Effects of ethanol and transforming growth factor beta (TGF beta) on neuronal proliferation and nCAM expression

BACKGROUND Developmental events targeted by ethanol are cell proliferation, neuronal migration, and neurite outgrowth; the latter processes being mediated by neural cell adhesion molecule (nCAM). TGFbeta1 affects all three of these events. Therefore, the effects of ethanol on transforming growth factor (TGF) beta1 mediated activities in neocortical neurons in vitro were examined.METHODS Primary cultures of cortical neurons were obtained from 16-day-old fetuses and were treated with TGFbeta1 (0 or 10 ng/ml) and ethanol (0 or 400 mg/dl) for 48 hr. The effects of these substances on cell numbers, [ H]thymidine incorporation, and the expression of nCAM were determined.RESULTS Both cell growth (the change in cell numbers over time) and cell proliferation were inhibited by TGFbeta1 and ethanol. The action of these two anti-mitogenic factors was additive. In contrast, TGFbeta1 also promoted the expression of three isoforms of nCAM. Likewise, ethanol also up-regulated nCAM expression. On the other hand, ethanol blocked TGFbeta1-mediated nCAM expression, particularly of the 120 and 180 kDa isoforms.CONCLUSIONS TGFbeta ligands inhibit neuronal proliferation and stimulate the expression of cell adhesion proteins that promote the movement of postmitotic neurons and process outgrowth. Ethanol alters these phenomena as well. Thus, in neurons, as in astrocytes, TGFbeta1 and ethanol may interact.