Increased serum inhibin B levels after varicocele treatment

OBJECTIVE: Inhibin B is secreted by Sertoli cells in response to FSH and is the major feedback regulator of FSH secretion in man. The serum inhibin B level has emerged as a good marker of spermatogenesis and Sertoli cell function. Varicocele has been associated with infertility and disturbed spermatogenesis. We have studied the effect of varicocele treatment on serum inhibin B levels, with the aim of investigating the effect on spermatogenesis and the involvement of the Sertoli cell in varicocele pathophysiology. DESIGN AND PATIENTS: In a pre-post test design, the effect of varicocele surgery on inhibin B levels was studied in 30 infertile men. MEASUREMENTS: Endocrinology (inhibin B, FSH, LH, SHBG and testosterone) and semen analysis (sperm concentration, motility and morphology). RESULTS: In men receiving varicocele treatment, a significant increase in serum inhibin B levels was observed from 133.9 +/- 13.4 pretreatment to 167.8 +/- 16.1 ng/l after treatment (mean +/- SEM, P < 0.0001). No significant changes were observed in serum levels of FSH, LH and testosterone. The serum SHBG level decreased from 32.9 +/- 3.5 to 28.6 +/- 3.4 nmol/l (mean +/- SEM, P = 0.04) and the free androgen index was significantly increased from 66 +/- 5.9 pretreatment to 85 +/- 6.8 after treatment (P = 0.02, mean +/- SEM). Semen analysis showed a significant improvement in sperm concentration, from 6.5 +/- 1.9 pretreatment to 19.3 +/- 4.9 x 106/ml after treatment (P = 0.003, mean +/- SEM), and in sperm motility from the baseline level of 17 +/- 3 to 32 +/- 4% after treatment (P = 0.001, mean +/- SEM). CONCLUSIONS: Varicocele treatment can increase serum inhibin B levels, indicating improvement of spermatogenesis and Sertoli cell function. This finding suggests that the pathophysiology of varicocele involves impairment of Sertoli cell function or a different distribution of germ cell stages.     

Endocrine correlates of reproductive development in the male tree-shrew (Tupaia belangeri) and the effects of infantile exposure to exogenous androgens

The developmental life-history of tree-shrews conforms with the general primate pattern. Consequently, elucidation of the tree-shrew's neuroendocrine reproductive axis could shed light on the mechanisms that underlie human pubertal development. In the present study, we examined plasma gonadotropin concentrations in male tree-shrews from birth to sexual maturity, and related them to changes in the androgenic and gametogenic status of the testis. A hypogonadotropic infantile phase, during which a stable population of primordial cells is established, extended from birth to approximately Day 30. Following a short juvenile phase (Days 30-40), a pubertal phase of accelerated reproductive development was initiated between Days 40-55. At this time, FSH and LH levels rose and testosterone concentrations reached peak levels coincident with the descent of the testes, accelerated growth in the reproductive tract and the onset of spermatogenesis. To test whether this developmental peak in testosterone secretion is an important determinant in the normal onset of puberty, we exposed male tree-shrews prematurely to high circulating androgen levels for various periods and then examined the impact on key components of the developing reproductive axis. The testosterone implants failed to initiate spermatogenesis and the testes remained in an infantile state for the duration of the treatment, whereas implant removal led to the development of full spermatogenic activity. In both normal and experimental situations, low levels of FSH were associated with a lack of spermatogenic activity while the progression of germ cell development was precisely correlated with rising FSH levels. Taken together, these data establish a comprehensive picture of reproductive development in the male tree-shrew, and also provide support for the hypothesis that FSH plays a primary role in the initiation of spermatogenesis.     

Permanent effects of neonatal estrogen exposure in rats on reproductive hormone levels, Sertoli cell number, and the efficiency of spermatogenesis in adulthood.

