The neurobiology of primate puberty.

Abstract

In higher primates the protracted prepubertal phase of development is occasioned by a mechanism that suppresses pulsatile hypothalamic gonadotropin-releasing hormone (GnRH) secretion from late infancy until the onset of puberty and thereby guarantees, in the juvenile, the quiescence of the pituitary-gonadal axis. Studies from our laboratory have employed the rhesus monkey, a representative higher primate, as an experimental paradigm. GnRH release has been measured using luteinizing hormone secretion by the in situ pituitary as a bioassay for the hypothalamic hormone. The nature of the prepubertal brake on pulsatile GnRH release in the monkey has been probed using physiological, neuroanatomical and neuropharmacological approaches. Such studies have led to the view that the prepubertal hiatus in pulsatile GnRH release results from a withdrawal in late infancy of a synchronized frequency-facilitated afferent neural input to the GnRH network, which in all other respects appears to exhibit properties identical to those in the postpubertal animal. The mechanism timing the onset of puberty, i.e. that responsible for the reactivation of synchronous activity in the GnRH network, is posited to be under the control of a central neural time- or growth-tracking device.