Smiley Rebecca, McCallum Richard, Showkat Ali Mohammed
Department of Clinical Investigation, William Beaumont Army Medical Center, 5005 N. Piedras Street, El Paso, TX 79920-5001, USA.
Department of Internal Medicine, Texas Tech Health Science Center, Paul L. Foster School of Medicine, 4800 Alberta Ave., El Paso, TX 79905-2709, USA.
Gastroenterology Res. 2020 Dec;13(6):246-252. doi: 10.14740/gr1322. Epub 2020 Dec 23.
Substance P (SP) and neuropeptide Y (NPY), excitatory and inhibitory neuropeptides, respectively, may impact gastric motility in patients with diabetic mellitus (DM). We investigated these neuropeptide levels, NPY receptors, total nitric oxide synthase (NOS) levels, and neuronal NOS alpha (nNOSα) activation status and levels in streptozotocin-induced type I diabetes in male rats.
Rats were grouped based on serum glucose and gastric emptying time: normal untreated control (CM), diabetic (DM) and diabetic gastroparesis (DM + GP). Neuropeptide serum levels were determined by enzyme-linked immunosorbent assay (ELISA). Sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) and western blotting measured NPY receptors, Y1 and Y2, and nNOSα expression. Low-temperature SDS-PAGE followed by western blotting was used to measure the dimerization of nNOSα. An NOS colorimetric assay kit was used to measure total NOS activity.
SP levels were significantly decreased (P < 0.05) in DM and DM + GP compared to CM. NPY levels were significantly decreased (P < 0.05) in DM compared to CM, and DM + GP had a more significantly decreased NPY when compared to both DM and CM. Protein levels of neuropeptide receptor Y1 (NPY-Y1) in the smooth muscle of pylorus were significantly increased in DM, but not in DM + GP when compared to CM. Neuropeptide receptor Y2 (NPY-Y2) was not detected. Changes in nNOSα activity and their protein levels, as well as total NOS activity, among the groups were insignificant.
Increased expression of pylorus NPY-1R and decreased serum NPY are present in diabetes. A more pronounced decreased serum NPY with no NPY-1R upregulation in pyloric smooth muscle is associated with gastroparesis. NPY levels show no relationship with nNOSα levels, their activation status, or total NOS activity in pyloric smooth muscle. These data suggest a pathophysiological role of severely depleted NPY and absence of NPY-Y1 upregulation for gastroparesis phenotype.
P物质（SP）和神经肽Y（NPY）分别为兴奋性和抑制性神经肽，可能影响糖尿病（DM）患者的胃动力。我们研究了链脲佐菌素诱导的雄性大鼠I型糖尿病中这些神经肽水平、NPY受体、总一氧化氮合酶（NOS）水平以及神经元型NOSα（nNOSα）的激活状态和水平。
根据血清葡萄糖和胃排空时间对大鼠进行分组：正常未处理对照组（CM）、糖尿病组（DM）和糖尿病胃轻瘫组（DM + GP）。通过酶联免疫吸附测定（ELISA）测定神经肽血清水平。采用十二烷基硫酸钠-聚丙烯酰胺凝胶电泳（SDS-PAGE）和蛋白质印迹法检测NPY受体Y1和Y2以及nNOSα表达。采用低温SDS-PAGE后蛋白质印迹法检测nNOSα的二聚化。使用NOS比色测定试剂盒测量总NOS活性。
与CM组相比，DM组和DM + GP组的SP水平显著降低（P < 0.05）。与CM组相比，DM组的NPY水平显著降低（P < 0.05），与DM组和CM组相比，DM + GP组的NPY水平降低更显著。与CM组相比，DM组幽门平滑肌中神经肽受体Y1（NPY-Y1）的蛋白水平显著升高，但DM + GP组未升高。未检测到神经肽受体Y2（NPY-Y2）。各组间nNOSα活性及其蛋白水平以及总NOS活性的变化无统计学意义。
糖尿病患者存在幽门NPY-1R表达增加和血清NPY降低。血清NPY更显著降低且幽门平滑肌中无NPY-1R上调与胃轻瘫相关。NPY水平与幽门平滑肌中nNOSα水平、其激活状态或总NOS活性无关。这些数据表明严重缺乏NPY和NPY-Y1上调缺失在胃轻瘫表型中具有病理生理作用。
