Abstract
In the present study we examined the expression of neurotransmitter receptors on human astrocytoma cell lines, U251-MG, U87-MG, and KINGS-1. Those cells were loaded with fura-2 AM, and subjected to Ca2+ imaging using a specific imaging device. The cells which showed the increase in [Ca2+]i during the administration of a neurotransmitter were determined as positive. We tested the effects of histamine, acetylcholine, noradrenaline, dopamine, GABA, serotonin, glutamate, and ATP on each cell line. Those cells showed the significant increase in [Ca2+]i during the administration of histamine, acetylcholine, noradrenaline, and ATP, but each cell line showed characteristic Ca2+ responses to those agonists. The amplitude of Ca response was dose-dependent (10–6∼10–3 M), and significantly blocked by each specific antagonist. Surprisingly, none of those cells responded to glutamate (100 μM), which had been reported to be an important mediator between glial and neuronal cells, cause significant increase in [Ca2+]i. Since recent studies on astrocytes have demonstrated the important participation of those cells on regulation of synaptic transmission, the expressed neurotransmitter receptors on those cells and the regulatory systems for expression of those receptors will provide us important clue for elucidating the glia-neuron inter-communication. [Jpn J Physiol 55 Suppl:S146 (2005)]
