Effect of preganglionic parasympathetic denervation on Nitric Oxide synthase in submandibular gland of adult albino rat

ABSTRACT

Adult albino rats were subjected to chorda tympani neurectomy on the right side and the left side served as the control. After different survival periods, the control and experimental submandibular glands were discected out and processed for histological and histochemical examinations. Chorda tympani neurectomy resulted in atrophic changes in about 90% of both seromucous acini and granular convoluted tubules of the submandibular gland. They showed statistically significant reduction in their mean diameters after denevation. The reduction in the diameter of the acini was more marked than that of the tubules. The atrophic acini became separated by wide spaces and their cells showed cytoplasmic vacuolation two weeks after chorda tympani neurectomy. At the third and the fourth weeks, an insignificant increase in the diameter was noticed in the tubules and acini. The interlobular striated ducts showed cytoplasmic vacuolation two weeks after denervation which became more prominent during the third and fourth week after chorda tympani neurectomy. After denervation, NADPH-d positive nerve terminals were absent around the majority of acini and the granular convoluted tubules and were seen around the remaining 7-10% of the acini and 10-23% of the tubules. Throughout the period of denervation, NADPH-d positive nerve terminals were found around the striated ducts, the interlobular ducts and the blood vessels. The majority of the NADPH-d positive nerve terminals around the acini and granular convoluted tubules are parasympathetic in origin derived from the chorda tympani. The origin of NADPH-d positive nerve fibers around some acini and granular convoluted tubules and in relation to the remaining duct system and blood vessels needs further investigation