The biochemical analysis of neurotransmitters in central neurocytomas

Central neurocytomas are rare benign intraventricular tumours composed of small round synaptophysin-positive cells, suggesting a neuronal origin of these tumour cells. Although past electron microscopic studies demonstrated synaptic vesicles in the synapse of central neurocytomas, the kinds of neurotransmitters in central neurocytomas have never been identified. In this study we analyzed neurotransmitters in an attempt to clarify the tumorigenesis of central neurocytomas. We studied frozen central neurocytoma specimens from four patients. The tissue levels of glutamate and GABA (gamma-aminobutyric acid) in the tumours were determined by gas chromatography-mass spectrometry (GC-MS) using a selected ion monitoring method. The tissue levels of acetylcholine, choline, catecholamines and metabolites of catecholamines in the tumours were measured by high-performance liquid chromatography combined with electrochemical detection. Choline was found in extremely high concentration in all central neurocytomas when compared with levels in controls. In one central neurocytoma, GABA was found in extremely high concentration compared with controls. In all central neurocytomas, glutamate was found in lower or identical concentrations compared with controls. In all central neurocytomas and controls, dopamine and catecholamine concentrations were extremely low. These results indicated that the histogenesis of central neurocytomas begins with the subependymal stem cells, which have the potential to differentiate into cholinergic or GABA neurons.