The identification and characterization of oligodendrocyte thromboxane A2 receptors

The presence of functional thromboxane A(2) receptors in neonatal rat oligodendrocytes and human oligodendroglioma cells was investigated using immunocytochemistry, ligand affinity chromatography, radioligand binding analysis, immunoblot analysis, and calcium mobilization studies. Immunocytochemical studies revealed the presence of receptor protein on both oligodendrocytes and human oligodendroglioma cells, Ligand affinity chromatography allowed for the purification of a protein with an electrophoretic mobility (55 kDa) indistinguishable from human platelet thromboxane A(2) receptors. This affinity purified protein was immunoreactive against a polyclonal anti-thromboxane A(2) receptor antibody. Intact human oligodendroglioma cells specifically bound [H-3]SQ29,548 with a K-D of 4 nM and were found to have approximately 3500 binding sites per cell. Human oligodendroglioma cells also demonstrated calcium mobilization in response to receptor activation with U46619. These results demonstrate the presence of a functional thromboxane A(2) receptor in oligodendrocytes and are consistent with previous observations indicating a high density of thromboxane A(2) receptors in myelinated brain and spinal cord fiber tracts.