Absence of effect of recombinant growth hormone to classic gonadotropin treatment on spermatogenesis of patients with severe hypogonadotropic hypogonadism

Effects of Growth Hormone on Adult Human Gonads: Action on Reproduction and Sexual Function

Growth hormone (GH), which is commonly considered to be a promoter of growth and development, has direct and indirect effects on adult gonads that influence reproduction and sexual function of humans and nonhumans. GH receptors are expressed in adult gonads in some species including humans. For males, GH can improve the sensitivity of gonadotropins, contribute to testicular steroidogenesis, influence spermatogenesis possibly, and regulate erectile function. For females, GH can modulate ovarian steroidogenesis and ovarian angiogenesis, promote the development of ovarian cells, enhance the metabolism and proliferation of endometrial cells, and ameliorate female sexual function. Insulin-like growth factor-1 (IGF-1) is the main mediator of GH. In vivo, a number of the physiological effects of GH are mediated by GH-induced hepatic IGF-1 and local IGF-1. In this review, we highlight the roles of GH and IGF-1 in adult human gonads, clarify potential mechanisms, and explore the efficacy and the risk of GH supplementation in associated deficiency and assisted reproductive technologies. Besides, the effects of excess GH on adult human gonads are discussed as well.

Growth Hormone Is Beneficial for Induction of Spermatogenesis in Adult Patients With Congenital Combined Pituitary Hormone Deficiency

BACKGROUND

Gonadotropins are effective in inducing spermatogenesis in patients with congenital combined pituitary hormone deficiency (CCPHD). Data on recombinant human growth hormone(rhGH) adjuvant treatment to improve gonadotropin-induced spermatogenesis are limited.

DESIGN AND SETTING

This retrospective study included 60 male patients with CCPHD on a relatively large case series in a single center from mainland China. Twenty-nine patients who received gonadotropin therapy alone were defined as the Gn group, while 31 patients treated with a combination of rhGH and gonadotropins were defined as GH/Gn group.

RESULTS

Spermatogenesis rate was 96.77% (30/31) and 62.07% (18/29) in the GH/Gn and Gn group, respectively (P < 0.001). The time for initial sperm appearance in the GH/Gn group was shorter than in the Gn group (14 versus 23 months, P < 0.001). A higher level of serum testosterone was achieved in the GH/Gn group than in the Gn group (4.79 versus 3.38 ng/mL, P = 0.026). After adjustment for potential confounders, rhGH supplementation was an independent beneficial factor on spermatogenesis (HR = 2.294, 95% CI: 1.143-4.604, P = 0.019).

CONCLUSIONS

rhGH induces earlier spermatogenesis in patients with CCPHD, which encourages the co-treatment with rhGH and gonadotropins in CCPHD patients.

GH Deficiency and Replacement Therapy in Hypopituitarism: Insight Into the Relationships With Other Hypothalamic-Pituitary Axes

GH deficiency (GHD) in adult patients is a complex condition, mainly due to organic lesion of hypothalamic-pituitary region and often associated with multiple pituitary hormone deficiencies (MPHD). The relationships between the GH/IGF-I system and other hypothalamic-pituitary axes are complicated and not yet fully clarified. Many reports have shown a bidirectional interplay both at a central and at a peripheral level. Signs and symptoms of other pituitary deficiencies often overlap and confuse with those due to GH deficiency. Furthermore, a condition of untreated GHD may mask concomitant pituitary deficiencies, mainly central hypothyroidism and hypoadrenalism. In this setting, the diagnosis could be delayed and possible only after recombinant human Growth Hormone (rhGH) replacement. Since inappropriate replacement of other pituitary hormones may exacerbate many manifestations of GHD, a correct diagnosis is crucial. This paper will focus on the main studies aimed to clarify the effects of GHD and rhGH replacement on other pituitary axes. Elucidating the possible contexts in which GHD may develop and examining the proposed mechanisms at the basis of interactions between the GH/IGF-I system and other axes, we will focus on the importance of a correct diagnosis to avoid possible pitfalls.

