Insulin and IGFs induce apoptosis in chick embryo retinas deprived of L-glutamine

In chick embryo retinas, cultured in serum-free mediumlacking L-glutamine, IGF-I, IGF-II and insulin inducedapoptotic DNA fragmentation and cell death, IGF-I being themost efficacious compound. The apoptotic effect, which wasparticularly evident in retinas removed from 7-day-old chickembryos, declined with the age of the embryos anddisappeared after day 11. Apoptosis appeared after a timelag of 8 h and then increased with time up to 16 h.Cycloheximide, an inhibitor of protein synthesis, was capableof entirely abolishing apoptotic cell death. The effect inducedby IGFs or insulin was suppressed by the addition ofglutamine. Cytokine-mediated apoptosis was also observedafter withdrawal of phosphate. We suggest that IGFs or insulinmay produce, in retinas cultured in medium lackingL-glutamine or phosphate, a conflict of signals that could belethal for retinal cells.Keywords: