Effect of ghrelin on the biochemical and histopathology parameters and spermatogenesis cycle following experimental varicocele in rat

Leptin promotes proliferation of human undifferentiated spermatogonia by activating the PI3K/AKT/mTOR pathway

BACKGROUND

Male infertility is a common disease affecting male reproductive health. Leptin is an important hormone that regulates various physiological processes, including reproductive function. However, few experimental studies have been carried out to elucidate the mechanism of leptin's effects on male reproductive function.

OBJECTIVE

The purpose of this study was to investigate the effects of leptin on testicular spermatogenesis and its mechanism, so as to provide potential targets for the treatment of patients with spermatogenic dysfunction.

METHODS

Testicular tissues were collected from eight prostate cancer patients undergoing surgical castration. GPR125-positive spermatogonia were isolated by two consecutive magnetic activated cell sorting (MACS), followed by incubation with conditioned medium. To identify the signaling pathway(s) involved in the effects of leptin, undifferentiated spermatogonia were treated with different concentrations of leptin and antagonists of leptin-related pathways. The proliferative effect of leptin was evaluated by cell counting using a hemocytometer. Expressions of p-AKT, p-ERK, p-STAT, and p-S6K were determined by western blotting analysis.

RESULTS

Leptin promoted the growth of human GPR125-positive spermatogonia in a concentration-dependent manner. The most significant proliferative effect was observed using 100 ng/mL leptin after 6 days of culture. Leptin significantly increased the phosphorylation of STAT3, AKT, and ERK in undifferentiated spermatogonia. Phosphatidylinositol 3-kinase (PI3K) inhibitor LY294002 inhibited the leptin-induced activation of AKT, ERK, and downstream S6K. Treatment with the mammalian target of rapamycin (mTOR) inhibitor rapamycin also inhibited S6K phosphorylation. Moreover, both LY294002 and rapamycin were found to inhibit the leptin-induced proliferation of undifferentiated spermatogonia. These results suggested that the leptin-induced proliferation of GPR125-positive spermatogonia was dependent on the PI3K/AKT/mTOR pathway. Further exploration of proliferation and apoptotic markers suggested that leptin may alleviate cell apoptosis by regulating the expression of Bax and FasL.

CONCLUSIONS

A certain concentration of leptin (25∼100 ng/mL) could promote proliferation of undifferentiated spermatogonia, which was mediated by PI3K/AKT/mTOR pathway.

Acylated ghrelin suppresses doxorubicin-induced testicular damage and improves sperm parameters in rats via activation of Nrf2 and mammalian target of rapamycin

Background

Exogenous administration of acylated ghrelin (AG) afforded reproductive protective effect in several animal models but not in those treated with doxorubicin (DOX). This study evaluated the protective effect of AG against DOX-induced testicular damage and impairment in sperm parameters in rats and examined the potential mechanisms of action.

Materials and Methods

Adult male rats were divided into five groups (n = 8/each) as control, control + AG (40 nmol/kg/day; subcutaneous), DOX (10 mg/kg/day 1; intraperitoneal [i.p.]), DOX + AG, and DOX + AG + brusatol (an Nrf2 inhibitor) (2 mg/kg/every 3 days; i.p.). The treatment regimen continued for 65 days.

Results

AG prevented testicular damage and apoptosis; increased sperm count, motility, and viability; and reduced the number of abnormal sperms. It also increased their circulatory levels of AG, des-acylated ghrelin (DAG), and AG/DAG ratio and the testicular mRNA levels of ghrelin and growth hormone secretagogue receptor 1a Concomitantly, AG increased serum and testicular testosterone levels, reduced serum levels of the follicle-stimulating hormone and luteinizing hormone, and upregulated the testicular protein levels of the steroidogenic acute regulatory protein and 3β-hydroxysteroid dehydrogenase in DOX-treated rats. In the testes of the control and DOX-treated rats, AG increased the phosphorylation of mammalian target of rapamycin and stimulated the levels of glutathione and superoxide dismutase, as well as the nuclear activation of Nrf2. All these effects were completely prevented by co-treatment with brusatol.

Conclusion

AG replacement therapy could be a novel strategy to prevent reproductive toxicity in cancer patients.

