Neuropeptide Y: A hypothalamic brake restraining the onset of puberty in primates

The adult reproductive axis is driven by an intermittent discharge of gonad otropin-releasing hormone (GnRH) generated by a network of hypothalamic neu rons known as the GnRH pulse generator. Although this signal generator is o perational in infant primates, puberty in these species is delayed by activ ation shortly after birth of a central neural mechanism that holds GnRH rel ease in check during juvenile development. Here, we show that, in the male rhesus monkey, the postnatal pattern in GnRH pulse generator activity is in versely related to that in neuropeptide Y (NPY) gene and protein expression in the mediobasal hypothalamus and that central administration of an NPY Y -1 receptor antagonist to juvenile animals elicits precocious GnRH release. Cell imaging indicated that the developmentally regulated NPY neurons may be located in regions dorsal to the arcuate nucleus. These findings lead us to propose that NPY is a fundamental component of the neurobiological brak e restraining the onset of puberty in primates.