Botulinum neurotoxin type A subtype 2 confers greater safety than subtype 1 in a rat Parkinson's disease model

Botulinum neurotoxin type A (BoNT/A) cleaves SNAP-25 and interrupts the release of acetylcholine. We previously reported that BoNT/A subtype 2 (BoNT/A2) ameliorates pathologic behavior more effectively than subtype 1 (BoNT/A1) in a rat Parkinson's disease model. Here, we further show BoNT/A2 has fewer adverse effects than BoNT/A1. We first confirmed that intrastriatal treatments of both BoNT/As had no-effect on dopaminergic terminals in the striatum. SNAP-25 cleaved by BoNT/A2 was strictly localized to the striatum on the injected side; however, SNAP-25 cleaved by BoNT/A1 diffused contralaterally. Furthermore, treatment with BoNT/A1 caused a significant reduction in body weight, while BoNT/A2 treatment did not. These results suggest that BoNT/A2 is more beneficial for clinical application against Parkinson's disease than BoNT/A1.