COVID-19 and varicocele: the possible overlap factors and the common therapeutic approaches

Varicocele is recognized as one of the main attributable causes of male infertility which can affect spermatogenesis by various pathophysiological mechanisms. Recent studies have identified oxidative stress and reduction in antioxidant, hyperthermia, hypoxia, hormonal dysfunction, and inflammatory conditions as major factors in the pathophysiology of varicocele, all of which have known direct associations with the coronavirus disease 2019 (COVID-19) and can significantly increase the risk of detrimental COVID-19-related outcomes. Emerging data have shown an association between COVID-19 and inflammation, overproduction of cytokine, and other pathophysiological processes. The present review, summarizes the current understanding of the pathophysiology of varicocele and investigates the potential correlation between the severity of COVID-19 and the varicocele disease. In addition, various possible treatments which can be effective in both diseases were examined. Despite numerous challenges associated with the prevalence of COVID-19 in healthcare systems in infected countries, special attention should be given to maintaining a high level of care for complex patients with a pre-existing disease such as varicocele and providing appropriate practical advice for optimal control of the COVID-19 disease. This article is protected by copyright. All rights reserved.

Effect of curcumin, and nano-curcumin on sperm function in varicocele rat model

Varicocele is one of the most important causes of infertility in men which gradually leads to testicular dysfunction. Testicular heat stress-induced oxidative stress is considered the main cause of pathology in these individuals. In this study, the effects of curcumin and nano-curcumin, as natural antioxidants, were investigated on spermatogenesis and sperm function in varicocele-induced rats. Seventy Wistar rats were randomly divided into seven groups; sham, control, varicocele, varicocele + curcumin 50 mg, varicocele + curcumin 100 mg, varicocele + nano-curcumin 4 mg and varicocele + nano-curcumin 8 mg. After 2 months of antioxidant therapy, all the rats were sacrificed. The results demonstrated that the mean sperm concentration and motility were significantly lower while the mean of abnormal morphology, lipid peroxidation, intracytoplasmic ROS and DNA damage was significantly higher in varicocelised rats compared to control and sham groups (p < .05). Both doses of curcumin and also nano-curcumin were significantly effective in improving the aforementioned parameters except for abnormal sperm morphology, and motility where nano-curcumin (4 mg) was significantly more effective than other groups (p < .05). The results of the current study suggest the application of nano-curcumin is more preferable to curcumin in infertile individuals with varicocele.

The Role of the Gastric Hormones Ghrelin and Nesfatin-1 in Reproduction

Ghrelin and nesfatin-1 are enteroendocrine peptide hormones expressed in rat X/A-like and human P/D1cells of the gastric mucosa. Besides their effect on food intake, both peptides are also implicated in various other physiological systems. One of these is the reproductive system. This present review illustrates the distribution of ghrelin and nesfatin-1 along the hypothalamus–pituitary–gonadal (HPG) axis, their modulation by reproductive hormones, and effects on reproductive functions as well as highlighting gaps in current knowledge to foster further research.

The Role of the Gastric Hormones Ghrelin and Nesfatin-1 in Reproduction

Ghrelin and nesfatin-1 are enteroendocrine peptide hormones expressed in rat X/A-like and human P/D1cells of the gastric mucosa. Besides their effect on food intake, both peptides are also implicated in various other physiological systems. One of these is the reproductive system. This present review illustrates the distribution of ghrelin and nesfatin-1 along the hypothalamus-pituitary-gonadal (HPG) axis, their modulation by reproductive hormones, and effects on reproductive functions as well as highlighting gaps in current knowledge to foster further research.

The Role of the Gastric Hormones Ghrelin and Nesfatin-1 in Reproduction

Ghrelin and nesfatin-1 are enteroendocrine peptide hormones expressed in rat X/A-like and human P/D1cells of the gastric mucosa. Besides their effect on food intake, both peptides are also implicated in various other physiological systems. One of these is the reproductive system. This present review illustrates the distribution of ghrelin and nesfatin-1 along the hypothalamus–pituitary–gonadal (HPG) axis, their modulation by reproductive hormones, and effects on reproductive functions as well as highlighting gaps in current knowledge to foster further research.

