NPY and polycystic ovary syndrome: Coutinho et.al showed that arcuate nucleus neurons (ARN) NPY neurons inhibit GnRH/LH pulse frequency and decreased LH secretion in PCOS-like mice models [53].These inhibitory effects of NPY on reproductive function may lead to a decline in fertility in conditions of negative energy balance, such as food restriction or strenuous exercise, that are related to an increase in hypothalamic NPY expression.