Influence of Intramasseteric Injection of Botulinum Toxin Type A on the Ipsilateral Submandibular Salivary Gland of Albino Rats

Abstract

Background: Botulinum toxins are used in treating involuntary muscle contraction such as hemifacial spasm and facial nerve palsy, hyperhidrosis or excessive saliva production. Minor side effects are reported like local hematoma, pain, dry mouth and viscous saliva. However; major complications may occur such as loss of motor head control and aspiration pneumonia. Some animal studies showed minimal histological changes. While, some authors have demonstrated significant structural and functional changes in the parotid gland of rats and the submandibular gland of rabbits after being injected with botulinum toxin type-A (BTX-A). Aim of the Study:To evaluate the effect of intramasseteric injection of BTX-A on the ipsilateral submandibular gland in Albino rats. Materials and Methods: Fifty six adult male Albino rats were divided into four groups. Rats of group (I) and group (II) received intramasseteric injection of 0.05 ml or 0.1 ml of 0.9% sodium chloride solution respectively. Rats of group (III) and group (IV) received intra-masseteric injection of 2.5 units or 5 units of BTX-A respectively. Each group was further subdivided into two subgroups according to the time of sacrifice which was at three or fourteen days. Sections of glands were stained by H&E and S100 protein antibody. Results: Glands' acini of group III and IV showed cytoplasmic vacuolations. Acini of group IV at fourteen days showed irregular outline with areas of complete degeneration. Duct system of both groups showed signs of degeneration. Using immunohistochemical staining, group III and IV showed increased area percentage of positive reaction than control groups. Statistical analysis of acini diameter and area percentage of anti-S100 protein revealed significant increase in botox injected subgroups. Conclusion: Intramasseteric injection with BTX-A was able to induce histological changes in submandibular gland of the ipsilateral side.