Cross-Sectional, Primary Care-Based Study of the Prevalence of Hypoandrogenemia in Nondiabetic Young Men with 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.

Androgens and erectile dysfunction: from androgen deficiency to treatment

INTRODUCTION

Androgens play important roles in regulating the growth and development of the male reproductive system and maintaining libido and erectile function. The specific mechanisms by which androgen deficiency leads to erectile dysfunction (ED) are not yet fully understood.

OBJECTIVES

To understand the mechanisms and treatment of androgen deficiency-related ED.

METHODS

A literature search in the past 10 years was conducted in PubMed and Google Scholar to determine the effects of androgen deficiency on erectile function and the treatment of androgen deficiency.

RESULTS

Androgen deficiency can be caused by hypothalamic-pituitary lesions and injuries, testicular-related diseases and injuries, endocrine and metabolic disorders, the side effects of medication, and age. Androgen deficiency can lead to ED by inhibiting the NOS/NO/cGMP pathway (nitric oxide synthase/nitric oxide/cyclic guanosine monophosphate) and altering the expression of ion channel proteins, as well as by inducing oxidative stress, death, and fibrosis in penile corpus cavernosum cells. Testosterone replacement therapy is effective at improving the serum testosterone levels and erectile function in patients with androgen deficiency. For patients who need to maintain a low androgenic state, erectile function can be improved by lifestyle changes, treatment with phosphodiesterase type 5 inhibitors, low-intensity extracorporeal shock wave therapy, and stem cell therapy.

CONCLUSIONS

Androgen deficiency can affect the structure and function of the penile corpus cavernosum, leading to ED. Areas of further study include how androgen replacement therapy can improve erectile function and how to improve the maintenance of erectile function in patients with hypoandrogenic status.

Impact of body composition analysis on male sexual function: A metabolic age study

Introduction

Metabolic Age (MetAge) and body composition analysis may reflect an individual's metabolic status, which is believed to influence male sexual and gonadal functions. Although erectile dysfunction (ED) and hypogonadism are increasingly prevalent with age, they are also detected among younger men. This study aims to assess the impact of MetAge and body composition on male sexual and gonadal status overall, and particularly in men younger than 40 years of age.

Methods

This was a cross-sectional study of 90 male healthcare workers, between the ages of 18-55, randomly selected based on their corporation numbers. In addition to Bioelectric Impedance Analysis, subjects were requested to fill the International Index of Erectile Function questionnaire (IIEF-5) and to provide an early morning serum testosterone (T) sample.

Results

The mean participants' age was 39.4 ± 9.4 years, MetAge was 45.54 ± 10.35 years, serum T level was 13.68 ± 4.49 nmol/L and BMI was 28.8 ± 4.7 kg/m2. Significant negative correlations were obtained between serum T, MetAge, body weight and fat composition. Significant negative correlations between the IIEF-5 score, MetAge, and fat composition, were only reported in subjects <40 years of age. Significantly lower T levels (p=0.002), significantly older MetAge (p=0.034), and higher BMI (p=0.044) and degree of obesity (p=0.042) were observed in participants <40 years with erectile dysfunction (ED) compared to their counterparts without ED.

Discussion

MetAge and body composition parameters significantly impact the androgenic state. ED in men <40 years is associated with lower T levels, older MetAge and higher BMI and degree of obesity.

Metformin, testosterone, or both in men with obesity and low testosterone: A double-blind, parallel-group, randomized controlled trial

BACKGROUND

Men with obesity tend to be insulin resistant and often have low-normal testosterone concentrations. We conducted a clinical trial aimed to evaluate potential therapeutic strategies for low testosterone in men with obesity.