This study aimed to identify the mechanism(s) for impairment of spermatogenesis in adulthood in rats treated neonatally with estrogens. Rats were treated (days 2-12) with 10, 1, or 0.1 microg diethylstilbestrol (DES), 10 microg ethinyl estradiol (EE), 10 mg/kg of a GnRH antagonist (GnRHa), or vehicle and killed in adulthood. DES/EE caused dose-dependent reductions in testis weight, total germ cell volume per testis, and Sertoli cell volume per testis. Sertoli cell number at 18 days of age in DES-treated rats was reduced dose dependently. GnRHa treatment caused changes in these parameters similar to those in rats treated with 10 microg DES. Plasma FSH levels were elevated (P < 0.001) to similar levels in all treatment groups regardless of differences in Sertoli cell number and levels of inhibin B; the latter reflected Sertoli cell number, but levels were disproportionately reduced in animals treated with high doses of DES/EE. Neonatal estrogen treatment, but not GnRHa, caused dose-dependent reductions (40-80%) in plasma testosterone levels in adulthood, but did not alter LH levels. Preliminary evidence suggests that the decrease in testosterone levels in estrogen-treated rats is not due to reduced Leydig cell volume per testis. GnRHa-treated rats exhibited a significant increase in germ cell volume per Sertoli cell and a reduction in germ cell apoptosis, probably because of the raised FSH levels. Despite similar raised FSH levels, rats treated with DES (10 or 1 microg) or EE (10 microg) had reduced germ cell volume/Sertoli cell and increased germ cell apoptosis, especially when compared with GnRHa-treated animals. The latter changes were associated with an increase in lumen size per testis, indicative of impaired fluid resorption from the efferent ducts, resulting in fluid accumulation in the testis. Rats treated neonatally with 0.1 microg DES showed reduced germ cell apoptosis comparable to that in GnRHa-treated animals. The changes in apoptotic rate among treatment groups occurred across all stages of the spermatogenic cycle. It is concluded that 1) neonatal estrogen treatment results in dose-dependent alterations in Sertoli cell numbers, germ cell volume, efficiency of spermatogenesis, and germ cell apoptosis in adulthood; 2) the relatively poor spermatogenesis in estrogen-treated animals is most likely due to altered testis fluid dynamics and/or altered Sertoli cell function; 3) as indicated by FSH (LH) and testosterone levels, the hypothalamic-pituitary axis and Leydig cells are probably more sensitive than the Sertoli cells to reprogramming by estrogens neonatally; and 4) elevated FSH levels in adulthood may improve the efficiency of spermatogenesis.     

Analysis of the testicular phenotype of the follicle-stimulating hormone beta-subunit knockout and the activin type II receptor knockout mice by stereological analysis.

This study evaluated the role of FSH and activin A on testicular function using quantitative stereological analysis of testicular cell types in mice with targeted disruption of genes encoding the FSH beta-subunit and the activin type IIA receptor (ActRIIA). Using the optical dissector technique, the numbers of Sertoli cells and germ cells per testis were determined. Testis weights in homozygous males lacking the FSHbeta gene or the ActRIIA gene were decreased approximately 60% compared with wild-type or respective heterozygotes. Sertoli cell numbers decreased in both homozygous mice by 30-39%, and there was a comparable decline in germ cell numbers in both models. The degree of germ cell attrition increased in the later stages of spermatogenesis from a 46% reduction of spermatogonia to a 60% decrease in round spermatids. As the FSH levels are decreased in both models, the cellular lesion in both is most likely due to the FSH deficiency. Although the decrease in the Sertoli cell complement represents one cause of lower germ cell numbers, the ability of Sertoli cells to nurture germ cells is compromised by the lower FSH levels, as shown by a decrease in the round spermatid to Sertoli cell ratios in both homozygous models. We conclude that the defects in FSH beta-subunit gene knockout and ActRIIA knockout mice are related to diminished FSH action on both Sertoli cell proliferation and the capacity of Sertoli cells to nurture germ cells.     

