Li Jun-Ping, Wang Xi-Yu, Gao Chang-Jun, Liao Yong-Hui, Qu Juan, He Zhong-Yi, Zhang Ting, Wang Guo-Du, Li Yun-Qing
Department of Anatomy, Histology and Embryology, K.K. Leung Brain Research Centre, The Fourth Military Medical University Xi'an, China ; Department of Anatomy, Histology and Embryology, Ningxia Medical University Yinchuan, China.
Department of Physiology and Cell Biology, Medical Center, Ohio State University Columbus, OH, USA.
Front Neuroanat. 2014 Dec 16;8:149. doi: 10.3389/fnana.2014.00149. eCollection 2014.
The distribution and activity of endomorphins (EMs), which are endogenous μ-opioid receptor (MOR) ligands in the gastrointestinal tract (GI), are yet to be elucidated. The current study aimed to shed light on this topic. EM2 was expressed in the enteric neurons in the myenteric plexus of the mid-colon. Of the EM2-immunoreactive (EM2-IR) neurons, 53 ± 4.6%, 26 ± 4.5%, 26 ± 2.8% and 49 ± 4.2% displayed immunopositive staining for choline acetyl transferase (ChAT), substance P (SP), vasoactive intestinal peptide (VIP) and nitric oxide synthetase (NOS), respectively. A bath application of EM2 (2 μM) enhanced spontaneous contractile amplitude and tension, which were reversed by β-FNA (an antagonist of MOR) but not NG-nitro-L-arginine methyl ether (L-NAME, a non-selective inhibitor of NOS) or VIP6-28 (an antagonist of the VIP receptor) in the colonic strips. EM2 significantly suppressed inhibitory junction potentials (IJPs) in 14 of the 17 examined circular muscle cells, and this effect was not antagonized by preincubation in L-NAME. EM2 was widely expressed in interneurons and motor neurons in the myenteric plexus and presynaptically inhibited fast IJPs, thereby enhancing spontaneous contraction and tension in the colonic smooth muscle.
内吗啡肽（EMs）作为胃肠道（GI）中的内源性μ-阿片受体（MOR）配体，其分布和活性尚未阐明。本研究旨在阐明这一主题。EM2在结肠中段肌间神经丛的肠神经元中表达。在EM2免疫反应性（EM2-IR）神经元中，分别有53±4.6%、26±4.5%、26±2.8%和49±4.2%的神经元对胆碱乙酰转移酶（ChAT）、P物质（SP）、血管活性肠肽（VIP）和一氧化氮合酶（NOS）呈免疫阳性染色。在结肠条中浴加EM2（2μM）可增强自发收缩幅度和张力，β-FNA（MOR拮抗剂）可逆转此作用，但NG-硝基-L-精氨酸甲酯（L-NAME，NOS的非选择性抑制剂）或VIP6-28（VIP受体拮抗剂）不能逆转。在17个被检测的环行肌细胞中，有14个细胞中EM2显著抑制抑制性接头电位（IJPs），且L-NAME预孵育不能拮抗此效应。EM2在肌间神经丛的中间神经元和运动神经元中广泛表达，并在突触前抑制快速IJPs，从而增强结肠平滑肌的自发收缩和张力。
