Effect of rabbit anti-asialo-GM1 (GA1) polyclonal antibodies on neuromuscular transmission and acetylcholine-induced action potentials: Neurophysiological and immunohistochemical studies

We produced anti-asialo-GM1 (GA1) polyclonal antibodies by sensitizing New Zealand rabbits with GA1 and investigated the epitopes and pathogenic role of anti-GA1 antibodies that appeared in serum. The serum blocked neuromuscular transmission, but not acetylcholine (ACh)-induced potentials, in muscle-spinal cord cocultured cells. The effect was complement independent. The antibodies inhibited voltage-gated Ca²⁺ channel (VGCC). The epitopes recognized by the antibodies were located in the outer membrane of Schwann cells and motor axons of Wistar rat ventral roots and on motor axons extended from spinal cord to muscle cells in muscle-spinal cocultured cells. The ACh-induced potential was not reduced by the addition of sera, suggesting the blockade is presynaptic. Thus, anti-GA1 antibodies may block neuromuscular transmission by suppressing VGCC on axonal terminals of motor nerves.