-The aim of our in vitro experiments was to study the role of growth factors and protein kinase A (PKA)-dependent intracellular mechanisms in the control of nuclear maturation of porcine oocytes. Oocytes were cultured with or without growth factors (IGF-I, IGF-II, EGF; 10 ng . mL -1 medium) and inhibitors of PKA (Rp-cAMPS or KT5720; 100 ng . mL -1 ). Stages of meiosis were determined from the structure of chromosomes after staining with Giemza. Intracellular levels of PKA were evaluated immunocytochemically using primary antisera against the PKA regulatory and catalytic subunits and by Western immunoblotting using primary antiserum against the PKA catalytic subunit. It was found that after 24 h culture the majority of oocytes had resumed nuclear maturation (they were at a stage of meiosis after diplotene) and that after 48 h culture the majority of cells had completed maturation (they had reached metaphase II of meiosis). Addition of IGF-I, IGF-II or EGF, or a combination of IGF-I and EGF, significantly increased the proportion of oocytes which resumed and completed meiosis. Immunocytochemistry demonstrated a significant increase in the proportion of cells containing catalytic and, in some cases, the regulatory subunits of PKA after addition of IGF-I, IGF-II and EGF. Immunoblotting showed the presence of 2 forms of the PKA catalytic subunit within the oocytes (MW approximately 52 and 40 kD). EGF, but not IGF-I or IGF-II, increased the content of both isoforms. Inhibitors of PKA, when given alone, did not substantially influence the proportion of oocytes which resumed or completed meiosis. However, Rp-cAMPS and KT5720 both prevented the stimulatory effects of IGF-I, IGF-II and EGF on the resumption and completion of oocyte maturation. The present observations suggest (1) that IGF-I, IGF-II and EGF are potent stimulators of both resumption and completion of porcine oocyte nuclear maturation, (2) that PKA is present in oocytes, and (3) that PKA-dependent intracellular mechanisms can mediate the action of growth factors on porcine oocytes.insulin-like growth factor / epidermal growth factor / protein kinase A / meiosis Reprod. Nutr. Dev. 40 (2000)

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Effects of a 50 Hz extra-low frequency electromagnetic field (ELF EMF) on in vitro rabbit spermatozoa motility were analyzed, as well as the effect on fertilization rates after insemination. Pooled semen samples and a control were exposed to 50 Hz ELF EMF. The difference of the samples of the test groups G1 and G2 with the control group CG (75.56%) for spermatozoa motility were found to be significant (P < 0.01). Differences were significant (P < 0.01) for curvilinear velocity (VCL) between the test group G3 (122.38 microm/s) and the control group CG (112.02 microm/s). Hormonally stimulated adult (9-12 months) females (n = 140) were inseminated with semen samples from G1, G2, G3 and CG (0.88 x 109 spermatozoa/0.5 mL average insemination portion) immediately after ELF EMF exposure and fertilization (kindling) rates were calculated. For the G2 it was 54.28% data indicate 50 Hz ELF EMF induced alterations of spermatozoa motility and kindling rate in rabbits, therefore influencing fertility.

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