The association between serum testosterone and insulin resistance: a longitudinal study

Intranasal insulin treatment ameliorates spatial memory, muscular strength, and frailty deficits in 5xFAD mice

The 5xFAD mouse model shows age-related weight loss as well as cognitive and motor deficits. Metabolic dysregulation, especially impaired insulin signaling, is also present in AD. This study examined whether intranasal delivery of insulin (INI) at low (0.875 U) or high (1.750 U) doses would ameliorate these deficits compared to saline in 10-month-old female 5xFAD and B6SJL wildtype (WT) mice. INI increased forelimb grip strength in the wire hang test in 5xFAD mice in a dose-dependent manner but did not improve the performance of 5xFAD mice on the balance beam. High INI doses reduced frailty scores in 5xFAD mice and improved spatial memory in both acquisition and reversal probe trials in the Morris water maze. INI increased swim speed in 5xFAD mice but had no effect on object recognition memory or working memory in the spontaneous alternation task, nor did it improve memory in the contextual or cued fear memory tasks. High doses of insulin increased the liver, spleen, and kidney weights and reduced brown adipose tissue weights. P-Akt signaling in the hippocampus was increased by insulin in a dose-dependent manner. Altogether, INI increased strength, reduced frailty scores, and improved visual spatial memory. Hypoglycemia was not present after INI, however alterations in tissue and organ weights were present. These results are novel and important as they indicate that intra-nasal insulin can reverse cognitive, motor and frailty deficits found in this mouse model of AD.

Risk of diabetes mellitus based on the interactive association between G6PD rs72554664 polymorphism and sex in Taiwan Biobank individuals

The presence of glucose-6-phosphate dehydrogenase (G6PD) deficiency may increase the risk of type 2 diabetes mellitus (T2DM), with differing prevalence between males and females. Although G6PD deficiency is an X-linked genetic condition, its interaction with sex regarding T2DM risk among the Taiwanese population has not been fully explored. This study aimed to investigate the association between G6PD deficiency and T2DM risk in the Taiwanese population, focusing on the potential influence of sex. Data were obtained from the Taiwan Biobank (TWB) database, involving 85,334 participants aged 30 to 70 years. We used multiple logistic regression analysis to assess the interaction between G6PD rs72554664 and sex in relation to T2DM risk. The T2DM cohort comprised 55.35% females and 44.65% males (p < 0.001). The TC + TT genotype of rs72554664 was associated with an increased risk of T2DM, with an odds ratio (OR) of 1.95 (95% CI: 1.39-2.75), and males showed an OR of 1.31 (95% CI: 1.19-1.44). Notably, the G6PD rs72554664-T allelic variant in hemizygous males significantly elevated the T2DM risk (OR), 4.57; p < 0.001) compared to females with the CC genotype. Our findings suggest that the G6PD rs72554664 variant, in conjunction with sex, significantly affects T2DM risk, particularly increasing susceptibility in males. The association of the G6PD rs72554664-T allelic variant with a higher risk of T2DM highlights the importance of sex-specific mechanisms in the interplay between G6PD deficiency and T2DM.

Testosterone therapy reduces insulin resistance in men with adult-onset testosterone deficiency and metabolic syndrome. Results from the Moscow Study, a randomized controlled trial with an open-label phase

AIMS

To describe changes in homeostasis model assessment of insulin resistance index (HOMA-IR) following testosterone therapy in men with hypogonadism and metabolic syndrome (MetS).

MATERIALS AND METHODS

A randomized, placebo-controlled, double-blind randomized controlled trial (RCT) comprising 184 men with MetS and hypogonadism (testosterone undecanoate [TU]: 113 men, placebo: 71 men) was conducted. This was followed by an open-label phase in which all men were given TU. We focused on men who were not receiving antiglycaemic agents (TU: 81 men; placebo: 54 men) as these could affect HOMA-IR. Inter-group comparison of HOMA-IR was restricted to the RCT (30 weeks), whilst intra-group comparison was carried out on men provided TU during the RCT and open-label phases (study cohort) and men given placebo during the RCT and then switched to TU during the open-label phase (confirmatory cohort). Regression analysis was performed to identify factors associated with change in HOMA-IR (∆HOMA-IR).

