IMMUNOHISTOLOGICAL ANALYSES OF NEUTRAL GLYCOSPHINGOLIPIDS AND GANGLIOSIDES IN NORMAL MOUSE SKELETAL-MUSCLE AND IN MICE WITH NEUROMUSCULAR DISEASES

The expression of neutral glycosphingolipids (GSLs) and gangliosides w as investigated in cryosections of normal mouse skeletal muscle and in muscle of mice with neuromuscular diseases using indirect immunofluor escence microscopy. Transversal and longitudinal sections were immunos tained with specific polyclonal antibodies against lactosylceramide, l acto-N-neotetraosylceramide, globoside, G(M3)(Neu5Ac), G(M3)(Neu5Gc) a nd G(M1)(NeuSAc) as well as monoclonal anti-Forssman GSL antibody. In normal CBA/J mouse muscle (control) the main immunohistochemically det ected ganglioside was G(M3)(Neu5Ac) followed by moderately expressed G (M3)(Neu5Gc) and G(M1). The neutral GSLs lactosylceramide and globosid e were stained with almost identical, high fluorescence intensity. Low amounts of lacto-N-neotetraosylceramide and trace quantities of Forss man GSL were immunostained. All GSLs were detected in the sarcolemma, but also in considerable amounts at the intracellular level. Mice with neuromuscular diseases were the A2G-adr mouse mutant (a model for hum an recessive myotonia of Becker type), the BM-wr mutant (a model for m otor neuron disease) and the BL10-mdx mouse mutant (a model for human Duchenne muscular dystrophy). No changes in GSL expression were found in the A2G-adr mouse, while muscle of the BL6-wr mouse showed increase d intensity of immunofluorescence in stainings with anti-lactosylceram ide and anti-G(M3)(NeuSAc) antibodies. Muscle of BL10-mdx mice showed the most prominent changes in GSL expression with reduced fluorescence intensity for all antibodies. Major differences were not observed in the intensities of GSLs, but there were significant differences in the patterns of distribution on plasma membrane and at the subcellular le vel. The exact nature and pathogenesis of these changes should be eluc idated since such investigations could furnish advances in understandi ng the functional role of neutral GSLs and gangliosides in normal as w ell as in diseased muscle.