Age-dependent inhibition of growth of mouse neuroblastoma cells by mouse brain extract

In the developing mouse brain, inhibition of cell proliferation and cell death occur naturally. In order to study the factors which control growth and differentiation of neural cells, we added brain extract of mice of various ages to N-18 mouse neuroblastoma cell cultures. Brain extract from newborn mice inhibited N-18 cell growth and, at high concentrations, induced cell death. The colony-forming ability of N-18 cells was also inhibited by brain extract. This inhibitory effect of brain extract on the colony-forming ability increased with fetal age and became most significant at birth, then gradually decreased. Brain extract of 19-day embryos promoted the neurite outgrowth of N-18 cells at low concentrations, at which cell growth was not affected. On the other hand, brain extract of adult mice had no effect on the growth and morphology of cells at the same concentration.