Acylated Ghrelin Attenuates l-Thyroxin-induced Cardiac Damage in Rats by Antioxidant and Anti-inflammatory Effects and Downregulating Components of the Cardiac Renin-angiotensin System

ABSTRACT

This study investigated the protective effect of acylated ghrelin (AG) against l-thyroxin (l-Thy)-induced cardiac damage in rats and examined possible mechanisms. Male rats were divided into five intervention groups of 12 rats/group: control, control + AG, l-Thy, l-Thy + AG, and l-Thy + AG + [D-Lys3]-GHRP-6 (AG antagonist). l-Thy significantly reduced the levels of AG and des-acyl ghrelin and the AG to des-acyl ghrelin ratio. Administration of AG to l-Thy-treated rats reduced cardiac weights and levels of reactive oxygen species and preserved the function and structure of the left ventricle. In addition, AG also reduced the protein levels of cleaved caspase-3 and cytochrome c and prevented mitochondrial permeability transition pore opening. In the left ventricle of both control + AG-treated and l-Thy + AG-treated rats, AG significantly increased left ventricular levels of manganese superoxide dismutase (SOD2), total glutathione (GSH), and Bcl2. It also reduced the levels of malondialdehyde, tumor necrosis factor-α (TNF-α), interleukin-6, and Bax and the nuclear activity of nuclear factor-kappa B. Concomitantly, in both treated groups, AG reduced the mRNA and protein levels of NADPH oxidase 1, angiotensin (Ang) II type 1 receptor, and Ang-converting enzyme 2. All the beneficial effects of AG in l-Thy-treated rats were prevented by the coadministration of [D-Lys3]-GHRP-6, a selective growth hormone secretagogue receptor subtype 1a antagonist. In conclusion, AG protects against hyperthyroidism-induced cardiac hypertrophy and damage, which is mainly due to its antioxidant and anti-inflammatory potentials and requires the activation of GHS-R1a.

Prokineticin 2 overexpression induces spermatocyte apoptosis in varicocele in rats

Varicocele is one of the most important causes of male infertility, as this condition leads to a decline in sperm quality. It is generally believed that the presence of varicocele induces an increase in reactive oxygen species levels, leading to oxidative stress and sperm apoptosis; however, the specific pathogenic mechanisms affecting spermatogenesis remain elusive. Prokineticin 2 (PK2), a secretory protein, is associated with multiple biological processes, including cell migration, proliferation, and apoptosis. In the testis, PK2 is expressed in spermatocytes under normal physiological conditions. To investigate the role of PK2 in varicocele, a rat varicocele model was established to locate and quantify the expression of PK2 and its receptor, prokineticin receptor 1 (PKR1), by immunohistochemistry and quantitative real-time PCR assays (qPCR). Moreover, H₂O₂ was applied to mimic the oxidative stress state of varicocele through coculturing with a spermatocyte-derived cell line (GC-2) in vitro, and the apoptosis rate was detected by flow cytometry. Here, we illustrated that the expression levels of PK2 and PKR1 were upregulated in the spermatocytes of the rat model. Administration of H₂O₂ stimulated the overexpression of PK2 in GC-2. Transfection of recombinant pCMV-HA-PK2 into GC-2 cells promoted apoptosis by upregulating cleaved-caspase-3, caspase-8, and B cell lymphoma 2-associated X; downregulating B cell lymphoma 2; and promoting the accumulation of intracellular calcium. Overall, we revealed that the varicocele-induced oxidative stress stimulated the overexpression of PK2, leading to apoptosis of spermatocytes. Our study provides new insight into the mechanisms underlying oxidative stress-associated male infertility and suggests a novel therapeutic target for male infertility.

