K_v channel antagonists attenuate Tat-induced microglia neurotoxicity.

<p>Neurons were exposed to conditioned media recovered from microglia pre-treated with MgTx (5 nM), PAP (10 nM), or 4-AP (1 mM) for 30 min followed by Tat at varied concentrations (0, 20, 200, 1000 ng/ml). After 24 hr treatment, TUNEL staining and MTT were performed. <b>A</b>: TUNEL positive neurons were visualized by confocal microscopy at ×400 original magnification. Scale bar equals 50 µm. Note that Tat-treated conditioned media, but not heat inactivated Tat (HI Tat)-treated conditioned media, induced neuronal apoptosis and that the Tat-induced neuronal apoptosis was blocked by MgTx, PAP or 4-AP. <b>B</b>: Quantitative exhibition of apoptotic neurons determined by ratio of the number of TUNEL-positive cells to the total number of Dapi-positive cells under different experimental conditions as indicated. <b>C</b>: MTT assay showed increased viabilities in MgTx, PAP, and 4-AP-treated groups, respectively. Data were from three independent experiments. ** p<0.01, *** p<0.001 vs Ctrl; ^## p<0.01, ^### p<0.001 vs conditioned media treated with Tat alone.