Green Benedict T, Lyte Mark, Chen Chunsheng, Xie Yonghong, Casey Melissa A, Kulkarni-Narla Anjali, Vulchanova Lucy, Brown David R
Pharmacology Section, Department of Veterinary and Biomedical Sciences, University of Minnesota, 1988 Fitch Ave., St. Paul, Minnesota 55108-6010, USA.
Am J Physiol Gastrointest Liver Physiol. 2004 Dec;287(6):G1238-46. doi: 10.1152/ajpgi.00471.2003.
Enteric neurotransmitters can modulate the biodefensive functions of the intestinal mucosa, but their role in mucosal interactions with enteropathogens is not well defined. Here we tested the hypothesis that norepinephrine (NE) modulates interactions between enterohemorrhagic Escherichia coli O157:H7 (EHEC) and the colonic epithelium. Mucosal sheets from porcine distal colon were mounted in Ussing chambers. Drugs and an inoculum of either Shiga toxin-negative or -positive EHEC were added to the contraluminal and luminal bathing medium, respectively. After 90 min, adherent bacteria were quantified by an adherence assay and by immunohistochemical methods; short-circuit current (I(sc)) was measured continuously to assess changes in active ion transport. NE-treated tissues exhibited concentration-dependent increases in I(sc) and EHEC adherence. NE did not alter adherence of a rodent-adapted, noninfectious E. coli strain or two porcine-adapted non-O157 E. coli strains. The actions of NE on EHEC adherence but not I(sc) were prevented by the alpha-adrenergic antagonist yohimbine and the PKA activator Sp-8-bromoadenosine-3',5'-cyclic monophosphorothioate. Like NE, the PKA inhibitor Rp-8-bromoadenosine-3',5'-cyclic monophosphorothioate or indirectly acting sympathomimetic agents increased EHEC adherence. Nerve fibers immunoreactive for the NE-synthesizing enzymes tyrosine hydroxylase and dopamine beta-hydroxylase appeared to innervate the colonic epithelium. EHEC-like immunoreactivity on the colonic surface had the appearance of bacterial microcolonies and increased after NE treatment by a phentolamine-sensitive mechanism. Through interactions with alpha(2)-adrenergic receptors, NE appears to increase EHEC adherence to the colonic mucosa. Changes in sympathetic neural outflow may alter intestinal susceptibility to infection.
肠道神经递质可调节肠黏膜的生物防御功能，但其在黏膜与肠道病原体相互作用中的作用尚不明确。在此，我们检验了去甲肾上腺素（NE）调节肠出血性大肠杆菌O157:H7（EHEC）与结肠上皮之间相互作用的假说。将猪远端结肠的黏膜片安装在尤斯灌流小室中。分别向对侧腔和管腔浴液中加入药物以及志贺毒素阴性或阳性EHEC的接种物。90分钟后，通过黏附试验和免疫组织化学方法对黏附细菌进行定量；连续测量短路电流（I(sc)）以评估主动离子转运的变化。经NE处理的组织I(sc)和EHEC黏附呈浓度依赖性增加。NE并未改变适应啮齿动物的非感染性大肠杆菌菌株或两种适应猪的非O157大肠杆菌菌株的黏附。α-肾上腺素能拮抗剂育亨宾和PKA激活剂Sp-8-溴腺苷-3',5'-环磷硫酯可阻止NE对EHEC黏附而非I(sc)的作用。与NE一样，PKA抑制剂Rp-8-溴腺苷-3',5'-环磷硫酯或间接作用的拟交感神经药可增加EHEC黏附。对NE合成酶酪氨酸羟化酶和多巴胺β-羟化酶呈免疫反应的神经纤维似乎支配结肠上皮。结肠表面的EHEC样免疫反应呈细菌微菌落外观，经NE处理后通过酚妥拉明敏感机制增加。通过与α(2)-肾上腺素能受体相互作用，NE似乎增加EHEC对结肠黏膜的黏附。交感神经传出活动的变化可能改变肠道对感染的易感性。
