Oleic acid increases hepatic sex hormone binding globulin production in men

Effect of zinc intake on association between fluoride exposure and abnormal sex steroid hormones among US pubertal males: NHANES, 2013-2016

Excessive fluoride exposure can disturb the balance of sex hormones. Zinc is essential for sex hormone synthesis and spermatogenesis. But it is not clear how zinc affects the relationship of fluoride exposure with abnormal sex steroid hormones. Here, a total of 1008 pubertal males from the National Health and Nutrition Examination Survey (NHANES) in two cycles (2013-2014, 2015-2016) were enrolled. The concentrations of water fluoride and plasma fluoride and the levels of serum testosterone, estradiol, and sex hormone binding globulin (SHBG) were measured. Two 24-h dietary recall interviews were conducted to assess the dietary zinc intake. The relationships of fluoride exposure and zinc intake with sex hormones were examined using linear regression and logistic regression models, while the generalized additive model was used to evaluate their non-linear relationship. Our findings revealed that for every two-fold increase in plasma fluoride concentration, testosterone levels decreased by 7.27% (95% CI - 11.49%, - 2.86%) and estradiol levels decreased by 8.73% (95% CI - 13.61%, - 3.57%). There was also significant non-linear association observed between zinc intake and SHBG levels. Being in the first tertile of plasma fluoride had a 60% lower risk of high SHBG (OR = 0.40, 95% CI 0.18, 0.89) compared with being in the second tertile. When compared to the first tertile, being in the second tertile of zinc intake was associated with a 63% (OR = 0.37, 95% CI 0.14, 0.98) lower risk of high SHBG. Furthermore, we observed an interactive effect between the plasma fluoride and zinc intake on estradiol and SHBG, as well as the risk of high SHBG (P-interaction < 0.10). These findings suggest that fluoride exposure and zinc intake can affect sex steroid hormone levels and the risk of high SHBG. Notably, zinc intake may alleviate the increased risk of high SHBG and the abnormal changes of estradiol and SHBG caused by higher fluoride exposure.

Pioglitazone can improve liver sex hormone-binding globulin levels and lipid metabolism in polycystic ovary syndrome by regulating hepatocyte nuclear factor-4α

Polycystic ovary syndrome (PCOS) is a common reproductive and metabolic disorder that is closely correlated with insulin resistance. Sex hormone-binding globulin (SHBG) is an important carrier for regulating androgen activity and is affected by insulin level, which is related to metabolic abnormalities and long-term prognosis of PCOS. Insulin sensitizer pioglitazone can improve the SHBG level and dyslipidaemia in PCOS, but the mechanism remains unclear. We investigated liver SHBG expression, liver lipid levels, and the effects and potential mechanisms of pioglitazone on reproductive and metabolic disorders in a rat model of polycystic ovary syndrome with insulin resistance (PCOS-IR). PCOS-IR was induced by letrozole and a high-fat diet. Metformin was used as a positive control. Additionally, dihydrotestosterone and oleic acid combined with palmitic acid were used to induce the HepG2 cell models with IR. The cells were exposed to pioglitazone alone or in combination with a hepatocyte nuclear factor (HNF)- 4α inhibitor. Changes in biochemical characteristics were analysed using an enzyme-linked immunosorbent assay. Vaginal smears were used to analyse the oestrous cycle, and ovarian histology was used to analyse the changes in ovarian morphology. The degree of IR in vivo and in vitro was measured using the hyperinsulinaemic-euglycaemic clamp and glucose oxidase techniques. The levels of key anabolism-related proteins, including SHBG, HNF-4α, and peroxidase proliferator-activated receptor (PPAR-γ), were measured using western blots. Pioglitazone and metformin significantly increased the SHBG levels in the sera and livers. Compared to metformin, pioglitazone significantly improved the lipid droplet deposition, triglyceride (TG) and total cholesterol (TC) levels, HNF-4α protein expression, and weights of the livers in the PCOS-IR rats. After applying pioglitazone with an HNF-4α inhibitor in the PCOS-IR cell models, we found that pioglitazone may increase SHBG and improve IR, TG, and TC levels by upregulating HNF-4α. Similar to metformin, pioglitazone also restored the oestrous cycle and ovarian morphology, ameliorated IR and hyperandrogenaemia in the PCOS-IR rats. Our findings hint at the value of HNF-4α in the treatment of PCOS by PIO, which could shed light on potential targets that may be used in treatments for PCOS with metabolic disorders.

