FIGURE 1.

Neuronal activity increased the expression and secretion of SST. A, microarray results from three independent hippocampal neuronal culture preparations showed that SST mRNA level was significantly elevated following global activity elevation with bicuculline (Bic.) and blocked by co-application of TTX (Bic., 4 h: 1.43 ± 0.005, p < 0.001; Bic., 4 h + TTX: 1.03 ± 0.02, p > 0.05; Bic., 48 h: 2.14 ± 0.15, p < 0.01; Bic., 48 h + TTX: 0.45 ± 0.06, p < 0.001). B, real time qPCR results from additional culture preparations showing that the SST mRNA level was significantly increased following different manipulations that elevated neuronal activity for 4 or 48 h (Bic., 4 h: 1.66 ± 0.26, p < 0.05; Bic., 48 h: 2.79 ± 0.71, p < 0.05; KA 4 h: 2.05 ± 0.27, p < 0.01; KA 48 h: 3.01 ± 0.41, p < 0.01; KCl 4 h: 2.16 ± 0.31, p < 0.01; KCl 48 h: 5.03 ± 0.73, p < 0.01). C, real time qPCR results showed that SST expression in the hippocampus was up-regulated following KA injection in vivo (KA 6 h: 1.78 ± 0.14, p < 0.01; KA 24 h: 1.72 ± 0.08, p < 0.001). D, ELISA results showed that the level of SST in the medium of hippocampal neuronal cultures was elevated following bicuculline treatment (4 h: 1.02 ± 0.07, p > 0.05; 12 h: 1.36 ± 0. 15, p > 0.05; 24 h: 1.65 ± 0.26, p < 0.05; 48 h: 5.78 ± 1.80, p < 0.05). In all experiments, the mRNA or protein levels were normalized to that of untreated controls. The results are shown as the means ± S.E. n, shown as white numbers in the bars, represents the number of independent culture preparations (A, B, and D) or the number of rats (C). *, p < 0.05; **, p < 0.01; ***, p < 0.001. Ctrl, control.