Hormonal imprinting in cell culture I. Impact of a single exposure to insulin on cellular insulin binding capacity in permanent cell lines.

Three permanent cell lines showed a durable change in cellular insulin binding capacity in response to a single exposure to insulin. Initial increase in binding of FITC-labeled insulin to both cytoplasmic and nuclear membrane was followed by a lasting decrease in the case of fibroblasts (NCTC) and return to approximately the control level in epithelial (Chang liver) and tumour (HeLa) cell cultures. While the amplifying effect of a single 4-h exposure was measurable as soon as after 24 h, that of a single 24-h exposure came into display only after 72 h in the epithelial and tumour cell cultures. The latter two lines showed return of the binding capacity to the control value and a drop of it to a minimum 20 days after exposure for 4 and 24 h, respectively. These observations support the implication that although the degree and manner of insulin binding differs between cell lines, the impact of a single exposure to insulin is durably "felt" by all.