Effect of Resveratrol Content in Red Wine on Circulating Sex Hormone-Binding Globulin: Lessons from a Pilot Clinical Trial

SCOPE

Low sex hormone-binding globulin (SHBG) levels are associated with higher risk of developing cardiovascular disease. Epidemiological studies have shown that red wine has beneficial effects on cardiovascular disease. In this work if resveratrol content in red wine increases SHBG levels is explored.

METHODS AND RESULTS

A pilot study aims at testing the effect of drinking for 14 days two types of red wine with different resveratrol content is conducted in 26 healthy volunteers. SHBG levels and several biochemical parameters are measured at the beginning and the end of every period. Results show that consumption of both wines does not change body mass index or biochemical markers of liver injury. The low resveratrol wine does not modify the lipid profile or SHBG levels. By contrast, red wine with high resveratrol content significantly reduces total cholesterol in both men and women. Finally, red wine with high resveratrol content increases circulating SHBG in women but not in men.

CONCLUSIONS

Red wine rich in resveratrol reduces total cholesterol in men and women and increases SHBG only in women. Further research aims at investigating the potential SHBG role enhancement mediated by resveratrol regarding cardiovascular protection that presents women in comparison with men seems warranted.

Sex hormone-binding globulin: biomarker and hepatokine?

Over the past decade, there have been important breakthroughs in our understanding of the regulation and function of sex hormone-binding globulin (SHBG). A recent genome-wide association and Mendelian randomization study has provided new insights at the population level. Thorough study of genetic variants affecting serum SHBG has identified de novo lipogenesis as one of the mechanistic links between the metabolic syndrome and reduced serum SHBG levels in humans. Furthermore, careful deduction of the Mendelian randomization results suggests a direct, causal role for SHBG in the pathogenesis of type 2 diabetes, as a hepatokine, in women. These findings prompt the development of SHBG-raising therapies as a means to prevent or treat disorders such as type 2 diabetes and polycystic ovary syndrome.

The effects of canola and olive oils consumption compared to sunflower oil, on lipid profile and hepatic steatosis in women with polycystic ovarian syndrome: a randomized controlled trial

BACKGROUND

Polycystic Ovarian Syndrome (PCOS) is one of the most common endocrinopathies and metabolic disorders in women during their reproductive years. It is often associated with dyslipidemia and other risk factors of cardiovascular diseases (CVD). This study was aimed to evaluate dietary intervention effects with canola and olive oils compared to sunflower oil on lipid profile and fatty liver severity among women with PCOS.

METHOD

This study was a 10-week intervention including 72 women with PCOS. Patients were randomly assigned to three groups for receiving 25 g/day canola, olive, or sunflower oils for 10 weeks. The primary and secondary outcomes were to assess changes in lipid profile and in fatty liver severity, respectively.

RESULT

At the end of the study, 72 patients with a mean age of 29.31 were analysed. Canola oil consumption resulted in a significant reduction in serum levels of TG (P = 0.002) and TC/HDL (P = 0.021), LDL/HDL (P = 0.047), and TG/HDL (P = 0.001) ratios, however, there was no significant reduction in lipid profile following olive oil consumption. Canola (P < 0.001) and olive oils (P = 0.005) could significantly reduce the fatty liver grade. Moreover, HOMA-IR in both canola (P < 0.001) and olive (P = 0.004) groups was significantly decreased.

CONCLUSION

In total, compared to olive and sunflower oils, significant improvements in lipid profile, liver function, and HOMA-IR were observed following canola oil consumption in women with PCOS.

TRIAL REGISTRATION

IR.MUI.

RESEARCH

REC.1397.315. Registered 30 JUNE 2019 - Retrospectively registered, https://www.irct.ir/trial/38684.

