Effects of ethanol and ipsapirone on the expression of genes encoding anti-apoptotic proteins and an antioxidant enzyme in ethanol-treated neurons

Previously, this laboratory found that apoptosis was augmented significantly in fetal rhombencephalic neurons when they were treated with 50 mM ethanol for 24 h. These changes were associated temporally with a reduction in the phosphatidylinositol 3-kinase (PI3K) pro-survival pathway and in the downstream expression of several NF-κB dependent anti-apoptotic genes. The serotonin-1A agonist ipsapirone prevented ethanol-associated apoptosis; it also activated the PI3K → pAkt pro-survival pathway and the expression of specific NF-κB dependent anti-apoptotic genes in ethanol-treated neurons. The present study investigated the temporal effects of both ethanol and ipsapirone on the expression of three NF-κB dependent genes, XIAP, Bcl-xl and catalase; these genes encode proteins that could potentially attenuate ethanol-induced apoptosis. Catalase activity was also measured. All three genes demonstrated an early activation by ethanol. After a brief treatment with 50 mM ethanol, i.e., 2 to 8 h depending on the gene, the expression of XIAP, Bcl-xl, and catalase was significantly increased, possibly as an initial attempt to survive. An ethanol-associated increase in catalase was followed by a rise in catalase activity. However, when ethanol treatment was continued for a longer time, there was a significant reduction in both XIAP and Bcl-xl. In addition, both catalase expression and activity returned to levels found in unstressed controls. Importantly, treatment with ipsapirone augmented the activity of catalase and the expression of Bcl-xl, XIAP, and catalase in ethanol-treated neurons at later time points. The latter effects are likely to contribute to the pro-survival effects of ipsapirone.