Compartmental distribution of parvalbumin and calbindin D-28k in rat globus pallidus

The cellular localization of parvalbumin (PV) and calbindin D-28k (CB) in the globus pallidus (GP) of rats was studied with double-immunohistochemical methods applied to single sections. The two calcium-binding proteins were found to be differentially distributed in GP. PV-positive cells were largely concentrated in the lateral part of GP where CB immunostaining was minimal. Their number and location varied along the rostrocaudal axis of GP. Pallidal PV cells were either large and multipolar or small and fusiform. In contrast, the medial part of GP was markedly enriched with CB neuropil but largely devoid of PV-positive cells. This spatial segregation indicates the existence of at least two different functional domains in the rat GP.