BV induced different activation patterns of p38 in neurons and microglia in the L4/5 rat spinal dorsal horn. (A-B) Double immunofluorescence in the dorsal horn of L4/5 spinal cord sections (16 μm) for p-p38 (green) and NeuN, a neuronal marker (red) at 2 h and 4 d after BV injection (10×). (C) Time course showing the number of p-p38-IR neurons and microglia in the I-II laminae in L4/5 dorsal horn. Double immunofluorescence and histograms show that p38 was activated in neurons as early as 1 hr and peaked at 2 hr; while p38 was activated in microglia at 1 d and peaked at 3 d after BV administration. (n = 4 or 5 each time point, ** p < 0.001; *p < 0.05; compared with controls; one-way AVOVA). Scale bars, 100 μm (A, B). cont, control.