Immunohistochemical investigations of the influence of botulinum toxin A on the immunoreactivity of nNOS in the parotid gland of the rat.
OBJECTIVE
We wanted to prove the hypothesis that local injections of botulinum toxin A have an influence on the immunoreactivity of neuronal nitric oxide synthase (nNOS) in parotid glands of adult rats.


METHODS
Our group carried out immunohistochemical reaction of neuronal nitric oxide synthase (nNOS) in the parotid gland of female adult Wistar rats, in native (untreated) glands and after intraglandular injection of botulinum toxin A under general anesthesia. The immunoreactivity of nNOS was investigated on different times after injection.


RESULTS
Compared with the untreated glands, there was a significant decrease of nNOS in the treated organs that became stronger with extended toxin exposure time. After our laboratory in a pilot study had already shown in general a decrease of nNOS immunoreactivity after injection of botulinum toxin A into the cephalic salivary glands of the rat, the present study shows more explicit data on the effect of botulinum toxin A injection on a higher number of examined parotid glands and analyzes a time course of the effect duration.


CONCLUSIONS
In our study, it was shown that botulinum toxin A had an influence on the immunoreactivity of neuronal nitric oxide synthase (nNOS) in parotid glands. Participation of nitric oxide (NO) in the regulation of secretion from the parotid gland of the rat seems to be likely. It might be assumed that the influence of botulinum toxin A on nNOS in the parotid gland of the rat is able to explain the sometimes longer duration of toxin effect at the neuroglandular junction than at the motor endplate.
Department of Otorhinolaryngology, Head and Neck Surgery, University of Göttingen, Germany. mellies@med.uni-goettingen.de
Maik
M
Ellies
Sebastian
S
Schütz
Fabio
F
Quondamatteo
Rainer
R
Laskawi
D000818:Animals; D019274:Botulinum Toxins, Type A / Q000494:pharmacology*; D005260:Female; D007150:Immunohistochemistry; D009465:Neuromuscular Agents / Q000494:pharmacology*; D009498:Neurotoxins / Q000494:pharmacology; D009569:Nitric Oxide / Q000378:metabolism; D052248:Nitric Oxide Synthase Type I / Q000096:biosynthesis / Q000187:drug effects*; D010306:Parotid Gland / Q000187:drug effects / Q000201:enzymology*; D051381:Rats; D017208:Rats, Wistar; D012472:Salivation / Q000187:drug effects; D013997:Time Factors
D009465:Neuromuscular Agents; D009498:Neurotoxins; D009569:Nitric Oxide; D052248:Nitric Oxide Synthase Type I; D019274:Botulinum Toxins, Type A