FIG. 10.

NK1 receptor-mediated T-type Ca²⁺ channel inhibition is a likely contributor to the anti-nociceptive effect of SP. (A) Plantar hind-paw injections of S9SP (50 μl; 0.5 nmol/site), RTG (50 μl; 1–10 nmol/site), Z944 (50 μl; 0.05–0.5 nmol/site) or a combination of RTG+Z944 solutions (at concentrations indicated) were administered 5 min before the injection of BK (10 nmol/site) and mixed together with the pre-injection drug or drug mixture in 50 μl saline [schematic of the double-injection protocol is shown in (D)]. The number of animals in each group is shown within the bars. (B) Intrathecal knock-down of Ca_V3.2 in lumbar DRG reduces anti-nociceptive effect of Z994 and S9SP. Animals with intrathecal injection of saline, Ca_V3.2 AS ODNs, or non-targeting “mismatch” ODNs were investigated. Hind-paw injections of S9SP (50 μl; 0.5 nmol/site) or Z944 (50 μl; 0.5 nmol/site) were administered 5 min before the injection of BK (10 nmol/site), similar to experiments shown in (A). (C) Quantification of knock-down efficiency; the analysis was performed on the second day after the last intrathecal injection. The Ca_V3.2 transcript levels in lumbar DRGs of AS ODN- and mismatch ODN-injected animals were normalized to those of saline-injected animals in the same experimental run; one to three animals per run, three independent runs. *, **, ***Significantly different from the group indicated by the line connector with p < 0.05, p < 0.01, or p < 0.001; Kruskal–Wallis ANOVA and Mann–Whitney test. All data are shown as mean ± SEM. AS, antisense; ODNs, oligodeoxynucleotides.