The possible mechanism of apoptosis alleviated by short term exposure of
methionine enkephalin to CEM x174 cells infected
with SIV was elucidated. The effects of
methionine enkephalin on the viability of normal CEM x174 cells and infected cells were determined by the method of MTS assay. The apoptosis induced by SIV and the effects of methionine
Enkephalin were analyzed by flow cytometry. The levels of cAMP, the activities of PKA and the levels of phosphorylation of histone H3 were measured.A pronounced decrease of the cell number in SIV infected group could be noticed compared with control. Methionine enkephalin could elevate the viability of cells in infected groups. The results exhibited that Methionine enkephalin at the concentrations of 1 μmol/L could increase the percentage of vital cells and decrease the apoptotic cells based on annexin Ⅴ binding assay. Methionine enkephalin could also downregulate the content of cAMP and the activity of PKA in both groups, but more obvious in SIV infected group. The phosphorylated histone H3 was elevated in the case of virus infection and quantitatively decreased in the presence of methionine enkephalin. All effects of methionine enkephalin could be blocked by naloxone. The results indicated that cAMP PKA signal transduction cascade was involved in the regulation of methionine enkephalin on apoptosis induced by SIV during early stages.