SELECTIVE INCREASE IN SOMATOSTATIN MESSENGER-RNA EXPRESSION IN HUMAN BASAL GANGLIA IN PARKINSONS-DISEASE

Levels of the neurotransmitter somatostatin (SS) have previously been shown to be reduced in the cortex and hippocampus of demented parkinso nian patients and patients with Alzheimer's disease. In situ hybridisa tion histochemistry (ISHH) was performed with an S-35 tail-labelled ol igonucleotide DNA probe to human SS mRNA, to examine its expression wi thin the striatum, medial medullary lamina (MML) and reticular thalami c nucleus in Parkinson's disease (PD) and in matched controls. A chron ic unilaterally MPTP-lesioned L-DOPA-naive primate model was also exam ined for comparison of SS mRNA expression with that in human L-DOPA tr eated PD subjects. Quantitation of SS mRNA expression on emulsion dipp ed sections revealed a significant increase (82%) in the MML of the gl obus pallidus in PD (56.5 mu m(2) of silver grain/cell, n = 9 cases) c ompared to controls (26.3 mu m(2)/cell, n = 13 cases, p < 0.01, Studen t's t-test), paralleling the increase previously observed by this grou p for NOS mRNA. SS mRNA expression was higher in the dorsolateral than ventromedial putamen in controls (p < 0.001; DL: 24.89 +/- SEM 1.35; VM: 17.96 +/- SEM 2.63; n = 14) but this gradient was lost in PD cases (p > 0.05; DL: 22.68 +/- 1.94; VM: 22.17 +/- 2.94; n = 10). These fin dings suggest specific modification of basal ganglia SS-ergic pathways in PD. (C) 1997 Elsevier Science B.V.