ESPE Abstracts

Background: The onset of puberty is a complex biological process involving numerous factors under the control of the neuroendocrine pathways that are regulated as part of the hypothalamus-pituitary-gonadal (HPG) axis. The key step in puberty onset is activation of gonadotropin releasing hormone (GnRH) pulses and secretion. Recent evidence suggests that the Lin28/let7 pathway might be a critical regulator of GnRH release and that it might play an important role in regulating the onset of puberty.

Objective: The present study aims to investigate the effects of the nourishing "Yin" and purging "Fire" Traditional Chinese Medicine (TCM)herb mixture on precocious puberty and TCM may act through hypothalamic Lin28/let7 pathway expression in the precocious puberty model rats. Meanwhile, to confirm the relationship between Lin28/let7 pathway and puberty by overexpression Lin28a.

Design and Methods: Female rats were randomly allocated into untreated controls, the precocious puberty (PP) model group, the PP control group, and the PP + TCM group. Rats on postnatal day 5 were injected danazol to establish the PP model. From days 15 to 35, the rats in the TCM group were given the TCM twice daily. Vaginal opening, sex-related hormones, and body and reproductive organ weights were measured, and the expressions of hypothalamic Lin28a and Lin28b mRNA and let7a and let7b miRNA were detected.

Results: we found that at the onset of puberty, a decrease in ovary weight, an increase in the serum levels of luteinizing hormone and progesterone, and increased expression levels of hypothalamic Lin28b mRNA were observed in the PP + TCM group compared to the PP model group. The vaginal opening time was significantly delayed upon overexpression of Lin28a.

Conclusion: The mechanism by which the TCM treats precocious puberty is thus likely to be associated with inhibition of the hypothalamic Lin28/let7 signaling pathway and our findings provide in-depth insight into the relationship between the overexpression of Lin28a gene in the hypothalamus and the onset of puberty.