Expression of major neurotansmitter receptors on human astrocytoma cell lines

Abstract

To elucidate functional properties of human astrocytoma cell lines, U-251MG, U-87MG, and KINGS-1, we examined the expression of neurotransmitter receptors with Ca²⁺ imaging. Those cells were loaded with Ca²⁺ sensitive dye (fura-2 AM), and subjected to measurement of the Ca²⁺-dependent fluorescence changes using a specific imaging device. The cells which showed the increase in [Ca²⁺]_i during the administration of a neurotransmitter were classfied as positive. We tested the effects of amino acid (glutamate), catecholamine (noradrenaline), autacoid (histamine), and others (ATP, acetylcholine) on each cell line. The astrocytoma cells showed positive responses during the administration of histamine, acetylcholine, noradrenaline, and ATP. The amplitude of Ca²⁺ response was dose-dependent (10 nM–1 mM), and significantly reduced by each specific antagonist. Surprisingly, Ca²⁺ measurement indicated that those cells showed a negative sensitivity to glutamate (100 μM), which had been reported to be an important mediator between glial cells and neuronal cells. Those results suggest that the loss of glutamate receptor is involved in an initial step of the functional disorder of communication between astrocytes and neurons in the human brain. [J Physiol Sci. 2008;58 Suppl:S82]