RESULTS

The median HOMA-IR was significantly reduced at almost every time point (after 18 weeks) compared to baseline in men receiving TU in both the study and confirmatory cohorts. There was a significant decrease in median values of fasting glucose (30 weeks: -2.1%; 138 weeks: -4.9%) and insulin (30 weeks: -10.5%; 138 weeks: -35.5%) after TU treatment. Placebo was not associated with significant ∆HOMA-IR. The only consistent predictor of HOMA-IR decrease following TU treatment was baseline HOMA-IR (r2 ≥ 0.64).

CONCLUSIONS

Baseline HOMA-IR predicted ΔHOMA-IR, with a greater percentage change in insulin than in fasting glucose. In men with MetS/type 2 diabetes (T2DM) not on antiglycaemic therapy, improvements in HOMA-IR may be greater than suggested by change in fasting glucose. Our results suggest that hypogonadism screening be included in the management of men with MetS/T2DM.

Testosterone therapy in females is not associated with increased cardiovascular or breast cancer risk: a claims database analysis

BACKGROUND

Testosterone therapy (TTh) has been shown to improve libido in women with sexual dysfunction, but its utilization has been limited due to concern for cardiovascular events and past studies reporting highly variable results.

AIM

To assess the association of TTh in women with major adverse cardiac events (MACEs), including heart attack, stroke, or death, using a large database.

METHODS

The TriNetX Diamond Network was queried from 2009 to 2022. Our study cohort included adult females with ≥3 systemic testosterone prescriptions within a year. Our control cohort excluded females with any testosterone prescriptions, polycystic ovary syndrome, or androgen excess. Both cohorts excluded females with prior heart failure, unstable angina, intersex surgery (female to male), personal history of sex reassignment, or gender identity disorders. Propensity matching between the cohorts was performed. A subanalysis by age was conducted (18-55 and >55 years).

OUTCOMES

We evaluated the association of TTh to the following: MACE, upper or lower emboli or deep vein thrombosis (DVT), pulmonary embolism (PE), breast neoplasm, and hirsutism within 3 years of TTh.

RESULTS

When compared with propensity-matched controls, adult females with TTh had a lower risk of MACE (risk ratio [RR], 0.64; 95% CI, 0.51-0.81), DVT (RR, 0.61; 95% CI, 0.42-0.90), PE (RR, 0.48; 95% CI, 0.28-0.82), and malignant breast neoplasm (RR, 0.48; 95% CI, 0.37-0.62). Similarly, females aged 18 to 55 years with TTh had a lower risk of MACE (RR, 0.49; 95% CI, 0.28-0.85) and DVT (RR, 0.48; 95% CI, 0.25-0.93) and a similar risk of malignant breast neoplasm (RR, 0.62; 95% CI, 0.34-1.12). Females aged ≥56 years with TTh had a similar risk of MACE (RR, 0.84; 95% CI, 0.64-1.10), DVT (RR, 0.82; 95% CI, 0.50-1.36), and PE (RR, 0.52; 95% CI, 0.26-1.05) and a significantly lower risk of malignant breast neoplasm (RR, 0.51; 95% CI, 0.38-0.68). Risk of hirsutism was consistently higher in those with TTh as compared with propensity-matched controls.

CLINICAL IMPLICATIONS

Our results contribute to safety data on TTh, a therapy for sexual dysfunction in women.

STRENGTHS AND LIMITATIONS

The TriNetX Diamond Network allows for significant generalizability but has insufficient information for some factors.

CONCLUSIONS

We found a decreased risk of MACE among women with TTh as compared with matched controls and a similar risk of MACE in postmenopausal women while demonstrating a similar or significantly lower risk of breast cancer on age-based subanalysis.

