SPARING OF STRIATAL NEURONS COEXPRESSING CALRETININ AND SUBSTANCE-P (NK1) RECEPTOR IN HUNTINGTONS-DISEASE

Immunohistochemical studies of the striatum in normal human subjects w ith a double-antigen localization method have revealed the presence of large and medium-sized aspiny neurons displaying immunoreactivity for both the calcium-binding protein calretinin and substance P (neurokin in-l) receptor. These large and medium-sized cells form two distinct c lasses of striatal interneurons, which together represent less than 3% of the total neuronal population of the human striatum. Observations made in four cases of Huntington's disease revealed that such doubly l abeled interneurons are still present in the striatum of these patient s, despite the marked atrophy of the structure. This study provides th e first evidence for the existence of interneurons containing calretin in and expressing tachykinin receptors in the human striatum. It also demonstrates the selective sparing of these chemospecific striatal neu rons in Huntington's disease.