Update: Hypogonadotropic hypogonadism in type 2 diabetes and obesity

The evolutionary conserved miR-137/325 tandem mediates obesity-induced hypogonadism and metabolic comorbidities by repressing hypothalamic kisspeptin

BACKGROUND

Obesity-induced hypogonadism (OIH) is a prevalent, but often neglected condition in men, which aggravates the metabolic complications of overweight. While hypothalamic suppression of Kiss1-encoded kisspeptin has been suggested to contribute to OIH, the molecular mechanisms for such repression in obesity, and the therapeutic implications thereof, remain unknown.

METHODS

A combination of bioinformatic, expression and functional analyses was implemented, assessing the role of the evolutionary-conserved miRNAs, miR-137 and miR-325, in mediating obesity-induced suppression of hypothalamic kisspeptin, as putative mechanism of central hypogonadism and metabolic comorbidities. The implications of such miR-137/325-kisspeptin interplay for therapeutic intervention in obesity were also explored using preclinical OIH models.

RESULTS

MiR-137/325 repressed human KISS1 3'-UTR in-vitro and inhibited hypothalamic kisspeptin content in male rats, while miR-137/325 expression was up-regulated, and Kiss1/kisspeptin decreased, in the medio-basal hypothalamus of obese rats. Selective over-expression of miR-137 in Kiss1 neurons reduced Kiss1/ kisspeptin and partially replicated reproductive and metabolic alterations of OIH in lean mice. Conversely, interference of the repressive actions of miR-137/325 selectively on Kiss1 3'-UTR in vivo, using target-site blockers (TSB), enhanced kisspeptin content and reversed central hypogonadism in obese rats, together with improvement of glucose intolerance, insulin resistance and cardiovascular and inflammatory markers, despite persistent exposure to obesogenic diet. Reversal of OIH by TSB miR-137/325 was more effective than chronic kisspeptin or testosterone treatments in obese rats.

CONCLUSIONS

Our data disclose that the miR-137/325-Kisspeptin repressive interaction is a major player in the pathogenesis of obesity-induced hypogonadism and a putative druggable target for improved management of this condition and its metabolic comorbidities in men suffering obesity.

SIGNIFICANCE STATEMENT

Up to half of the men suffering obesity display also central hypogonadism, an often neglected complication of overweight that can aggravate the clinical course of obesity and its complications. The mechanisms for such obesity-induced hypogonadism remain poorly defined. We show here that the evolutionary conserved miR137/miR325 tandem centrally mediates obesity-induced hypogonadism via repression of the reproductive-stimulatory signal, kisspeptin; this may represent an amenable druggable target for improved management of hypogonadism and other metabolic complications of obesity.

Apigenin improves testosterone synthesis by regulating endoplasmic reticulum stress

Obesity is a growing epidemic among reproductive-age men, which can cause and exacerbate male infertility by means of associated comorbidities, endocrine abnormalities, and direct effects on the fidelity and throughput of spermatogenesis. A prominent consequence of male obesity is a reduction in testosterone levels. Natural products have shown tremendous potential anti-obesity effects in metabolic diseases. This study aimed to investigate the potential of apigenin (AP) to alleviate testicular dysfunction induced by a high-fat diet (HFD) and to investigate the underlying mechanisms, focusing on endoplasmic reticulum stress (ERS) and testosterone synthesis. A murine model of obesity was established using HFD-fed mice. The effects of AP on obesity, lipid metabolism, testicular dysfunction, and ERS were assessed through various physiological, histological, and molecular techniques. Administration of AP (10 mg/kg) ameliorated HFD-induced obesity and testicular dysfunction in a mouse model, as evidenced by decreased body weight, improved lipid profiles and testicular pathology, and restored protein levels related to testosterone. Furthermore, in vitro studies demonstrated that AP relieved ERS and recovered testosterone synthesis in murine Leydig cells (TM3) treated with free fatty acids (FFAs). It was also observed that AP rescued testosterone synthesis enzymes in TM3 cells, similar to that observed with the inhibitor of the PERK pathway (GSK2606414). In addition, ChIP, qPCR, and gene silencing showed that the C/EBP homologous protein (CHOP) bound directly to the promoter region of steroidogenic STAR and negatively modulated its expression. Collectively, AP has remarkable potential to alleviate HFD-induced obesity and testicular dysfunction. Its protective effects are attributable partly to mitigating ERS and restoring testosterone synthesis in Leydig cells.

Imaging-based body fat distribution and diabetic retinopathy in general US population with diabetes: an NHANES analysis (2003-2006 and 2011-2018)

BACKGROUND

Limited studies have investigated the correlation between fat distribution and the risk of diabetic retinopathy (DR) in the general population with diabetes. The relationship between obesity and DR remains inconclusive, possibly due to using simple anthropometric measures to define obesity. This study investigates the relationships between the android-to-gynoid fat ratio (A/G ratio, measured using dual-energy X-ray absorptiometry) and DR within the US population with diabetes.

METHODS

The study used a population-based, cross-sectional approach based on the 2003-2006 and 2011-2018 data of the National Health and Nutrition Examination Survey (NHANES). Multivariable logistic regression analyses were performed on participants with diabetes to evaluate the contribution of body mass index (BMI), waist-to-height ratio (WHtR), and A/G ratio to the prevalence of DR.

RESULTS

The prevalence of DR was 22.2, 21.2, and 17.6% among participants with A/G ratios <1.0, 1.0-1.2, and ≥1.2, respectively. After adjusting sex, age, ethnicity, diabetes duration, hemoglobin A1c level, blood pressure level, and non-high-density lipoprotein cholesterol level, a higher A/G ratio (≥1.2) was independently associated with decreased odds of DR (odds ratio [OR], 0.565; 95% CI: 0.372-0.858) compared with the A/G ratio of 1.0-1.2. Associations between a higher A/G ratio and DR remained statistically significant after adjusting for BMI (OR, 0.567; 95% CI: 0.373-0.861) and WHtR (OR, 0.586; 95% CI: 0.379-0.907). Moreover, these associations remained statistically significant in analyses using the ethnic-specific tertiles for the A/G ratio. In sex-stratified models, these correlations remained in males. There was a significant inverse association between the A/G ratio and diabetes duration in males, which persisted after multivariable adjustments (p < 0.05).

CONCLUSIONS

A novel finding indicates that a higher A/G ratio is associated with a reduced likelihood of DR in males with diabetes. The results from NHANES underscore the importance of considering imaging-based fat distribution as a critical indicator in clinical practice.

Obesity and male fertility disorders

Often associated with obesity, male infertility represents a widespread condition that challenges the wellbeing of the couple. In this article, we provide a comprehensive and critical analysis of studies exploring the association between obesity and male reproductive function, to evaluate the frequency of this association, and establish the effects of increased body weight on conventional and biofunctional sperm parameters and infertility. In an attempt to find possible molecular markers of infertility in obese male patients, the numerous mechanisms responsible for infertility in overweight/obese patients are reviewed in depth. These include obesity-related functional hypogonadism, insulin resistance, hyperinsulinemia, chronic inflammation, adipokines, irisin, gut hormones, gut microbiome, and sperm transcriptome. According to meta-analytic evidence, excessive body weight negatively influences male reproductive health. This can occurr through a broad array of molecular mechanisms. Some of these are not yet fully understood and need to be further elucidated in the future. A better understanding of the effects of metabolic disorders on spermatogenesis and sperm fertilizing capacity is very useful for identifying new diagnostic markers and designing therapeutic strategies for better clinical management of male infertility.

A ripple effect? The impact of obesity on sperm quality and function

Infertility affects approximately 15% of couples trying to conceive. Male-related causes account for roughly 50% of cases, with obesity emerging as a possible significant factor. Obesity, defined as a body mass index of 30.0 or higher, has become a widespread epidemic associated with numerous health issues, including a decrease of fertility. This review discusses the relationship between obesity and male infertility, particularly focusing on sperm quality and function. An overview of the literature suggests that obesity may influence the male reproductive system via disruptions in hormonal profiles, oxidative stress, and inflammation, leading to changes in sperm parameters. Several studies have discussed if obesity causes a decrease in sperm concentration, motility, and normal morphology, so far without a consensus being reached. However, available evidence suggests an impairment of sperm function in obese men, due to an increase in DNA damage and oxidative stress, impaired mitochondrial function and acrosome reaction in response to progesterone. Finally, the relationship between obesity and assisted reproductive technologies outcomes remains debatable, with conflicting evidence regarding the influence on fertilisation, pregnancy, and live birth rates. Therefore, the actual impact of obesity on human spermatozoa still needs to be clarified, due to the multiple factors potentially in play.

