Effects of growth hormone on testicular dysfunction induced by cyclophosphamide (CP) in GH-deficient rats

Alkylating agents-induced gonadotoxicity in prepubertal males: Insights on the clinical and preclinical front

Rising cure rates in pediatric cancer patients warrants an increased attention toward the long-term consequences of the diagnosis and treatment in survivors. Chemotherapeutic agents can be gonadotoxic, rendering them at risk for infertility post-survival. While semen cryopreservation is an option that can be provided for most (post)pubertal boys before treatment, this is unfortunately not an option prepubertal in age, simply due to the lack of spermatogenesis. Over the last couple of years, studies have thus focused on better understanding the testis niche in response to various chemotherapeutic agents that are commonly administered and their direct and indirect impact on the germ cell populations. These are generally compounds that have a high risk of infertility and have been classified into risk categories in curated fertility guidelines. However, with it comes the lack of evidence and the challenge of using informative models and conditions most reflective of the physiological scenario, in short, the appropriate study designs for clinically relevant outcomes. Besides, the exact mechanism(s) of action for many of these "risk" compounds as well as other agents is unclear. Understanding their behavior and effect on the testis niche will pave the way for incorporating new strategies to ultimately combat infertility. Of the various drug classes, alkylating agents pose the highest risk of gonadotoxicity as per previously established studies as well as risk stratification guidelines. Therefore, this review will summarize the findings in the field of male fertility concerning gonadotoxicity of akylating agents as a result of chemotherapy exposure.

Study on the Reparative Effect of PEGylated Growth Hormone on Ovarian Parameters and Mitochondrial Function of Oocytes From Rats With Premature Ovarian Insufficiency

Premature ovarian insufficiency (POI) is a heterogeneous disorder and lacks effective interventions in clinical applications. This research aimed to elucidate the potential effects of recombinant human PEGylated growth hormone (rhGH) on follicular development and mitochondrial function in oocytes as well as ovarian parameters in POI rats induced by the chemotherapeutic agent. The impacts of rhGH on ovarian function before superovulation on follicles, estrous cycle, and sex hormones were evaluated. Oocytes were retrieved to determine oocyte quality and oxidative stress parameters. Single-cell sequencing was applied to investigate the latent regulatory network. This study provides new evidence that a high dosage of rhGH increased the number of retrieved oocytes even though it did not completely restore the disturbed estrous cycle and sex hormones. rhGH attenuated the apoptosis of granulosa cells and oxidative stress response caused by reactive oxygen species (ROS) and mitochondrial superoxide. Additionally, rhGH modulated the energy metabolism of oocytes concerning the mitochondrial membrane potential and ATP content but not mtDNA copy numbers. Based on single-cell transcriptomic analysis, we found that rhGH directly or indirectly promoted the balance of oxidative stress and cellular oxidant detoxification. Four hub genes, Pxmp4, Ehbp1, Mt-cyb, and Enpp6, were identified to be closely related to the repair process in oocytes as potential targets for POI treatment.

Ameliorative Effects of Aquilaria malaccensis Leaves Aqueous Extract on Reproductive Toxicity Induced by Cyclophosphamide in Male Rats

Background

Cyclophosphamide (CP) is a widely used anti-neoplastic and immunosuppressive agent that is associated with adverse side effects including reproductive toxicity. Aquilaria malaccensis (AM) is a traditional medicinal plant which was reported to exhibit high anti-oxidant and free radical scavenging properties. The present study was aimed to evaluate the protective effects of AM leaves extract on sperm quality following toxic exposure to CP.

Methods

Forty-eight male Sprague Dawley rats were allocated into eight groups of six rats (n = 6): control, CP only (200 mg kg⁻¹), AM only (100 mg kg⁻¹, 300 mg kg⁻¹ and 500 mg kg⁻¹) and CP + AM (100 mg kg⁻¹, 300 mg kg⁻¹ and 500 mg kg⁻¹). Animals were sacrificed after 63 days of treatment and the sperm from the caudal epididymis was taken for sperm analysis.

Results

The body and the reproductive organs weight, sperm count and motility did not differ between CP and other groups (P > 0.05). A significant increase (P < 0.05) in percentage of the dead and abnormal sperm were seen in the CP alone treated group compared to the control group. Co-administration of AM to the CP exposed rats significantly reduced the (P < 0.05) percentage of abnormal sperm as compared to the CP only group.

Conclusion

Overall, the present results represent the potential of AM to protect against CP induced reproductive toxicity.

Growth Hormone and Insulin-Like Growth Factor Action in Reproductive Tissues

The role of growth hormone (GH) in human fertility is widely debated with some studies demonstrating improvements in oocyte yield, enhanced embryo quality, and in some cases increased live births with concomitant decreases in miscarriage rates. However, the basic biological mechanisms leading to these clinical differences are not well-understood. GH and the closely-related insulin-like growth factor (IGF) promote body growth and development via action on key metabolic organs including the liver, skeletal muscle, and bone. In addition, their expression and that of their complementary receptors have also been detected in various reproductive tissues including the oocyte, granulosa, and testicular cells. Therefore, the GH/IGF axis may directly regulate female and male gamete development, their quality, and ultimately competence for implantation. The ability of GH and IGF to modulate key signal transduction pathways such as the MAP kinase/ERK, Jak/STAT, and the PI3K/Akt pathway along with the subsequent effects on cell division and steroidogenesis indicates that these growth factors are centrally located to alter cell fate during proliferation and survival. In this review, we will explore the function of GH and IGF in regulating normal ovarian and testicular physiology, while also investigating the effects on cell signal transduction pathways with subsequent changes in cell proliferation and steroidogenesis. The aim is to clarify the role of GH in human fertility from a molecular and biochemical point of view.

