Insulin reverses the growth retardation effect of phorbol ester in chicken embryos during organogenesis

The tumor promoting phorbol esters can affect early embryonic development by causing interference with the normal pathways of cellular growth and differentiation. The present study was designed to: a) define a time in organogenesis when a vertebrate embryo model, the chicken, was sensitive to the phorbol ester 12-0-tetradecanoyl-13-acetate (TPA), and b) attempt a rescue of the embryos disturbed by TPA with simultaneous addition of insulin. In embryos treated at days 2 and 3 of development, TPA caused dose-dependent mortality. Survivors were biochemically retarded as indicated by their decreased weight, protein, DNA, RNA, total creatine kinase, triglycerides, phospholipids and cholesterol contents. When intermediate doses of TPA (50 ng/embryo) were applied together with insulin (100 ng/embryo), the embryonic growth disturbance was largely antagonized. These data, generated with an in vivo whole embryo, These data, generated with an in vivo whole embryo, support the strong link between the mode of action of insulin and signal transduction mechanisms typical of phorbol esters.