Fukushima Kouhei, Naito Hiroo, Funayama Yuji, Yonezawa Hitoshi, Haneda Sho, Shibata Chikashi, Sasaki Iwao
Department of Surgery, Tohoku University, Graduate School of Medicine, 1-1 Seiryomachi, Aoba-ku, 980-8574, Sendai, Japan.
J Gastroenterol. 2004 Oct;39(10):940-7. doi: 10.1007/s00535-004-1425-7.
Parallel induction of prostasin, a novel serine protease, together with epithelial sodium channel (ENaC) in the colon, may be essential for physiological response to increased circulating aldosterone. The aim of the present study was to investigate whether aldosterone induces prostasin mRNA in parallel with enhanced expression of ENaC in colonic epithelial cells.
Sprague-Dawley rats were maintained on a sodium-depleted diet or subjected to continuous aldosterone infusion up to 4 weeks. Rats were necropsied at 1, 2, or 4 weeks after the beginning of each treatment. Blood was immediately collected and the large intestine was removed. Plasma aldosterone and arginine-vasopressin (AVP) levels were measured by radio-immunoassay. Epithelial cells were isolated from the right and left colon and RNA was extracted. Expression of prostasin and the alpha-, beta-, and gamma-subunits of ENaC was evaluated by quantitative RT-PCR or Northern blot analysis. In another series of experiments, T84 cells were stimulated with aldosterone, dexamethasone, and AVP alone or in combination, and prostasin mRNA was measured by quantitative RT-CPR.
Treatment with sodium-depleted diet and aldosterone infusion resulted in an increase of plasma aldosterone and induction of prostasin mRNA in the left colon. Expression of three subunits of ENaC also increased in the left colon. Induction of prostasin mRNA was observed when T84 cells were stimulated with corticosteroids plus AVP in vitro.
Aldosterone has a pivotal role for increasing expression of prostasin in epithelial cells of the left colon. AVP may have a synergistic effect on aldosterone-mediated prostasin induction.
一种新型丝氨酸蛋白酶——前列腺素酶（prostasin）与结肠上皮钠通道（ENaC）的平行诱导，可能是对循环中醛固酮增加产生生理反应所必需的。本研究的目的是调查醛固酮是否与结肠上皮细胞中ENaC表达增强同时诱导前列腺素酶mRNA表达。
将Sprague-Dawley大鼠维持在低钠饮食状态或持续输注醛固酮长达4周。在每种处理开始后的1、2或4周对大鼠进行尸检。立即采集血液并取出大肠。通过放射免疫测定法测量血浆醛固酮和精氨酸加压素（AVP）水平。从左右结肠分离上皮细胞并提取RNA。通过定量RT-PCR或Northern印迹分析评估前列腺素酶以及ENaC的α、β和γ亚基的表达。在另一系列实验中，用醛固酮、地塞米松和AVP单独或联合刺激T84细胞，并通过定量RT-CPR测量前列腺素酶mRNA。
低钠饮食和醛固酮输注处理导致血浆醛固酮增加以及左结肠中前列腺素酶mRNA的诱导。左结肠中ENaC的三个亚基的表达也增加。当在体外用皮质类固醇加AVP刺激T84细胞时，观察到前列腺素酶mRNA的诱导。
醛固酮在增加左结肠上皮细胞中前列腺素酶的表达方面起关键作用。AVP可能对醛固酮介导的前列腺素酶诱导具有协同作用。
