THE EFFECTS OF BLACK WIDOW SPIDER VENOM ON THE INNERVATION OF MUSCLES PARALYSED BY BOTULINUM TOXIN

¹ Department of Neuropathology, Institute of Neurology, The National Hospital, Queen Square, London WC1N 3BG
² Department of Pathology, State University of Campinas, School of Medicine (FCM-UNICAMP), Caixa Postal 1170, 13100 Campinas, S.P., Brazil

Botulinum toxin (BoTx) was injected into the muscles of one leg in mice causing local paralysis. Black widow spider venom (b.w.s.v.) was then injected into the paralysed muscles 3 or 15 d later. In both groups b.w.s.v. destroyed the nerve terminals poisoned by BoTx. In the 15 d group axonal sprouts, which had formed due to the block of neuromuscular transmission by BoTx, were also destroyed. Within a few days the motor nerve terminals regenerated and the muscles recovered from paralysis at a faster rate than after BoTx alone. Recovery seemed to begin earlier in muscles where axonal sprouting was already advanced when b.w.s.v. was injected. The normal pattern of innervation was re-established in both groups, which was in marked contrast with muscles after BoTx alone where numerous sprouts and many ectopic end-plates had formed.