Terashima Reiko, Kimura Maki, Higashikawa Asuka, Kojima Yuki, Ichinohe Tatsuya, Tazaki Masakazu, Shibukawa Yoshiyuki
Department of Dental Anesthesiology, Tokyo Dental College, Tokyo, 101-0061, Japan.
Department of Physiology, Tokyo Dental College, Tokyo, 101-0061, Japan.
J Physiol Sci. 2019 Mar;69(2):199-209. doi: 10.1007/s12576-018-0635-3. Epub 2018 Sep 4.
Bradykinin (BK) and its receptors, B and B, in trigeminal ganglion (TG) neurons are involved in the regulation of pain. Recent studies have revealed that B receptors are expressed in neonatal rat TG neurons; however, the intracellular signaling pathway following B receptor activation remains to be elucidated. To investigate the mechanism by which B receptor activation leads to intracellular Ca mobilization, we measured the intracellular free Ca concentration ([Ca]) in primary-cultured TG neurons. The application of Lys-[Des-Arg]BK (B receptor agonist) increased the [Ca] in these TG neurons even in the absence of extracellular Ca. Pretreatment with inhibitors of ryanodine receptors or sarco/endoplasmic reticulum Ca-ATPase suppressed the increase in Lys-[Des-Arg]BK-induced [Ca]. The Lys-[Des-Arg]BK-induced [Ca] increase was unaffected by phospholipase-C inhibitor. B receptor activation-induced [Ca] increase was suppressed by phosphodiesterase inhibitor and enhanced by adenylyl cyclase inhibitor. These results suggest that B receptor activation suppresses intracellular cAMP production via adenylyl cyclase inhibition and mobilizes intracellular Ca via ryanodine receptors that access intracellular Ca stores.
缓激肽（BK）及其在三叉神经节（TG）神经元中的B1和B2受体参与疼痛调节。最近的研究表明，B1受体在新生大鼠TG神经元中表达；然而，B1受体激活后的细胞内信号通路仍有待阐明。为了研究B1受体激活导致细胞内Ca2+动员的机制，我们测量了原代培养的TG神经元中的细胞内游离Ca2+浓度（[Ca2+]i）。即使在没有细胞外Ca2+的情况下，应用Lys-[Des-Arg]BK（B1受体激动剂）也会增加这些TG神经元中的[Ca2+]i。用ryanodine受体抑制剂或肌浆网/内质网Ca2+-ATP酶抑制剂预处理可抑制Lys-[Des-Arg]BK诱导的[Ca2+]i增加。Lys-[Des-Arg]BK诱导的[Ca2+]i增加不受磷脂酶C抑制剂的影响。B1受体激活诱导的[Ca2+]i增加被磷酸二酯酶抑制剂抑制，并被腺苷酸环化酶抑制剂增强。这些结果表明，B1受体激活通过抑制腺苷酸环化酶抑制细胞内cAMP产生，并通过ryanodine受体动员细胞内Ca2+，ryanodine受体可进入细胞内Ca2+储存库。
