Immunohistochemical localization of the GM1, GD1a, GD1b and GQ1b gangliosides in the neuronal endings of rat muscle spindles

Muscle spindles are known to be innervated by both sensory and motor nerve endings. Sensory nerves are mainly distributed in the equatorial regions of muscle spindles, while motors are distributed in the polar regions. To examine the ganglioside expression in sensory and motor nerve endings, we investigated the topographical difference in the distribution of GM1, GD1a, GQ1b and GD1b gangliosides in the muscle spindles of masseter, flexor carpi ulnaris and lumbar paraspinal muscles of adult rats. Whereas GM1, GD1a and GD1b are distributed widely in both the sensory and motor regions of muscle spindles, GQ1b is restricted to the sensory regions. When GQ1b stain was compared with parvalbumin, known as a marker of proprioceptive neuron in dorsal root ganglia, parvalbumin staining was completely negative in the nerve endings of motor regions, whereas a few of them were GQ1b positive. GQ1b stain may reflect a few distribution of group II sensory nerve endings in the polar regions, and anti-GQ1b antibodies may be useful as a sensory nerve marker in muscle spindles. Anti-parvalbumin antibody may be used as a putative proprioceptive (group Ia) nerve marker also in the muscle spindle.