Demonstration of a pallidostriatal pathway by retrograde transport of HRP-labeled lectin.

A projection from the globus pallidus (GP) to the striatum in the rat was demonstrated by a retrograde tracer technique. After injections of lectin-conjugated horseradish peroxidase (WGA-HRP) which were wholly confined to the striatum, the GP exhibited reaction product characteristic of both retrograde and anterograde transport of marker. Electron microscopic examination of the GP confirmed the presence of both perikaryal and terminal labeling. Coinjection of kainic acid and WGA-HRP into the striatum blocked the appearance of anterograde label in the GP but the retrogradely labeled pallidal neurons remained visible.