Low testosterone at age 31 associates with maternal obesity and higher body mass index from childhood until age 46: A birth cohort study

BACKGROUND

Low testosterone (T) levels in men associate with increased risks of obesity, type 2 diabetes, metabolic syndrome, and cardiovascular diseases. However, most studies are cross-sectional with follow-up-time < 10 years, and data on early growth are limited.

OBJECTIVE

To compare prenatal factors and body mass index (BMI) development from birth to age 46 in relation to low T at age 31.

MATERIALS AND METHODS

Men with low T (T < 12.1 nmol/L, n = 132) and men with normal T at age 31 (n = 2561) were derived from the Northern Finland Birth Cohort 1966. Prenatal factors, longitudinal weight and height data from birth to age 14, and cross-sectional weight and height data at ages 31 and 46, and waist-hip-ratio (WHR) and T levels at age 31 were analyzed. Longitudinal modeling and timing of adiposity rebound (AR, second BMI rise at age 5-7 years) were calculated from fitted BMI curves. Results were adjusted for mother's pre-pregnancy BMI and smoking status, birth weight for gestational age, alcohol consumption, education level, smoking status, and WHR at age 31.

RESULTS

Neither gestational age nor birth weight was associated with low T at age 31; however, maternal obesity during gestation was more prevalent among men with low T (9.8% vs. 3.5%, adjusted aOR: 2.43 [1.19-4.98]). Men with low T had earlier AR (5.28 vs. 5.82, aOR: 0.73 [0.56-0.94]) and higher BMI (p < 0.001) from AR onward until age 46. Men with both early AR and low T had the highest BMI from AR onward.

CONCLUSIONS

In men, maternal obesity and early weight gain associate with lower T levels at age 31, independently of adulthood abdominal obesity. Given the well-known health risks related to obesity, and the rising prevalence of maternal obesity, the results of the present study emphasize the importance of preventing obesity that may also affect the later reproductive health of the offspring.

Examining the associations between testosterone and biomarkers as men age

OBJECTIVES

Testosterone concentrations in men decline with advancing age. However, the cause of the decline is yet to be fully elucidated. Therefore, the aims of this study were to examine the associations between chronic diseases such as obesity and type 2 diabetes mellitus (T2DM) with total testosterone (TT) and sex hormone-binding globulin (SHBG), using a large nationally-representative data set (National Health and Nutrition Examination Survey; NHANES).

METHODS

NHANES is a cross-sectional survey, physical examination, and laboratory evaluation of a nationally-representative sample of a non-institutionalized United States population. Male participants aged ≥18 years during the NHANES 2013-2014 and NHANES 2015-2016 survey periods were selected for this analysis. The analysis included the following data: body mass index (BMI), oral glucose tolerance test (OGTT), homeostatic model assessment of insulin resistance (HOMA-IR), insulin, glucose, and age.

RESULTS

An overweight or obese condition was significantly inversely associated with TT and SHBG, even after adjusting for other variables. Several variables associated with T2DM (OGTT, HOMA-IR, insulin, and glucose) were also inversely associated with TT; however, only the associations between OGTT and insulin with TT remained significant after adjusting for the other variables. Insulin and HOMA-IR levels were significantly inversely associated with SHBG; however, only the association between SHBG and pre-diabetic HOMA-IR levels remained significant after adjusting for the other variables. OGTT became significantly associated with SHBG after adjusting for the other variables. Age was significantly inversely associated with TT, but positively associated with SHBG, even after adjusting for other variables.

CONCLUSION

The results of the present study, which is the largest to date, indicate that a marker of obesity, BMI, and some markers of T2DM are both independently and significantly inversely associated with TT and SHBG.

Association of Acculturation and Hispanic/Latino Background with Endogenous Sex and Thyroid-Related Hormones Among Middle-Aged and Older Hispanic/Latino Adults: the HCHS/SOL Study

BACKGROUND

Hormones are linked to cardiometabolic diseases and may be impacted by acculturation though multiple mechanisms. We evaluated associations of Hispanic/Latino background and acculturation with levels of sex- and thyroid-related hormones and the potential mediating effect of adiposity, lifestyle factors, and sleep apnea syndrome on these associations.

