Vomeronasal Organ: Critical Role in Mediating Sexual Behavior of the Male Hamster

Abstract

Sexual behavior in male hamsters is totally abolished by bilateral removal of the olfactory bulbs. This operation eliminates sensory input from both the olfactory and the vomeronasal systems. We previously demonstrated that peripheral destruction of the olfactory receptors caused anosmia but did not impair male hamster mating behavior. Here we demonstrate that peripheral deafferentation of the vomeronasal system produces severe sexual behavior deficits in approximately one-third of the treated animals. Combined deafferentation of both the vomeronasal and the olfactory systems eliminates copulation in 100 percent of the animals. This is the first experimental demonstration of a functional role for the vomeronasal organ in a mammalian species.

Olfactory and vomeronasal system participation in male hamsters' attraction to female vaginal secretions

“…Based on the findings presented here and the results from our earlier studies [35,36,42] we conclude that in all male hamsters the vomeronasal system, functioning in the absence of olfactory input, can subserve both persistent investigation of female vaginal secretions and overt copulatory behavior. In contrast, olfactory stimulation in the absence of vomeronasal input can mediate these 2 behavioral functions in only a subpopulation of animals.…”

“…Our work was the first to demonstrate conclusively the relevance of VNO activity in subserving reproductive activities in a mammalian species [36,42]. We have indicated elsewhere that indirect evidence suggests a comparable role for the VNO in male rats [42].…”

“…This procedure also destroys afferents from the olfactory mucosa to the main olfactory bulb (MOB), connections of the vomeronasal organ (VNO) with the accessory olfactory bulb (AOB), the nerves of the septal olfactory organ and the nervus terminalis [2,5]. Although the contribution which each of these systems might make to the behavioral effects of bulbectomy in any species has not been ascertained, recent work in this laboratory has indicated that the olfactory and vomeronasal systerns together comprise an essential substrate in the regulation of male hamster copulation [36,42]. Although deafferentation of the olfactory system alone by intranasal infusion of zinc sulfate has no effect on mating behavior in male hamsters, combined olfactory and vomeronasal deafferentation eliminates copulation in all animals and thus mimicks the effect of bulbectomy.…”

The main and the accessory olfactory systems interact in the control of mate recognition and sexual behavior

“…However, genetic ablation of a subset of V1Rs has significant effects on sexual behavior in males [23]. In other species such as hamsters or prosimian primates (Microcebus murinus), surgical ablation of the VNO seemed to have more dramatic effects on the display of sexual behaviors [2,87]. However, in mice, male sexual behavior has been shown to be more generally dependent on a functioning MOE.…”

The evolution of pheromonal communication

“…Lesions to the VNO have also been shown to disrupt pheromonally-induced behaviours, such as the absence of oestrous cyclicity that occurs in group-housed female mice (the LeeBoot effect), and the induction of early puberty in young female mice that are exposed to male odours (the Vandenbergh effect) [47]. Surgical ablation of the VNO has dramatic effects on reproductive behaviours that are dependent on pheromones, compromising copulatory behaviour in both female [45] and male rodents [66,71].…”