Effect of growth hormone and inhibitors of protein kinase A on IGF-I, oxytocin and progesterone release by cultured bovine granulosa cells |
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Authors: | Sirotkin A V Makarevich A V Hetényi L |
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Institution: | Research Institute of Animal Production, Hlohovská 2, 949 92 Nitra, Slovakia. sirotkin@vuzv.sk. |
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Abstract: | In our experiments we studied the action of GH on the release of nonapeptide, steroid hormones and growth factor, in bovine ovarian granulosa cells, as well as the role of cAMP-stimulated protein kinase A (PKA) in the mediation of these GH effects. For this purpose, the effects of exogenous bGH (0.001-10 mg/ml), PKA blockers KT5720 (100 ng/ml) and Rp-cAMPS (1 mmol), alone and in combination, on IGF-I, oxytocin and progesterone secretion were investigated. It was found that GH addition to culture medium strongly (p<0.05) stimulated IGF-I (at a concentration of 0.01-0.1 mgGH/ml medium), oxytocin (0.01-10 mgGH/ml) and progesterone (0.01-1 mgGH/ml medium) secretion into the culture medium. PKA blockers KT5720 and Rp-cAMPS given alone did not affect release of these substances. Rp-cAMPS partially prevented GH effect on IGF-I release, but enhanced GH action on progesterone output. KT5720 did not modify action of GH on oxytocin release. These observations confirm the involvement of GH in the control of IGF-I, oxytocin and progesterone release by bovine ovarian granulosa cells. Effects of PKA blocker on several GH-induced effects suggest that GH effects on IGF-I and progesterone, but not on oxytocin release may be partially mediated by the cAMP/PKA-dependent intracellular mechanisms. |
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