Department of Gastroenterology, Renmin Hospital of Wuhan University, Wuhan, Hubei Province, People's Republic of China.
Key Laboratory of Hubei Province for Digestive System Diseases, Renmin Hospital of Wuhan University, Wuhan, Hubei Province, People's Republic of China.
Drug Des Devel Ther. 2021 Feb 10;15:441-452. doi: 10.2147/DDDT.S298954. eCollection 2021.
EVO is a natural alkaloid that reportedly has potential value in regulating gastrointestinal motility, but this conclusion remains controversial, and the molecular mechanism is unclear. In this study, we aimed to explore the effect of short-chain fatty acids on rat colonic hypermotility induced by water avoidance stress and the underlying mechanism.
We constructed a hypermotile rat model by chronic water avoidance stress, and Western blot was used to detect the protein level of nNOS in colon tissue. The organ bath and multichannel physiological signal acquisition systems were used to examine the spontaneous contractions of smooth muscle strips. The whole-cell patch-clamp technique was used to investigate L-type voltage-dependent calcium and BK channel currents in colonic smooth muscle cells.
EVO inhibited the spontaneous contractions of colonic smooth muscle strips in a dose-dependent manner. Moreover, EVO decreased the fecal output induced by chronic water avoidance stress. TTX did not block the inhibitory effect of EVO on spontaneous colon contractions, while L-NNA, a selective nNOS synthase inhibitor, did partially abolish this inhibitory effect. The protein expression of nNOS in the colon tissues of rats administered EVO was significantly increased compared to that in control rats. EVO reversibly inhibited the L-type calcium channel current without changing the steady-state activation or inactivation in colonic smooth muscle cells. EVO significantly inhibited the BK current but did not change the shape of the I-V curves.
EVO inhibits gastrointestinal motility by inhibiting L-type calcium and BK channels in colonic smooth muscle cells and indirectly interacting with nNOS.
EVO 是一种天然生物碱，据报道具有调节胃肠道动力的潜在价值，但这一结论仍存在争议，其分子机制尚不清楚。本研究旨在探讨短链脂肪酸对水回避应激诱导的大鼠结肠高动力的影响及其潜在机制。
我们通过慢性水回避应激构建了高动力大鼠模型，并用 Western blot 检测结肠组织中 nNOS 的蛋白水平。使用器官浴和多通道生理信号采集系统检测平滑肌条的自发性收缩。使用全细胞膜片钳技术研究结肠平滑肌细胞中的 L 型电压依赖性钙和 BK 通道电流。
EVO 呈剂量依赖性抑制结肠平滑肌条的自发性收缩。此外，EVO 减少了慢性水回避应激引起的粪便排出量。TTX 不能阻断 EVO 对自发性结肠收缩的抑制作用，而选择性 nNOS 合酶抑制剂 L-NNA 则部分消除了这种抑制作用。与对照组大鼠相比，给予 EVO 的大鼠结肠组织中 nNOS 的蛋白表达明显增加。EVO 可逆性抑制 L 型钙通道电流，而不改变结肠平滑肌细胞中的稳态激活或失活。EVO 显著抑制 BK 电流，但不改变 I-V 曲线的形状。
EVO 通过抑制结肠平滑肌细胞中的 L 型钙和 BK 通道，并间接与 nNOS 相互作用，抑制胃肠道动力。
