Multiple forms of biologically active insulin-like material from mouse fetal brain cells in culture

The biological and immunological properties of insulin-like material produced by brain cells from 12 day old mice, cultured in serum-free media were examined. Differences were seen in the rate of appearance, relative amounts and behaviour on HPLC between immunoreactive and biologically active insulin-like material. Excess anti-insulin sera failed to suppress most of the biological activity and the culture medium was shown to contain relatively large quantities of immunoreactive IGF-I (590 ng/30 ml). The elution profile of this material on HPLC overlapped but was not identical with the insulin biological activity, which indicated that other insulin-like growth factors were also present. The relatively high concentration of IGF-I produced by the brain cell cultures suggest that this preparation may be suitable for biosynthetic studies of this growth factor.