METHODS

We did a 1-year, parallel, randomized, double-blind, placebo-controlled trial, where we evaluated the independent and combined effects of metformin and testosterone in 106 men with obesity, aged 18-50 years, who had low levels of testosterone and no diabetes mellitus. The primary outcome was change in insulin resistance, measured as Homeostasis Model Assessment for Insulin Resistance (HOMA-IR) index. Secondary outcomes included changes in total and free serum testosterone, body composition, metabolic variables, erectile function, and health-related quality of life (HRQoL).

RESULTS

In the intention-to-treat analysis, the HOMA-IR index decreased significantly in all active groups compared to placebo (metformin -2.4, 95 % CI -4.1 to -0.8, p = 0.004; testosterone -2.7, 95 % CI -4.3 to -1.1, p = 0.001; combination -3.4, 95 % CI -5.0 to -1.8, p < 0.001). Combination therapy was not superior to testosterone alone in decreasing insulin resistance (-0.7, 95 % CI -2.3 to 0.9, p = 0.383). Only the combination of metformin plus testosterone significantly increased total and free testosterone concentrations, compared to placebo. No significant changes in body composition (except for a higher decrease in fat mass in the metformin and combination group), metabolic variables, erectile function, or HRQoL were found with any treatment.

CONCLUSIONS

Among men with obesity and low testosterone concentrations, the combination of metformin plus testosterone, metformin only, and testosterone only, compared to placebo, reduced insulin resistance with no evidence of additive benefit.

The Role of Adiponectin in the Resolution of Male-Obesity-Associated Secondary Hypogonadism after Metabolic Surgery and Its Impact on Cardiovascular Risk

Male-obesity-associated secondary hypogonadism (MOSH) is a very prevalent entity that may resolve after marked weight loss. Adiponectin (APN) is an adipokine with anti-inflammatory properties that regulates metabolism. Low-circulating APN is associated with obesity, diabetes, and cardiovascular risk, along with circulating testosterone. We aimed to evaluate APN changes in men with MOSH (low circulating free testosterone (FT) with low or normal gonadotropins) and without it after metabolic surgery. We look for their possible association with cardiovascular risk measured by carotid intima-media thickness (cIMT). We included 60 men (20 submitted to lifestyle modification, 20 to sleeve gastrectomy, and 20 to gastric bypass) evaluated at baseline and 6 months after. The increase in APN at follow-up was reduction in patients with persistent MOSH (n = 10) vs. those without MOSH (n = 30) and MOSH resolution (n = 20), and the former did not achieve a decrease in cIMT. The increase in APN correlated positively with FT (r = 0.320, p = 0.013) and inversely with cIMT (r = −0.283, p = 0.028). FT inversely correlated with cIMT (r = −0.269, p = 0.038). In conclusion, men without MOSH or with MOSH resolution showed a high increase in APN after weight loss with beneficial effects on cIMT. Those without MOSH resolution failed to attain these effects.

Adipose Tissue Dysfunction and Obesity-Related Male Hypogonadism

Obesity is a chronic illness associated with several metabolic derangements and comorbidities (i.e., insulin resistance, leptin resistance, diabetes, etc.) and often leads to impaired testicular function and male subfertility. Several mechanisms may indeed negatively affect the hypothalamic–pituitary–gonadal health, such as higher testosterone conversion to estradiol by aromatase activity in the adipose tissue, increased ROS production, and the release of several endocrine molecules affecting the hypothalamus–pituitary–testis axis by both direct and indirect mechanisms. In addition, androgen deficiency could further accelerate adipose tissue expansion and therefore exacerbate obesity, which in turn enhances hypogonadism, thus inducing a vicious cycle. Based on these considerations, we propose an overview on the relationship of adipose tissue dysfunction and male hypogonadism, highlighting the main biological pathways involved and the current therapeutic options to counteract this condition.

25-hydroxyvitamin D and testosterone levels association through body mass index: A cross-sectional study of young men with obesity

BACKGROUNDS

Vitamin D and testosterone deficiency have been widely related to obesity. However, only a few studies have investigated the effect of vitamin D on testosterone in the context of obesity, in which controversial results have been raised.