A comparative study of Caesalpinia bonduc (L.) Roxb. root extracts on sexual behaviour in male Wistar rats

Caesalpinia bonduc is among the traditionally used plant in Benin, for its enhancement of male sexual activity. This study was undertaken to investigate the potential effect of C. bonduc root extracts on sexual behaviour of male Wistar rats. For that, thirty-six rats were allocated into six groups and orally treated with dimethyl sulfoxide (control), Sildenafil citrate (standard) and C. bonduc root extracts (hexane, ethyl acetate, ethanol and methanol) orally for twenty-eight days. Sexual behaviour parameters such as intromission frequency, intromission latency, mount latency and mount frequency were evaluated on day 0, 14 and 28. After the study completion, the body and reproductive organ weights as well as testicular histology and testosterone level were recorded. C. bonduc root extracts treatments had no significant effect on the body weight of rats. Enhancement in sexual behaviour was observed in ethanolic extract treated rats. An significant increase in mount frequency and intromission frequency as well as significant reduction in mount latency and intromission latency were noticed for ethanolic extract. The same extract caused an improvement in testosterone levels, relative testes weight and histological architecture. The findings demonstrate the aphrodisiac potential of C. bonduc root and lend support to the folkloric use as aphrodisiac.

NLRP3 Inflammasome: A New Pharmacological Target for Reducing Testicular Damage Associated with Varicocele

Many bioactive natural compounds are being increasingly used for therapeutics and nutraceutical applications to counteract male infertility, particularly varicocele. The roles of selenium and Polydeoxyribonucleotide (PDRN) were investigated in an experimental model of varicocele, with particular regard to the role of NLRP3 inflammasome. Male rats underwent sham operation and were daily administered with vehicle, seleno-L-methionine (Se), PDRN, and with the association Se-PDRN. Another group of rats were operated for varicocele. After twenty-eight days, sham and varicocele rats were sacrificed and both testes were weighted and analyzed. All the other rats were challenged for one month with the same compounds. In varicocele animals, lower testosterone levels, testes weight, NLRP3 inflammasome, IL-1β and caspase-1 increased gene expression were demonstrated. TUNEL assay showed an increased number of apoptotic cells. Structural and ultrastructural damage to testes was also shown. PDRN alone significantly improved all considered parameters more than Se. The Se-PDRN association significantly improved all morphological parameters, significantly increased testosterone levels, and reduced NLRP3 inflammasome, caspase-1 and IL-1β expression and TUNEL-positive cell numbers. Our results suggest that NLRP3 inflammasome can be considered an interesting target in varicocele and that Se-PDRN may be a new medical approach in support to surgery.

Varicocoele and oxidative stress: New perspectives from animal and human studies

BACKGROUND

Varicocoele (VCL), one of the main causes of male subfertility, negatively affects testicular function. Due to limited access to human testicular tissue, animal model studies have been used to evaluate molecular and, recently, epigenetic changes attributed to pathophysiology induced by VCL.

OBJECTIVES

This review aims to provide an update on the latest findings regarding the link between VCL-induced biochemical stress and molecular changes in germ cells and spermatozoa. Endocrine and antioxidant status, testicular chaperone-specific hemostasis failure, altered testicular ion balance, metabolic disorders, and altered carbon cycling during spermatogenesis are among the many features that will be presented.

DISCUSSION

Literature review coupled with our own findings suggests that ionic imbalance, hypoxia, hyperthermia, and altered blood flow could lead to severe chronic oxidative and nitrosative stress in patients with VCL leading to defective spermatogenesis and impairment of the integrity of all sperm cell components and compartments down to the epigenetic information they carry.

CONCLUSION

Since oxidative stress is an important feature of the reproductive pathology of VCL, therapeutic strategies such as the administration of appropriate antioxidants could be undertaken as a complementary non-invasive treatment line.

Nutraceutical Effects of Lycopene in Experimental Varicocele: An "In Vivo" Model to Study Male Infertility

