FIGURE 4.
Endogenous calcium is involved in the Arc expression induced by PDGF in rat hippocampal neurons. A, changes in intracellular [Ca2+]i levels in neurons after PDGF treatment were measured using the fluorescence intensity of Fluo-4 in a typical neuron. Pretreatment of cells with either EGTA or thapsigargin resulted in inhibition of PDGF-induced increase in intracellular Ca2+. B, pretreatment of rat hippocampal neurons with cells with either EGTA or thapsigargin resulted in decreased expression of Arc as well as Egr-1 but not Egr-3. The image is representative of at least three independent experiments. THA, thapsigargin. **, p < 0.01 versus control group; #, p < 0.05; ##, p < 0.01 versus PDGF (20 ng/ml) group.