Sex hormone-binding globulin overexpression protects against high-fat diet-induced obesity in transgenic male mice

Obese subjects of all ages and sex have reduced plasma SHBG levels. Whether these low plasma SHBG levels play a role in obesity development is unknown. In the present work we wanted to explore if SHBG overexpression could prevent obesity development induced by high fat diet (HFD). To do so, we fed humanized SHBG transgenic male mice and their wild-type littermates with control diet (CD) or HFD over the course of 8 weeks. The results showed that SHBG overexpression protected against body weight gain and fat accumulation induced by HFD. In addition, SHBG overexpression also abrogated the increase in insulin, leptin and resistin levels, as well as the reduction in adiponectin, induced by HFD. Mechanistically, the SHBG protection against HFD-induced obesity was achieved by stimulating lipolysis in white adipose tissue. Furthermore, we have demonstrated the SHBG cell-autonomous effect using human primary visceral adipocytes. Taking together, our results demonstrate that SHBG overexpression protects against diet-induced obesity and improves the metabolic profile of male mice fed a HFD diet.

Caffeine Upregulates Hepatic Sex Hormone-Binding Globulin Production by Increasing Adiponectin Through AKT/FOXO1 Pathway in White Adipose Tissue

SCOPE

Epidemiological studies have shown that caffeine increases serum sex hormone-binding globulin (SHBG) levels. The relationship between caffeine and SHBG production has never been studied before at molecular level. The aim of this study is to examine whether caffeine regulates SHBG production and to determine the associated molecular mechanisms.

METHODS AND RESULTS

Two different studies are performed; in vitro studies using human HepG2 cells treated with caffeine (100 and 500 µm) and in vivo studies using a humanized SHBG transgenic mice drinking caffeine in the water (0.1 mg mL^-1 ) for 12 days. The results show that caffeine does not change SHBG production in HepG2 cells. By contrast, caffeine treatment increases significantly hepatic SHBG production in human SHBG transgenic mice when compared with control mice. Caffeine increases adiponectin levels in epididymal adipose tissue of human SHBG transgenic mice. Moreover, caffeine increases adiponectin production by reducing protein kinase B (AKT) phosphorylation which increases forkhead box protein O1 (FOXO1) protein levels in 3T3-L1 mature adipocytes and human SHBG transgenic mice. Finally, caffeine-induced increase in adiponectin in turn upregulates hepatic hepatocyte nuclear receptor 4-alpha (HNF-4α) levels in human SHBG transgenic mice.

CONCLUSIONS

The results show that caffeine upregulates hepatic SHBG expression by increasing adiponectin production through AKT/FOXO1 pathway in the adipose tissue.

Negative effect of feeding with high energy diets on testes and metabolic blood parameters of male Japanese quails, and positive role of milk thistle seed

In this study, it was aimed to investigate the changes in testicular tissue and cell count, testicular oxidative stress and some metabolic blood parameters of male broiler Japanese quails fed with high energy diet and milk thistle (Silybum marianum) seed. One hundred-twenty male 15-day-old Japanese quail chicks were divided into 4 equal groups with 30 each. The applications in each group were repeated 3 times with 10 animals each. Control group was fed with basal diet. Milk thistle seed group was fed with diet including 1% milk thistle seed. High energy diet group was fed with high energy diet including 10% corn syrup. High energy diet + milk thistle seed group was fed with high energy diet including 10% corn syrup along with 1% milk thistle seed. The feeding period in all groups was 35 days. When the quails reached 50 days old, a total of 48, 12 from each group (4 from each replication) were euthanized and blood samples and testes were collected. Compared with the control group, significant increases in body weight, serum cholesterol and glucose level, aspartate aminotransferase activity and testicular malondialdehyde level; however, significant decreases in serum testosterone level, testicular glutathione peroxidase activity, counts of round and elongated spermatid and sperm as well as histopathologically, significant decreases in seminiferous tubular diameter and seminiferous epithelium thickness, and marked disorganization in germinal cells were determined in quails fed with high energy diet. It was observed that almost all of the disturbances in testicular tissue, cell number, oxidant-antioxidant balance and metabolic blood parameters caused by feeding with high energy diet were significantly prevented by supplementation of milk thistle seed to the diet with high energy. On the other hand, alone milk thistle seed and high energy diet + milk thistle seed administrations decreased body weight in comparison to control and high energy diet groups. As a result, feeding with high energy diet causes disturbances in testes of male quails by affecting liver metabolic functions and testicular oxidant-antioxidant balance, but milk thistle seed addition to diet plays a protective role.

