Department of Digestive Diseases, Zhejiang Integrated Medical Hospital, Hangzhou 310003, China.
Chin J Integr Med. 2011 Jul;17(7):525-30. doi: 10.1007/s11655-011-0786-z. Epub 2011 Jul 3.
To explore the significance of colonic epithelial cell apoptosis and tumor necrosis factor α (TNF-α) changing in pathogenesis of melanosis coli (MC) in guinea pig and the molecular mechanism of rhubarb (Rhu) in inducing the disease, by means of using different dosages of Rhu to induce the disease.
One hundred and forty-four male guinea pigs, clean grade, were randomized according to their body weight into 5 groups, the untreated normal group and the 4 Rhu groups treated, respectively, with different doses of Rhu, 3 g/kg·d for low dose (Rhu-l) group, 6 g/kg·d for moderate dose (Rhu-m) group, 12 g/kg·d for high dose (Rhu-h) group and 24 g/kg·d for super-high dose (Rhu-s) group via gastric infusion. All animals were sacrificed 60 days later, their viscera were taken for observing the pathologic and morphologic changes with HE, melanin and melatonin staining, and the apoptosis of colonic epithelial cells was detected with TUNEL stain and transmission electric microscopy. In addition, the levels of TNF-α in serum and colonic tissue were measured using ELISA and RT-PCR.
The pathological changes of MC could be found by naked eye in all Rhu groups, especially apparent at caecum and proximal end of colon, but did not found in gallbladder, jejunum and ileum. In normal guinea pigs, the colonic membrane was pink in color with no apparent pigment deposition. Membranous color deepened in the Rhu groups depending on the dosage of Rhu used. MC scoring showed the highest scores revealed in the Rhu-s group (6.00±0.00), which was significantly different to those in the Rhu-l (3.86±0.69), Rhu-m (4.43±0.79) and Rhu-h groups (4.88±0.35, all P<0.05). Levels of cell apoptosis in colon and TNF-α in serum in all Rhu groups were higher than those in the normal group (P<0.01), but showed no significant difference among the Rhu groups (P>0.05). Moreover, a positive correlation was found in the degree of induced MC with apoptosis rate and TNF-α level.
Rhu (anthraquinone purgatives) had apparent effect on inducing MC; its molecular mechanism is maybe to destroy intestinal mucosal barrier and advance proinflammatory factor TNF-α releasing, which leads to colonic epithelial cells apoptosis, and finally induce the change of MC due to the deposition of brown pigments, i.e. the macrophage phagocytized apoptotic body, on the colonic membrane.
通过采用不同剂量大黄灌胃诱导实验豚鼠发病，探讨结肠黏膜上皮细胞凋亡和肿瘤坏死因子-α（TNF-α）变化在黑变病发病机制中的意义，以及大黄诱导黑变病的分子机制。
清洁级雄性豚鼠 144 只，按体重随机分为 5 组，即未处理的正常组和分别用不同剂量大黄处理的 4 个大黄组，3 g/kg·d 为低剂量组（大黄-l 组）、6 g/kg·d 为中剂量组（大黄-m 组）、12 g/kg·d 为高剂量组（大黄-h 组）和 24 g/kg·d 为超高剂量组（大黄-s 组），灌胃给药。60 天后处死所有动物，观察 HE、黑色素和褪黑素染色的病理形态学变化，用 TUNEL 染色和透射电镜检测结肠上皮细胞凋亡，用 ELISA 和 RT-PCR 检测血清和结肠组织中 TNF-α的水平。
肉眼观察发现，所有大黄组均出现黑变病的病理变化，尤其是盲肠和近端结肠，而胆囊、空肠和回肠未见明显变化。正常豚鼠结肠黏膜呈粉红色，无明显色素沉着。随着大黄剂量的增加，膜色加深。大黄-s 组 MC 评分最高（6.00±0.00），与大黄-l（3.86±0.69）、大黄-m（4.43±0.79）和大黄-h（4.88±0.35）组比较，差异均有统计学意义（均 P<0.05）。所有大黄组的结肠细胞凋亡率和血清 TNF-α水平均高于正常组（均 P<0.01），但大黄组间比较差异均无统计学意义（均 P>0.05）。此外，诱导 MC 的程度与细胞凋亡率和 TNF-α水平呈正相关。
大黄（蒽醌类泻药）对诱导黑变病有明显作用；其分子机制可能是破坏肠黏膜屏障，促进前炎症因子 TNF-α释放，导致结肠上皮细胞凋亡，最终由于巨噬细胞吞噬凋亡体，导致结肠黏膜上褐色色素沉着而发生黑变病的变化。
