Selective noradrenergic denervation and 3H-prazosin binding sites in rat neocortex

Biochemical determinations of alpha 1-noradrenergic binding sites were performed in the neocortex of normal rats and of rats which had been subjected to a selective noradrenergic deafferentation obtained by microinjecting 6-OHDA in the dorsal noradrenergic bundle. The extent and the specificity of the deafferentation was assessed by measuring the catecholamines dopamine, epinephrine and norepinephrine, as well as the indoleamine serotonin using radioenzymatic assays. In the denervated animals (90% reduction in NE levels) specific binding of the alpha 1-noradrenergic antagonist prazosin revealed an increase only in the number of binding sites (Bmax) without changes in the dissociation constant (Kd).