Neuropeptide content of purified rat brain cholinergic synaptosome subpopulations.
Cholinergic synaptosomes from rat cerebral cortex were isolated by a magnetic immunoaffinity technique, i.e. immunomagnetophoresis. This subpopulation was extracted and subjected to radioimmunoassay for 4 neuropeptides:neuropeptide Y (NPY); vasoactive intestinal peptide (VIP); substance P (SP); and somatostatin (SRIF). Three of the 4 neuropeptides were enriched in the sorted fraction compared with the mother fraction with respect to the cytosolic marker lactate dehydrogenase (LDH). The most enriched neuropeptide was NPY followed by SP and VIP. Somatostatin was not enriched in the cholinergic synaptosome subpopulation. The presence of NPY has not previously been reported in cortical cholinergic neurones.