Desmopressin Suppresses Gonadotropin-Induced Spermatogenesis in Patients With Pituitary Stalk Interruption Syndrome: A Retrospective, Single-Center Cohort Study

OBJECTIVE

To explore the influence of desmopressin on gonadotropin-induced spermatogenesis in patients with pituitary stalk interruption syndrome (PSIS).

METHODS

A single-center retrospective cohort study was conducted. All patients with PSIS had both gonadotropin and growth hormone (GH) deficiency. Patients were divided into desmopressin and nondesmopressin groups. The desmopressin and nondesmopressin groups were defined by the presence or absence of central diabetes insipidus, which determined whether the patient received desmopressin or not.

RESULTS

The average age of gonadotropin therapy was 24.3 and 26.1 in the desmopressin and nondesmopressin groups, respectively. The rate of successful spermatogenesis in the 2 groups was 31.58% and 77.27%, respectively. The period for first sperm appearance was 13.62 ± 5.95 and 13.48 ± 6.69 months, respectively. A multivariable Cox proportional hazards model found that the adjusted hazard ratio for desmopressin was 0.260, indicating a "possible" detrimental effect of desmopressin on spermatogenesis. Central diabetes insipidus would be expected to show a similar detrimental effect. The spermatogenesis rate decreased with increased dosage of desmopressin. In the nondesmopressin group, the rate of spermatogenesis was similar between the GH group and the non-GH subgroup. The GH group had higher sperm count and concentration than the non-GH group.

CONCLUSION

A minority of patients with PSIS had mild diabetes insipidus and received desmopressin therapy. The spermatogenesis rate decreased with increasing desmopressin dosage. In addition, GH supplementation did not affect the spermatogenesis rate.

Somatotropic-Testicular Axis: A crosstalk between GH/IGF-I and gonadal hormones during development, transition, and adult age

BACKGROUND

The hypothalamic-pituitary-gonadal (HPG) and hypothalamic-pituitary-somatotropic (HPS) axes are strongly interconnected. Interactions between these axes are complex and poorly understood. These interactions are characterized by redundancies in reciprocal influences at each level of regulation and the combination of endocrine and paracrine effects that change during development.

OBJECTIVES

To comprehensively review the crosstalk between the HPG and HPS axes and related pathological and clinical aspects during various life stages of male subjects.

MATERIALS AND METHODS

A thorough search of publications available in PubMed was performed using proper keywords.

RESULTS

Molecular studies confirmed the expressions of growth hormone (GH) and insulin-like growth factor-I (IGF-I) receptors on the HPG axis and reproductive organs, indicating a possible interaction between HPS and HPG axes at various levels. Insulin growth factors participate in sexual differentiation during fetal development, indicating that normal HPS axis activity is required for proper testicular development. IGF-I contributes to correct testicular position during minipuberty, determines linear growth during childhood, and promotes puberty onset and pace through gonadotropin-releasing hormone activation. IGF-I levels are high during transition age, even when linear growth is almost complete, suggesting its role in reproductive tract maturation. Patients with GH deficiency (GHD) and insensitivity (GHI) exhibit delayed puberty and impaired genital development; replacement therapy in such patients induces proper pubertal development. In adults, few studies have suggested that lower IGF-I levels are associated with impaired sperm parameters.

DISCUSSION AND CONCLUSION

The role of GH-IGF-I in testicular development remains largely unexplored. However, it is important to evaluate gonadic development in children with GHD. Additionally, HPS axis function should be evaluated in children with urogenital malformation or gonadal development alterations. Correct diagnosis and prompt therapeutic intervention are needed for healthy puberty, attainment of complete gonadal development during transition age, and fertility potential in adulthood.

