Olfactory bulb norepinephrine depletion abolishes vasopressin and oxytocin preservation of social recognition responses in rats.

Male rats were implanted bilaterally with cannulae directed at the olfactory bulbs and infused with either vehicle or 6-OHDA to selectively deplete norepinephrine concentrations at this site. At 5-7 days following this treatment, these animals received a bilateral infusion of either arginine vasopressin (AVP) or oxytocin (OXT) through these same guide cannulae and were then tested for their capacity to maintain social recognition responses. Neither infusion of AVP nor OXT were able to preserve recognition responses in the animals treated with 6-OHDA. In contrast, comparably tested animals who received a vehicle infusion showed clear recognition responses following either the AVP or OXT infusion. These results suggest that this capacity for these neuropeptides to preserve social recognition responses is mediated through the norepinephrine system of the olfactory bulb.