Role of neuropeptide Y in regulating hypothalamus–pituitary–gonad axis in the rats treated with electro-acupuncture

Neuropeptide Y (NPY) is an important regulator of reproductive axis, which mainly plays some roles in regulating secretion of gonadotropin-releasing hormone (GnRH) in hypothalamus. In previous studies, we found that the repeated low frequency electro-acupuncture (EA) down-regulated hypothalamus–pituitary–gonad (HPG) axis of common rats and rabbits during puberty. In this study, we investigated the role of NPY in regulating the reproductive axis of common rats at different developmental stages and rats treated with the repeated EA. Low frequency EA (3 Hz) was performed at acupoints (treatment groups) or non-acupoints (control groups) for 20 min daily for 10 days in Sprague–Dawley (SD) rats at four developmental stages, which were juvenile stage, early puberty stage, later puberty stage and adult stage. NPY expression in the hypothalamus were determined using RT-PCR and real-time quantitative PCR (qPCR) after 10 days-treatments. The results showed that NPY expression in the early pubertal group (EPG) was significantly depressed after repeated EA (P < 0.05). Compared with the results of GnRH expression and body weights, the change of NPY expression was similar with the fluctuation of GnRH expression after EA and the increase of body weights of rats was not influenced by the depression of NPY expression after EA during early puberty. The results demonstrated that repeated low frequency EA was an effective method on down-regulating not only the GnRH expression but also the NPY expression in the hypothalamus without reducing body weights of rats during early puberty.