Fig. 4.
Relative levels of cytosolic (a, b), reticular (c, d) and nuclear (e, f) calcium in differentiated NG-108 cells treated with haloperidol (Hμ; 10 µmol/L), BD 1047 (BDµ; 10 µmol/L), the IP3R blocker Xestospongin C (Xest; 1 µmol/L), and the combination of Xest with Hμ or BDµ (comb) for 24 h (a, c, e). Combination of Hμ with SA4503 (1 µmol/L) and also with silenced σ1R was used (b, d, f). As a control serves scrambled siRNA (scr). Hμ treatment significantly increased the levels of cytosolic calcium, while Xest treatment in combination with Hμ completely prevented this increase (a). Silencing of the σ1R in Hμ-treated cells significantly decreased a level of cytosolic calcium compared to scr or plain Hμ-treated cells (b). The σ1R-agonist SA4503 further decreased a level of cytosolic calcium compared to control cells (b). Accordingly, reticular calcium was decreased in Hμ-treated cells compared to control cells, but Xest, SA4503 treatment, or silencing of the σ1R increased a level of reticular calcium compared to Hμ-treated cells (c, d). The results observed following BDµ treatment were similar to those following Hμ treatment. In nuclei, Hμ increased nuclear calcium level, which was decreased by Xest, SA4503, or silencing of the σ1Rs (e, f). Surprisingly, when cells were treated in parallel with BDµ and Xest, huge increase in nuclear calcium level was observed compared to plain BDµ-treated cells (e). Each column represents an average of six independent cultivations and is displayed as the mean ± S.E.M. Statistical significance compared to controls is * p < 0.05, ** p < 0.01, *** p < 0.001, and compared to the haloperidol group is ++p < 0.01 and +++p < 0.001