[The mitogenic effect of insulin isolated from the mammalian brain on Swiss 3T3 cells]

Mitogenic properties of the insulin derived from pig brain were compared with the action of pancreatic (standard) pig insulin and epidermal growth factor (EGF) using the culture of Swiss 3T3 cells. The brain insulin, likely as the pancreatic insulin, induced uptake of 14C-thymidine by resting cells in a dose-dependent manner at concentration of 0.5-2.0 micrograms/ml in culture medium. However, at equal concentrations of these hormones the proliferating effect of the brain insulin appeared to be 2-fold higher than the effect of the pancreatic hormone. At the same time the mitogenic action of both hormones was lower than that of EGF (10 ng/ml). The additive effect of the brain insulin and EGF, administered in combination, was more pronounced than the effect of the pancreatic insulin combined with EGF. The data obtained suggest a possible participation of brain insulin in the process of nerve cell proliferation.