OXIDATIVE PROCESSES IN GRANULOSA CELLS OF COW OVARIAN FOLLICLES AT FOLLICULAR GROWTH

Article presents the research results on the respiratory activity and redox capacity of granulose layer cells of cow ovarian follicles under the physiological state of follicular growth. After the slaughter of the cows, the ovaries in physiological state of follicular growth were selected and the size of the follicles was evaluated. Cells of the granulosa layer were aspirated from small (< 4 mm), medium (4–7 mm) and large (> 7 mm) follicles and determined: intensity of oxygen absorption – polarographically, redox capacity – potentiometrically. K3[Fe(CN)6] was used as an extracellular electron acceptor. The share of oxygen consumed by aerobic glycolysis was determined by using sodium fluoride inhibitor, the NAD-dependent link of the mitochondrial electron transport chain - amytal, and the terminal (cytochrome oxidase) – sodium azide. The share of free-radical oxidation of unsaturated fatty acids in the realization of oxygen was detected by Na2EDTA. Granulosa cells from the ovary of follicular growth are characterized by respiratory activity and regenerative capacity, the intensity of which depends on the size of the follicles from which they are extracted. The highest values of the investigated indicators are characteristic of cells extracted from large follicles, lower – from small follicles, and the lowest values are from medium follicles. The high intensity of oxidative processes in granulosa from small follicles ensures the growth of oocytes, and from large follicles – maturation of the germ cell in the dominant follicle. At the same time, the increased intensity of oxygen consumption by the cells of small and dominant follicles is manifested against the background of limitations in electron acceptors in the extracellular environment. The use of inhibitors of ATP resynthesis of both glycolysis and individual links of the mitochondrial respiratory chain testify the activity of the indicated metabolic pathways in granulosa and the possibility of using alternative substrates to ensure the existence of cells. The main way of utilization of oxygen in the granulosa layer cells of small and large follicles is aerobic glycolysis, and from the medium there are alternative ways of supplying and using substrates. The largest flow of reducing equivalents into the extracellular space from the granulosa of a medium-sized follicle due to inhibition of glycolysis indicates that the source of the supply of reducing equivalents into the follicle cavity is glycolysis and this characterizes the dependence of the existence of cells on the indicated metabolic pathway.