The treatment effect of novel hGHRH homodimer to male infertility hamster

Extra-hypothalamic growth hormone-releasing hormone (GHRH) plays an important role in reproduction. To study the treatment effect of Grin (a novel hGHRH homodimer), the infertility models of 85 male Chinese hamsters were established by intraperitoneally injecting 20 mg/kg of cyclophosphamide once in a week for 5 weeks and the treatment with Grin or human menopausal gonadotropin (hMG) as positive control was evaluated by performing a 3-week mating experiment. 2-8 mg/kg of Grin and 200 U/kg of hMG showed similar effect and different pathological characteristics. Compared to the single cyclophosphamide group (0%), the pregnancy rates (H-, M-, L-Grin 26.7, 30.8, 31.3%, and hMG 31.3%) showed significant difference, but there was no difference between the hMG and Grin groups. The single cyclophosphamide group presented loose tubules with pathologic vacuoles and significant TUNEL positive cells. Grin induced less weight of body or testis, compactly aligned tubules with little intra-lumens, whereas hMG caused more weight of body or testis, enlarging tubules with annular clearance. Grin presented a dose-dependent manner or cell differentiation-dependentincrease in testicular GHRH receptor, and did not impact the levels of blood and testicular GH, testosterone. Grin promotes fertility by proliferating and differentiating primitive cells through up-regulating testicular GHRH receptor without triggering GH secretion, which might solve the etiology of oligoasthenozoospermia.

Effects of the insulin-like growth factor system on testicular differentiation and function: a review of the literature

We recently described the occurrence of cryptorchidism, oligoasthenoteratozoospermia, and genital abnormalities in patients with distal 15q chromosome structural abnormalities. This observation brought us to hypothesize that insulin-like growth factor (IGF) receptor (IGF1R), mapping on the 15q 26.3 chromosomal band, may be involved in testicular function. To further evaluate this topic, we reviewed in vitro and in vivo studies exploring the role of the IGF system [IGF1, IGF2, IGF1R, insulin receptor substrates (IRS)] at the testicular level both in animals and in humans. In animals, IGF1/IGF1R has been found to be involved in testicular development during embryogenesis, in Sertoli cell (SC) proliferation, and in germ cell (GS) proliferation and differentiation. Interestingly, IGF1R seems to mediate follicle-stimulating hormone (FSH) effects through the PI3K/AKT pathway. In humans, IGF1 directly increases testicular volume. The molecular pathways responsible for testicular differentiation and IGF1/IGF1R signaling are highly conserved among species; therefore, the IGF system may be involved in FSH signaling also in humans. We suggest a possible molecular pathway occurring in human SCs, which involves both IGF1 and FSH through the PI3K/AKT pathway. The acknowledgment of an IGF1 mediation of the FSH-induced effects may open new ways for a targeted therapy in idiopathic non-FSH-responder oligoasthenoteratozoospermia.

Congenital combined pituitary hormone deficiency patients have better responses to gonadotrophin-induced spermatogenesis than idiopathic hypogonadotropic hypogonadism patients

STUDY QUESTION

Do patients with congenital combined pituitary hormone deficiency (CCPHD) have different responses to gonadotrophin-induced spermatogenesis compared with those with idiopathic hypogonadotropic hypogonadism (IHH)?

SUMMARY ANSWER

CCPHD patients have a better response to gonadotrophin therapy than IHH patients.

WHAT IS KNOWN ALREADY

Gonadotrophins are effective in inducing spermatogenesis in patients with hypogonadotropic hypogonadism.

DESIGN, SIZE AND DURATION

This retrospective cohort study included 75 patients, 53 of whom had IHH and 22 CCPHD. They were diagnosed, treated and followed up between January 2008 and December 2013.

PARTICIPANTS/MATERIALS, SETTING AND METHODS

Combined gonadotrophin therapy, consisting of human chorionic gonadotrophin and human menopausal gonadotrophin, was administered for 24 months. The success rate of spermatogenesis (≥1 sperm in ejaculate), serum total testosterone level, testicle size and sperm concentration during the treatment, as well as the first time sperm were detected in the ejaculate, were compared between the two diagnostic groups. All patients were treated in Peking Union Medical College Hospital.

