Regional distribution of vasoactive intestinal peptide in brains from normal and parkinsonian subjects

The distribution of vasoactive intestinal peptide (VIP) in the post-mortem human brain was determined by radioimmunoassay using a highly specific antiserum. The detection limit of the assay was 4 fmol/tube. The highest concentrations of VIP were found in the cerebral cortex, amygdala, hypothalamus and hippocampus. The lowest levels of peptide were detected in basal ganglia including caudate nucleus, external pallidum, putamen and substantia nigra. All dilution curves of acetic acid extracts from different brain areas were strictly parallel to the standard curve. Sephadex G-50 gel filtration of frontal cortex extract showed that VIP-like immunoreactivity (VIP-LI) eluted as a major peak comigrating with synthetic hVIP. Detailed mapping of VIP in the human cerebral cortex showed the existence of a rostro-caudal gradient of VIP-LI concentrations: the frontal cortex exhibited the highest VIP levels, the parietal and temporal cortex contained medium values and the occipital cortex contained the lowest VIP levels. The concentrations of VIP-LI were compared in various regions of the human brain from normal and parkinsonian subjects. No significant changes in VIP-LI levels occurred in the brains of patients dying with Parkinson's disease. No difference in VIP levels could be found either when the parkinsonian group was subdivided into nondemented and demented patients. These data indicate that VIP-containing neurons are not affected in parkinsonian patients. Our results also suggest that VIP neuronal systems are not involved in the course of dementing process in Parkinson's disease.