Vagal pathways for systemic regulation of glucose metabolism

Maintaining blood glucose at an appropriate physiological level requires precise coordination of multiple organs and tissues. The vagus nerve bidirectionally connects the central nervous system with peripheral organs crucial to glucose mobilization, nutrient storage, and food absorption, thereby presenting a key pathway for the central control of blood glucose levels. However, the precise mechanisms by which vagal populations that target discrete tissues participate in glucoregulation are much less clear. Here we review recent advances unraveling the cellular identity, neuroanatomical organization, and functional contributions of both vagal efferents and vagal afferents in the control of systemic glucose metabolism. We focus on their involvement in relaying glucoregulatory cues from the brain to peripheral tissues, particularly the pancreatic islet, and by sensing and transmitting incoming signals from ingested food to the brain. These recent findings - largely driven by advances in viral approaches, RNA sequencing, and cell-type selective manipulations and tracings - have begun to clarify the precise vagal neuron populations involved in the central coordination of glucose levels, and raise interesting new possibilities for the treatment of glucose metabolism disorders such as diabetes.

Combined obesity- and lipid-related indices are associated with hypogonadism in Chinese male patients with type 2 diabetes: a cross-sectional study

Background

There is insufficient attention to hypogonadism in Chinese males with type 2 diabetes mellitus (T2DM). We evaluated the relationship between Combined obesity- and lipid-related indices [Visceral Adiposity Index (VAI), Chinese Visceral Adiposity Index (CVAI), Triglyceride Glucose Index (TyG) and Lipid Accumulation Product (LAP)] with total testosterone (TT) and analyzed the predictive capability of the respective cut-off values.

Methods

We recruited 958 hospitalized male patients with T2DM at the Affiliated Hospital of Qingdao University, collected baseline data and four calculated indices, and obtained their dominance ratio (OR) and corresponding 95% confidence intervals (CI) with TT by multivariate logistic regression. Receiver operating characteristic (ROC) curves were then used to determine cutoff values in predicting hypogonadism (TT< 12 nmol/L), and we also analyzed the combinations between the different indices.

Results

VAI, CVAI, TyG, and LAP all have satisfactory predictive capabilities. The test capability (sensitivity and specificity) of all four indices was better or not worse than that of body mass index (BMI), homeostasis model assessment of insulin resistance (HOMA-IR) and waist circumference (WC). All four indices were effective predictors of hypogonadism at their respective cutoff values (VAI ≥ 2.284, CVAI ≥ 145.779, TyG ≥ 4.308, and LAP ≥ 59.850). Of these, LAP had the largest area under the curve (AUC, AUC = 0.852, Std. Error = 0.014, 95% CI = 0.818-0.873). However, the predictive capability of the combined indices was not significantly improved over the individual indices.

Conclusions

VAI, CVAI, TyG, and LAP are sensitive indices for predicting hypogonadism in Chinese male patients with T2DM. Considering the need for concise and accurate indices in clinical practice, we suggest LAP as a commonly used index.

Type 2 diabetes mellitus and the risk of male infertility: a Mendelian randomization study

Objective

To assess the causal effect of type 2 diabetes mellitus (T2DM) on male infertility (MI) and erectile dysfunction (ED) by Mendelian randomization (MR) analysis.

Methods

Data for T2DM, MI, and ED were obtained from genome-wide association studies (GWAS) involving 298, 957, 73, 479, and 223, 805 Europeans, respectively. We performed univariate MR analysis using MR Egger, Weighted median (WM) and Inverse variance weighted (IVW) methods to assess causal effects among the three. Through the Genotype Tissue Expression (GTEx) database, single-nucleotide polymorphisms (SNPs) that affect the expression levels of T2DM-related genes were located using expression quantitative trait loci (eQTL).

Results

MR analysis showed a significant causal relationship between T2DM and ED (WM, OR: 1.180, 95%CI: 1.010-1.378, P = 0.037; IVW, OR: 1.190, 95%CI: 1.084-1.300, P < 0.001). There is also a significant causal relationship between T2DM and MI (MR Egger, OR: 0.549, 95%CI: 0.317-0.952, P = 0.037; WM, OR: 0.593, 95%CI: 0.400, P = 0.010; IVW, OR: 0.767, 95%CI: 0.600-0.980, P = 0.034). ED may not cause MI (P > 0.05). We also found that rs6585827 corresponding to the PLEKHA1 gene associated with T2DM is an eQTL variant affecting the expression of this gene.

Conclusion

T2DM has a direct causal effect on ED and MI. The level of PLEKHA1 expression suppressed by rs6585827 is potentially associated with a lower risk of T2DM.

Adult Male Hypogonadism: A Laboratory Medicine Perspective on Its Diagnosis and Management

Testosterone (T), the principal androgen secreted by the testes, plays an essential role in male health. Male hypogonadism is diagnosed based on a combination of associated clinical signs and symptoms and laboratory confirmation of low circulating T levels. In this review, we have highlighted factors, both biological and analytical, that introduce variation into the measurement of serum T concentrations in men; these need to be considered when requesting T levels and interpreting results. There is an ongoing need for analytical standardisation of T assays and harmonisation of pre- and post-analytical laboratory practices, particularly in relation to the laboratory reference intervals provided to clinicians. Further, there is a need to share with service users the most up-to-date and evidence-based action thresholds for serum T as recommended in the literature. Estimation of free testosterone may be helpful. Causes of secondary hypogonadism should be considered. A comprehensive approach is required in the management of male hypogonadism, including lifestyle modification as well as medication where appropriate. The goal of treatment is the resolution of symptoms as well as the optimisation of metabolic, cardiovascular, and bone health. The advice of an endocrinologist should be sought when there is doubt about the cause and appropriate management of the hypogonadism.

High-fructose consumption suppresses insulin signaling pathway accompanied by activation of macrophage and apoptotic markers in rat testis

Dietary high-fructose may cause metabolic disturbances; however, its effect on the reproductive system is little understood. The insulin signaling pathway is critical in testicular development, maintenance of microcirculation and spermatogenesis. Therefore, in this study, we aimed to investigate the impact of dietary high-fructose on insulin signaling pathway as well as macrophage and apoptotic markers in testicular tissue of rats. Fructose was administered to male Wistar rats as a 20% solution in drinking water for fifteen-week. Gene expression of ir-β, irs-1, irs-2, pi3k, akt, mtor, and enos in the testicular samples was determined by real-time PCR. Protein expression of IR, IRS-1, IRS-2, PI3K, Akt, phospho-Akt (p-Akt), mTOR, eNOS, phospho-eNOS (p-eNOS), and GLUT5 was established by analysis of Western Blot. Testicular expression of occludin, CD163, CD68, caspase-8, and caspase-3 was analyzed by using immunohistochemical assay. Testicular level of fructose was measured by colorimetric method. Dietary high-fructose decreased mRNA expressions of irs-1, irs-2, pi3k, and mtor in the testicular tissue of rats. Also, this dietary intervention impaired protein expressions of IR, IRS-1, IRS-2, PI3K, p-Akt, mTOR, eNOS, and p-eNOS as well as p-Akt/Akt and p-eNOS/eNOS ratios in the testis of rats. However, a high-fructose diet increased the expression of CD163, CD68, caspase-8 and caspase-3, but decreased that of occludin, in the testicular tissue of rats. The high-fructose consumption in rats suppresses testicular insulin signaling but activates macrophages-related factors and apoptotic markers. These changes induced by dietary fructose could be related to male reproductive dysfunction.

Body composition and testosterone in men: a Mendelian randomization study

Background

Testosterone is an essential sex hormone that plays a vital role in the overall health and development of males. It is well known that obesity decreases testosterone levels, but it is difficult to determine the causal relationship between body composition and testosterone.

Methods

To investigate potential causal associations between body composition and testosterone levels by a first time application of Mendelian randomization methods. Exposure variables in men included body composition (fat mass, fat-free mass, and body mass index). In addition to whole body fat and fat-free mass, we examined fat and fat-free mass for each body part (e.g., trunk, left arm, right arm, left leg and right leg) as exposures. Instrumental variables were defined using genome-wide association study data from the UK Biobank. Outcome variables in men included testosterone levels (total testosterone [TT], bioavailable testosterone [BT], and sex hormone-binding globulin [SHBG]). A one-sample Mendelian randomization analysis of inverse-variance weighted and weighted median was performed.

Results

The number of genetic instruments for the 13 exposure traits related to body composition ranged from 156 to 540. Genetically predicted whole body fat mass was negatively associated with TT (β=-0.24, P=5.2×10-33), BT (β=-0.18, P=5.8×10-20) and SHBG (β=-0.06, P=8.0×10-9). Genetically predicted whole body fat-free mass was negatively associated with BT (β=-0.04, P=2.1×10-4), but not with TT and SHBG, after multiple testing corrections. When comparing the causal effect on testosterone levels, there was a consistent trend that the effect of fat mass was more potent than that of fat-free mass. There were no differences between body parts.

Conclusion

These results show that reducing fat mass may increase testosterone levels.

Effect of GH Deficiency Caused by Nonfunctioning Pituitary Masses on Serum C-reactive Protein Levels

Context

GH supplementation for GH deficiency (GHD) has been reported to decrease high-sensitivity C-reactive protein (hs-CRP), an inflammatory marker; however, the association between GHD and hs-CRP remains unclear.

Objective

We aimed to clarify the impact of impaired GH secretion due to pituitary masses on hs-CRP levels.

Methods

We retrospectively examined the association between GH secretion, assessed using GH-releasing peptide-2, and serum hs-CRP levels before and a year after the pituitary surgery in patients with nonfunctioning pituitary neuroendocrine tumor or Rathke cleft cyst.