OBJECTIVES

The purpose of this study was to determine the relationship between serum 25-hydroxyvitamin D (25(OH)D) and testosterone levels in young men with different grade of obesity.

DESIGN AND METHODS

This cross-sectional study included 269 healthy young men with obesity (body mass index (BMI) ≥ 30 kg/m²). Participants were divided into two groups based on their serum 25(OH)D levels (134 subjects with vitamin D sufficiency and 135 participants with vitamin D deficiency, according to the 50^th percentile of 25(OH)D). Serum 25(OH)D and sex hormones have been measured. The relationships between 25(OH)D, sex hormones, and obesity grades were investigated with linear and binary logistic regression analyses, as well as mediation analysis.

RESULTS

Compared to the 25(OH)D sufficiency group, total and free testosterone levels were found to be decreased, whereas serum androstenedione levels were increased in the 25(OH)D deficiency group (p<0.05). Using multivariable lineal regression analyses, 25(OH)D was correlated with the majority of sex hormones (p<0.05). When mediation with BMI was performed, the direct effect between 25(OH)D and sex hormones disappeared, and only the indirect effect via BMI remained (demonstrating the importance of BMI). Furthermore, after controlling for age and smoking status, we discovered that total testosterone and SHBG were both significantly associated with 25(OH)D (p<0.05) in subjects with obesity type III. Using a mediation analysis, we discovered that BMI had a partial effect on the association between 25(OH)D and total testosterone levels in morbidly obese participants, indicating that a direct association between 25(OH)D and total testosterone levels, and that BMI partially mediated this association.

CONCLUSIONS

Serum 25(OH)D is associated with total testosterone levels in only those subjects with morbid obesity, suggesting a specific benefit in severe cases of obesity. Additional research is needed to elucidate possible common mechanisms.

Obstructive Sleep Apnea Is Associated With Low Testosterone Levels in Severely Obese Men

Background

Disrupted sleep affects cardio-metabolic and reproductive health. Obstructive sleep apnea syndrome represents a major complication of obesity and has been associated with gonadal axis activity changes and lower serum testosterone concentration in men. However, there is no consistent opinion on the effect of obstructive sleep apnea on testosterone levels in men.

Objective

The aim of this study was to determine the influence of obstructive sleep apnea on total and free testosterone levels in severely obese men.

Materials and methods

The study included 104 severely obese (Body Mass Index (BMI) ≥ 35 kg/m2) men, aged 20 to 60, who underwent anthropometric, blood pressure, fasting plasma glucose, lipid profile, and sex hormone measurements. All participants were subjected to polysomnography. According to apnea-hypopnea index (AHI) patients were divided into 3 groups: <15 (n = 20), 15 - 29.9 (n = 17) and ≥ 30 (n = 67).

Results

There was a significant difference between AHI groups in age (29.1 ± 7.2, 43.2 ± 13.2, 45.2 ± 10.2 years; p < 0.001), BMI (42.8 ± 5.9, 43.2 ± 5.9, 47.1 ± 7.8 kg/m2; p = 0.023), the prevalence of metabolic syndrome (MetS) (55%, 82.4%, 83.6%, p = 0.017), continuous metabolic syndrome score (siMS) (4.01 ± 1.21, 3.42 ± 0.80, 3.94 ± 1.81, 4.20 ± 1.07; p = 0.038), total testosterone (TT) (16.6 ± 6.1, 15.2 ± 5.3, 11.3 ± 4.44 nmol/l; p < 0.001) and free testosterone (FT) levels (440.4 ± 160.8, 389.6 ± 162.5, 294.5 ± 107.0 pmol/l; p < 0.001). TT level was in a significant negative correlation with AHI, oxygen desaturation index (ODI), BMI, MetS and siMS. Also, FT was in a significant negative correlation with AHI, ODI, BMI, age, MetS and siMS. The multiple regression analysis revealed that both AHI and ODI were in significant correlation with TT and FT after adjustment for age, BMI, siMS score and MetS components.

