Aging-related increases in serum sex hormone-binding globulin levels in men might be related to increased synthesis.

BACKGROUND: Previous studies have indicated that serum sex hormone-binding globulin (SHBG) levels increase with age; however, the causes remain unknown. The present study aimed to clarify whether the increase in SHBG levels is attributable to aging-related increases in SHBG synthesis. METHODS: We examined and evaluated the association of serum SHBG levels with synthesis-related factors in men aged 18-80 years. Additionally, we examined the serum and liver levels of SHBG, hepatic nuclear factor 4α (HNF-4α), and peroxisome proliferator-activated receptor γ (PPAR-γ) in young, middle-aged, and old Sprague-Dawley rats. RESULTS: The study included 209 men in the young group (median age, 33 ± 10 years), 174 men in the middle-aged group (median age, 53 ± 8 years), and 98 men in the elderly group (median age, 71 ± 8 years). Serum SHBG levels increased with age (P < 0.05), whereas HNF-4α and PPAR-γ levels decreased with age (both P < 0.05). Compared with the findings in the young group, the average decline in HNF-4α levels was 2.61 % and 18.46 % in the middle-aged and elderly groups, respectively; the average decreases in PPAR-γ levels in these groups were 12.86 % and 20.76 %, respectively. The results in rats illustrated that liver SHBG and HNF-4α levels increased with age, whereas PPAR-γ and chicken ovalbumin upstream promoter-transcription factor (COUP-TF) levels decreased with age (all P < 0.05). Serum SHBG levels increased in rats with age, whereas HNF-4α and PPAR-γ levels decreased with age (all P < 0.05). CONCLUSIONS: The aging-related increased liver levels of the SHBG synthesis promoter HNF-4α and decreased levels of the SHBG inhibitory factors PPAR-γ and COUP-TF suggest that the aging-related increases in SHBG levels are associated with increased SHBG synthesis.

Nickel nanoparticles affect the migration and invasion of HTR-8/SVneo cells by downregulating MMP2 through the PI3K/AKT pathway.

Proper migration and invasion of extravillous trophoblast cells into the endometrium in early gestation is essential for successful embryo implantation. The development of nanotechnology has led to the emergence of nickel nanoparticles (Ni NPs), for which attendant health concerns are widespread. Ni NPs are known to affect reproduction and be embryotoxic, but whether they affect the migration and invasion functions of trophoblast cells is unclear. We investigated the effects of Ni NPs on the migration and invasion of HTR-8/SVneo in extravillous trophoblast cells and explored the possible role of the PI3K/AKT/MMP2 signaling pathway in this regard. Results showed that the migration and invasion of cells was significantly inhibited by the exposure of Ni NPs. The protein and mRNA levels of PI3K/AKT/MMP2 signaling pathway were significantly reduced with the increase in Ni NPs concentration. The presence of the PI3K activator 740Y-P partially attenuated the inhibition of cell migration and invasion by Ni NPs, confirming the involvement of this pathway. Thus, Ni NPs inhibit migration and invasion of human trophoblast HTR-8/SVneo cells by downregulating the PI3K/AKT/MMP2 signaling pathway. This study is important for the development of safety evaluation criteria for Ni NPs.

Research progress on the relationship between sex hormone-binding globulin and male reproductive system diseases.

Sex hormone-binding globulin, also known as testosterone-estradiol-binding globulin, is a multifunctional protein synthesised by hepatocytes. Sex hormone-binding globulin specifically binds and transports sex hormones to regulate plasma bioactive sex hormone levels and affects their bioavailability. As male sex hormone expression is dominated by testosterone, the binding of sex hormone-binding globulin with testosterone leads to the reduction in bioavailable testosterone, which cannot fulfil its physiological roles, thereby resulting in male infertility, erectile and gonadal dysfunction, prostate cancer and other male reproductive system diseases. Sex hormone-binding globulin may be involved in the pathogenesis of male reproductive system diseases, seriously affecting the quality of life of men. In this article, we review the association between sex hormone-binding globulin and male reproductive system diseases.

Bioavailable testosterone is associated with symptoms of depression in adult men.

OBJECTIVE: This study aimed to determine the relationship between serum testosterone levels and depressive symptoms in an adult male population. METHODS: We conducted a cross-sectional study of 1166 male participants from Zunyi, Guizhou, China. Each participant completed a questionnaire, a brief clinical exam, and had a fasting blood sample taken. We measured serum testosterone, sex hormone-binding globulin, and luteinizing hormone levels. Multiple linear regression was used to evaluate the effect of demographic factors on the relationship between the depressive symptom score and serum sex hormone levels. RESULTS: Mean testosterone, sex hormone-binding globulin, and luteinizing hormone levels were significantly higher in the depressive symptom group than in the non-depressed group. The mean calculated free serum testosterone level and free testosterone index (FTI) were significantly lower in the depressive symptom group than in the non-depressed group. Additionally, the mean FTI was significantly negatively correlated with the Beck Depression Inventory scale score in the multiple linear regression model (95% confidence interval: -3.274 to -0.406). CONCLUSIONS: Decreased bioactive testosterone levels might be a contributing factor of depression in adult men. The FTI could be the most sensitive biomarker reflecting the level of bioavailable testosterone in patients with depression.