Results

Among 171 patients, 55 (32%) presented with severe GHD (peak GH response to GH-releasing peptide-2 < 9 ng/mL). Serum hs-CRP levels were significantly higher in patients with severe GHD than in those without (P < .001) and significantly correlated with the peak GH (r = -0.50, P < .001). Multiple regression analyses showed that the peak GH significantly and negatively predicted hs-CRP levels (β = -0.345; 95% CI, -0.533 to -0.158) and the lowest quartile of the peak GH (<5.04 ng/mL) were significantly associated with increase in hs-CRP levels (exp [β] = 1.840; 95% CI, 1.209 to 2.801), after controlling for other anterior hormones and metabolic parameters. Postoperative change in the peak GH (N = 60) significantly predicted change in hs-CRP levels (β = -0.391; 95% CI, -0.675 to -0.108), independent of alterations in other anterior hormones and metabolic parameters.

Conclusion

The inverse association between GH secretion and hs-CRP levels highlights the protective role of GH in the increase in hs-CRP.

A National Multicenter Study of Leptin and Leptin Receptor Deficiency and Systematic Review

CONTEXT

Homozygous leptin (LEP) and leptin receptor (LEPR) variants lead to childhood-onset obesity.

OBJECTIVE

To present new cases with LEP and LEPR deficiency, report the long-term follow-up of previously described patients, and to define, based on all reported cases in literature, genotype-phenotype relationships.

METHODS

Our cohort included 18 patients (LEP = 11, LEPR = 7), 8 of whom had been previously reported. A systematic literature review was conducted in July 2022. Forty-two of 47 studies on LEP/LEPR were selected.

RESULTS

Of 10 new cases, 2 novel pathogenic variants were identified in LEP (c.16delC) and LEPR (c.40 + 5G > C). Eleven patients with LEP deficiency received metreleptin, 4 of whom had been treated for over 20 years. One patient developed loss of efficacy associated with neutralizing antibody development. Of 152 patients, including 134 cases from the literature review in addition to our cases, frameshift variants were the most common (48%) in LEP and missense variants (35%) in LEPR. Patients with LEP deficiency were diagnosed at a younger age [3 (9) vs 7 (13) years, P = .02] and had a higher median body mass index (BMI) SD score [3.1 (2) vs 2.8 (1) kg/m2, P = 0.02], which was more closely associated with frameshift variants (P = .02). Patients with LEP deficiency were more likely to have hyperinsulinemia (P = .02).

CONCLUSION

Frameshift variants were more common in patients with LEP deficiency whereas missense variants were more common in LEPR deficiency. Patients with LEP deficiency were identified at younger ages, had higher BMI SD scores, and had higher rates of hyperinsulinemia than patients with LEPR deficiency. Eleven patients benefitted from long-term metreleptin, with 1 losing efficacy due to neutralizing antibodies.

The Association between Inflammation, Testosterone and SHBG in men: A cross-sectional Multi-Ethnic Study of Atherosclerosis

CONTEXT

Earlier studies have investigated the role of obesity-related inflammation and endogenous sex hormones in men. The role of interleukin-6 (IL-6) and C-reactive protein (CRP) with testosterone and sex hormone binding globulin (SHBG) levels in men is still debated.

OBJECTIVE

To investigate the independent association between levels of high sensitivity CRP (hsCRP) and IL-6 with endogenous sex hormones in men.

DESIGN

Cross-sectional observational study using data from the Multi-Ethnic Study of Atherosclerosis.

PATIENTS OR OTHER PARTICIPANTS

A community-based sample of 3212 men aged 45-84 years was included. After exclusions, 3041 men remained for the analyses.

MAIN OUTCOME MEASURE(S)

Serum concentrations of testosterone, SHBG, hsCRP, IL-6, and sTNFR were measured from the baseline exam. Multivariable linear regressions were used to examine the association of inflammatory markers with sex hormones.

RESULTS

An inverse association was found between levels of hsCRP and levels of testosterone and SHBG, even after adjustment for confounders and IL-6 (Total Testosterone; B = -0.14, Bioavailable Testosterone; B = -0.06, and SHBG; B = -0.66). Similar results were found for IL-6, although a positive association was found for SHBG (B = 0.95). Notably, an inverse association was found for IL-6 with bioavailable testosterone in African Americans and Hispanic Americans aged 45-54 years. No associations were found for sTNFR and endogenous sex hormones.

CONCLUSION

Our results indicate that inflammatory markers have independent associations with levels of testosterone (total and bioavailable) and furthermore, appear to associate differently with SHBG levels.

The impact of dietary fructose on gut permeability, microbiota, abdominal adiposity, insulin signaling and reproductive function

The excessive intake of fructose in the regular human diet could be related to global increases in metabolic disorders. Sugar-sweetened soft drinks, mostly consumed by children, adolescents, and young adults, are the main source of added fructose. Dietary high-fructose can increase intestinal permeability and circulatory endotoxin by changing the gut barrier function and microbial composition. Excess fructose transports to the liver and then triggers inflammation as well as de novo lipogenesis leading to hepatic steatosis. Fructose also induces fat deposition in adipose tissue by stimulating the expression of lipogenic genes, thus causing abdominal adiposity. Activation of the inflammatory pathway by fructose in target tissues is thought to contribute to the suppression of the insulin signaling pathway producing systemic insulin resistance. Moreover, there is some evidence that high intake of fructose negatively affects both male and female reproductive systems and may lead to infertility. This review addresses dietary high-fructose-induced deteriorations that are obvious, especially in gut permeability, microbiota, abdominal fat accumulation, insulin signaling, and reproductive function. The recognition of the detrimental effects of fructose and the development of relevant new public health policies are necessary in order to prevent diet-related metabolic disorders.

Management of congenital hypogonadotropic hypogonadism in females

This review explores the challenges in the diagnosis of hypogonadotropic hypogonadism, the transition of care from paediatric to adult care and the considerable health implications of this condition. The role gynaecologists and general practitioners have in managing hormone replacement therapy and reproductive potential is also highlighted. The fertility treatment options, which include ovulation induction with gonadotrophins and in-vitro fertilisation, are discussed in detail along with highlighting the fact that anovulation and markers of low ovarian reserve prior to priming treatment may not be reflective of poor reproductive potential. The holistic management of women with hypogonadotropic hypogonadism is still not standardised and evidence for subfertility management is scarce. This review aims to highlight this concern and provide guidance by evaluating current evidence.

Sex/gender differences in metabolic syndrome among cancer survivors in the US: an NHANES analysis

BACKGROUND

The purpose of this study was to assess the association of metabolic syndrome (MetS) and its individual components in cancer survivors (CS) by gender, in comparison to participants without a history of cancer who have at least one chronic disease (CD) and those without a chronic disease diagnosis (NCD).

METHODS

Data from participants 40 years and older (n = 12,734) were collected from the 2011 to 2018 National Health and Nutrition Examination Survey dataset. MetS was defined based on the National Cholesterol Education Program's Adult Treatment Panel III. Chi-square test and multivariate-adjusted logistic regression was used to assess group comparisons and associations respectively.

RESULTS

Compared to NCD, CS and CD men had increased odds of meeting MetS, OR 2.60 (CI 1.75-3.87) and OR 2.18 (CI 1.59-2.98) respectively. For women, CS and CD participants also had higher odds of meeting MetS criteria compared to their healthy counterparts, OR 2.05 (CI 1.44-2.93) and OR 2.14 (CI 1.63-2.81) respectively. In subgroup analysis by cancer site, CS men with a history of hematologic malignancies (OR 4.88, CI 1.30-18.37) and CS women with cervical cancer (OR 4.25, CI 1.70-10.59) had highest odds of developing MetS, compared to NCD. CS men also showed a strong association with elevated waist circumference, low high density lipoprotein-c, and elevated triglycerides, even by cancer site, but there were no consistent findings among women.

CONCLUSION

This study indicates that CS men have a strong association with MetS, especially among those with blood-related cancers.

How much obesity and diabetes do impair male fertility?

BACKGROUND

Subfertility in obese and diabetic men during the reproductive age is evident, but the mechanisms by which obesity and diabetes mellitus cause male infertility are not entirely understood. The current study aimed to evaluate the effects and potential mechanisms of obesity and diabetes on male fertility.

METHODS

We enrolled control = 40, obese = 40, Lean-DM = 35, and Obese-DM = 35 individuals. The obesity-associated markers, diabetic markers, hormonal and lipid profile, inflammatory indices, and semen analysis were assessed in four experimental groups.

RESULTS

Our finding showed that diabetic markers were significantly increased in two diabetic groups, while obesity indices were markedly increased in two obese groups. Conventional sperm parameters were significantly lower in three groups compared with the control. Serum levels of total testosterone and sex hormone-binding globulin were significantly lower in men with obesity and DM compared with the control. There was a significant difference in the concentration of high-sensitivity C-reactive protein among four experimental groups. Moreover, serum leptin was significantly increased in obese DM, lean DM, and obese groups. Serum insulin levels had a positive correlation with metabolic-associated indices and high-sensitivity C-reactive protein levels, whereas it had a negative correlation with count, motility, and morphology.

