Division of Gastroenterology and Hepatology, Key Laboratory of Gastroenterology and Hepatology, Ministry of Health, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai Institute of Digestive Disease, Shanghai, China.
Neurogastroenterol Motil. 2020 Oct;32(10):1514-1528. doi: 10.1111/nmo.13877. Epub 2020 May 11.
Psychological stress is an important factor for the development and recurrence of irritable bowel syndrome (IBS). The mechanisms underlying stress-induced visceral hypersensitivity (VH), a key pathophysiological component in IBS, are still incompletely understood. We aimed to test whether transient receptor potential melastatin 8 (TRPM8) participates in acute stress-induced VH.
Rats were subjected to 1-hour water avoidance stress (WAS). Visceral sensitivity was measured with visceromotor response to colorectal distension. Western blot and immunofluorescence were applied to evaluate the expression of GR and TRPM8 and activation of PKA, Akt, and PKC pathways.
WAS-caused VH depended on glucocorticoid receptors (GRs) and TRPM8 channels. In a dorsal root ganglion (DRG)-derived cell line, corticosterone rapidly (within 30 minutes) induced membrane expression of TRPM8. This effect was inhibited by GR antagonism and was mimicked by membrane-impermeable corticosterone. PKA, PI3K/Akt, and PKC pathways, which lied downstream of GR and acted in parallel to promote membrane expression of TRPM8, contributed to WAS-induced VH. The non-receptor tyrosine kinase Pyk2, which may serve as a convergence point for PKA, PI3K/Akt, and PKC pathways, facilitated membrane insertion of TRPM8 via tyrosine-phosphorylating TRPM8 in L6-S2 DRGs and participated in WAS-induced VH.
Collectively, acute stress-induced VH could involve membrane-bound GR-dependent enhancement of TRPM8 function in nociceptive DRG neurons. Mechanistically, Pyk2 could act as a key mediator that coordinates multiple protein kinase signaling and triggers phosphorylation and membrane insertion of TRPM8.
心理应激是肠易激综合征（IBS）发生和复发的重要因素。心理应激引起内脏高敏（VH）的机制仍不完全清楚，VH 是 IBS 的一个关键病理生理组成部分。本研究旨在探讨瞬时受体电位 melastatin 8（TRPM8）是否参与急性应激诱导的 VH。
大鼠进行 1 小时的水回避应激（WAS）。通过结直肠扩张的内脏运动反应测量内脏敏感性。应用 Western blot 和免疫荧光评估 GR 和 TRPM8 的表达以及 PKA、Akt 和 PKC 途径的激活。
WAS 引起的 VH 依赖于糖皮质激素受体（GRs）和 TRPM8 通道。在背根神经节（DRG）衍生细胞系中，皮质酮迅速（30 分钟内）诱导 TRPM8 的膜表达。该作用被 GR 拮抗剂抑制，并被膜不可渗透的皮质酮模拟。位于 GR 下游并平行作用以促进 TRPM8 膜表达的 PKA、PI3K/Akt 和 PKC 途径，有助于 WAS 诱导的 VH。非受体酪氨酸激酶 Pyk2 可能作为 PKA、PI3K/Akt 和 PKC 途径的汇聚点，通过在 L6-S2 DRG 中使 TRPM8 酪氨酸磷酸化，促进 TRPM8 的膜插入，并参与 WAS 诱导的 VH。
总之，急性应激诱导的 VH 可能涉及伤害性 DRG 神经元中膜结合的 GR 依赖性增强 TRPM8 功能。从机制上讲，Pyk2 可以作为关键的中介物，协调多种蛋白激酶信号转导，并触发 TRPM8 的磷酸化和膜插入。
