Endogenous brain norepinephrine levels following bilateral olfactory bulb ablation.

Changes in endogenous norepinephrine (NE) levels after bilateral olfactory bulb section have been found to occur in the rat brain. Since olfactory tract projections are confined to the ventral adrenergic pathway, and this pathway projects to the pyriform cortex, it was decided to examine the distribution of endogenous NE between the pyriform cortex and the remaining neocortex. It was demonstrated that significant reductions in NE content occurred in both brain regions, although the greater reduction occurred in the pyriform cortex. there were no significant changes in hypothalamic NE. It is concluded that sensory deprivation plus olfactory system damage induce specific changes in central function, which relate to noradrenergic pathways.