Further evidence for the presence of nigro‐neostriatal dopamine neurons in the rat

Abstract

With the help of the highly specific and sensitive histochemical fluorescence method of Falck and Hillarp for the cellular demonstration of monoamines the catecholamine‐containing cell‐bodies within the brain stem have been studied after unilateral removal of a large part of the neostriatum 1 to 28 days after the operation. Most of the catecholamine‐containing cell‐bodies within the substantia nigra — but no other monoamine‐containing cell‐bodies — appeared to be distinctly increased in fluorescence intensity and somewhat swollen 2 to 4 days after operation while after 3 to 4 weeks they showed a marked to very marked decrease in fluorescence intensity together with marked degenerative changes. Parallel with the changes in the cell‐bodies there occurred a rapid and marked accumulation of catecholamines within very abundant swollen nerve fibers in the internal capsule. These nerve fibers were traced caudally via the retrolenticular part of the internal capsule down to the crus cerebri. These results together with those in a previous paper (Andén, Carlsson, Dahlström, Fuxe, Hillarp and Larsson, 1964) seem to provide conclusive evidence for the presence of nigro‐neostriatal dopamine neurons.