MAIN RESULTS AND THE ROLE OF CHANCE

Spermatogenesis was successfully induced in 85% of IHH patients and 100% of CCPHD patients after 24-month combined gonadotrophin treatment (P = 0.03). In comparison with IHH, CCPHD patients had larger mean testicle sizes during the gonadotrophin treatment at 6, 12, 18 and 24 months (all P < 0.05). The initial time for sperm appearance in IHH group (n = 45) and CCPHD group (n = 22) was 13.2 ± 5.9 versus 10.4 ± 3.8 months (P = 0.045). Generally, CCPHD patients had higher sperm counts [median (quartiles)] than IHH patients during the treatment, but the difference was only statistically significant at 12 months of treatment, 3.3 (1.8, 12.0) versus 1.0 (0.0, 4.6) million/ml, P = 0.001. There was a higher level of serum total testosterone [mean (SD)] in the CCPHD group than the IHH group (676 ± 245 versus 555 ± 209 ng/dl, P = 0.035).

LIMITATIONS, REASONS FOR CAUTION

First, the inherent nature of a retrospective designed study was a main shortcoming. Secondly, pathological gene mutations in IHH and CCPHD patients should be further investigated. Clarification of the underlying mechanisms between cryptorchidism and mutated genes may provide more information for the divergent therapeutic responses between two groups. Only a minority of patients were actively seeking to have children so information about fertility is limited.

WIDER IMPLICATIONS OF THE FINDINGS

CCPHD patients had a lower incidence of cryptorchidism and a better response to gonadotrophin therapy than IHH patients, reflecting multiple defects on the different levels of reproduction axis in IHH. Furthermore, growth hormone is not indispensable for spermatogenesis in CCPHD patients.

STUDY FUNDING/COMPETING INTERESTS

The study was supported by Natural Science Foundation of China (No: 81100416). None of the authors has any conflicts of interest to declare.

Factors affecting spermatogenesis upon gonadotropin-replacement therapy: a meta-analytic study

A meta-analysis was performed to systematically analyse the results of gonadotropin and GnRH therapy in inducing spermatogenesis in subjects with hypogonadotropic hypogonadism (HHG) and azoospermia. An extensive Medline and Embase search was performed including the following words: 'gonadotropins' or 'GnRH', 'infertility', 'hypogonadotropic', 'hypogonadism' and limited to studies in male humans. Overall, 44 and 16 studies were retrieved for gonadotropin and GnRH therapy, respectively. Of those, 43 and 16 considered the appearance of at least one spermatozoa in semen, whereas 26 and 10 considered sperm concentration upon gonadotropin and GnRH, respectively. The combination of the study results showed an overall success rate of 75% (69-81) and 75% (60-85) in achieving spermatogenesis, with a mean sperm concentration obtained of 5.92 (4.72-7.13) and 4.27 (1.80-6.74) million/mL for gonadotropin and GnRH therapy, respectively. The results upon gonadotropin were significantly worse in studies involving only subjects with a pre-pubertal onset HHG, as compared with studies involving a mixed population of pre- and post-pubertal onset [68% (58-77) vs. 84% (76-89), p = 0.011 and 3.37 (2.25-4.49) vs. 12.94 (8.00-17.88) million/mL, p < 0.0001; for dichotomous and continuous data, respectively]. A similar effect was observed also upon GnRH. No difference in terms of successful achievement of spermatogenesis and sperm concentration was found for different FSH preparations. Previous use of testosterone replacement therapy (TRT) did not affect the results obtained with gonadotropins. Finally, a higher success rate was found for subjects with lower levels of gonadotropins at the baseline and for those using both human chorionic gonadotropin and FSH. Gonadotropin therapy, even with urinary derivatives, is a suitable option in inducing/restoring fertility in azoospermic HHG subjects. Gonadotropins appear to be more efficacious in subjects with a pure secondary nature (low gonadotropins) and a post-pubertal onset of the disorder, whereas previous TRT does not affect outcome.

Association between GH receptor polymorphism (exon 3 deletion), serum IGF1, semen quality, and reproductive hormone levels in 838 healthy young men

INTRODUCTION

GH activity may be involved in male reproductive function. A common genetic polymorphism in the gene encoding the GH receptor (GHR) results in deletion of the entire exon 3 sequence (GHRd3 isoform). The short GHRd3/d3 isoform seems more sensitive compared with full-length receptors (GHRfl/fl).

