色氨酸羟化酶在中华绒螯蟹中肠、肠球和后肠组织中的分布和定位

5-羟色胺(5-hydroxytryptamine,5-HT)存在于各种动物的消化道中,并影响甲壳动物的生长和繁殖。色氨酸羟化酶是5-HT生物合成中的限速酶,可作为5-HT免疫活性细胞的特异标志。运用组织学和免疫组织化学技术对中华绒鳌蟹中肠、肠球和后肠的形态学及色氨酸羟化酶在其中的分布进行研究,结果显示:中华绒螯蟹肠道中肠和后肠组织结构组成基本相似,均由黏膜层、黏膜下层、肌层和外膜四部分组成。然而,肠球外膜非常发达,由结缔组织组成。其余组织形态一部分与中肠相似(近头端),另一部分与后肠相似(近尾端)。色氨酸羟化酶在中华绒螯蟹中肠、肠球和后肠均有分布,阳性物质呈棕褐色。在中肠,主要分布在黏膜上皮细胞的胞核中;在肠球,主要分布在近中肠端黏膜上皮细胞的胞核中、近后肠端的黏膜上皮细胞的胞浆中、以及外周结缔组织中;在后肠,主要分布在黏膜上皮细胞的胞浆中。为进一步了解5-HT在甲壳动物消化道中的生理调节机制奠定了基础。

Immunohistochemistry localization of tryptophan hydroxylase of the midgut, the hindgut ampulla and hindgut in the Chinese mitten crab, Eriocheir sinensis

Serotonin (5-HT) exists in all kinds of animals' digestive tract, which has some important physiology effects on the growth and reproduction of crustaceans. Tryptophan hydroxylase (TPH) is the rate-limiting enzyme for 5-HT biosynthesis and can be used to identify 5-HT as a marker. The morphology and distribution of TPH in the midgut, the hindgut ampulla and hindgut of Eriocheir sinensis were mainly studied in this research by using histology and immunohistochemical technique. The result shows that: the histology of the crab intestine in midgut is similar to that in hindgut. There four layers can be identified in midgut and hindgut including the mucosa, submucosa, muscularis and adventitia. However, the size of adventitia of the hindgut ampulla composed of connective tissue is larger than that of midgut and hindgut. Except adventitia, the histology of distant rostrol and near rostrol of hindgut ampulla is similar to midgut and hindgnut respectively. TPH can be detected by immunolocalization in the midgut, the hindgut ampulla and hindgut. In the midgut, TPH is mainly distributed in the nucleus of mucosal epithelial cells. In the hindgut ampulla, TPH was widely distributed in the nucleus of mucosal epithelial cells close to the midgut and the cytoplasm of mucosal epithelial cells close to the hindgut,and peripheral connective tissue. In the hindgut, TPH is mainly found in the cytoplasm of mucosal epithelial cells. These results will be helpful for future studies on physiological regulation mechanism of 5-HT in the digestive tract of the crustaceans.