Department of Basic Medical Sciences, College of Osteopathic Medicine of the Pacific, Western University of Health Sciences, 309 East Second Street, Pomona, CA, 91766, USA.
Department of Basic Medical Sciences, College of Osteopathic Medicine of the Pacific, Western University of Health Sciences, 309 East Second Street, Pomona, CA, 91766, USA.
Neurochem Int. 2019 Jan;122:106-119. doi: 10.1016/j.neuint.2018.11.012. Epub 2018 Nov 16.
To characterize mechanisms involved in neurokinin type 1 receptor (NKR)-mediated emesis, we investigated the brainstem emetic signaling pathways following treating least shrews with the selective NKR agonist GR73632. In addition to episodes of vomiting over a 30-min observation period, a significant increase in substance P-immunoreactivity in the emetic brainstem dorsal motor nucleus of the vagus (DMNX) occurred at 15 min post an intraperitoneal (i.p.) injection GR73632 (5 mg/kg). In addition, time-dependent upregulation of phosphorylation of several emesis -associated protein kinases occurred in the brainstem. In fact, Western blots demonstrated significant phosphorylations of Ca/calmodulin kinase IIα (CaMKIIα), extracellular signal-regulated protein kinase1/2 (ERK1/2), protein kinase B (Akt) as well as α and βII isoforms of protein kinase C (PKCα/βII). Moreover, enhanced phospho-ERK1/2 immunoreactivity was also observed in both brainstem slices containing the dorsal vagal complex emetic nuclei as well as in jejunal sections from the shrew small intestine. Furthermore, our behavioral findings demonstrated that the following agents suppressed vomiting evoked by GR73632 in a dose-dependent manner: i) the NKR antagonist netupitant (i.p.); ii) the L-type Ca channel (LTCC) antagonist nifedipine (subcutaneous, s.c.); iii) the inositol trisphosphate receptor (IPR) antagonist 2-APB (i.p.); iv) store-operated Ca entry inhibitors YM-58483 and MRS-1845, (i.p.); v) the ERK1/2 pathway inhibitor U0126 (i.p.); vi) the PKC inhibitor GF109203X (i.p.); and vii) the inhibitor of phosphatidylinositol 3-kinase (PI3K)-Akt pathway LY294002 (i.p.). Moreover, NKR, LTCC, and IPR are required for GR73632-evoked CaMKIIα, ERK1/2, Akt and PKCα/βII phosphorylation. In addition, evoked ERK1/2 phosphorylation was sensitive to inhibitors of PKC and PI3K. These findings indicate that the LTCC/IPR-dependent PI3K/PKCα/βII-ERK1/2 signaling pathways are involved in NKR-mediated vomiting.
为了阐明神经激肽 1 型受体（NK1R）介导呕吐的机制，我们用选择性 NK1R 激动剂 GR73632 处理鼩鼱，研究了脑干呕吐信号通路。腹腔注射 GR73632（5mg/kg）后 15min，除了在 30min 观察期内出现呕吐发作外，呕吐脑干背侧迷走神经运动核（DMNX）中的 P 物质免疫反应性也显著增加。此外，脑干中与呕吐相关的几种蛋白激酶的磷酸化也呈现时间依赖性上调。事实上，Western blot 显示 Ca/calmodulin 激酶 IIα（CaMKIIα）、细胞外信号调节蛋白激酶 1/2（ERK1/2）、蛋白激酶 B（Akt）以及蛋白激酶 C（PKC）的α和β II 同工型的磷酸化显著增加。此外，在含有迷走神经复合体呕吐核的脑干切片以及鼩鼱小肠的空肠切片中，也观察到增强的磷酸化 ERK1/2 免疫反应性。此外，我们的行为学研究结果表明，以下药物可剂量依赖性地抑制 GR73632 诱发的呕吐：i）NK1R 拮抗剂 netupitant（腹腔内注射）；ii）L 型钙通道（LTCC）拮抗剂硝苯地平（皮下注射）；iii）三磷酸肌醇受体（IPR）拮抗剂 2-APB（腹腔内注射）；iv）储存操纵性钙内流抑制剂 YM-58483 和 MRS-1845（腹腔内注射）；v）ERK1/2 通路抑制剂 U0126（腹腔内注射）；vi）PKC 抑制剂 GF109203X（腹腔内注射）；以及 vii）磷脂酰肌醇 3-激酶（PI3K）-Akt 通路抑制剂 LY294002（腹腔内注射）。此外，NK1R、LTCC 和 IPR 是 GR73632 诱导的 CaMKIIα、ERK1/2、Akt 和 PKCα/βII 磷酸化所必需的。此外，诱发的 ERK1/2 磷酸化对 PKC 和 PI3K 的抑制剂敏感。这些发现表明，LTCC/IPR 依赖性 PI3K/PKCα/βII-ERK1/2 信号通路参与了 NK1R 介导的呕吐。
