The effect of local injection of botulinum toxin A on the parotid gland of the rat:: An immunohistochemical and morphometric study

Purpose: In this investigation, the effect of a local injection of botulinum toxin A on the concentration of acetylcholinesterase in the parotid gland of the rat was examined. Materials and Methods: After local injection into the parotid glands of female Wistar rats, the treated glands were excised, and immunohistochemical staining for acetylcholinesterase was performed. To discover possible changes in cell morphology after local application of botulinum toxin A, morphometric measurements also were performed on the excised parotid glands. Results: In contrast to the untreated, physiologic saline-injected, glands, there was a decrease in the concentration of acetylcholinesterase in the glands treated with botulinum toxin. No persistent changes in the number of acinar cells could be observed. Conclusions: Because the cholinergic pathway of the autonomic nervous system has great importance in the secretion of fluid from the salivary glands, blocking this pathway and local application of botulinum toxin offers a possible therapeutic option for the treatment of hypersalivation in various otolaryngologic and neurologic diseases. (C) 2000 American Association of Oral and Maxillofacial Surgeons.