CONCLUSIONS

Our findings showed the metabolic changes, hormonal dysfunction and inflammatory disturbance might be suspected mechanisms of subfertility in obese and diabetic subfertile men.

A cross-sectional analysis of the association between testosterone and biopsy-proven non-alcoholic fatty liver disease in men with obesity

PURPOSE

To study the association between testosterone and non-alcoholic fatty liver disease (NAFLD) since prior studies have reported inconsistent results.

METHODS

A retrospective analysis was performed including obese men who underwent a liver biopsy and a metabolic and hepatological work-up. Free testosterone (CFT) was calculated by the Vermeulen equation. The association between total testosterone (total T) and CFT on the one hand and NAFLD and fibrosis on the other hand was investigated and corrected for biasing factors such as metabolic parameters.

RESULTS

In total, 134 men (mean age 45 ± 12 years, median BMI 39.6 (25.0-64.9) kg/m²) were included. The level of total T and CFT did not significantly differ between NAFL and NASH and the stages of steatosis and ballooning. CFT was significantly lower in a higher stage of fibrosis (p = 0.013), not seen for total T and not persisting after controlling for the influence of BMI, HDL cholesterol and HOMA-IR. A higher stage of lobular inflammation was associated with a lower level of total T (p = 0.033), not seen for CFT and not persisting after controlling for the influence of visceral adipose tissue surface and HOMA-IR.

CONCLUSIONS

This is the second largest study investigating the association between testosterone and biopsy-proven NAFLD. No significant association between testosterone levels and NAFLD, and the different histological subgroups or fibrosis was seen. The lower level of CFT in a higher stage of fibrosis and the association between total T and lobular inflammation was driven by poor metabolic parameters.

Hypothalamic-Pituitary-Gonadal Axis Disorders Impacting Fertility in Both Sexes and the Potential of Kisspeptin-Based Therapies to Treat Them

Impaired function of the hypothalamic-pituitary-gonadal (HPG) axis can lead to a vast array of reproductive disorders some of which are inherited or acquired, but many are of unknown etiology. Among the clinical consequences of HPG impairment, infertility is quite common. According to the latest report from the World Health Organization, the global prevalence of infertility during a person's lifetime is a staggering 17.5% which translate into 1 out of every 6 people experiencing it. In both sexes, infertility is associated with adverse health events, and if unresolved, infertility can cause substantial psychological stress, social stigmatization, and economic strain. Even though significant advances have been made in the management and treatment of infertility, low or variable efficacy of treatments and medication adverse effects still pose a significant problem. However, the discovery that in humans inactivating mutations in the gene encoding the kisspeptin receptor (Kiss1R) results in pubertal failure and infertility has expanded our understanding of the mechanisms underlying the neuroendocrine control of reproduction, opening up potential new therapies for the treatment of infertility disorders. In this chapter we provide an overview of common infertility disorders affecting men and women, their recommended treatments, and the potential of kisspeptin-based pharmacotherapies to treat them.

Testosterone deficiency in non-obese type 2 diabetic male patients

BACKGROUND AND AIMS

it is unclear whether male hypogonadism is ascribable to the diabetic state per se, or because of other factors, such as obesity or age. We aimed to investigate the prevalence and identify the predictors for testosterone deficiency among non-obese type 2 diabetic males.

METHODS

This cross-sectional study was conducted on 95 nonobese type 2 diabetic males with BMI below 30. We evaluated the total testosterone (TT) levels to determine prevalence and risk factors of testosterone deficiency. Serum TT ≤ 300 ng/dl defined testosterone deficiency.

RESULTS

The prevalence of testosterone deficiency was 29.1%. Testosterone deficient patients had statistically significantly higher visceral adiposity index (VAI), waist, and triglyceride in comparison with normal testosterone patients. TT level correlated with VAI, waist, BMI, LH, and age. VAI was the only significant predictor of TT levels even after adjustment for age and BMI in regression analysis. Furthermore, VAI was a statistically significant risk factor for testosterone deficiency in binary logistic analysis.

CONCLUSIONS

testosterone deficient non-obese type 2 diabetic male patients had elevated VAI, waist, and triglyceride. Moreover, elevated VAI was a risk factor for testosterone deficiency. VAI could be an easily applicable and reliable index for the evaluation and prediction in type 2 non-obese diabetic males.

Endoscopic Enucleation of Prostate Could Increase Testosterone Levels in Hypotestosteronemic Patients with Bladder Outlet Obstruction

Background: We evaluated the impact of endoscopic enucleation of the prostate on testosterone levels in hypotestosteronemic patients with bladder outlet obstruction. Methods: We enrolled 294 men with lower urinary tract symptoms (LUTS) who received surgery between January 2019 and December 2020 in simple tertiary centre. The inclusion criteria were as follows: being a male patient aged 45−95 years and having recurrent urinary tract infection, having previously failed medical treatment for LUTS or urine retention, and undergoing bipolar or thulium laser enucleation of the prostate. The preoperative and postoperative data were retrospectively reviewed. Results: This study included 112 men with a mean age of 69.4 years. The mean preoperative and postoperative testosterone levels were 4.8 and 4.98, respectively. Of the patients, 88 (78.6%) received ThuLEP and 24 received BipolEP. We divided the patients into two groups according to preoperative serum testosterone levels: normal-testosterone (≥3 ng/mL) and low-testosterone (<3 ng/mL) groups. A significant change in testosterone levels (p = 0.025) was observed in the low-testosterone group. In contrast, no significant difference in testosterone levels was noted in the normal-testosterone group (p = 0.698). Conclusions: Endoscopic enucleation surgery of the prostate could improve postoperative testosterone levels in hypotestosteronemic patients with bladder outlet obstruction.

Invited review: Translating kisspeptin and neurokinin B biology into new therapies for reproductive health

The reproductive neuropeptide kisspeptin has emerged as the master regulator of mammalian reproduction due to its key roles in the initiation of puberty and the control of fertility. Alongside the tachykinin neurokinin B and the endogenous opioid dynorphin, these peptides are central to the hormonal control of reproduction. Building on the expanding body of experimental animal models, interest has flourished with human studies revealing that kisspeptin administration stimulates physiological reproductive hormone secretion in both healthy men and women, as well as patients with common reproductive disorders. In addition, emerging therapeutic roles based on neurokinin B for the management of menopausal flushing, endometriosis and uterine fibroids are increasingly recognised. In this review, we focus on kisspeptin and neurokinin B and their potential application as novel clinical strategies for the management of reproductive disorders.

Melatonin supplementation preserves testicular function by attenuating lactate production and oxidative stress in high fat diet-induced obese rat model

Metabolic syndrome, including obesity has been documented as a critical factor in male reproductive dysfunction with subsequent reduction in male fertility. The therapeutic potential of melatonin has been demonstrated against oxidative stress-induced pathologies. Therefore, the present study investigated the effects of melatonin on testicular dysfunction associated with high fat diet (FD)-induced obese rat model, and the possible involvement of peroxisome proliferator-activated receptor-γ (PPAR-γ). Adult male Wistar rats (n = 6/group) were used: control group received vehicle (normal saline), obese group received 40% FD, melatonin-treated group received melatonin (4 mg/kg), and obese plus melatonin group received melatonin and 40% FD and the treatment lasted for 12 weeks. High fat diet caused increased body weight and testicular triglyceride, total cholesterol, malondialdehyde, γ-glutamyl transferase, lactate production and lactate/pyruvate ratio as well as decreased glutathione/glutathione peroxidase, nitric oxide and PPAR-γ and circulating testosterone. Nevertheless, all these alterations were attenuated when supplemented with melatonin. Taken together, these results demonstrates that FD-induced obesity causes testicular dysfunction. In addition, the results suggest that melatonin supplementation protects against obesity-associated testicular dysfunction and this effect is accompanied by upregulation of PPAR-γ.

The occurrence of hypogonadotropic hypogonadism in Chinese men with type 2 diabetes

CONTEXT

The previous studies showed that hypogonadotropic hypogonadism (HH) occurred commonly in men with type 2 diabetes. However, since all the cohorts tested were from American and European studies, the occurrence of HH/nongonadal illness (NGI) in Chinese populations is unclear.

OBJECTIVE

The study aimed to explore the occurrence of HH/NGI in Chinese men with type 2 diabetes. Furthermore, the correlative factors and predictors of hypogonadism were investigated.

DESIGN

We conducted a cross-sectional study of 637 Chinese men with type 2 diabetes aged 20-75 years in our clinic. The prevalence of HH/NGI was investigated by measuring serum total testosterone (TT), sex hormone-binding globulin (SHBG), luteinizing hormone (LH) and follicle-stimulating hormone (FSH) in the enrolled subjects. Free testosterone (FT) was calculated by using SHBG and TT levels and hypogonadism was defined as TT lower than 10.4 nmol/L and calculated FT (cFT) lower than 0.225 nmol/L. The LH cut-off value for defining HH/NGI was 9.4 mIU/ml.

