Influence of General Cooling on Morphometric Indicators of Ovarians and Brown Fatty Tissue in Rats in Experiment

To study the effect of total cooling on the morphometric parameters of the ovaries and brown fatty tissue (BFT), we carried out studies of 40 white 4-week-old female rats of the Vistar line, weighing 30-40, which were divided into 5 groups: 1st-8 rats, which were subjected to constant cold exposure (CCE); the 2 nd – 8 rats who were injected with dehydroepiandrostenediol-sulfate (DHA-sulfate) dissolved in 0.2 ml of purified and sterilized olive oil against the background of CCE; the 3rd – 8 rats, who were induced with experimental polycystic ovary syndrome (PCOS) by administration of only DHA-sulfate, without CCE; the 4 th group – 8 animals, who received only olive oil without DHA-sulfate and CCE; and the 5th group comprised 8 rats, who did not receive anything: neither intact control nor CCE exposure. The CCE was carried out by holding the animals for 4 hours in a chamber where the light regime and temperature of + 4 ° C. The remaining 20 h animals were in normal conditions of ambient temperature and light conditions. The rats were cooled daily for 25 days. At the 26th day, the animals were sacrificed; the ovaries and BFT were taken from the interscapular area. The organs were fixed in 4% paraformaldehyde for 4 hours, after which it was transferred for 12 hours to a 25% sucrose solution on phosphate buffered saline (PBS). The organs in the mounting medium Tissue-Tek, were frozen and before the preparation of the cryostat sections were stored in nitrogen liquid. Histological examination was performed on BFT and ovaries of experimental animals. For the preparation of cryostat sections, the organs were removed from the low-temperature storage and fabric sections were made with the thickness of 5 μm on the cryovicrotome MEV (Germany). Sections were stained with hematoxylin and eosin according to the standard procedure. The number of adipocytes of BFT of different types was counted. The daily placement of rats in conditions of general cooling (4 h at + 4 ° C) led to a change in the cytomorphological characteristics of BFT. In group 1, there was a decrease in the number of type 1 and type 2 adipocytes in comparison with intact tissue. Visually, the tissue acquired a denser package and a pronounced brownish-brown color. Animals of the 2nd group, who underwent DHA- sulfate administration in conditions of general cooling, had sign characteristics of intact tissue: cells with large fat vacuoles were preserved. In this case, areas with tightly packed adipocytes with small fatty inclusions (A1) were alternated with zones represented by type 1 and type 2 adipocytes. Against the background of the introduction of DHA-sulfate without CCE (group 3), the main morphological features characteristic of groups 4 and 5 were preserved in BFT. Morphometric analysis allowed making a quantitative assessment of the changes in the cytomorphological profile of the BFT under the applied effects. A significant decrease in the number of A1 type cells in BFT animals with CCE (group 1) and A3 cells in BFT animals with CCE + DHA-sulfate (group 2) was found in comparison with the intact control. Changes occurred not only in the quantitative ratio of the types of adipocytes, but also in terms of area and diameter of lipid droplets. Summarizing the results, it can be noted that under the influence of cold occur adaptive reactions in the BFT animals.