Somatostatin-like immunoreactivity, its molecular forms and monoaminergic metabolites in aged and demented patients with Parkinson's disease--effect of L-Dopa

Abstract

There is some evidence that Parkinson's disease (PD) seems to be a heterogenous and generalized brain disorder reflecting a degeneration of multiple neuronal networks, including somatostatinergic neurons. Somatostatin-like immunoreactivity (SLI) and its molecular forms, high molecular weight form (HMV-SST), somatostatin-14 (SST-14), somatostatin-25/28 (SST-25/28) and Des-ala-somatostatin (Des-ala-SST), as well as homovanillic acid (HVA) and 5-hydroxyindoleacetic acid (5-HIAA) were estimated using HPLC and radioimmunoassay in the cerebrospinal fluid (CSF) of 35 aged parkinsonian patients with different stages of intellectual deterioration. The influence of L-dopa-treatment on these neurochemical parameters was evaluated. Without a correlation with dementia scores (p = 0.11), SLI was significantly reduced in PD in comparison to the control group (p < 0.05). The reduction was related to the progression of the disease. Correlations between SLI, HVA and 5-HIAA indicate a heterogenous brain disorder in PD with alterations of several transmitter systems and functions. Complex qualitative and quantitative changes in the molecular pattern of SLI are compatible with a dysregulated synthesis and/or posttranslational processing. L-dopa-treatment was associated with a significant increase of HVA (p < 0.05) and HMV-SST (p < 0.05) and a slight, but insignificant increase of SLI (p = 0.11).