OBJECTIVETo investigate the protective mechanism of neuroactive steroid allopregnanolone on N-methyl-D-aspartate (NMDA) induced toxicity in primary mouse cortical neurons.

METHODSPrimary cultured mouse cortical neurons were subjected to allopregnanolone, the expression of beta-aminobutyric acid receptor beta2 subunit (beta2-GABA-R) mRNAs was detected by RT-PCR and Akt phosphorylation was assayed by Western blot using Akt-phosphoserine 473-specific antibody. After the cultured mouse cortical neurons were pretreated with or without allopregnanolone prior to treatment with NMDA , DNA isolated was analyzed by agarose gel electrophoresis and proteins collected were analyzed by Western blot with anti-cleaved-PARP, anti-cleaved caspase-3, and anti-cleaved caspase-9 antibodies.

RESULTSWhen cultured mouse cortical neurons were exposed to allopregnanolone both the expression of beta2-GABA-R mRNAs and Akt phosphorylation increased. Allopregnanolone inhibited the NMDA-induced apoptosis and decreased the level of active-PARP, active-caspase-3 and active-caspase-9 notably at a final concentration of 5 x 10(6) mol/L.

CONCLUSIONPretreatment with allopregnanolone may be neuroprotective on NMDA-induced neuronal cells apoptosis by increasing beta2-GABA-R expression and Akt phosphorylation.