Apoptosis during the salivary gland enlargement

Abstract

Aims: A close relationship between cell proliferation and subsequent apoptosis has been established in several organs and tissues. The aim of the present study was to investigate whether there is an increased apoptotic activity in the hypertrophy/hyperplasia of the rat parotid and submandibular glands induced by the β-agonist stimulation (isoproterenol, IPR) and soy feeding. In both experimental models hypertrophy and hyperplasia developed simultaneously. Material and methods: Female Wistar rats weighing 200–250g were used. The level of apoptosis was measured by the activity of caspase-3/7 (effector caspase) from the mitochondria-free supernatants of tissue homogenates using a chemiluminescent assay. Results and conclusion: Marked enlargement of the parotids were detected in both IPR-treated and soya fed animals but the same increase of submandibular gland weights were produced only by IPR. In enlarged glands the elevated level of apoptosis was demonstrated. The soy feeding failed to induce glandular enlargement and increased caspase-3/7 activity on submandibular glands. The mastication plays an important role in maintaining normal morphology and function of the salivary glands whereby increased mastication leads to hypertrophy of glands. The animals fed by raw soybean had to exert a higher chewing activity. To eliminate this effect subsequent experiment we used dry powder or powdered soy mixed with water. The data of this experiment confirmed the effect of mastication on the condition of salivary glands. At the same time our findings demonstrated that by switching off the higher masticatory activity it could not inhibit the effect of soy feeding on the parotid enlargement. In the investigated experimental models enlargement of the salivary glands and the increased level of the apoptosis seem to be coupled processes. Supported by: OTKA T-046511 and ETT-384, Hungary