Teratogenicity Involved in Experimental Diabetic Pregnancy
Sammanfattning: Maternal diabetes is associated with increased risk of growth disturbances and congenital malformations. The malformations rate in the offspring of diabetic mothers is 2-3 fold higher compared to infants of nondiabetic mothers. In this thesis we have investigated the role of the protein kinase C (PKC) pathway and the apoptotic machinery in embryopathy.We investigated the involvement of PKC isoforms in the embryopathy of diabetic rat pregnancy. Embryos of diabetic rats showed altered activity and protein distribution of several PKC isoforms compared with embryos of normal rats. Using whole embryo culture we found increased activity of PKC-delta and PKC-zeta after 24h of culture and increased rate of malformations and growth retardation in embryos cultured in high glucose concentration compared to embryos cultured in low glucose concentration. Addition of ?-cyano-4-cinnamic acid and N-acetylcysteine to the culture medium normalized malformations and growth retardations whereas specific PKC-inhibitors abolished malformations and partly restored the growth retardations. All treatment normalized glucose-induced increase of PKC activity.Estimated occurrence of apoptosis in embryos of diabetic rats and in embryonic cells exposed to high glucose concentration showed increased rate of pro-apoptotic markers. The increased apoptosis in the high glucose exposed embryonic cells was normalized by supplementation of N-acetylcysteine or apoptosis inhibitor. Treatment with vitamin E and folic acid to diabetic pregnant rats decreased diabetes-induced malformations and resorptions, concomitant with normalization of apoptotic protein levels.These results suggest that oxidative stress is augmented in embryos of diabetic rats and that it also plays a role in the activation of PKC and apoptosis. We used antioxidative treatment with beneficial effect although we could not completely abolish the embryonic demise; this may indicate that other mechanisms are involved in diabetic embryopathy. Further studies are needed to develop multi-nutrient dietary supplement to eliminate embryonic abnormalities induced by maternal diabetes.
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