FLIP AND FLOP VARIANTS OF AMPA RECEPTORS IN THE RAT LUMBAR SPINAL-CORD

The expression of eight messenger RNA splice forms encoding the Flip a nd Flop variants of AMPA receptor subunits GluR-A to -D in the rat lum bar spinal cord was examined by in situ hybridization using specific o ligonucleotides. In the dorsal horn (laminae I, II and III) the predom inant mRNA was GluR-B flip. Much lower levels of GluR-A Flip were foun d in lamina I and in superficial parts of lamina II outer. In the vent ral horn, motor neurons expressed mainly GluR-B Flip, GluR-C Flip and Flop, and GluR-D Flip. Serial sectioning through large motor neurons i ndicated that a given cell contained, for example, both GluR-C Flip an d Flop splice types.