Metachromatic, tryptase- and ghrelin-positive mast cells in the blood vessels of rat’s lung

Mast cells and the mediators they release play a major role in the pathogenesis of lung diseases. They regulate the function of the smooth muscle layer of the pulmonary airways and the same layer of the blood vessels. There are no data about the distribution of metachromatic and tryptase-positive mast cells in the blood vessels’ wall as well as on the content of ghrelin in mast cell granules in rat’s lung. The aim of this research was to present an analysis of the number and localisation of tryptase-positive, ghrelin-positive and metachromatic mast cells in the blood vessels (arteries, capillaries, venules and veins) in rats of different age. Six male Wistar rats were used for each age group - 20 days, 3 months and 1 year. Tissue slices for histochemical examination were taken from the caudal lobe of the left lung and stained with toluidine blue. Immunohistochemical reactions were then performed to indicate the expression of tryptase and ghrelin, allowing comparing the presence of tryptase-, ghrelin-positive and metachromatic mast cells in the wall of the blood vessels of different diameters. The light microscopical study showed that in all types of blood vessels from the three age groups, the number of ghrelin positive cells was the largest, followed by tryptase-positive and metachromatic mast cells. The observed differences in the distribution of these cells are important for maintaining the lung homeostasis and can be used as reference values in experimental studies in order to obtain accurate results.