Sex hormone-binding globulin and polycystic ovary syndrome

Polycystic ovary syndrome (PCOS), one of the most common endocrine diseases that causes infertility in reproductive women, is characterized by hyperandrogenemia, chronic anovulation, and polycystic ovary morphology (PCOM), and most women with PCOS have metabolic abnormalities. A reduction in plasma sex hormone-binding globulin (SHBG), a transport carrier that binds estrogen and androgens and regulates their biological activities, is often used as an indicator of hyperandrogenism in women with PCOS. Low serum SHBG levels are considered a biomarker of abnormal metabolism and are related to insulin resistance (IR), compensatory hyperinsulinemia and abnormalities in glucose and lipid metabolism in PCOS patients. SHBG is also associated with the long-term prognosis of PCOS. SHBG gene polymorphism is correlated with the risk of PCOS. As SHBG plays a vital role in the occurrence and development of PCOS, knowledge regarding its role in PCOS is helpful for further understanding the molecular mechanism of SHBG in PCOS development and providing new ideas for the treatment of female infertility. Hepatocyte nuclear factor-4α (HNF-4α) is a vital transcription factor in the SHBG synthesis process. HNF-4α binds to the cis-type element DR1 in the SHBG promoter to initiate transcription and regulates hepatic SHBG levels by modulating glucose and lipid metabolism and inflammatory factors. However, it remains unclear whether HNF-4α is indirectly involved in the pathogenesis of PCOS via regulation of hepatic SHBG synthesis. Therefore, this review discusses the interaction between SHBG and the various complications of PCOS as well as the regulatory effect of HNF-4α on SHBG expression.

Aging and the Male Reproductive System

This narrative review presents an overview of current knowledge on fertility and reproductive hormone changes in aging men, the factors driving and modulating these changes, their clinical consequences, and the benefits and risks of testosterone (T) therapy. Aging is accompanied by moderate decline of gamete quality and fertility. Population mean levels show a mild total T decline, an SHBG increase, a steeper free T decline, and a moderate LH increase with important contribution of comorbidities (e.g., obesity) to these changes. Sexual symptoms and lower hematocrit are associated with low T and are partly responsive to T therapy. The relationship of serum T with body composition and metabolic health is bidirectional; limited beneficial effects of T therapy on body composition have only marginal effects on metabolic health and physical function. Skeletal changes are associated primarily with estradiol and SHBG. Cognitive decline is not consistently linked to low T and is not improved by T therapy. Although limited evidence links moderate androgen decline with depressive symptoms, T therapy has small beneficial effects on mood, depressive symptoms, and vitality in elderly patients with low T. Suboptimal T (and/or DHT) has been associated with increased risk of stroke, but not of ischemic heart disease, whereas an association with mortality probably reflects that low T is a marker of poor health. Globally, neither severity of clinical consequences attributable to low T nor the nature and magnitude of beneficial treatment effects justify the concept of some broadly applied "T replacement therapy" in older men with low T. Moreover, long-term safety of T therapy is not established.

Association of SOD2 A16V and PON2 S311C polymorphisms with polycystic ovary syndrome in Chinese women

PURPOSE

To investigate the relationship between superoxide dismutase 2 (SOD2) A16V and paraoxonase 2 (PON2) S311C gene variants and the risk of polycystic ovary syndrome (PCOS) and evaluate the effects of the genotypes on clinical, hormonal, metabolic and oxidative stress indexes in Chinese women.

METHODS

This is a cross-sectional study of 932 patients with PCOS and 745 control women. For the clinical and metabolic association study of genotypes, 631 patients and 492 controls were included after excluding the subjects with interferential factors. Genotypes were determined by polymerase chain reaction (PCR) and restriction fragment length polymorphism analysis. Serum total oxidant status, total antioxidant capacity (T-AOC), oxidative stress index and malondialdehyde (MDA) levels, and clinical and metabolic parameters were also analyzed.

RESULTS

The prevalence of the A allele of SOD2 A16V polymorphism was significantly greater in patients with PCOS than in control subjects. Genotype (AA + AV) remained a significant predictor for PCOS in prognostic models including age, body mass index, insulin resistance index, high-density lipoprotein (HDL), low-density lipoprotein (LDL), and triglycerides (TGs) as covariates. Patients carrying the A allele had significantly higher serum luteinizing hormone (LH) levels, and the ratio of LH to follicle-stimulating hormone compared with patients with the VV genotype. We also showed that patients carrying the C allele of the PON2 S311C polymorphism had lower T-AOC compared with patients carrying the SS genotype. However, no significant differences were observed in the frequencies of the S311C genotypes and alleles of the PON2 gene between PCOS and control groups.