RESULTS

The results suggested that 31.9% of male Chinese type 2 diabetes patients had hypogonadism and 26.5% of subjects in our cohort were determined as HH/NGI. The occurrence of hypogonadism was markedly correlated with body mass index (BMI). There was a significant association between TT, cFT and SHBG levels with BMI. TT levels are inversely correlated with BMI and homeostasis model assessment-estimated insulin resistance (HOMA-IR) while positively related with SHBG. The cFT levels were inversely correlated with age, LH, FSH, BMI and HOMA-IR. Multiple regression analysis suggested that SHBG, BMI and HOMA-IR were significant predictors of TT and cFT.

CONCLUSION

Our present study offered the first evidence that the occurrence of HH/NGI in Chinese male type 2 diabetes was 26.5%. TT and cFT were significantly correlated with BMI, SHBG and HOMA-IR in Chinese men with type 2 diabetes.

Obesity and male infertility: multifaceted reproductive disruption

Background

The global prevalence of obesity has soared to a concerning height in the past few decades. Interestingly, the global decline in semen quality is a parallel occurrence that urges researchers to evaluate if obesity is among the most essential causatives of male infertility or subfertility.

Main body

Obesity may alter the synchronized working of the reproductive-endocrine milieu, mainly the hypothalamic-pituitary-gonadal (HPG) axis along with its crosstalks with other reproductive hormones. Obesity-mediated impairment in semen parameters may include several intermediate factors, which include physical factors, essentially increased scrotal temperature due to heavy adipose tissue deposits, and systemic inflammation and oxidative stress (OS) initiated by various adipose tissue-derived pro-inflammatory mediators. Obesity, via its multifaceted mechanisms, may modulate sperm genetic and epigenetic conformation, which severely disrupt sperm functions. Paternal obesity reportedly has significant adverse effects upon the outcome of assisted reproductive techniques (ARTs) and the overall health of offspring. Given the complexity of the underlying mechanisms and rapid emergence of new evidence-based hypotheses, the concept of obesity-mediated male infertility needs timely updates and pristine understanding.

Conclusions

The present review comprehensively explains the possible obesity-mediated mechanisms, especially via physical factors, OS induction, endocrine modulation, immune alterations, and genetic and epigenetic changes, which may culminate in perturbed spermatogenesis, disrupted sperm DNA integrity, compromised sperm functions, and diminished semen quality, leading to impaired male reproductive functions.

Erectile dysfunction and diabetes: A melting pot of circumstances and treatments

Diabetes mellitus (DM), a chronic metabolic disease characterised by elevated levels of blood glucose, is among the most common chronic diseases. The incidence and prevalence of DM have been increasing over the years. The complications of DM represent a serious health problem. The long-term complications include macroangiopathy, microangiopathy and neuropathy as well as sexual dysfunction (SD) in both men and women. Erectile dysfunction (ED) has been considered the most important SD in men with DM. The prevalence of ED is approximately 3.5-fold higher in men with DM than in those without DM. Common risk factors for the development of DM and its complications include sedentary lifestyle, overweight/obesity and increased caloric consumption. Although lifestyle changes may help improve sexual function, specific treatments are often needed. This study aims to review the definition and prevalence of ED in DM, the impact of DM complications and DM treatment on ED and, finally, the current and emerging therapies for ED in patients with DM.

Endocrinopathies and Male Infertility

Male infertility is approaching a concerning prevalence worldwide, and inflicts various impacts on the affected couple. The hormonal assessment is a vital component of male fertility evaluation as endocrine disorders are markedly reversible causatives of male infertility. Precise hormonal regulations are prerequisites to maintain normal male fertility parameters. The core male reproductive event, spermatogenesis, entails adequate testosterone concentration, which is produced via steroidogenesis in the Leydig cells. Physiological levels of both the gonadotropins are needed to achieve normal testicular functions. The hypothalamus-derived gonadotropin-releasing hormone (GnRH) is considered the supreme inducer of the gonadotropins and thereby the subsequent endocrine reproductive events. This hypothalamic–pituitary–gonadal (HPG) axis may be modulated by the thyroidal or adrenal axis and numerous other reproductive and nonreproductive hormones. Disruption of this fine hormonal balance and their crosstalk leads to a spectrum of endocrinopathies, inducing subfertility or infertility in men. This review article will discuss the most essential endocrinopathies associated with male factor infertility to aid precise understanding of the endocrine disruptions-mediated male infertility to encourage further research to reveal the detailed etiology of male infertility and perhaps to develop more customized therapies for endocrinopathy-induced male infertility.

The relation between obesity, kisspeptin, leptin, and male fertility

Over the past decades, obesity and infertility in men increased in parallel, and the association between both phenomena have been examined by several researchers. despite the fact that there is no agreement, obesity appears to affect the reproductive potential of men through various mechanisms, such as changes in the hypothalamic-pituitary-testicular (HPT) axis, spermatogenesis, sperm quality and/or alteration of sexual health. Leptin is a hormone produced by the adipose tissue, and its production elevates with increasing body fat. Many studies have supported the relationship between raised leptin production and reproductive function regulation. In fact, Leptin acts on the HPT axis in men at all levels. However, most obese men are insensitive to increased production of endogenous leptin and functional leptin resistance development. Recently, it has been recommended that Kisspeptin neurons mediate the leptin's effects on the reproductive system. Kisspeptin binding to its receptor on gonadotropin-releasing hormone (GnRH) neurons, activates the mammal's reproductive axis and stimulates GnRH release. Increasing infertility associated with obesity is probably mediated by the Kisspeptin-GnRH pathway. In this review, the link between obesity, kisspeptin, leptin, and male fertility will be discussed.

Voluntary exercise could reduce sperm malformations by improving hypothalamus-hypophysis-gonadal axis and kisspeptin/leptin signaling in type 2 diabetic rats

Objectives

Most male patients with type 2 diabetes mellitus (T2DM) experience infertility. It is well established that regular physical activity could alleviate diabetic infertility symptoms. This study was designed to determine the effect of voluntary exercise on sperm malformation.

Materials and Methods

Thirty-two male Wistar rats were randomly divided into control (C), diabetic (D), voluntary exercise (Ex), and diabetic-voluntary exercise (D-Ex) groups. Diabetes was induced by an intraperitoneal injection of streptozotocin (35 mg/kg) followed by a high-fat diet for four weeks. Voluntary exercise was performed by placing the animals in the rotary wheel cages for ten weeks. Sperm malformations were analyzed. Moreover, the hypothalamic leptin, kisspeptin, kisspeptin receptors (KissR), as well as plasma LH, FSH, testosterone, and leptin levels were evaluated.

Results

Results showed that induction of T2DM caused increased sperm malformation, plasma, and hypothalamic leptin as well as decreased hypothalamic kisspeptin, KissR, and plasma LH levels compared with the C group (P<0.001 to P<0.01). Voluntary exercise in the Ex group increased hypothalamic KissR, plasma FSH, LH, and testosterone levels compared with the C group; however, it decreased sperm malformation and hypothalamic leptin levels (P<0.001 to P<0.05). Voluntary exercise in the D-Ex group reduced sperm malformation, hypothalamic leptin, and plasma testosterone while elevated hypothalamic kisspeptin and KissR protein levels compared with the D group (P<0.001 to P<0.01).

Conclusion

The results illustrated voluntary exercise reduces sperm malformations by improving the HHG axis and kisspeptin/leptin signaling in rats with T2DM.

Type 2 diabetes mellitus increases risk of erectile dysfunction independent of obesity and dyslipidemia: A Mendelian randomization study

BACKGROUND

The causal effects of individual risk factors of metabolic syndrome on erectile dysfunction (ED) are still unclear.

OBJECTIVES

To evaluate the causal effect of risk factors of metabolic syndrome on ED through Mendelian randomization (MR).

MATERIALS AND METHODS

Data for risk factors were obtained from multiple databases with 173,082-757,601 individuals, and that for ED were collected from a genome-wide association study including 223,805 Europeans. We performed univariate MR analysis using inverse-variance weighted, MR-Egger, weighted-median, weighted mode methods and multivariable MR analysis to evaluate the total and direct causal effects.

RESULTS

The univariable MR supported that type 2 diabetes mellitus (odds ratios [OR] = 1.14, 95% confidence intervals [CI]: 1.08-1.21, p < 0.001) and body mass index (BMI) (OR = 1.27, 95% CI: 1.12-1.44, p < 0.001) were associated with ED. After excluding the SNPs associated with BMI and other risk factors, the results of multivariable MR for T2D (OR = 1.15, 95% CI: 1.05-1.25, p = 0.001) remained consistent. However, the results of multivariable MR provided limited evidence for the causality between BMI and ED (OR = 1.06, 95% CI: 0.88-1.29, p = 0.532). For systolic blood pressure and lipid components (low-density lipoprotein, high-density lipoprotein and triglycerides), both univariable and multivariable MR failed to offer sufficient evidence to confirm their causal effect on ED.

CONCLUSION

T2D showed a direct causal effect on ED independent of obesity and dyslipidemia.

Obesity and reproduction: a committee opinion

The purpose of this American Society for Reproductive Medicine Practice Committee report is to provide clinicians with principles and strategies for the evaluation and treatment of couples with infertility associated with obesity. This revised document replaces the Practice Committee document titled "Obesity and reproduction: an educational bulletin" last published in 2015 (Fertil Steril 2015;104:1116-26).

