REDUCED CEREBRAL CORTICAL BUT ELEVATED STRIATAL CONCENTRATION OF SOMATOSTATIN-LIKE IMMUNOREACTIVITY IN DOMINANTLY INHERITED OLIVOPONTOCEREBELLAR ATROPHY

Somatostatin-like immunoreactivity (SLI) was measured in the brains of nine patients with dominantly inherited olivopontocerebellar atrophy (OPCA), who all had a marked deficit of the cholinergic marker choline acetyltransferase (ChAT) in the cerebral cortex and striatum. Mean con centrations of SLI in OPCA were significantly reduced by 42-58% in par ietal and occipital cortices and frontal cortical eye fields, but were normal in other cortical areas, including two subdivisions of the tem poral cortex which show marked depletions of both SLI and ChAT in Alzh eimer's disease. This dissociation of SLI and ChAT indicates that a co rtical cholinergic deficit does not invariably lead to reduction of so matostatin. In the caudate nucleus, the region of OPCA brain having th e most severe ChAT deficit (- 8 1%), SLI levels were significantly ele vated by 46% and were negatively and significantly correlated with ChA T activities (r = -0.66). The SLI alterations could be due to abnormal somatostatin metabolism or release, or an increased number of somatos tatin-containing neurons and could contribute to the brain dysfunction of OPCA.