Botulinum toxin induces nitric oxide synthase activity in motoneurons.
Intramuscular injections of botulinum toxin A were made into the snout of 3-month- and 3-week-old rats, resulting in transient paralysis of the facial muscles. Nicotinamide adenine dinucleotide phosphate (NADPH)-diaphorase histochemistry, which is a marker of nitric oxide synthase activity in fixed tissue and, in particular, in injured motoneurons, was studied in the facial nucleus. At variance with control injections of saline, the histochemical staining was found to be induced in facial motoneurons after botulinum toxin injection. The occurrence and persistence of the histochemical positivity in facial motoneurons paralleled that of muscle paralysis. These findings indicate that the enzyme of synthesis of the free radical nitric oxide can be induced in motoneurons after a functional disconnection from the target, which spares the axon and is associated with cell survival.
Mariotti
R
R
Institute of Anatomy and Histology, Medical Faculty, University of Verona, Italy.
Bentivoglio
M
M
D000818:Animals; D001905:Botulinum Toxins / Q000494:pharmacology*; D006651:Histocytochemistry; D008297:Male; D009046:Motor Neurons / Q000187:drug effects*; D019001:Nitric Oxide Synthase / Q000187:drug effects*; D051381:Rats; D017208:Rats, Wistar
D019001:Nitric Oxide Synthase; D001905:Botulinum Toxins