METHODS

We studied 1789 adults, aged 45-74, from a sub-cohort of the Hispanic Community Health Survey/Study of Latinos. Peri/pre-menopausal women and individuals on medications related to hormones were excluded. Our study assessed eleven sex- and thyroid-related hormones, Hispanic/Latino background, and five acculturation measures. Associations were assessed using multivariable linear and logistic regression adjusted for survey design and confounding variables. We explored potential mediation using a path analysis.

RESULTS

In postmenopausal women, acculturation score-MESA was associated with decreased thyroid-stimulating hormone (β = - 0.13;95%CI = - 0.22, - 0.03) while age at immigration greater than the median (vs US-born) was associated with decreased (β = - 14.6; 95%CI = - 28.2, - 0.99) triiodothyronine (T3). In men, language acculturation and acculturation score-MESA were associated with increased estradiol and sex hormone-binding globulin (SHBG) while age at immigration greater and lesser than the median (vs US-born) was associated with decreased SHBG. Hispanic/Latino background (Mexicans as reference) were selectively associated with sex- and thyroid-related hormone levels in both sexes. Current smoking and sleep apnea syndrome partially mediated the association of Cuban and Puerto Rican heritage (vs Mexican) with T3 levels in men and postmenopausal women, respectively.

CONCLUSION

Selected acculturation measures were associated with thyroid-related hormones in postmenopausal women and sex-related hormones in men. Understanding the mechanisms involved in the relationship of acculturation and Hispanic/Latino background with hormones warrants additional investigation.

Sex Hormones and Diabetes in 45- to 74-year-old Men and Postmenopausal Women: The Hispanic Community Health Study

Previous studies demonstrated associations of endogenous sex hormones with diabetes. Less is known about their dynamic relationship with diabetes progression through different stages of the disease, independence of associations, and role of the hypothalamic-pituitary gonadal axis. The purpose of this analysis was to examine relationships of endogenous sex hormones with incident diabetes, prediabetes, and diabetes traits in 693 postmenopausal women and 1015 men aged 45 to 74 years without diabetes at baseline participating in the Hispanic Community Health Study/Study of Latinos and followed for 6 years. Baseline hormones included estradiol, luteinizing hormone (LH), follicle stimulating hormone (FSH), sex hormone-binding globulin (SHBG), dehydroepiandrosterone sulfate (DHEAS), and, in men, testosterone and bioavailable testosterone. Associations were analyzed using multivariable Poisson and linear regressions. In men, testosterone was inversely associated with conversion from prediabetes to diabetes (incidence rate ratio [IRR] for 1 SD increase in testosterone: 0.821; 95% CI, 0.676, 0.997; P = 0.046), but not conversion from normoglycemia to prediabetes. Estradiol was positively associated with increase in fasting insulin and homeostatic model assessment of insulin resistance. In women, SHBG was inversely associated with change in glycosylated hemoglobin, postload glucose, and conversion from prediabetes to diabetes (IRR = 0.62; 95% CI, 0.44, 0.86, P = 0.005) but not from normoglycemia to prediabetes. Relationships with other hormones varied across glycemic measures. Stronger associations of testosterone and SHBG with transition from prediabetes to diabetes than from normoglycemic to prediabetes suggest they are operative at later stages of diabetes development. Biologic pathways by which sex hormones affect glucose homeostasis await future studies.

