Neural and endocrinological regulation on the mucosal defence system in fish intestine

为了原位杂交检测虹鳟鱼肠道中产生IgM的细胞，制备了膜结合IgM （mIgM）和分泌IgM （sIgM）特异性引物，并分别对石蜡切片进行了标记。表达sIgM的细胞很少分布在肠粘膜下区。产生mIgM的细胞被检测到，可能是由于其表达水平较低。这些结果表明，非特异性防御分子在鱼类消化道中起着更重要的作用。Congerin是一种从日本长须鲸的皮肤粘液中纯化的原型凝集素，也分布于长须鲸的上消化道。在目前的研究中，western blotting明确了凝血素到达肠腔。用较长胃匀浆进行消化试验表明，即使在6小时后，凝血素也只被部分降解，而牛血清白蛋白在30分钟内被完全消化。这些结果表明，从消化道分泌的凝血素可以成功到达愤怒的肠腔并作为防御剂发挥作用。温度应力导致被膜凝聚蛋白减少。然而，腹腔注射皮质醇对凝集素含量没有影响。这表明凝血素吸入或分泌受皮质醇以外的未知因素调节。另一方面，在相同条件下，上消化道凝聚素含量变化不显著。这表明，在皮肤和上消化道中产生凝聚素的俱乐部细胞受到不同方式的调节。

In order to detect IgM producting cells in the gut cf rainbow trout by in situ hybridization, specific primer for membrane-binding IgM (mIgM) and secretory IgM (sIgM) was prepared and to paraffin sections, respectively. Cells expressing sIgM were distributed very scarcely in the submucosal region in the intestine. mIgM producing cells were to be detected, probably due to low level of its expression. These results suggest that non-specific defence molecules play more significant roles in fish alimentary canals. Congerin, a proto-type galectin purified from skin mucus cf Japanese conger is also distributed in the upper digestive tract of conger. In the current study it is clarified by western blotting that congerin reaches intestinal lumen. Digestion test using homogenates of conger stomach exhibited that congerin were degraded only partially even after 6 hours, while bovine serum albumin was completely digested within 30 min. These results indicate that congerin secreted from the digestive tract can successfully arrive to and function in the intestinal lumen of anger as defensive agents. Temperature stress induced decrease of congerin in the integument. However, intraperitoneal administration of cortisol showed no effect on the congerin contents. This indicates that congerin suction or secretion is regulated by unknown factors other than cortisol. On the other hand, congerin content in the upper digestive tract was not changed significantly under the same condition. This indicates that club cells, which produce congerin, in the skin and the upper digestive tract are regulated in the different way.