The results clearly indicate that TGFp modulates both glycolysis and Krebs cycle activities during human preantral follicle development. TGFp has been shown to stimulate glycolytic activity in rat kidney cells and glucose uptake by cell monolayers. The induction of key glycolytic enzymes in human preantral follicles by TGFp1 may reflect an additional level of regulation by this growth modulator to promote follicular differentiation. TGFp1 potentiates FSH action on hamster follicular cells and estrogen-induced DNA synthesis in rat granulosa cells. FSH induces TGFp receptor type II in human preantral follicles in classes 1 and 2 and in hamster preantral follicles, and TGFp2 in hamster preantral follicles. Granulosa cells of human preovulatory follicles exposed in vivo to exogenously administered gonadotropins express TGFp receptor types I and II protein, and TGFp1 ligand has been detected in human follicular fluid. Development of class 1 follicles to class 2 requires cell division as well as the onset of functionality, such as steroidogenesis. The unique regulation of some of the key enzymes of glucose metabolism by TGFp in class 1 and class 2 follicles indicates that this growth factor differentially influences preantral follicles at different stages of development. buy yasmin online
In summary, we provide here direct in vitro evidence to suggest that gonadotropins and growth factors significantly influence several regulatory enzymes of glucose metabolism in human preantral follicles. Considering the importance of these enzymes for the flow of the glycolytic and Krebs cycles, glycolysis appears to be favored at early preantral stages, but energy production by Krebs cycle activity may also be augmented.