Varicocele is one of the main causes of infertility in men. Oxidative stress and consequently apoptosis activation contribute to varicocele pathogenesis, worsening its prognosis. Natural products, such as lycopene, showed antioxidant and anti-inflammatory effects in several experimental models, also in testes. In this study we investigated lycopene effects in an experimental model of varicocele. Male rats (n = 14) underwent sham operations and were administered with vehicle (n = 7) or with lycopene (n = 7; 1 mg/kg i.p., daily). Another group of animals (n = 14) underwent surgical varicocele. After 28 days, the sham and 7 varicocele animals were euthanized, and both operated and contralateral testes were weighted and processed. The remaining rats were treated with lycopene (1 mg/kg i.p., daily) for 30 days. Varicocele rats showed reduced testosterone levels, testes weight, Bcl-2 mRNA expression, changes in testes structure and increased malondialdehyde levels and BAX gene expression. TUNEL (Terminal Deoxynucleotidyl Transferase dUTP Nick End Labeling) assay showed an increased number of apoptotic cells. Treatment with lycopene significantly increased testosterone levels, testes weight, and Bcl-2 mRNA expression, improved tubular structure and decreased malondialdehyde levels, BAX mRNA expression and TUNEL-positive cells. The present results show that lycopene exerts beneficial effects in testes, and suggest that supplementation with the tomato-derived carotenoid might be considered a novel nutraceutical strategy for the treatment of varicocele and male infertility.

Comparison effects of olive leaf extract and oleuropein compounds on male reproductive function in cyclophosphamide exposed mice

Spermatogenesis is a complicated process in which sperm is susceptible to various chemotherapy drugs such as cyclophosphamide (CP). As olive leaf extract (OLE) and its active ingredient, oleuropein, have variousantioxidant, anti-apoptotic, and anti-inflammatory properties the aim of the present study was to investigate the effects of OLE and oleuropein on male reproductive function focusing antioxidative effects and histological modifications in the testes of CP-exposed mice. In order to do this, 80 NMRI male mice were divided into eight groups including control group, group received CP, group received OLE, group received oleuropein, group received OLE following CP exposure, group received oleuropein following CP exposure, group received OLE plus oleuropein and group received OLE plus oleuropein following CP exposure. In all groups CP (single dose of 100 mg/kg (, OLE (100 mg/kg for consequence 28 days) and oleuropein (100 mg/kg for consequence 28 days) were injected intraperitoneally. Moreover, testis histology, sperm parameters and serum levels of LH, FSH, MDA and antioxidant capacity were investigated. Results showed that CP caused oxidative state and abnormal changes in sperms and testes. Besides, treatments with oleuropein and OLE led to mitigate the harmful effects of CP on the male reproductive system. In conclusion, our findings showed that olive's compounds can diminish the hazardous effects of CP on spermatogenesis in mice.

Modulatory effects of ghrelin on sperm quality alterations induced by a fructose-enriched diet

The objectives of this study were: 1) to evaluate the effects of a fructose enriched diet (FED) on rat sperm quality, epididymal function (i.e. oxidative stress and alpha-glucosidase expression) and testosterone concentrations; 2) to determine if the administration of ghrelin (Ghrl), reverses the effects induced by FED. After validating the protocol as an inductor of metabolic syndrome like-symptoms, adult male rats were assigned to one of the following treatments for 8 weeks: FED = 10% fructose enriched in water (v/v); FED + Ghrl = fructose enriched diet plus Ghrl (6 nmol/animal/day, s.c.) from week 6-8; or C = water without fructose (n = 5-10 animals/group). FED significantly decreased sperm concentration and motile sperm count/ml vs C (FED: 19.0 ± 1.6 × 10⁶sperm/ml and 834.6 ± 137.0, respectively vs C: 25.8 ± 2.8 × 10⁶ and 1300.4 ± 202.4, respectively; p < 0.05); ghrelin injection reversed this negative effect (23.5 ± 1.6 × 10⁶sperm/ml and 1381.7 ± 71.3 respectively). FED resulted in hypogonadism, but Ghrl could not normalize testosterone concentrations (C: 1.4 ± 0.1 ng/ml vs FED: 0.8 ± 0.2 ng/ml and FED + Ghrl: 0.6 ± 0.2 ng/ml; p < 0.05). Ghrelin did not reverse metabolic abnormalities secondary to FED. FED did not alter epididymal expression of antioxidants enzymes (superoxido-dismutase, catalase and glutathione peroxidases -Gpx-). Nevertheless, FED + Ghrl significantly increased the expression of Gpx3 (FED + Ghrl: 3.47 ± 0.48 vs FED: 0.69 ± 0.28 and C: 1.00 ± 0.14; p < 0.05). The expression of neutral alpha-glucosidase, which is a marker of epididymal function, did not differ between treatments. In conclusion, the administration of Ghrl modulated the negative effects of FED on sperm quality, possibly by an epididymal increase in Gpx3 expression. However, Ghrl could not neither normalize the metabolism of FED animals, nor reverse hypogonadism.