Mechanisms of Central Hypogonadism

Reproductive function depends upon an operational hypothalamo–pituitary–gonadal (HPG) axis. Due to its role in determining survival versus reproductive strategies, the HPG axis is vulnerable to a diverse plethora of signals that ultimately manifest with Central Hypogonadism (CH) in all its many guises. Acquired CH can result from any pituitary or hypothalamic lesion, including its treatment (such as surgical resection and/or radiotherapy). The HPG axis is particularly sensitive to the suppressive effects of hyperprolactinaemia that can occur for many reasons, including prolactinomas, and as a side effect of certain drug therapies. Physiologically, prolactin (combined with the suppressive effects of autonomic neural signals from suckling) plays a key role in suppressing the gonadal axis and establishing temporary CH during lactation. Leptin is a further key endocrine regulator of the HPG axis. During starvation, hypoleptinaemia (from diminished fat stores) results in activation of hypothalamic agouti-related peptide neurons that have a dual purpose to enhance appetite (important for survival) and concomitantly suppresses GnRH neurons via effects on neural kisspeptin release. Obesity is associated with hyperleptinaemia and leptin resistance that may also suppress the HPG axis. The suppressibility of the HPG axis also leaves it vulnerable to the effects of external signals that include morphine, anabolic-androgenic steroids, physical trauma and stress, all of which are relatively common causes of CH. Finally, the HPG axis is susceptible to congenital malformations, with reports of mutations within >50 genes that manifest with congenital CH, including Kallmann Syndrome associated with hyposmia or anosmia (reduction or loss of the sense of smell due to the closely associated migration of GnRH with olfactory neurons during embryogenesis). Analogous to the HPG axis itself, patients with CH are often vulnerable, and their clinical management requires both sensitivity and empathy.

The influence of intermittent hypoxia, obesity, and diabetes on male genitourinary anatomy and voiding physiology

We used male BTBR mice carrying the Lep^ob mutation, which are subject to severe and progressive obesity and diabetes beginning at 6 wk of age, to examine the influence of one specific manifestation of sleep apnea, intermittent hypoxia (IH), on male urinary voiding physiology and genitourinary anatomy. A custom device was used to deliver continuous normoxia (control) or IH to wild-type and Lep^ob/ob (mutant) mice for 2 wk. IH was delivered during the 12-h inactive (light) period in the form of 90 s of 6% O₂ followed by 90 s of room air. Continuous room air was delivered during the 12-h active (dark) period. We then evaluated genitourinary anatomy and physiology. As expected for the type 2 diabetes phenotype, mutant mice consumed more food and water, weighed more, and voided more frequently and in larger urine volumes. They also had larger bladder volumes but smaller prostates, seminal vesicles, and urethras than wild-type mice. IH decreased food consumption and increased bladder relative weight independent of genotype and increased urine glucose concentration in mutant mice. When evaluated based on genotype (normoxia + IH), the incidence of pathogenic bacteriuria was greater in mutant mice than in wild-type mice, and among mice exposed to IH, bacteriuria incidence was greater in mutant mice than in wild-type mice. We conclude that IH exposure and type 2 diabetes can act independently and together to modify male mouse urinary function. NEW & NOTEWORTHY Metabolic syndrome and obstructive sleep apnea are common in aging men, and both have been linked to urinary voiding dysfunction. Here, we show that metabolic syndrome and intermittent hypoxia (a manifestation of sleep apnea) have individual and combined influences on voiding function and urogenital anatomy in male mice.

Association of night-time sleep and day napping with the prevalence of MOSH in young obese men

BACKGROUND

Obesity in men is also shown to be associated with reduced reproductive potential, and this particular subtype was described as male obesity-associated secondary hypogonadism (MOSH). Recent studies showing the influence of sleep disorders on testosterone levels suggested a potential role of sleep disorders in determining the development of MOSH.

OBJECTIVES

To assess the association between night-time sleep duration and day napping and the prevalence of MOSH.

MATERIALS AND METHODS

In this cross-sectional study, 226 obese male participants aged 18-30 years were enrolled. Daytime napping and night-time sleep duration data were collected using a standardized self-reported Chinese-language questionnaire. MOSH was defined as obese men (BMI ≥ 30 kg/m² ) with hypogonadal symptoms and decreased total testosterone level and/or free testosterone level, excluding other causes of hypogonadism.

RESULTS

The overall prevalence of MOSH was 48.2% in this study. An inverse association was observed between night sleep duration and the risk of prevalent MOSH. Men who reported fewer than 6 h of night-time sleep had reduced total testosterone and free testosterone levels and an increased risk of MOSH. Further regression analysis revealed that after adjustment for potential confounders, the odds ratio of MOSH for the short night-time sleep group (<6 h vs. 6-8 h) was 6.17 (p = 0.040). No significant association was observed between day napping status and prevalence of MOSH.

DISCUSSION AND CONCLUSION

Short night sleep duration was associated with an increased risk of MOSH in the young obese Chinese population. Chronic sleep curtailment has a negative effect on obese men's health in terms of hypogonadism.

Recent Update on the Molecular Mechanisms of Gonadal Steroids Action in Adipose Tissue

The gonadal steroids, including androgens, estrogens and progestogens, are involved in the control of body fat distribution in humans. Nevertheless, not only the size and localization of the fat depots depend on the sex steroids levels, but they can also highly affect the functioning of adipose tissue. Namely, the gonadocorticoids can directly influence insulin signaling, lipid metabolism, fatty acid uptake and adipokine production. They may also alter energy balance and glucose homeostasis in adipocytes in an indirect way, e.g., by changing the expression level of aquaglyceroporins. This work presents the recent advances in understanding the molecular mechanism of how the gonadal steroids influence the functioning of adipose tissue leading to a set of detrimental metabolic consequences. Special attention is given here to highlighting the sexual dimorphism of adipocyte functioning in terms of health and disease. Particularly, we discuss the molecular background of metabolic disturbances occurring in consequence of hormonal imbalance which is characteristic of some common endocrinopathies such as the polycystic ovary syndrome. From this perspective, we highlight the potential drug targets and the active substances which can be used in personalized sex-specific management of metabolic diseases, in accord with the patient's hormonal status.

Analysis of the Functional Aspects of Sperm and Testicular Oxidative Stress in Individuals Undergoing Metabolic Surgery

PURPOSE

Metabolic surgery is a recommended treatment for obese patients that results in BMI reduction; however, the observed impact of this therapy on male fertility is inconsistent. This research aimed to study the effects of BMI changes after metabolic surgery on seminal analysis, sex hormonal profile, sperm functional integrity, and the seminal plasma lipid peroxidation levels.

MATERIALS AND METHODS

A prospective study was performed in 15 patients for whom metabolic surgery was recommended. The patients were evaluated by the techniques proposed in this study before and after the surgical procedure for 12 months. In each analysis, the male sex hormonal profile, semen analysis, sperm functional integrity, and seminal lipid peroxidation levels were assessed.

RESULTS

The surgery resulted in BMI reduction and improvement in seminal characteristics and male sex hormone profile. The semen analysis showed increases in volume, sperm progressive motility, and in sperm morphology and a decrease in immotile sperms. Sperm mitochondrial activity and sperm DNA integrity were improved, and the levels of seminal lipid peroxidation were decreased. The hormonal profile showed lower levels of estradiol and highest levels of luteinizing hormone (LH), sex hormone-binding globulin (SHBG), and testosterone.

CONCLUSION

BMI changes resulting from this treatment and its metabolic consequences can be associated with changes in the male fertile potential, leading to an improvement in the seminal quality, male sex hormone profile, sperm functional aspects, and levels of seminal lipid peroxidation, thus decreasing the testicular oxidative stress.

Testosterone activates glucose metabolism through AMPK and androgen signaling in cardiomyocyte hypertrophy

Background

Testosterone regulates nutrient and energy balance to maintain protein synthesis and metabolism in cardiomyocytes, but supraphysiological concentrations induce cardiac hypertrophy. Previously, we determined that testosterone increased glucose uptake—via AMP-activated protein kinase (AMPK)—after acute treatment in cardiomyocytes. However, whether elevated glucose uptake is involved in long-term changes of glucose metabolism or is required during cardiomyocyte growth remained unknown. In this study, we hypothesized that glucose uptake and glycolysis increase in testosterone-treated cardiomyocytes through AMPK and androgen receptor (AR).

Methods

Cultured cardiomyocytes were stimulated with 100 nM testosterone for 24 h, and hypertrophy was verified by increased cell size and mRNA levels of β-myosin heavy chain (β-mhc). Glucose uptake was assessed by 2-NBDG. Glycolysis and glycolytic capacity were determined by measuring extracellular acidification rate (ECAR).

Results

Testosterone induced cardiomyocyte hypertrophy that was accompanied by increased glucose uptake, glycolysis enhancement and upregulated mRNA expression of hexokinase 2. In addition, testosterone increased AMPK phosphorylation (Thr172), while inhibition of both AMPK and AR blocked glycolysis and cardiomyocyte hypertrophy induced by testosterone. Moreover, testosterone supplementation in adult male rats by 5 weeks induced cardiac hypertrophy and upregulated β-mhc, Hk2 and Pfk2 mRNA levels.

