Previously we have shown that class 1 and 2 human preantral follicles grow in vitro in response to FSH and produce estradiol. Moreover, epidermal growth factor (EGF) modulation of transforming growth factor (3 (TGFp) receptor induction in human preantral follicles in vitro has been demonstrated. The presence of EGF and TGFp in the human ovary has been documented. Although the effect of EGF on ovarian glucose metabolism is unknown, EGF has been shown to transiently increase hepatic Krebs cycle and gluconeogenesis via a calcium-sensitive metabolic flux through mitochondrial 2-oxoglutarate dehydrogenase systems and inhibition of pyruvate kinase (PK).
On the other hand, EGF administration in vitro induces glycolysis and the pentose phosphate pathway, and it decreases gluconeogenesis in rat proximal tubular cells before they proliferate. Moreover, EGF stimulates phosphofructokinase (PFK) activity in A431 cells and in rat oocytes during their maturation in vitro. These lines of evidence suggest that EGF action may differ depending on cell type and developmental condition. On the other hand, virtually nothing is known about the insulin-like growth factor-I (IGF-I) effect on follicular glucose metabolism during folliculogenesis. Nevertheless, the presence of IGF-I in mammalian ovaries, including those of the human, and its role in ovarian steroidogenesis is well documented. Similarly, the presence of TGFp in the ovary and its influence on a variety of ovarian functions are well known, but the effect of TGFp on follicular glucose metabolic enzymes, especially in the human, remains unclear. buy flovent inhaler
The objective of the present studies was to determine whether gonadotropins, EGF, IGF-I, or TGFp1 influence the activities of some important glycolytic and Krebs cycle enzymes in human preantral follicles as a mechanism to regulate folliculogenesis.