CONCLUSION

The SOD2 A16V, but not PON2 S311C, polymorphism may be one of the genetic determinants for PCOS in Chinese women.

Relevance of functional foods in the Mediterranean diet: the role of olive oil, berries and honey in the prevention of cancer and cardiovascular diseases

The traditional Mediterranean diet (MedDiet) is a well-known dietary pattern associated with longevity and improvement of life quality as it reduces the risk of the most common chronic pathologies, such as cancer and cardiovascular diseases (CVDs), that represent the principal cause of death worldwide. One of the most characteristic foods of MedDiet is olive oil, a very complex matrix, which constitutes the main source of fats and is used in the preparation of foods, both raw as an ingredient in recipes, and in cooking. Similarly, strawberries and raspberries are tasty and powerful foods which are commonly consumed in the Mediterranean area in fresh and processed forms and have attracted the scientific and consumer attention worldwide for their beneficial properties for human health. Besides olive oil and berries, honey has lately been introduced in the MedDiet thanks to its relevant nutritional, phytochemical and antioxidant profile. It is a sweet substance that has recently been classified as a functional food. The aim of this review is to present and discuss the recent evidence, obtained from in vitro, in vivo and epidemiological studies, on the potential roles exerted by these foods in the prevention and progression of different types of cancer and CVDs.

Cross-sectional and longitudinal determinants of serum sex hormone binding globulin (SHBG) in a cohort of community-dwelling men

Despite its widespread clinical use, there is little data available from population-based studies on the determinants of serum sex hormone binding globulin (SHBG). We aimed to examine multifactorial determinants of circulating SHBG levels in community-dwelling men. Study participants comprised randomly selected 35–80 y.o. men (n = 2563) prospectively-followed for 5 years (n = 2038) in the Men Androgen Inflammation Lifestyle Environment and Stress (MAILES) study. After excluding men with illness or medications known to affect SHBG (n = 172), data from 1786 men were available at baseline, and 1476 at follow-up. The relationship between baseline body composition (DXA), serum glucose, insulin, triglycerides, thyroxine (fT4), sex steroids (total testosterone (TT), oestradiol (E2)), and pro-inflammatory cytokines and serum SHBG level at both baseline & follow-up was determined by linear and penalized logistic regression models adjusting for age, lifestyle & demographic, body composition, metabolic, and hormonal factors. Restricted cubic spline analyses was also conducted to capture possible non-linear relationships. At baseline there were positive cross-sectional associations between age (β = 0.409, p<0.001), TT (β = 0.560, p<0.001), fT4 (β = 0.067, p = 0.019) and SHBG, and negative associations between triglycerides (β = -0.112, p<0.001), abdominal fat mass (β = -0.068, p = 0.032) and E2 (β = -0.058, p = 0.050) and SHBG. In longitudinal analysis the positive determinants of SHBG at 4.9 years were age (β = 0.406, p = <0.001), TT (β = 0.461, p = <0.001), and fT4 (β = 0.040, p = 0.034) and negative determinants were triglycerides (β = -0.065, p = 0.027) and abdominal fat mass (β = -0.078, p = 0.032). Taken together these data suggest low SHBG is a marker of abdominal obesity and increased serum triglycerides, conditions which are known to have been associated with low testosterone and low T4.

Resveratrol Increases Hepatic SHBG Expression through Human Constitutive Androstane Receptor: a new Contribution to the French Paradox

Sex hormone-binding globulin (SHBG) carries sex steroids in blood regulating their bioavailability. Red wine consumption increases plasma SHBG levels, and we have discovered that resveratrol, a polyphenol enriched in red wine, acts specifically through the human constitutive androstane receptor (CAR), a drug/xenobiotic detoxification gene regulator, to increase hepatic SHBG production. Chromatin immunoprecipitation and luciferase reporter gene assays show that human CAR binds to a typical direct repeat 1 nuclear hormone receptor-binding element in the human SHBG proximal promoter. Resveratrol also increased hepatic SHBG production in humanized SHBG/CAR transgenic mice. Moreover, SHBG expression correlated significantly with CAR mRNA levels in human liver biopsies. We conclude that the beneficial effects of red wine on the metabolic syndrome and it associated co-morbidities, including cardiovascular disease and type 2 diabetes, may be mediated in part by resveratrol acting via CAR to increase plasma SHBG levels.

