Associations of waist circumference with sex steroid hormones among 4031 USA children and adolescents.

In the recent decades, obesity rates among children and adolescents, especially males, have increased significantly. This worldwide phenomenon is thought to significantly affect the levels of sex hormones. However, the association between waist circumference (a marker of abdominal obesity) and sex hormone levels in children and adolescents is unknown. In this study, 4031 participants aged 6-19 years from the United States National Health and Nutrition Examination Survey (NHANES) in the USA were enrolled in this study. The common confounders of age, race, body mass index, educational level, family income, diabetes, and time of sample collection were also collected. The participants missing any of the above information were excluded from the study. We used multiple linear regression and other multiple statistics to assess the associations between waist circumference and serum testosterone, estradiol, sex hormone-binding globulin (SHBG), free androgen index (FAI), and testosterone/estradiol ratio (T/E2). Waist circumference remained associated with sex hormone levels in children and adolescents after controlling for covariates. As waist circumference increases, testosterone levels in children and adolescents show an overall decline after a brief increase, with the inflection point for waist circumference of 65-66 cm. In addition, waist circumference positively correlates with estradiol levels in male children (ß = 0.007, 95% confidence interval: 0.004-0.009). Moreover, circulating SHBG decreases in children and adolescents as waist circumference increases. In conclusion, this study highlighted waist circumference as a vital indicator affecting sex hormone levels in children and adolescents.

[Action mechanisms of prolactin and its receptors on penile erection and ejaculation].

Prolactin is a polypeptide hormone which mainly acts on the reproductive system and plays an important role in penile erection and ejaculation. Prolactin receptors have a variety of short forms apart from the classic long form, which are widely expressed in male reproductive glands. High levels of prolactin can induce erectile dysfunction and results in secondary male infertility, which are mainly associated with the inhibition of dopaminergic activity, reduction of the testosterone level, and contraction of the cavernous smooth muscle. Moreover, low levels of prolactin can result in ejaculatory dysfunction. This article updates the views on the expressions of prolactin receptors in the male reproductive system, the effects of prolactin on penile erection and ejaculation, and its action mechanisms.