Olfactory and vomeronasal deafferentation of male hamsters: Histological and behavioral analyses

Abstract

Deafferentation of the vomeronasal system by cutting the vomeronasal nerves severely impaired mating behavior in 44% of male hamsters over a 1--2 month period of postoperative testing, but the remaining males mated normally after the surgery. Damage to the main olfactory bulbs, concomitant to vomeronasal nerve cuts, did not account for this behavioral difference. Subsequent deafferentation of olfactory system by intranasal infusion of zinc sulfate solution (5 g ZnSO4--7H2O in 95 ml 0.5% NaCl) had no effect on intromission or ejaculation latencies of sham vomeronasal cut males but eliminated mating behavior 2 days after treatment in males with bilateral vomeronasal nerve cuts. Some of these males recovered the behavior in 1--3 weeks of post zinc sulfate testing. Histological analyses of the olfactory mucosa in 7 males on day 2 after zinc sulfate showed that 89--97% of the mucosa had been destroyed in 6 out of 7 of the males and 78% in the seventh. We conclude that destruction of the vomeronasal system irreparably reduces arousal necessary for mating in some hamsters but in other males sufficient arousal for this behavior to occur is mediated through the olfactory system, presumably in conjunction with other sensory inputs. Subsequent removal of the olfactory input in these animals eliminates the behavior.

Chemosensory Cues are Essential for Mating-Induced Dopamine Release in MPOA of Male Syrian Hamsters

“…In the control of male hamster mating behavior, nonvolatile cues detected in the vomeronasal organ are more important than volatile odors transduced in the olfactory mucosa. Selective destruction of the olfactory mucosa by nasal irrigation with zinc sulfate does not interrupt mating, while severing the vomeronasal nerves blocks sexual activity in 0-44% of males (Winans and Powers, 1977). However, combining zinc sulfate with vomeronasal nerve cuts eliminates copulation.…”

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

“…EXPERIMENT 1 We have previously shown that ZS treatment abolishes detectability of either amyl acetate or FHVS as tested by a Y-maze discrimination task 2 days after treatment [35]. At this time, over 90% of the olfactory epithelium is destroyed, whereas the VNO epithelium is unaffected [42]. Further, we have found that ZS treatment by itself has no effect on male sexual behavior but renders all animals vulnerable to the effects of VN deafferentation.…”

“…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.…”

“…Olfactory and vomeronasal deafferentations were accomplished by intranasal zinc sulfate (ZS) infusions and surgical interruptions of the vomeronasai nerves, respectively. Both techniques as performed in this laboratory have been fully described previously [35,42]. For OLF Deaff, ZS was administered to etherized hamsters using a rigid 18 ga tubing outer hook which accommodated a 30 ga insert.…”

“…When the VN nerves are completely severed bilaterally and no care is taken to avoid scarfing, the central ends of the nerves degenerate, the AOB glomerular layer shrinks and the glomeruli are obliterated by gliosis [42]. VN deafferentation was considered complete only if there were no remaining giomeruli in either AOB.…”