Alterations in spermatogenic activity and hormonal status in a seasonally breeding rat,Rattus fuscipes

The changes in the levels of serum FSH, LH, and testosterone have been studied during the seasonal reproductive cycle in males of the species Rattus fuscipes. In males captured in winter the seminiferous tubules were small, spermatogenesis was arrested at the primary spermatocyte stage, and the Sertoli cells contained increased numbers of lipid inclusions. The Leydig cells were atrophic and contained large crystalloids. The aspermatic state was accompanied by low levels of serum FSH, LH, and androgen. Reactivation of spermatogenesis occurred in spring and was accompanied by a rise in the levels of FSH, LH, and androgen. These hormonal changes were associated with a depletion of lipid inclusions from the Sertoli cells which paralleled the activation of spermatogenesis. The rising androgen levels were accompanied by the enlargement of Leydig cells and the disappearance of the crystalloids. In summer the fully active testes were associated with further increments of serum FSH and androgen levels above those seen during spring. It is concluded that the environmental cues controlling the seasonal reproductive cycle exert their influence on the testis through changes in gonadotrophin secretion by the pituitary gland.     

Effects of a single injection of a new depot formulation of an LH-releasing hormone agonist on spermatogenesis in adult rats

Adult male Wistar rats were treated with a single injection (500 micrograms s.c.) of a new biodegradable depot formulation of the LH-releasing hormone (LHRH) analogue [D-Ser(But)6]AzGly10-LH-RH (Zoladex; ICI 118,630) to evaluate its potential for inhibiting spermatogenesis. The drug produced a marked (P less than or equal to 0.05) decrease in serum concentrations of FSH, LH and testosterone with a maximum effect 14 days after treatment. Since striking focal histological changes were seen in the testis after only 1 week, at a time when changes in serum gonadotrophins were minimal, there may be a direct effect of the LHRH analogue on spermatogenesis. Degenerative changes in germ cells as well as Sertoli cells could be observed. Flow-cytometric analysis of testicular cell suspensions showed a significant decline in the absolute numbers of haploid cells (spermatids), tetraploid cells (mainly pachytene spermatocytes) and of the numbers of cells in the S-phase of the cell cycle. This suggests that the drug also inhibits proliferation of spermatogonia and/or primary spermatocytes. Testis weight, serum hormone concentrations, and histological and cytological parameters returned to essentially normal values 52 days after the injection. It is concluded that this new method of administration may have practical and pharmacokinetic advantages for the purpose of reversible inhibition of spermatogenesis.     

Effects of an early postnatal treatment of hypogonadotropic hypogonadism with a continuous subcutaneous infusion of recombinant follicle-stimulating hormone and luteinizing hormone

BACKGROUND: The neonatal-midinfancy surge in pulsatile gonadotropin secretion is attributable to an increase in GnRH pulse amplitude and is associated with a rapid expansion of Leydig and Sertoli cell populations with concomitant surges in testosterone, inhibin, and anti-Mullerian hormone production as well as an increase in testicular volume. Boys with congenital hypogonadotropic hypogonadism (HH) do not activate these processes. A potential cause for azoospermia and infertility in adult life is deficient proliferation of immature Sertoli cells before and during puberty due to the absence of FSH. OBJECTIVE: The objective of the study was to investigate whether early postnatal continuous sc infusion of gonadotropins could mimic the physiological growth of testes and to evaluate responses of the Leydig and Sertoli cells to early gonadotropin replacement. DESIGN AND METHODS: Two neonates (P1 with hypotuitarism and P2 with HH) with micropenis and microorchidism were treated for 6 months with high doses of recombinant LH and FSH (a gift of Luveris and Gonal-F from Serono, Lyon, France) delivered sc with an insulin pump. RESULTS: Gonadotropin continuous sc infusion increased mean serum LH and FSH to normal or supranormal levels. Mean testosterone increased from undetectable levels to 7.6 and 5.2 nmol/liter, respectively, in P1 and P2. Inhibin B and anti-Müllerian hormone increased to normal levels. Mean testicular volume increased from 0.45 to 0.57 ml at birth to 2.10 ml at 7 months. Stretched penile length increased from 8 to 30 mm (P1) and 12 to 48 mm (P2). CONCLUSIONS: The present regimen induced physiological postnatal testes growth and high-normal activation of Leydig and Sertoli cells.