Lesion-induced catecholaminergic sprouting in the interpeduncular nucleus.

This work examined the capacity of intact catecholaminergic axon terminals to sprout in the partially deafferented interpeduncular nucleus (IPN). The results show that norepinephrine and dopamine levels were markedly increased in the IPN 6 weeks after bilateral habenula (Hb) lesions. These changes were accompanied by intensified fluorescence of sprouting axon terminals, as demonstrated by fluorescent histochemistry. The results suggest that both noradrenergic (NA) and dopaminergic neuronal systems respond concomitantly to removal of converging but heterogeneous input to the IPN.