Neural abnormalities in insulin-deprived frog embryos are associated with altered gene expression

Insulin plays an essential role in the prepancreatic embryonic development of the frog, Microhyla ornata. While exogenous insulin stimulates neurulation as well as overall embryonic development in this organism, immunoneutralization of endogenous insulin leads to peculiar abnormalities in the developing nervous system. In the present report, we demonstrate that neural abnormalities in embryos treated with antiserum to insulin are associated with altered gene expression. By using whole-mount in situ hybridization, we show that the expression of noggin, the product of which is involved in dorsalization and neural induction, is altered in such embryos concomitant with abnormal nervous system development. The action of exogenous insulin also seems to be mediated through crucial developmental genes such as Brachyury and noggin. This report demonstrates that developmental gene expression is altered in frog embryos developing under conditions of excess/scarcity of insulin.