Conclusion

Obstructive sleep apnea is associated with low TT and FT levels in severely obese men.

Measurement of Serum Testosterone in Nondiabetic Young Obese Men: Comparison of Direct Immunoassay to Liquid Chromatography-Tandem Mass Spectrometry

Hypoandrogenemia, a frequent finding in men with obesity, is defined by low concentrations of serum testosterone. Although immunoassay (IA) is the most used method for the determination of this steroid in clinical practice, liquid chromatography-mass spectrometry (LC-MS/MS) is considered a more reliable method. In this study, we aimed to compare IA versus LC-MS/MS measurement for the diagnosis of hypoandrogenemia in a cohort of 273 nondiabetic young obese men. Mean total testosterone (TT) levels were 3.20 ± 1.24 ng/mL for IA and 3.78 ± 1.4 ng/mL for LC-MS/MS. 53.7% and 26.3% of patients were classified as presenting hypoandrogenemia with IA and LC-MS/MS, respectively. Considering LC-MS/MS as the reference method, sensitivity and specificity of IA were 91.4% (95% CI 82.3-96.8) and 61.1% (95% CI 54.0-67.8), respectively. IA presented an AUC of 0.879 (95% CI 0.83-0.928). Multivariate regression analysis indicated that sex hormone-binding globulin (SHBG) concentrations (p = 0.002) and insulin resistance (p = 0.008) were factors associated with discrepant IA values. In conclusion, the determination of TT by IA in nondiabetic young men with obesity yields lower concentrations of TT than LC-MS/MS, resulting in an equivocal increased diagnosis of hypoandrogenemia, which could lead to inaccurate diagnosis and unnecessary treatment.

Adiposity is Associated with Decreased Serum 17-Hydroxyprogesterone Levels in Non-Diabetic Obese Men Aged 18-49: A Cross-Sectional Study

Obesity is associated with decreased circulating testosterone levels, the main male sex hormone. However, there are a number of different male sex hormones whose dynamics remain poorly understood regarding this pathology. In this regard, 17 hydroxyprogesterone (17-OH progesterone), as an important precursor of testosterone synthetized in testes and adrenal glands, could play an essential role in testosterone deficiency in male obesity. Moreover, similarly to testosterone, 17-OH progesterone could be closely associated with visceral fat distribution and metabolic dysfunction. Thus, the aim of this study was to assess serum 17-OH progesterone levels in non-diabetic obese young men and to evaluate their relationship with clinical, analytical, and anthropometric parameters. We conducted a cross-sectional study including 266 non-diabetic men with obesity (BMI ≥ 30 kg/m²) aged 18-49 years; 17-OH progesterone and total testosterone (TT) were determined by high-performance liquid chromatography mass spectrometry. 17-OH progesterone levels were significantly lower in tertile 3 of body fat percentage in comparison with tertile 1 (0.74 ng/mL vs. 0.94 ng/mL, p < 0.01; Bonferroni correction) and in comparison with tertile 2 (0.74 ng/mL vs. 0.89 ng/mL, p = 0.02; Bonferroni correction). 17-OH progesterone levels correlated negatively with weight, BMI, waist circumference, insulin, homeostatic model assessment of insulin resistance (HOMA-IR), and visceral fat, and positively with TT, free testosterone (FT), luteinizing hormone, and fat-free mass percentage. Multivariate linear-regression analysis showed that body fat percentage and HOMA-IR were inversely associated with 17-OH progesterone levels, while FT and ACTH were positively linked to circulating 17-OH progesterone levels. In conclusion, in a population of non-diabetic obese young men, 17-OH progesterone levels were inversely associated with adiposity. Body fat percentage and insulin resistance were negatively related to 17-OH progesterone levels, whereas FT and ACTH levels were positively associated with 17-OH progesterone levels.