MYASTHENIA GRAVIS ASSOCIATED WITH NEUROPSYCHOSIS : SERUM AUTOANTIBODIES RECOGNIZE NEURONAL NICOTINIC ACETYLCHOLINE RECEPTORS

Abstract

The α₄ subunits of neuronal nicotinic acetylcholine receptor (nAChR) are widely expressed throughoUt the brain, and the α₁ subunits of muscle nAChR are localized at the muscle endplates. Most patients with myasthenia gravis (MG) are seropositive for anti-muscle nAChR antibody, and the peptide comprising residues 125-147 of the human α₁ subunit is myasthenogenic. We synthesized a peptide of the α₄ subunit counterpart of the α₁ 125-147 to investigate cross-reactivity of neuronal nAChR with autoantibodies in MG patients. The synthetic peptide α₄ 160-182 was injected into rabbits, and produced anti- bodies caused a loss of net muscle nAChR. Three myasthenic patients with neuropsy- chiatric symptoms had autoantibodies of which bindings to muscle nAChR were inhibited with anti-α₄ 160-182 antibodies. The serum autoantibodies from these patients recognized the α₄ 160-182.