Secretion and effects of growth factors in farm animal and human ovaries
1997
Sirotkin, A. | Makarevic, A. | Chrenek, P. (Research Inst. of Animal Production, Nitra (Slovak Republic)) | Chribikova, J. | Genieser, H. | Taradajnik, T. | Marnet, P. | Schaeffer, H. | Mlyncek, M. | Kubek, A. | Bulla, J.
The results of growth factor studies are briefly reviewed. Regulators, mechanisms of control and effects of growth factors on both secretory and generative activity of ovarian cells in farm animals and in humans are investigated. Ovarian cells (whole ovarian follicles and isolated granulosa cells) were found to be able to produce in culture insulin-like growth factor I (IGF-I) and epidermal growth factor (EGF). It was demonstrated that the release of these factors is induced by gonadotropins, growth hormone, oxytocin and steroid hormones. These hormones activate growth factor production via intracellular messengers cAMP/protein kinase A and tyrosine kinase. IGF-I was observed to stimulate the release of progesterone, oxytocin and cAMP by cultured bovine granulosa cells, the secretion of progesterone, androstenedione, estradiol, oxytocin, prostaglandin F2-alpha and cAMP by isolated porcine granulosa cells and ovarian follicles. IGF-I also influences the secretion of progesterone and estradiol by rabbit granulosa cells. EGF enhanced the progesterone and estradiol release by bovine and rabbit granulosa cells. It was also found that IGF-I can be a stimulator of porcine oocyte maturation, while investigated growth factors (IGF-I and EGF) can support rabbit embryo development in vitro. These effects of growth factors were realised mainly through the cAMP/protein kinase A, but not through tyrosine kinase-dependent intracellular mechanisms. The observations demonstrate the secretion of growth factors IGF-I and EGF by ovarian cells, and the importance of growth factors in the regulation of hormone, prostaglandin and cyclic nucleotide secretion by these cells, in control of oocyte maturation and embryogenesis, as well as in defining extra- and intracellular regulators and mechanisms of these processes
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