AIM

TO INVESTIGATE THE ASSOCIATIONS BETWEEN GH ACTIVITY, EVALUATED BY EXON 3 GHR POLYMORPHISM, AND SERUM IGF1 VS REPRODUCTIVE HORMONES, SEMEN QUALITY, AND PRE- AND POSTNATAL GROWTH IN HEALTHY YOUNG MALES (N=838, MEAN AGE: 19.4 years).

RESULTS

Compared with GHRfl/fl homozygous individuals (n=467) GHRd3/d3 homozygous individuals (n=69) tended to have larger semen volume (3.2 (2.4-4.3) vs 3.6 (2.6-4.7) ml, P=0.053) and higher serum inhibin-B levels (208 pg/ml (158-257) vs 227 pg/ml (185-264), P=0.050). Semen quality, levels of gonadotropins, testosterone, estradiol, sex hormone-binding globulin, and IGF1 were not associated with GHRd3 genotype. A twofold increase in serum IGF1 was associated with a 13% (4-23) increase in calculated free testosterone (P=0.004). By contrast IGF1 was inversely associated with serum inhibin-B (P=0.027), but showed no associations to semen quality. GHR genotype and serum IGF1 were not associated with size at birth or final height.

CONCLUSIONS

GHRd3 polymorphism seemed only to have a weak influence on male reproductive function of borderline significance. The sensitive GHRd3/d3 genotype may slightly increase testicular function, as evaluated by semen volume and levels of inhibin-B, but does not seem to influence Leydig cell steroidogenesis. GHR genotype did not influence pre- and postnatal growth.

Hormonal control of inhibin B in men

Serum inhibin B (IB) and testosterone (T) levels, secreted by Sertoli cells (SC) and Leydig cells (LC), respectively, are parameters of the functional state of these cells. Whereas LC activity and, consequently, T secretion are regulated by serum LH, factors regulating IB secretion by SC are still partially unknown. There is evidence that under certain conditions such as puberty, aging or some spermatogenesis defects, LH levels or Gn-independent factors might contribute to regulating SC activity and IB secretion. Among these factors, GH and IGF-I as well as PRL might have a role. Therefore, in order to explore the possible effects of either LH alone and FSH alone or a combination of both Gn, respectively, on SC function, IB plasma levels and spermatogenesis, we studied their effects in 6 patients with hypogonadotropic hypogonadism (HH), whereas the effects of GH on these parameters were studied in 6 men with panhypopituitarism (PH). Finally, the possible effects of PRL on SC function and spermatogenesis were studied in 6 patients with hyperprolactinemia (HPRL); 24 normal, fertile adults served as control group. In men with HH, neither human chorionic Gn (hCG) nor FSH, respectively, were able to increase serum IB after 3 months of therapy, whereas combined Gn therapy for 24 months increased IB plasma levels and stimulated spermatogenesis in 4 out of 6 hypogonadal men. In panhypopituitaric men, GH added to the classical Gn therapy did not have an additional effect on serum IB levels or spermatogenesis. Surprisingly, in our hyperprolactemic men, IB plasma levels were increased and positively correlated (p<0.01) with serum PRL levels, whereas normalization of the latter by cabergoline treatment caused a decrease of IB levels and a moderate increase in T, LH and FSH. In conclusion, the lack of SC response to FSH therapy alone, as opposed to the response to combined Gn therapy, might indicate that normalization of serum T by hCG is required to obtain IB secretion by SC. Addition of GH did not affect SC function, serum IB levels or spermatogenesis. Finally, our data suggest that PRL plasma levels might have a direct role on IB secretion, suggesting that the hypogonadism found in patients with HPRL might be a consequence of both central (inhibition of Gn secretion) and peripheral (stimulation of IB secretion) origin.

Growth hormone: roles in male reproduction

Growth hormone (GH), as its name suggests, is obligatory for growth and development. It is, however, also required for sexual differentiation and pubertal maturation and participates in gonadal steroidogenesis and gametogenesis. These roles are likely to reflect the endocrine actions of pituitary GH, directly at gonadal sites and indirectly via hepatic insulin-like growth factor-1. However, because GH is also produced in gonadal tissues, it may act in paracrine or autocrine ways to regulate local processes that are strategically regulated by pituitary GH. The concept that GH is a major regulator of male reproduction is the focus of this review.