Castration differentially alters [H-3]nisoxetine binding to norepinephrineuptake sites in olfactory bulb and frontal cortex of male rats

In the present study, [H-3]nisoxetine binding to norepinephrine (NE) uptake sites and [H-3]norepinephrine uptake were investigated within olfactory bu lb (OB) and frontal cortex homogenates from intact and castrated male rats. Statistically significant reductions in the number of [H-3] nisoxetine bin ding sites (B-max) were found in OB from the castrates, while significantly increased B-max values were obtained in the frontal cortex. Castration als o significantly altered the affinity (K-d) of [H-3]nisoxetine binding in th e frontal cortex, but not in the OB. Assessment of [H-3]norepinephrine upta ke showed that in neither brain regions were there any statistically signif icant differences in K-m nor V-max between the castrated and intact male ra ts, indicating that the basal uptake process is not changed following castr ation in either of these brain areas. These results demonstrate the differe ntial effects of castration upon [H-3]nisoxetine binding sites between the OB and frontal cortex. Such findings provide new evidence for one of the me chanisms by which androgens may modulate central noradrenergic activity. Sy napse 31:250-255, 1999. (C) 1999 Wiley-Liss, Inc.