The Effects of Local and Systemic Growth Hormone Treatment on Germ Cell Population and Fertility in an Experimental Unilateral Testicular Torsion and Orchiectomy Model

PURPOSE

We evaluated the effects of local and systemic growth hormone on the germ cell population of the contralateral testes of pubertal rats subjected to unilateral testicular torsion and orchiectomy 24 hours later.

MATERIALS AND METHODS

A total of 40 male Wistar-Albino rats at age 3 weeks were divided into 5 groups. In the sham operated group the right testis was sutured and orchiectomy was performed 24 hours later. In groups 2 to 5 orchiectomy was performed 24 hours later following testicular torsion. In groups 3 and 4 unloaded and growth hormone loaded gelatin films, respectively, were sutured on the contralateral testes. In group 5 systemic growth hormone was administered for 7 days. Five weeks later each rat was cohabited with 2 female rats and the left testes were removed for evaluation. Mean seminiferous tubular diameter, mean testicular biopsy score and the mean haploid cell percentage were calculated. Mating studies were performed and fertility parameters were assayed.

RESULTS

Mean seminiferous tubular diameter, mean testicular biopsy score and the mean haploid cell percentage of the contralateral testes were significantly decreased in the control and gelatin groups compared with the other groups. There was no difference between the local and systemic growth hormone groups regarding the haploid cell percentage. There were no differences between the groups in mean fetus numbers, mating or fertility and fecundity indexes except in the gelatin group, in which the mean fetus number was significantly lower.

CONCLUSIONS

Fertility is not affected in rats after 24 hours of testicular torsion and orchiectomy, although there is germ cell injury and a decrease in the percent of haploid cells. Growth hormone administration resulted in the restoration of germ cell histology and an increase in the haploid cell percentage of the contralateral testes. Growth hormone may improve fertility after unilateral testicular torsion and orchiectomy.

Growth hormone and reproduction: a review of endocrine and autocrine/paracrine interactions

The somatotropic axis, consisting of growth hormone (GH), hepatic insulin-like growth factor I (IGF-I), and assorted releasing factors, regulates growth and body composition. Axiomatically, since optimal body composition enhances reproductive function, general somatic actions of GH modulate reproductive function. A growing body of evidence supports the hypothesis that GH also modulates reproduction directly, exerting both gonadotropin-dependent and gonadotropin-independent actions in both males and females. Moreover, recent studies indicate GH produced within reproductive tissues differs from pituitary GH in terms of secretion and action. Accordingly, GH is increasingly used as a fertility adjunct in males and females, both humans and nonhumans. This review reconsiders reproductive actions of GH in vertebrates in respect to these new conceptual developments.

Antiperoxidative and anti-apoptotic effects of lycopene and ellagic acid on cyclophosphamide-induced testicular lipid peroxidation and apoptosis

The present study was conducted to investigate the possible protective effects of lycopene (LC) and ellagic acid (EA) on cyclophosphamide (CP)-induced testicular and spermatozoal toxicity associated with the oxidative stress and apoptosis in male rats. Forty-eight healthy adult male Sprague-Dawley rats were divided into six groups of eight rats each. The control group was treated with placebo; the LC, EA and CP groups were given LC (10 mg kg–1), EA (2 mg kg–1) and CP (15 mg kg–1), respectively, alone; the CP+LC group was treated with a combination of CP (15 mg kg–1) and LC (10 mg kg–1); and the CP+EA group was treated with a combination of CP (15 mg kg–1) and EA (2 mg kg–1). All treatments were maintained for 8 weeks. At the end of the treatment period, bodyweight and the weight of the reproductive organs, sperm concentration and motility, testicular tissue lipid peroxidation, anti-oxidant enzyme activity and apoptosis (i.e. Bax and Bcl-2 proteins) were determined. Administration of CP resulted in significant decreases in epididymal sperm concentration and motility and significant increases in malondialdehyde levels. Although CP significantly increased the number of Bax-positive (apoptotic) cells, it had no effect on the number of Bcl-2-positive (anti-apoptotic) cells compared with the control group. However, combined treatment of rats with LC or EA in addition to CP prevented the development of CP-induced lipid peroxidation and sperm and testicular damage. In conclusion, CP-induced lipid peroxidation leads to structural and functional damage, as well as apoptosis, in spermatogenic cells of rats. Both LC and EA protect against the development of these detrimental effects.

Maternal Exposure of Low Dose of TCDD Modulates the Expression of Estrogen Receptor Subunits of Male Gonads in Offspring

We have analyzed the effects of low-dose transplacental and lactational exposure of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) on gene expression relating to the dioxin and sexual hormone cascade, and demonstrated the effects on testicular growth and sexual maturation in male offspring rats. TCDD (10 ng/kg) was administered to dams on Days 7 and 14 of gestation, and on Days 0, 7 and 14 after delivery. Gene expression of cytochrome P450 family 1 subfamily A polypeptide 1 (CYP1A1) in the liver of 17-day-old rats was significantly increased compared with controls. Furthermore, expression of estrogen receptors (ER)alpha and ERbeta was significantly increased at 17 and 42 days old, respectively in the testis of TCDD-administered rats compared with controls. Although testicular weight and the seminiferous tubule diameter were increased in 17-day-old rats, there was no difference in the number of germ cells between TCDD-treated and control animals. The expressions of androgen receptor and inhibin subunit genes were not significantly changed. These findings suggest that low-dose exposure of TCDD leads to unusual development of the testis by perturbation of steroid hormone homeostasis.