Effects of gut hormones on the large bowel injury

本研究的第一个目的是评价炸弹素（BBS）对大鼠醋酸性结肠炎的影响。选用雄性Fischer大鼠344只。在降结肠处做了两个末端结肠造口术以分离大肠。大鼠术后每8 h皮下注射生理盐水或BBS，剂量分别为3、10或30 mug/kg，直至术后第4天（POD）。第4次POD处死大鼠，切除大肠远端段。采用组织学分级法测定粘膜炎症反应的程度（Scand J Gastroenterol 1993; 28: 155-162）。评估的因素包括溃疡、粘液细胞衰竭、隐窝脓肿、炎性囊肿、粘膜萎缩、水肿、炎性细胞浸润和血管扩张。施用BBS可显著降低醋酸性结肠炎的组织学评分，且呈剂量相关。本研究的第二个目的是评估BBS对直肠和小肠粘膜增生的影响。为了分析肠道黏膜的标记指数，计数增殖细胞区BrdU标记和未标记的细胞数量。标记指数表示为brdu标记的细胞数/区域内增殖细胞总数。BBS显著增加直肠和空肠粘膜的标记指数，且呈剂量相关。以30 mg /kg剂量给药5 d，可显著提高大鼠空肠重量及DNA、RNA和蛋白质含量。

The first purpose of this study was to evaluate the effect of bombesin (BBS) on acetic acid-induced colitis in rats. Male Fischer 344 rats were used. Two end colostomies were made at the descending colon to separate the large bowel. Colitis was induced in the distal segment of large bowel by administration of 4% acetic acid for 15 sec. Rats were administered subcutaneous injection of saline or BBS every 8 h at doses of 3,10 or 30 mug/kg after the operation until the 4th postoperative day (POD). Rats were sacrificed on the 4th POD and the distal segment of large bowel was excised. A histologic grading scale was used for determination of the extent of inflammatory reaction in the mucosa (Scand J Gastroenterol 1993 ; 28 : 155-162). The factors evaluated were ulceration, mucus cell depletion, crypt abscess, inflammatory cyst, mucosal atrophy, edema, inflammatory cell infiltration and vascular dilatation. Administration of BBS significantly decreased the histologic scoring of acetic acid-induced colitis in a dose-related manner.The second purpose of this study was to evaluate the effect of BBS on the proliferation of rectal and small intestinal mucosa. For analysis of the labelling index of the gut mucosa, the numbers of bromodeoxyuridine (BrdU)-labelled and unlabeled cells in the zone of proliferating cells were counted. The labelling index was expressed as the number of BrdU-labelled cells/total number of cells within the zone proliferating cells. BBS significantly increased the labelling indices of rectal and jejunal mucosa in a dose-related manner. Furthermore, administration of BBS for 5 days at the dose of 30 mug/kg significantly increased the weight and contents of DNA,RNA and protein in rat jejunum.