Ghrelin alleviates endoplasmic reticulum stress and inflammation-mediated reproductive dysfunction induced by stress

PURPOSE

Psychological stress exists widely in modern society and results in the disruption of testicular tight junctions, germ cell apoptosis, and the disorder of fertility hormones and even causes infertility. Ghrelin (GHRL), a 28-amino acid peptide secreted mainly by the stomach and pancreas, has been reported to alleviate male reproductive injury through inhibiting apoptosis. However, whether GHRL has a beneficial effect on psychological stress-induced testicular injury and the possible mechanisms remain poorly understood.

METHODS

Male mice were immobilized in Decapicone bags for 3 h daily for 14 days treated with or without GHRL (i.p. 100 mg/kg body weight). Body weight and testicular weight were measured. Histological alterations and apoptosis were examined by H.E. staining and TUNEL staining, respectively. The expression of endoplasmic reticulum (ER) stress markers, inflammatory cytokines, Toll-like receptor 4 (TLR4), and nuclear factor-κB (NF-κB) in the testes was investigated.

RESULTS

Exposure to stress caused testicular histological alterations, an elevation of the Johnsen score, and germ cell apoptosis, while GHRL partially alleviated the adverse effects. The expression of ER stress marker proteins, including GRP78, CHOP, ATF6, p-JNK, and XBP-1, was upregulated in the stress group; however, GHRL treatment significantly suppressed the activation of ER stress in the testes. GHRL also inhibited the expression of TNF-α, IL-1β, IL-6, IL-10, TLR4, and NF-κB.

CONCLUSIONS

GHRL alleviated testicular injury induced by ER stress and inflammation which is associated with the TLR4/NF-κB signaling pathway, and these findings may provide a novel strategy for preventing and treating reproductive dysfunction.

Relationships between Ghrelin and Obestatin with MDA, Proinflammatory Cytokines, GSH/GSSG Ratio, Catalase Activity, and Semen Parameters in Infertile Patients with Leukocytospermia and Varicocele

Ghrelin and obestatin are involved in many biological functions including reproduction. Growing evidences suggest that both peptides could exert protective and antioxidant activities. In this study, the relationships between ghrelin/obestatin, interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α), malondialdehyde (MDA), reduced glutathione (GSH), oxidized glutathione (GSSG), expressed as the GSH/GSSG ratio, catalase (CAT), and semen parameters in infertile patients with varicocele or leukocytospermia and controls were investigated. Fifty-six infertile patients (32 with leukocytospermia and 24 with varicocele) and 14 controls participated in this study. Semen analysis was performed following the WHO guidelines. Apoptotic and necrotic sperm were scored by annexin V/propidium iodide assay. Seminal plasma samples were used for the following determinations: ghrelin, obestatin, IL-6, and TNF-α were measured by an immunological method, GSH/GSSG by an enzymatic method, and CAT by spectrophotometric determination. With respect to controls, both the leukocytospermia and varicocele groups showed altered sperm parameters, significantly increased sperm apoptosis (P = 0.009 and P = 0.011, respectively), IL-6 (P = 0.0001 and P = 0.004, respectively), and TNF-α levels (P = 0.0001 and P = 0.002, respectively); both groups had significantly decreased levels of ghrelin (P = 0.0001), obestatin (P = 0.0001 and P = 0.006, respectively), and GSH/GSSG ratio (P = 0.003 and P = 0.0001, respectively). The MDA concentration was significantly increased in the leukocytospermia group vs. controls (P = 0.0001), in the varicocele group vs. controls (P = 0.011), and in the leukocytospermia group vs. the varicocele group (P = 0.008). CAT activity was augmented in both the leukocytospermia and varicocele groups (P = 0.0001)vs. controls. The results indicate that both ghrelin and obestatin may play a protective role in human semen and this effect is probably due to their antioxidant properties.