微囊藻毒素-LR对小鼠肠道消化酶的影响

微囊藻毒素-LR（MCLR）是一类对动物和人类健康影响很大的蓝藻毒素。已有调查认为MCLR能导致某些胃肠道疾病，相关实验室资料也证实MCLR能在肠道积累并引起肠道损伤。研究对小鼠连续腹腔染毒MCLR 28d，观察肠道病理水平及超微结构的变化，并测定肠黏膜刷状缘膜酶活性。结果显示，小肠绒毛受损较严重，绒毛数量减少、部分脱落至肠腔，固有层及黏膜下层水肿、充血；电镜观察发现肠细胞细胞质电子密度降低，伴有线粒体肿胀、细胞核变形现象；肠黏膜二糖酶（蔗糖酶、麦芽糖酶、乳糖酶）、碱性磷酸酶及-谷氨酰转移酶活性均呈下降趋势。在亚慢性MCLR染毒条件下，肠道的消化功能可能受到抑制，进而导致机体对营养物质吸收不良。研究对理解蓝藻毒素引起的胃肠道不适（如恶心、呕吐、腹痛、腹泻）提供了新的证据。  

EFFECTS OF MICROCYSTIN-LR ON THE DIGESTIVE ENZYME ACTIVITY OF INTESTINAL TRACT IN BALC/C MICE

Microcystin-LR has been known to harm the health in both humans and animals. Recently there has been an increase in reports about gastrointestinal ailments resulting from the ingestion of MCLR. Some data also indicated that MCLR could accumulate in the intestinal tract and cause injuries. In this study, we intraperitoneally injected mice with MCLR for 28 days, and observed the pathophysiological and ultrastructural changes. We also examined the activities of intestinal mucosal brush border membrane enzymes. Severe injuries were found in villi, such as a decrease in villi number and the exfoliation of villi into gut cavity. The cells of lamina propria and submucosa showed swell and hyperemia. In the ultrathin sections, loss of density in the cytoplasm associated with swollen mitochondria as well as nuclei deformation was observed. The activities of intestinal disaccharidase (sucrase, maltase, lactase), alkaline phosphatase, and -glutamyl transferase decreased after the MCLR exposure. Based on these results, we reasoned that the digestion capacity of small intestine might be inhibited after subchronic exposure of MCLR, which led to malabsorption. Our study suggested new cellular mechanisms that explain gastrointestinal sickness, such as nausea, vomiting and diarrhea, induced by cyanobacterial toxins.