Exposure to polyethylene and polyvinylchloride microplastics caused advanced puberty onset in females through promoting hypothalamic GnRH expression

Precocious puberty (PP) is a common pediatric endocrine disorder that affects children's growth and sexual development. Environmental pollutants, especially microplastics (MPs), may be an important triggering factors in PP. MPs were widely found in children's living environment, while the impact of MPs on pubertal development remains unknown. In this study, 14 serum samples were collected from central precocious puberty (CPP) girls and healthy controls. The concentration of total MPs in CPP girls (68.19 ± 26.49 mg/kg) showed significant increase than healthy controls (36.94 ± 13.22 mg/kg). 5 of 11 types of MPs were detected, among which PE (CPP, 28.22 %; Control, 31.62 %) and PVC (CPP, 62.67 %; Control, 58.14 %) being the dominant ones. Correlation analysis between MPs and sex hormone revealed that total MPs were negatively correlated with progesterone and positively correlated with dehydroepiandrosterone (DHEAS). In order to investigate the toxic effects of MPs on pubertal onset, young female mice at 21 days were orally administered various concentrations of MPs for two weeks. Female mice exposed to MPs (PE, 3 mg/day; PVC, 6 mg/day) had an advanced vaginal opening, while none significant changes in body weight. Immunohistochemical staining demonstrated that MPs exposure during puberty could activate microglia, astrocytes and promote GnRH expression in the hypothalamus, which leading to an earlier pubertal onset. These data suggested that MPs can be absorbed and accumulated in brain and gonad after gavage, and accelerate female pubertal initiation. This study provided valuable evidence that MPs threatened the normal progression of female pubertal development.