Conclusion

These results indicate that testosterone stimulates glucose metabolism by activation of AMPK and AR signaling which are critical to induce cardiomyocyte hypertrophy.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40659-021-00328-4.

Serum testosterone in Nigerian men with type 2 diabetes mellitus and its relationship with insulin sensitivity and glycemic control

BACKGROUND

There is increasing evidence that testosterone deficiency has key associations with insulin sensitivity and glycemic control. Its presence may therefore contribute to and/or exacerbate clinical disease in men with type 2 diabetes mellitus (T2DM). This study sought to determine the frequency of low free testosterone and explore its relationship with, insulin sensitivity and glycemic control among Nigerian men with T2DM.

METHODS

One hundred and four men with type 2 DM and one hundred and one apparently healthy non-diabetic men matched for age, were recruited into the study Socio-demographic data, anthropometric measurements and blood samples were obtained for measurement of serum total testosterone (TT), sex hormone binding globulin (SHBG), fasting plasma insulin, fasting plasma glucose (FPG), glycated hemoglobin (HbA1c) and fasting lipid profile in all the subjects. Insulin sensitivity (%IS) and free testosterone (CFT) were then calculated.

RESULTS

The median CFT for men with T2DM was significantly lower than that of non-diabetic controls (0.17 nmol/L vs 0.58 nmol/L respectively; P < 0.001). 52.9% of men with T2DM had low CFT, as compared with 21.4% amongst the non-diabetic controls; P < 0.001. Among men with T2DM, those with lower CFT had significantly lower median % S and higher mean HbA1c than those with normal CFT (37.0% versus 63.0%; P = 0.021 and 7.79 (2.03) % versus 7.02 (1.94) %; P = 0.038 respectively]. HbA1c had significant negative correlations with both CFT (correlation coefficient: -0.239 (P < 0.05) and TT (correlation coefficient: 0.354; P < 0.01. There was no significant difference in serum lipids when T2DM men with low serum CFT were compared with T2DM men with normal serum CFT levels.

CONCLUSION

We conclude that low serum testosterone is common among men with T2DM and has a significant association with glycemic control (HbA1c) and insulin sensitivity.

Primary and Secondary Hypogonadism in Male Persons with Diabetes Mellitus

AIMS

To characterize hypogonadism in male persons with diabetes mellitus. Patients and Methods. 184 consecutive male persons with diabetes were studied. Besides the usual care, total testosterone (TT), estradiol (E2), FSH, and LH were measured in the last appointment and in 40 patients, also in the next two appointments. Statistical analysis compared groups and explored factors for TT and LH levels.

RESULTS

TT levels were stable and highly correlated (r > 0.750, p < 0.001) over a 6-12-month period. 20% of the patients presented secondary hypogonadism (SH) and 18% presented primary hypogonadism (PH). SH was inversely related to HbA1 (partial r (rp) = 0.229, p < 0.005), while PH was directly related to age (r = 0.356, p < 0.001). TT levels were reduced independently by metformin (364 ± 160 vs. 431 ± 242 ng/dL, t = 2.241, p < 0.05) and statins (359 ± 156 vs. 424 ± 230 ng/dl, t = 2.224, p < 0.05). TT levels were inversely related to microvascular disease (rp = -0.169, p < 0.05). Discussion. TT levels were stable over time and hypogonadism was common. SH, generally clinically, is related to the diabetic state, while PH, generally subclinically, is an age-dependent process unrelated to diabetes. Low TT levels were related to older age, poor metabolic control, metformin and statins use, and microvascular disease.

Classic and Novel Sex Hormone Binding Globulin Effects on the Cardiovascular System in Men

In men, 70% of circulating testosterone binds with high affinity to plasma sex hormone binding globulin (SHBG), which determines its bioavailability in their target cells. In recent years, a growing body of evidence has shown that circulating SHBG not only is a passive carrier for steroid hormones but also actively regulates testosterone signaling through putative plasma membrane receptors and by local expression of androgen-binding proteins apparently to reach local elevated testosterone concentrations in specific androgen target tissues. Circulating SHBG levels are influenced by metabolic and hormonal factors, and they are reduced in obesity and insulin resistance, suggesting that SHBG may have a broader clinical utility in assessing the risk for cardiovascular diseases. Importantly, plasma SHBG levels are strongly correlated with testosterone concentrations, and in men, low testosterone levels are associated with an adverse cardiometabolic profile. Although obesity and insulin resistance are associated with an increased incidence of cardiovascular disease, whether they lead to abnormal expression of circulating SHBG or its interaction with androgen signaling remains to be elucidated. SHBG is produced mainly in the liver, but it can also be expressed in several tissues including the brain, fat tissue, and myocardium. Expression of SHBG is controlled by peroxisome proliferator-activated receptor γ (PPARγ) and AMP-activated protein kinase (AMPK). AMPK/PPAR interaction is critical to regulate hepatocyte nuclear factor-4 (HNF4), a prerequisite for SHBG upregulation. In cardiomyocytes, testosterone activates AMPK and PPARs. Therefore, the description of local expression of cardiac SHBG and its circulating levels may shed new light to explain physiological and adverse cardiometabolic roles of androgens in different tissues. According to emerging clinical evidence, here, we will discuss the potential mechanisms with cardioprotective effects and SHBG levels to be used as an early metabolic and cardiovascular biomarker in men.

Hypothalamic reproductive neurons communicate through signal transduction to control reproduction

Gonadotropin-releasing hormone (GnRH) neurons in the hypothalamus coordinate fertility and puberty. In order to achieve successful reproductive capacity, they receive signals from the periphery and from other hypothalamic neurons that coordinate energy homeostasis. Hormones, such as estradiol, insulin, leptin, and adiponectin, act directly or indirectly on GnRH and its associated reproductive neurons. Nutrients like glucose and fatty acids can also affect reproductive neurons to signal nutrient availability. Additionally, acute and chronic inflammation is reported to detrimentally affect GnRH and kisspeptin expression. All of these cues activate signal transduction pathways within neurons that lead to the changes in GnRH neuronal function. The signalling pathways can also be dysregulated by endocrine disrupting chemicals, which impair fertility by misappropriating common signalling pathways. The complex mechanisms controlling the levels of GnRH during the reproductive cycle rely on a carefully orchestrated set of signal transduction events to regulate the positive and negative feedback arms of the hypothalamic-pituitary-gonadal axis. If these signalling events are dysregulated, this will result is a downregulatory event leading to hypogonadal hypogonadism with decreased or absent fertility. Therefore, an understanding of the mechanisms involved in distinct neuronal signalling could provide an advantage to inform therapeutic interventions for infertility and reproductive disorders.

Lifestyle, metabolic disorders and male hypogonadism - A one-way ticket?

Hypogonadism is more frequent among men with common metabolic diseases, notably obesity and type 2 diabetes. Indeed, endocrine disruption caused by metabolic diseases can trigger the onset of hypogonadism, although the underlying molecular mechanisms are not entirely understood. Metabolic diseases are closely related to unhealthy lifestyle choices, such as dietary habits and sedentarism. Therefore, hypogonadism is part of a pathological triad gathering unhealthy lifestyle, metabolic disease and genetic background. Additionally, hypogonadism harbors the potential to aggravate underlying metabolic disorders, further sustaining the mechanisms leading to disease. To what extent does lifestyle intervention in men suffering from these metabolic disorders can prevent, improve or reverse hypogonadism, is still controversial. Moreover, recent evidence suggests that the metabolic status of the father is related to the risk of inter and transgenerational inheritance of hypogonadism. In this review, we will address the proposed mechanisms of disease, as well as currently available interventions for hypogonadism.

The effect of metformin treatment on the basal and gonadotropin-stimulated steroidogenesis in male rats with type 2 diabetes mellitus

Type 2 diabetes mellitus impairs reproductive functions in men, and important tasks are deciphering the mechanisms of testicular dysfunctions in diabetes and the search of effective approaches to their correction. The purpose was to study the effect of four-week metformin treatment (120 mg kg^-1  day^-1 ) of male Wistar rats with high-fat diet/low-dose streptozotocin-induced type 2 diabetes on basal and gonadotropin-stimulated steroidogenesis, intratesticular content of leptin and the leptin and luteinising hormone receptors and on spermatogenesis. Diabetic rats had hyperleptinaemia, androgen deficiency and reduced sperm count and quality, and in the testes, they had the increased leptin level and the decreased content of the leptin and luteinising hormone receptors and 17-hydroxyprogesterone. The stimulating effects of chorionic gonadotropin on testosterone production and expression of steroidogenic genes (Star, Cyp11a1) were decreased. Metformin restored basal and gonadotropin-stimulated blood testosterone levels. In the testes, it restored gonadotropin-stimulated 17-hydroxyprogesterone, androstenedione and testosterone levels, Star expression and the content of leptin and the leptin and luteinising hormone receptors. Metformin also improved epididymal sperm count and morphology. We concluded that metformin treatment normalises the testicular steroidogenesis in diabetic rats, which is due to restoration of the gonadotropin and leptin systems in the testes and is associated with an improvement in spermatogenesis.

