THE FUNCTIONALITY OF THE HUMAN VOMERONASAL ORGAN (VNO) - EVIDENCE FORSTEROID-RECEPTORS

The human vomeronasal organ (VNO) is an anatomical entity which is gen erally considered to be vestigial or non-functional. Nevertheless, a s teroidal vomeropherint applied to the human VNO, results in changes of autonomic function, pulsatile release of luteinizing and follicle-sti mulating hormones, autonomic and electroencepholographic activity. The vomeropherin pregna-4,20-diene-3,6-dione (PDD) was delivered as pulse s in an air stream directed into the lumen of the VNO or to the surfac e of the olfactory epithelium and respiratory epithelium of the nasal septum. Single stimuli at a concentration of 10(-10) to 10(-8) M produ ced dose-dependent changes of the electrovomerogram. No significant ef fects were observed when the same applicator delivered identical stimu li to the nasal respiratory epithelium or to the olfactory epithelium. Administration of the vomeropherin to male subjects changed gonadotro pin pulsatility. In males, PDD (5 x 10-(9)M) decreased luteinizing hor mone (LH) pulsatility which resulted in a statistically significant re duction of plasma LH levels (P < 0.009) and follicle-stimulating hormo ne (FSH) pulsatility (P < 0.021), but it produced no significant effec ts in female subjects. Prolactin (PRL) was not significantly affected by this vomeropherin in either male or female subjects. These data dem onstrate, for the first time, the existence of a functional vomeronasa l-pituitary pathway in adult humans. In addition to the effect on gona dotropin pulsatility, the vomeropherin also produces concurrent reflex autonomic effects after VNO stimulation. These included decreased res piratory frequency, increased cardiac frequency, and event-related cha nges of electrodermal activity and EEG pattern. Therefore, this invest igation also provides evidence for functional connections between the VNO and a variety of hypothalamic areas in adult humans. Copyright (C) 1996 Elsevier Science Ltd.