Biomarkers to Be Used for Decision of Treatment of Hypogonadal Men with or without Insulin Resistance

Male hypogonadism is a result of low testosterone levels, but patients could be insulin-sensitive (IS) or insulin-resistant (IR), showing different impaired metabolic pathways. Thus, testosterone coadministration, which is commonly used to reestablish testosterone levels in hypogonadism, must take into account whether or not insulin is still active. By comparing metabolic cycles recorded in IS and IR plasma before and after testosterone therapy (TRT), it is possible to know what metabolic pathways can be reactivated in the two different groups upon testosterone recovery, and it is possible to understand if antagonism or synergy exists between these two hormones. IS hypogonadism uses glycolysis, while IR hypogonadism activates gluconeogenesis through the degradation of branched-chain amino acids (BCAAs). Upon administration of testosterone, acceptable improvements are observed in IS patients, wherein many metabolic pathways are restored, while in IR patients, a reprogramming of metabolic cycles is observed. However, in both subgroups, lactate and acetyl-CoA increases significantly. In IS patients, lactate is used through the glucose-lactate cycle to produce energy, while in IR patients, both lactate and acetyl-CoA are metabolized into ketone bodies, which are used to produce energy. Thus, in IR patients, an ancestral molecular mechanism is activated to produce energy, mimicking insulin effects. Regarding lipids, in both groups, the utilization of fatty acids for energy (β-oxidation) is blocked, even after TRT; free fatty acids (FFAs) increase in the blood in IS patients, while they are incorporated into triglycerides in those with IR. In both subgroups of hypogonadism, supplementation of useful chemicals is recommended during and after TRT when metabolites are not restored; they are listed in this review.

Effect of High-Fructose Diet-Induced Metabolic Syndrome on the Pituitary-Gonadal Axis in Male Rats

Plasma testosterone levels have been found to decrease in older insulin-resistant male patients. Both lower total testosterone levels and a higher incidence of metabolic syndrome have also been reported. The aim of this study was to investigate the effects of high-fructose diet-induced diabetes on both the testosterone release by Leydig cells and the activity of the hypothalamus-pituitary-gonadal (HPG) axis in male rats. Male rats were fed with either standard chow (control group) or a high-fructose diet (fructose-fed group) for 21 weeks. Hyperglycemia, hyperinsulinemia, and hypertension were observed in the fructose-fed group. Moreover, plasma testosterone and LH levels decreased in the fructose-fed group compared to the control group. Sperm motility was also reduced by 15% in the fructose-fed rats. In contrast, the basal release of testosterone from rat Leydig cells was not altered by fructose feeding. Moreover, in vitro studies showed that the testosterone release, in response to different stimulants, including forskolin (an adenylyl cyclase activator, 10^-5 M), 8-Br-cAMP (a permeable analog of cAMP, 10^-5 M), A23187 (a calcium ionophore, 10^-5 M), or 25-hydroxy-cholesterol (water-soluble cholesterol, 10^-5 M), did not significantly differ between the fructose-fed and control groups. Interestingly, the release of testosterone in response to human chorionic gonadotropin (hCG, 0.05 IU/mL) was enhanced by eightfold in the control group, but elevenfold in the fructose-fed group. LH receptor expression in rat Leydig cells was also increased. Moreover, LH secretion from the anterior pituitary was altered in the fructose diet-fed group. These results suggest that fructose diet-fed rats have lower plasma testosterone levels, which can lead to a higher sensitivity of hCG in Leydig cells.

On the Need to Distinguish between Insulin-Normal and Insulin-Resistant Patients in Testosterone Therapy