Follicle stimulating hormone, its novel association with sex hormone binding globulin in men and postmenopausal women

PURPOSE

Follicle stimulating hormone plays direct roles in a variety of nongonadal tissues and sex hormone binding globulin is becoming the convergence of the crosstalk among metabolic diseases. However, no studies have explored the association between follicle stimulating hormone and sex hormone binding globulin. We aimed to study this association among men and women.

METHODS

SPECT-China is a population-based study conducted since 2014. This study included 4206 men and 2842 postmenopausal women. Collected serum was assayed for gonadotropins, sex hormone binding globulin, sex hormones etc. Regression analyses were performed to assess the relationship between sex hormone binding globulin and follicle stimulating hormone and other variables including metabolic factors, thyroid function and sex hormones. Treatment with follicle stimulating hormone at different concentrations of 0, 5, 50 and 100 IU/L for 24 h was performed in HepG2 cells.

RESULTS

In Spearman correlation, sex hormone binding globulin was significantly correlated with FSH, triglycerides, thyroxins, body mass index and blood pressure in men and postmenopausal women (all P < 0.05). In regression analyses, follicle stimulating hormone was a significant predictor of sex hormone binding globulin in men and postmenopausal women (P < 0.05), independent of above variables. Follicle stimulating hormone induced sex hormone binding globulin expression in a dose-dependent fashion in HepG2 cells.

CONCLUSION

Serum follicle stimulating hormone levels were positively associated with circulating sex hormone binding globulin levels in men and postmenopausal women. This association is independent of age, insulin resistance, hepatic function, lipid profile, thyroid function, adiposity, blood pressure, and endogenous sex hormones.

SHBG-C57BL/ksJ-db/db: A New Mouse Model to Study SHBG Expression and Regulation During Obesity Development

Low plasma sex hormone-binding globulin (SHBG) levels in overweight individuals are a biomarker for the metabolic syndrome and are predictive of type 2 diabetes and cardiovascular disease risk. There are no in vivo models to study SHBG expression and regulation during obesity development. The main reason for this is that the obesity-prone rodent models cannot be used to study this issue, because rodents, unlike humans, do not express the SHBG gene in their livers. We have developed a unique mouse model that expresses the human SHBG, and it develops obesity, by crossing the human SHBG transgenic mice with the C57BL/ksJ-db/db mice. The results obtained with the SHBG-C57BL/ksJ-db/db mouse model have allowed us to determine that the SHBG overexpression in the C57BL/ksJ-db/db reduced the body weight gain but did not change the metabolic profile of these mice. Moreover, we elucidated the molecular mechanisms and transcription factors causing the SHBG down-regulation during obesity development, which involved changes in liver hepatocyte nuclear factor 4α and peroxisome proliferator-activated receptor-γ mRNA and protein levels. Furthermore, these results were confirmed using human liver biopsies. Importantly, we also showed that this model resembles what occurs in human obese subjects, because plasma SHBG and total testosterone levels where reduced in obese mice when compared with lean mice. Future research using this unique mouse model will determine the role of SHBG in the development and progression of obesity, type 2 diabetes, or fatty liver disease.

Novel insights in SHBG regulation and clinical implications

Sex hormone-binding globulin (SHBG) is produced and secreted by the liver into the bloodstream where it binds sex steroids and regulates their bioavailability. Traditionally, body mass index (BMI) was thought to be the major determinant of SHBG concentrations and hyperinsulinemia the main cause for low SHBG levels found in obesity. However, no mechanisms have ever been described. Emerging evidence now shows that liver fat content rather than BMI is a strong determinant of circulating SHBG. In this review we discuss evidence demonstrating that insulin might not regulate SHBG production, describe putative molecular mechanisms by which proinflammatory cytokines downregulate SHBG, and comment on recent findings suggesting dietary SHBG regulation. Finally, clinical implications of all of these findings and future perspectives are discussed.