505. Striatal preprosomatostatin mRNA in schizophrenia

Abstract

We have observed a reduction in the density of choline acetyl-transferase (ChAT)-positive neurons in the striatum of schizophrenic patients, relative to normal controls, using both immunohistochemical (1) and in situ hybridization (2) techniques. To investigate whether cell groups of the striatum other than the cholinergic interneurons are affected in schizophrenia, we also examined, in the same cohort, expression of striatal preprosomatostatin (ppSS) mRNA, a marker for GABA neurons. We used in situ hybridization to measure the density of neurons positive for ppSS mRNA. An [35-S]-labeled oligonucleotide probe complementary to human ppSS mRNA was applied to 14 μ thick coronal striatal sections containing caudate nucleus, ventral striatum and putamen, from normal controls (n = 10) and schizophrenics (n = 7). Emulsion-dipped slides were examined for density of positively labeled neurons/mm2 in these brain regions. Statistics were performed using 1-tailed t-tests on the means corrected for postmortem interval and brain pH, both of which were significantly correlated with the data among the normal controls. There were no differences in densities of ppSS mRNA-positive (presumably GABA-expressing) neurons in caudate nucleus (p = .75), ventral striatum (p = .87) or putamen (p = .57). These results suggest that the reduction in density of ChAT mRNA-containing cells in the striatum in schizophrenia is somewhat specific and not likely to be due to a global pathological process affecting the entire striatum, inasmuch as the somatostatin/GABA-containing neurons do not appear to be affected.