Male hypogonadism is a disorder characterized by low levels of the hormone testosterone and patients may also have insulin sensitivity (IS) or insulin resistance (IR), such that they show different clinical complications and different metabolic pathways. In this review, we compare metabonomic differences observed between these two groups before and after testosterone therapy (TRT) in order to obtain information on whether the two hormones testosterone and insulin are synergistic or antagonistic. IS hypogonadism uses glucose as the main biofuel, while IR activates gluconeogenesis by the degradation of branched-chain amino acids. The Krebs (TCA) cycle is active in IS but connected with glutaminolysis, while in IR the TCA cycle stops at citrate, which is used for lipogenesis. In both cases, the utilization of fatty acids for energy (β-oxidation) is hampered by lower amounts of acetylcarnitine, although it is favored by the absence of insulin in IR. Increased free fatty acids (FFAs) are free in the blood in IS, while they are partially incorporated in triglycerides in IR. Thus, upon TRT, the utilization of glucose is increased more in IS than in IR, revealing that in IR there is a switch from preferential glucose oxidation to lipid oxidation. However, in both cases, a high production of lactate and acetyl-CoA is the final result, with these levels being much higher in IR. Lactate is used in IS in the glucose–lactate cycle between the liver and muscle to produce energy, while in IR lactate and acetyl-CoA are biotransformed into ketone bodies, resulting in ketonuria. In conclusion, the restoration of testosterone values in hypogonadism gives better results in IS than in IR patients: in IS, TRT restores most of the metabolic pathways, while in IR TRT impairs insulin, and when insulin is inactive TRT activates an ancestral molecular mechanism to produce energy. This evidence supports the hypothesis that, over time, hypogonadism switches from IS to IR, and in the latter case most of the insulin-related metabolisms are not reactivated, at least within 60 days of TRT. However, testosterone therapy in both IS and IR might be of benefit given supplementation with metabolites that are not completely restored upon TRT, in order to help restore physiological metabolisms. This review underlines the importance of using a systems biology approach to shed light on the molecular mechanisms of related biochemical pathways involving insulin and testosterone.

Plasma Metabonomics in Insulin-Resistant Hypogonadic Patients Induced by Testosterone Treatment

Hypogonadic subjects with insulin resistance (IR) showed different metabonomic profiles compared to normo-insulinemic subjects (IS). Testosterone replacement therapy (TRT) may have a different impact on the metabolisms of those with the presence or absence of insulin resistance. We evaluated the changes in the metabolism of IR hypogonadic patients before and after 60 days of TRT. The metabonomic plasma profiles from 20 IR hypogonadal patients were recorded using ultra-high-performance liquid chromatography (UHPLC) and high-resolution mass spectrometry (HRMS). Plasma metabolites, before and after 60 days of TRT, were compared. In hypogonadic patients, carnosine, which is important for improving performance during exercise, increased. Conversely, proline and lysine—amino acids involved in the synthesis of collagen—reduced. Triglycerides decreased and fatty acids (FFAs) increased in the blood as a consequence of reduced FFA β-oxidation. Glycolysis slightly improved, while the Krebs cycle was not activated. Gluconeogenesis (which is the main energy source for hypogonadal IR before TRT) stopped after treatment. As a consequence, lactate and acetyl CoA increased significantly. Both lactate and acetyl CoA were metabolized into ketone bodies which increased greatly, also due to leucine/isoleucine degradation. Ketone bodies were derived predominantly from acetyl CoA because the reaction of acetyl CoA into ketone bodies is catalyzed by mtHMGCoA synthase. This enzyme is inhibited by insulin, which is absent in IR patients but overexpressed following testosterone administration. Ketosis is an alternative route for energy supply and provides the same metabolic effects as insulin but at the metabolic or primitive control level, which bypasses the complex signaling pathway of insulin. After treatment, the hypogonadic patients showed clinical symptoms related to ketonuria. They presented similarly to those following a ketogenic diet, the so-called ‘keto flu’. This must be taken into account before the administration of TRT to hypogonadic patients.

Sex hormones, adiposity, and metabolic traits in men and women: a Mendelian randomisation study

OBJECTIVE

Epidemiological and clinical studies have highlighted important roles for sex hormones in the regulation of fat distribution and systemic metabolism. We investigated the bidirectional associations between bioavailable serum testosterone (BioT) in both sexes and oestradiol (E2) in men and adiposity and metabolic traits using Mendelian randomisation (MR).

DESIGN AND METHODS

As genetic instruments for sex hormones, we selected all the genome-wide significant, independent signals from a genome-wide association studies (GWAS) in up to 425 097 European ancestry UK Biobank participants. European population-specific, summary-level data for adiposity, metabolic, and blood pressure traits were obtained from the largest publicly available GWAS. Sex-specific, two-sample MR analyses were used to estimate the associations of sex hormones with these traits and vice versa.

