Estradiol treatment increases viability of glioma and neuroblastoma cells in vitro.

The present study provides evidence that 17-beta-estradiol (E2) exerts cytoprotective effects on both glial and neuronal cell lines. In C6 rat glioma cells, the addition of E2 to serum free media enhances live cell number by 40% at 24 h and 75% at 96 h when compared to serum free media conditions. E2 treatment of C6 cells in serum free medium did not increase thymidine uptake at any sampling time, indicating that the observed effect of E2 on C6 cell number was not due to a mitogenic effect of the steroid hormone. The addition of E2 to SK-N-SH cells in serum free media maintained both total and live cell number at a level comparable to the fetal bovine serum (FBS) treated cells at both 24 and 48 h. At 96 h after treatment with E2, total and live cell numbers were diminished relative to the 48-h sample and the 96-h FBS group, but were still more than twice the number observed in serum free media. Associated with the reduced effects of E2 at 96 h was an increase in the ratio of dead to total cells, although it remained about 50% less than the serum free group. Through 48 h, E2 exposure did not increase thymidine uptake in SK-N-SH cells, indicating that the effect of E2 on SK-N-SH cells was cytoprotective rather than mitogenic. Collectively, these data support a cytoprotective action of E2 on neuronal or glial cell types in vitro.