The Effects of Venlafaxine and Dexamethasone on the Expression of HSP70 in Rat C6 Glioma Cells

OBJECTIVE The present study aimed to determine the intracellular action of the antidepressant, venlafaxine, in C6 glioma cells using heat shock protein 70 (HSP70) immunocytochemistry and HSP70 Western blots; HSP70 is known to be associated with stress and depression. METHODS The extent of HSP70 expression was measured after rat C6 glioma cells were treated with 1) dexamethasone only, 2) venlafaxine only, 3) simultaneous venlafaxine and dexamethasone, or 4) dexamethasone after venlafaxine pretreatment. Dexamethasone (10 microM, 6 hours) did not affect the level of HSP70 expression relative to control. RESULTS Short-term (1 hour) venlafaxine treatment significantly increased the level of HSP 70 expression. Simultaneous long-term (72 hours) venlafaxine and dexamethasone treatment significantly reduced the level of HSP70 expression. Dexamethasone treatment administered following long-term (24 and 72 hours) pretreatment with venlafaxine also significantly reduced the level of HSP70 expression. CONCLUSION Short-term treatment with venlafaxine increases the expression of HSP70, but prolonged treatment with dexamethasone suppresses the venlafaxine-induced expression of HSP70. These findings suggest that HSP70 and dexamethasone play a significant role in the pathophysiology of depression.