THE HUMAN VOMERONASAL SYSTEM

We studied the functional characteristics of the vomeronasal system in clinically normal adult subjects of both sexes (ages 20-45). Chemosen sory substances were administered in punctate pulses in a continuous a ir stream from the tip of a multifunctional miniprobe, which contained a nonpolarizable electrode. Negative potentials with the characterist ics of receptor potentials were recorded from the surface of the vomer onasal organ (VNO) and olfactory epithelium (OE) in response to certai n substances defined here as vomeropherins (see definition in the intr oduction of the main text) and to olfactants. Stimulation of the VNO w ith femtomole amounts of vomeropherins produced a local depolarization with the characteristics of a receptor potential. The same substances produced only a small response from the OE, and no response from the nasal respiratory mucosa. Three vomeropherins PH15, PH78, and PH84 wer e particularly well recognized by the VNO of most male subjects (p < . 01; n = 30). Substances PH30, PH56, and PH94B, produced similar effect s in the VNO of most female subjects (p < .01; n = 30). Responses to v irtually all vomeropherins exhibited a sexual dimorphism. Stimulation of the OE with the same quantity of odorants 1,8-cineole and l-carvone produced depolarization of 6.8 +/- 2.6 mV, but little or no response in the VNO. Therefore, the human VNO seems to have a unique specificit y for certain chemosensory substances when compared to the OE. Adminis tration of PH15 and PH78 to the VNO of male subjects (but not to femal e subjects) significantly increased electrodermal activity (p < .02) a nd skin temperature (p < .01). On the other hand, administration of PH 84 to the VNO of male subjects decreased skin temperature but had litt le effect on electrodermal activity. Autonomic changes were accompanie d by an increased percentage of alpha-cortical activity for all three vomeropherins. In female subjects (but not in male subjects) vomerophe rins PH56 and PH94B significantly increased electrodermal activity (p < .01), skin temperature (p < .01), and alpha-cortical activity (p < . 01). Local application of the olfactants 1,8-cineole and l-carvone to the VNO did not trigger autonomic responses or significant changes in the electroencephalographic pattern in male or in female subjects. Our studies indicate the adult human VNO is a functional chemosensory org an with a sexually dimorphic specificity and the ability to transduce signals which modulate certain autonomic parameters.