Intraductal injection of botulinum toxin induces functional changes in rat submandibular gland cells

Abstract

Botulinum toxin (BoNT) disrupts neurotransmitter release from cholinergic nerves. We investigated whether temporary acinar atrophy occurs simultaneously with chemical denervation of the glands. Male Wistar rats weighing 250-300g were used. Intraductal injection of BoNT induced a transient denervation of the submandibular gland, which is associated with reduced salivary secretion. Morphological and ultra structural analyses of the cell organelles and secretory granules showed a clear atrophy of the acini, which was more prominent in glands treated with BoNT. Morphometric measurements of the glandular acini revealed a significant reduction in the area of the acinar cells after BoNT treatment. The expression of amylase was significantly reduced in BoNT treated glands. Intraductal injection of BoNT induced structural and functional changes in the salivary glands, which was indicated by glandular atrophy. These effects may be the results of glandular denervation induced by the inhibition of the soluble N-ethylmaleimide-sensitive fusion protein attachment protein receptors (SNAREs) involved in acetylcholine release at the neuro-glandular junction, and especially the results of the inhibition of the cells involved in exocytosis of the acinar cell granules.