Metabolic regulation of kisspeptin - the link between energy balance and reproduction

Hypothalamic kisspeptin neurons serve as the nodal regulatory centre of reproductive function. These neurons are subjected to a plethora of regulatory factors that ultimately affect the release of kisspeptin, which modulates gonadotropin-releasing hormone (GnRH) release from GnRH neurons to control the reproductive axis. The presence of sufficient energy reserves is critical to achieve successful reproduction. Consequently, metabolic factors impose a very tight control over kisspeptin synthesis and release. This Review offers a synoptic overview of the different steps in which kisspeptin neurons are subjected to metabolic regulation, from early developmental stages to adulthood. We cover an ample array of known mechanisms that underlie the metabolic regulation of KISS1 expression and kisspeptin release. Furthermore, the novel role of kisspeptin neurons as active players within the neuronal circuits that govern energy balance is discussed, offering evidence of a bidirectional role of these neurons as a nexus between metabolism and reproduction.

Serum vitamin D levels and type 2 diabetic erectile dysfunction: A protocol for systematic review and meta-analysis

INTRODUCTION

Diabetic erectile dysfunction (DED) has gradually become a worldwide problem. Due to the mechanism of DED is not clear, it is impossible to treat it pertinently. Recently, some studies have shown that vitamin D is associated with DED, type 2 diabetes mellitus (T2DM) and erectile dysfunction (ED), but there is no systematic review and meta-analysis on the relationship between vitamin D and DED.

METHODS AND ANALYSIS

The databases of English databases (PubMed, MEDLINE, EMBASE, Web of Science, Cochrane Library) and Chinese databases (China National Knowledge Infrastructure, China Biology Medicine Database, Wanfang Database, VIP Database) will be retrieved. The search strategy that will be run in the PubMed and tailored to the other database when necessary is presented in . RevMan 5.3 and Stata 11.0 will be used for Systematic Review and Meta-analysis. This protocol reported under the Preferred Reporting ltems for Systematic Reviews and Meta-Analyses Protocols (PRISMA-P) statement, and we will report the systematic review by following the PRISMA statement.(Table is included in full-text article.) RESULTS:: Through a systematic review, and meta-analysis when necessary, we can obtain the relationship between vitamin D and DED. We will share our findings in the third quarter of 2021.

CONCLUSION

The association between serum vitamin D levels and type 2 diabetic erectile dysfunction will be assessed. Besides, the results of this review may provide some help for clinicians to make decisions.

ETHICS AND DISSEMINATION

Ethical approval is not required as the review is a secondary study based on published literature. The results will be published in a public issue journal to provide evidence-based medical evidence for urologists and andrologists to make better clinical decisions.

PROTOCOL REGISTRATION NUMBER

INPLASY202040164.

Cx30.2 deletion causes imbalances in testicular Cx43, Cx46, and Cx50 and insulin receptors. Reciprocally, diabetes/obesity alters Cx30.2 in mouse testis

Cx30.2 protein content and localization were assessed during development. An account of Cx30.2, Cx43, Cx46, and Cx50, and insulin receptor (IR) responses to Cx30.2, Cx46, or Cx50 deficiency in mouse interstitial tissue (ITf)- and seminiferous tubule-enriched fractions (STf) is given. The impact of high glucose/insulin on Cx30.2 was investigated in spontaneously diabetic and obese db/db and ob/ob mouse testis and anterior pituitary (AP). Cx30.2 labeled contacts in vascular endothelial and Leydig cells and Sertoli cell junctions in stage V-VII. Cx30.2 expression is regulated differently in the interstitium and tubules. Cx30.2 at 30-kDa levels peaked by 28 days in ITf and by 14 days in STf. In STf, deleting Cx30.2 decreased Cx43 and Cx50, whereas deleting Cx50 downregulated Cx30.2. The opposite occurred in ITf. In STf, deleting Cx30.2 upregulated Cx46 except the full-length reciprocally, deleting Cx46 upregulated Cx30.2. In ITf, Cx30.2 deficiency upregulated full-length and phosphorylated Cx46, whereas deleting Cx46 downregulated 48- to 50-kDa Cx30.2. The db/db and ob/ob mouse ITf, STf, and AP showed imbalanced Cx30.2 levels. IRα levels at 135 kDa declined in Cx30.2-/- and Cx50-/- mouse ITf and Cx46-/- and Cx50-/- STf. IRβ at 98 to 110 kDa dropped in Cx30.2-/- and Cx46-/- mice STf suggesting that Cx30.2 deficiency decreases active IR sites. The results show the connexins interdependence and interaction and that altering a single connexin changes the remaining connexins expression, which can modify gap junction-mediated glucose exchanges in contacting cells. Data suggest that glucose/insulin influences Cx30.2 turnover in testis and AP and, reciprocally, that connexins modulate testis glucose uptake and response to insulin.

Nesfatin-1 ameliorates type-2 diabetes-associated reproductive dysfunction in male mice

PURPOSE

The present study was aimed to demonstrate the recuperative effect of nesfatin-1 on testicular dysfunction in the high-fat diet (HFD)/streptozotocin (STZ)-induced type-2 diabetes mellitus (T2DM) mice.

METHOD AND RESULTS

Three experimental groups were formed: (1) vehicle control (VC), (2) T2DM mice, (3) T2DM + nesf-1. The mice with blood glucose level higher than 300 mg/dL following HFD and a single dose of STZ were used for the experiment. The T2DM mice showed increases in body mass, blood glucose and insulin levels, reductions in spermatogenesis and steroidogenesis, production of antioxidative enzymes, and disturbed lipid profile. These alterations were all ameliorated by administration of nesfatin-1 at 20 μg/Kg BW for 15 days. Nesfatin-1 treatment also increased the production of testosterone (T), improved insulin sensitivity, and effectively ameliorated the testicular aberrations, and increased spermatogenesis and steroidogenesis. In addition, nesfatin-1 treatment upregulated the PCNA and Bcl2 expression and inhibited the caspase-3 and prohibitin expression in T2DM mice. Nesfatin-1 increased insulin receptor (IR) and GLUT8 expressions, and lactate production, the changes that further substantiate the increase of energy influx to the testis.

CONCLUSION

Altogether, the results suggest the ameliorative effect of nesfatin-1 against T2DM-associated testicular dysfunctions and improved insulin sensitivity along with promoting T production and fertility in T2DM mice.

Glucose, insulin, insulin receptor subunits α and β in normal and spontaneously diabetic and obese ob/ob and db/db infertile mouse testis and hypophysis

BACKGROUND

Type 2 diabetes touches young subjects of reproductive age in epidemic proportion. This study assesses glucose, total InsulinT, Insulin2 and insulin receptor subunits α and β in testis during mouse development then, in the spontaneously type 2 diabetes models associated with infertility db/db and ob/ob mice. IR-β and α were also assessed in spermatozoa (SPZ), anterior pituitary (AP) and serum.

METHODS

Serum and tissue glucose were measured with enzymatic colorimetric assays and InsulinT and Insulin2 by ELISAs in serum, interstitial tissue- (ITf) and seminiferous tubule (STf) fractions in14- > 60-day-old normal and db/db, ob/ob and wild type (WT) mice. IR subunits were assessed by immunoblotting in tissues and by immunoprecipitation followed by immunoblotting in serum.

RESULTS

Development: Glucose increased in serum, ITf and STf. InsulinT and Insulin2 dropped in serum; both were higher in STf than in ITf. In > 60-day-old mouse ITf, insulinT rose whereas Insulin2 decreased; InsulinT and Insulin2 rose concurrently in STf. Glucose and insulin were high in > 60-day-old ITf; in STf high insulin2 accompanied low glucose. One hundred ten kDa IR-β peaked in 28-day-old ITf and 14-day-old STf. One hundred thirty five kDa IR-α was high in ITf but decreased in STf. Glucose escalated in db/db and ob/ob sera. Glucose doubled in ITf while being halved in STf in db/db mice. Glucose significantly dropped in db/db and ob/ob mice spermatozoa. InsulinT and Insulin2 rose significantly in the serum, ITf and STf in db/db and ob/ob mice. One hundred ten kDa IR-β and 135 kDa IR-α decreased in db/db and ob/ob ITf. Only 110 kDa IR-β dropped in db/db and ob/ob STf and AP. One hundred ten kDa IR-β fell in db/db and ob/ob SPZ. One hundred ten kDa sIR-α rose in the db/db and ob/ob mouse sera.

CONCLUSION

Insulin regulates glucose in tubules not in the interstitium. The mouse interstitium contains InsulinT and Insulin2 whereas tubules contain Insulin2. Decreased 110 kDa IR-β and 135 kDa IR-α in the db/db and ob/ob interstitial tissue suggest a loss of active receptor sites that could alter the testicular cell insulin binding and response to the hormone. Decreased IR-β levels were insufficient to stimulate downstream effectors in AP and tubules. IR-α shedding increased in db/db and ob/ob mice.