RESULTS

In women, higher BioT was associated with obesity, upper-body fat distribution, and low HDL-cholesterol although, based on analyses modelling the sex hormone-binding globulin-independent effects of BioT, the last two associations might be indirect. Conversely, obesity and android fat distribution were associated with elevated serum BioT. In men, higher BioT was associated with lower hip circumference and lower fasting glucose. Reciprocally, obesity was associated with lower BioT and higher E2, while upper-body fat distribution and raised triglycerides were associated with lower E2.

CONCLUSIONS

Adipose tissue and metabolic dysfunction are associated with deranged sex hormone levels in both sexes. In women, elevated BioT might be a cause of obesity. Conversely, in men, higher BioT appears to have beneficial effects on adiposity and glucose metabolism.

The dose-response relationship between sex hormones and hyperuricemia in different gender: NHANES 2013-2016

OBJECTIVES

To access the dose-response relationship between sex hormones and hyperuricemia (HUA), and to find the cut-off value in different gender.

METHODS

9,685 participants were derived from the database of National Health and Nutrition Examination Survey (NHANES). Restricted cubic spline (RCS) analysis were applied to explore the relationship between sex hormones and HUA after adjusting for confounding factors by propensity score match (PSM). Logistic regression was used to estimate the odds ratio (OR) and 95% CI.

RESULTS

The prevalence of HUA was 15.13% in female participants and 22.30% in male participants. Logistic regression analysis showed that estradiol (E2) was independently associated with HUA for a P value of 0.003 and 0.01in female and male participants, respectively. Testosterone (T) was only independently associated with HUA in male participants (P&lt;0.001) but not in female participants (P = 0.59). RCS analysis showed a dose-response relationship between sex hormones and HUA. The risk of HUA increased as E2 lower than 29.6pg/mL in female participants and T lower than 389.1ng/dL in male participants. E2 higher than 23.6pg/ml was an independent risk factor for HUA in male participants.

CONCLUSION

A dose-response relationship was found between sex hormones and HUA. The cut-off value of E2 in male and female participants was 29.6pg/mL and 23.6pg/mL, respectively, and the cut-off value of T in male participants was 389.1ng/dL. These results provide a reference for preventing HUA and hormone supplement therapy.

Sex Differences in the Effect of Testosterone on Adipose Tissue Insulin Resistance From Overweight to Obese Adults

OBJECTIVE

Adipose tissue distribution and glucose metabolism differ between men and women. Few studies have investigated sex differences in adipose tissue insulin resistance (adipose-IR). Herein, we investigated sex differences in adipose-IR in adults ranging from overweight to obese and the potential factors associated with sex differences in adipose-IR.

METHODS

A total of 424 adults had their body mass index (BMI), adipose-IR, and sex hormones evaluated. Based on BMI, males and females were assigned to 4 groups.

RESULTS

In total, males (n = 156) had higher adipose-IR than females with similar BMI levels (n = 268) (P < 0.05). Adipose-IR progressively increased from overweight to class III obesity in both males and females (all P < 0.0001); however, only in the class III obesity group was the adipose-IR significantly higher in males than in females (P = 0.025). There were significant differences in testosterone between males and females (all P < 0.01); testosterone levels were negatively correlated with adipose-IR (r = -0.333, P < 0.001) in males but positively correlated with adipose-IR (r = 0.216, P < 0.001) in females. For the logistic regression analysis, testosterone was an independent protective factor against adipose-IR in males, with an odds ratio of 0.858 (B = -0.153 [95% CI, 0.743-0.991], P = 0.037).

CONCLUSIONS

Adipose-IR reflects the progressive deterioration in adipose tissue insulin sensitivity from overweight to obesity in both males and females. Males with class III obesity have more severe adipose-IR than similarly obese females. The sex difference is associated with testosterone, and low testosterone levels may contribute to more severe adipose-IR in obese males.

