MORPHOLOGICAL CHANGES IN THE SPLEEN OF RAT UNDER IMMOBILIZATION STRESS

The aim of the study was to investigate structural changes in the red and the white pulp of the rat spleen under immobilization stress when introducing bacterial lipopolysaccharide.Material and methods. The experiment was performed on 60 white rats of the Wistar line. The first control group received physiological saline, the second one received lipopolysaccharide. In the experimental group of rats, the immobilization stress was 24 hours duration. The first experimental group was administered physiological saline solution, the second experimental group was administered 100 μg/kg dose of lipopolysaccharide Pyrogenal («Medgamal», Russia). The material sampling was peformed after 3 hours, on the 3rd day and the 8th day of the experiment. Paraffin sections of 4-5 microns thickness were made from the spleen fragments fixed in 10% solution of neutral formalin, then they were stained with hematoxylin and eosin. The areas of the organ's longitudinal section, the white and the red pulp, the width of the lymph nodes reactive center of the white pulp, the width of the nodules, mantle and marginal zones as well as the width of the periarterial lymphoid muff were measured (40-50 measurements for each animal).Results. It was found that on the 3rd day after the stress, morphological signs of the white pulp activity reduction were detected via the decrease in the white pulp area (by 39.7%), as well as a general decrease of the spleen section area by 4.3%. On the 8th day, there were recovery processes in the spleen, but there was no complete restoration of the spleen structure - the white pulp area was11.55% less than the control group values, and the red pulp area was 6.7% less than the control group values. When lipopolysaccha-ride was administered under stress, there were no signs of the white and the red spleen pulp activity inhibition; the morphological parameters of the spleen did not differ from the control values.

spleen, white and red pulp, periarterial lymphoid sheaths, immobilization, lipopolysaccharide

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