Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Capital Medical University, Beijing, China.
Endoscopy Center, Senior Department of Hepatology, The Fifth Medical Center of Chinese PLA General Hospital, Beijing, China.
Br J Pharmacol. 2024 Feb;181(3):413-428. doi: 10.1111/bph.16226. Epub 2023 Sep 26.
Glial cell-derived neurotrophic factor (GDNF) maintains gut homeostasis. Dopamine promotes GDNF release in astrocytes. We investigated the regulation by dopamine of colonic GDNF secretion.
D receptor knockout (D R ) mice, adeno-associated viral 9-short hairpin RNA carrying D receptor (AAV9-shD R)-treated mice, 6-hydroxydopamine treated (6-OHDA) rats and primary enteric glial cells (EGCs) culture were used. Incubation fluid from colonic submucosal plexus and longitudinal muscle myenteric plexus were collected for GDNF and ACh measurements.
D receptor-immunoreactivity (IR), but not D receptor-IR, was observed on EGCs. Both D receptor-IR and D receptor-IR were co-localized on cholinergic neurons. Low concentrations of dopamine induced colonic GDNF secretion in a concentration-dependent manner, which was mimicked by the D receptor agonist SKF38393, inhibited by TTX and atropine and eliminated in D R mice. SKF38393-induced colonic ACh release was absent in D R mice. High concentrations of dopamine suppressed colonic GDNF secretion, which was mimicked by the D receptor agonist quinpirole, and absent in AAV-shD R-treated mice. Quinpirole decreased GDNF secretion by reducing intracellular Ca levels in primary cultured EGCs. Carbachol ( ACh analogue) promoted the release of GDNF. Quinpirole inhibited colonic ACh release, which was eliminated in the AAV9-shD R-treated mice. 6-OHDA treated rats with low ACh and high dopamine content showed decreased GDNF content and increased mucosal permeability in the colon.
Low concentrations of dopamine promote colonic GDNF secretion via D receptors on cholinergic neurons, whereas high concentrations of dopamine inhibit GDNF secretion via D receptors on EGCs and/or cholinergic neurons.
胶质细胞衍生的神经营养因子（GDNF）维持肠道内环境稳态。多巴胺促进星形胶质细胞中 GDNF 的释放。本研究旨在探讨多巴胺对结肠 GDNF 分泌的调控作用。
使用 D 受体敲除（D R ）小鼠、携带 D 受体短发夹 RNA 的腺相关病毒 9（AAV9-shD R ）处理的小鼠、6-羟多巴胺（6-OHDA）处理的大鼠和原代肠神经胶质细胞（EGCs）培养物。收集结肠黏膜下丛和纵行肌肌间神经丛的孵育液，用于 GDNF 和 ACh 的测量。
在 EGCs 上观察到 D 受体免疫反应性（IR），但没有 D 受体 IR。D 受体-IR 和 D 受体-IR 均与胆碱能神经元共定位。低浓度多巴胺呈浓度依赖性诱导结肠 GDNF 分泌，D 受体激动剂 SKF38393 模拟该作用，该作用被 TTX 和阿托品抑制，且在 D R 小鼠中被消除。D R 小鼠中 SKF38393 诱导的结肠 ACh 释放缺失。高浓度多巴胺抑制结肠 GDNF 分泌，D 受体激动剂喹吡罗尔模拟该作用，而在 AAV-shD R 处理的小鼠中缺失。喹吡罗尔通过降低原代培养的 EGCs 中的细胞内 Ca 水平来减少 GDNF 的分泌。卡巴胆碱（ACh 类似物）促进 GDNF 的释放。喹吡罗尔抑制结肠 ACh 释放，在 AAV9-shD R 处理的小鼠中该作用被消除。6-OHDA 处理的大鼠 ACh 含量低、多巴胺含量高，其结肠 GDNF 含量降低，黏膜通透性增加。
低浓度多巴胺通过胆碱能神经元上的 D 受体促进结肠 GDNF 分泌，而高浓度多巴胺通过 EGCs 和/或胆碱能神经元上的 D 受体抑制 GDNF 分泌。
