Castration reduces olfactory bulb norepinephrine transporter function as indicated by responses to noradrenergic uptake blockers

Abstract

It has been demonstrated that castration alters the functioning of the olfactory bulb (OB)–norepinephrine (NE) system. In the present experiment, we examined one of the mechanisms by which castration modulates the OB–NE system by comparing NE uptake activity between intact and castrated male rats as studied using an in vitro superfusion technique. To accomplish this goal, NE output from the OB of intact and castrated male rats in response to infusion with two different drugs which alter NE uptake functions, tomoxetine and talsupram, were tested. Overall, NE outputs in response to tomoxetine were significantly higher in the castrated than in intact rats and both groups were significantly greater than non-infused controls. For the talsupram infusion group, NE outputs from the castrated, but not intact rats, were significantly greater than controls. No statistically significant differences were detected between the castrated and intact rats. These results demonstrate that castration alters the NE uptake activities in response to these noradrenergic uptake blockers and suggest that one mechanism by which castration alters OB–NE functioning is through reducing the uptake activity of NE within the OB. Such findings have important implications for olfactory-based learning and memory/recognition processes which are believed to involve the OB–NE system and are altered following castration.