Environmental and occupational exposures associated with male infertility

The upsurge in male infertility over the last two decades, possibly due to environmental exposure, has raised significant interest, particularly boosted by reports from fertility clinics, which showed that chronic diseases and hereditary or other medical conditions might only partially explain current incidence of male infertility. Both environmental and occupational settings may have a significant role in exposure to complex mixtures of endocrine disruptors (ED), which play a major role in fertility disorders. The aim of this review is to give an insight into the current knowledge on exposure settings which may be associated with male infertility. Our study relied on a systematic search of PubMed, Scopus, and Web of Science for articles published between January 2000 and September 2020. It showed that some well documented factors associated with male infertility include smoking, and physiological disturbances or chronic diseases such as obesity and diabetes, which in turn, may also reflect lifestyle choices and environmental exposures, especially to EDs such as phthalates, bisphenols, pesticides, and flame retardants. However, the number of studies on the aetiology of male infertility is still too low in comparison with the size of affected population. Occupational health follow-ups and medical surveillance do not collect any data on male infertility, even though ED chemicals are part of many technological processes.

Changes in sexual function and serum testosterone levels in patients with prostate cancer after image-guided proton therapy

Since sexual function and testosterone levels after image-guided proton therapy (IGPT) have not yet been examined in detail, we prospectively evaluated changes before and after IGPT. Among patients treated with IGPT with or without combined androgen blockade (CAB) therapy between February 2013 and September 2014, patients who agreed to participate in the study and were followed up for >3 years after IGPT were evaluated. Serum testosterone levels were regularly measured together with prostate-specific antigen (PSA) levels before and after IGPT. The Erection Hardness Score (EHS) and the sexual domain summary, function subscale and bother subscale of the sexual domain in the Expanded Prostate Cancer Index Composite (EPIC) were assessed. There were 38 low-risk, 46 intermediate-risk and 43 high- or very-high-risk patients (NCCN classification). Although serum testosterone levels in low-risk patients did not decrease after IGPT, reductions were observed in the average EHS and the sexual domain summary score of the EPIC. In intermediate-, high- and very-high-risk patients, testosterone and PSA levels both increased following the termination of CAB after IGPT, and the average EHS increased. The sexual domain summary score gradually increased, but not above minimally important differences. In intermediate-risk patients, the function subscale increased from 4.4 to 14.8 (P < 0.05) 12 months after IGPT and reached a plateau after 60 months. The results of the present study would suggest the potential of IGPT, and further prospective studies to directly compare IGPT with other modalities are warranted.

In utero low-protein-diet-programmed type 2 diabetes in adult offspring is mediated by sex hormones in rats†

Sex steroids regulate insulin sensitivity and glucose metabolism. We had characterized a lean type 2 diabetes (T2D) rat model using gestational low-protein (LP) diet programming. Our objective was to identify if endocrine dysfunction leading to decreased sex hormone levels will precede the development of T2D and if steroid replacement will prevent the onset of the disease. Pregnant rats were fed control or isocaloric LP diet from gestational day 4 until delivery. Normal diet was given to all mothers after delivery and to pups after weaning. LP offspring developed glucose intolerance and insulin resistance at 4 months. We measured sex steroid hormone profiles and expression of key genes involved in steroidogenesis in testis and ovary. Furthermore, one-month old rats were implanted with 90-day slow release T and E2 pellets for males and females, respectively. Glucose tolerance test (GTT) and euglycemic hyperinsulinemic clamp was performed at 4 months. LP-programmed T2D males had low T levels and females had low E2 levels due to dysregulated gene expression during steroidogenesis in gonads. GTT and euglycemic hyperinsulinemic clamp showed that LP males and females were glucose intolerant and insulin resistant; however, steroid supplementation prevented the onset of glucose intolerance and insulin resistance. Rats that developed T2D by LP programming have compromised gonadal steroidogenesis leading to low T and E2 in males and females, respectively. Sex steroid supplementation prevented the onset of glucose intolerance and insulin resistance indicating low sex steroid levels could cause compromised glucose metabolism ultimately leading to T2D.