Haond C, Nolan D T, Ruane N M, Rotllant J, Wendelaar Bonga S E
Department of Animal Ecology and Ecophysiology, Faculty of Science, University of Nijmegen, Toernooiveld 1, 6525 ED Nijmegen, The Netherlands.
Parasitology. 2003 Dec;127(Pt 6):551-60. doi: 10.1017/s0031182003004116.
The host-parasite interaction between the rainbow trout Oncorhynchus mykiss and the fish louse Argulus japonicus was investigated by administering low levels of dietary cortisol before infecting the fish with low numbers of the parasite. After 24 h, the dietary cortisol treatment elevated blood cortisol and glucose levels and stimulated the synthesis of secretory granules in the upper layer of skin cells. Infection with 6 lice per fish caused skin infiltration by lymphocytes, also in areas without parasites. The lymphocyte numbers in the blood at 48 h post-parasite infection were reduced. Other changes, typical for exposure to many stressors and mediated by cortisol, were also found in the epidermis of parasitized fish, although neither plasma cortisol nor glucose levels were noticeably affected. Glucocorticoid receptors were localized immunohistochemically and found in the upper epidermal layer of pavement and filament cells, and in the leucocytes migrating in these layers. Cortisol-fed fish had reduced numbers of parasites and the changes in the host skin are likely involved in this reduction. Thus a mild cortisol stress response might be adaptive in rejecting these parasites. Further, the data suggest that this effect of cortisol is mediated by the glucocorticoid receptor in the skin epidermis, as these are located directly at the site of parasite attachment and feeding in the upper skin cells that produce more secretory granules in response to cortisol feeding.
在以少量寄生虫感染虹鳟鱼（Oncorhynchus mykiss）之前，通过投喂低剂量的膳食皮质醇，研究了虹鳟鱼与鱼虱（Argulus japonicus）之间的宿主 - 寄生虫相互作用。24小时后，膳食皮质醇处理提高了血液皮质醇和葡萄糖水平，并刺激了皮肤细胞上层分泌颗粒的合成。每条鱼感染6只鱼虱会导致淋巴细胞浸润皮肤，在没有寄生虫的区域也是如此。寄生虫感染后48小时，血液中的淋巴细胞数量减少。在受寄生虫感染的鱼的表皮中也发现了其他典型的、由皮质醇介导的对应激源暴露的变化，尽管血浆皮质醇和葡萄糖水平均未受到明显影响。通过免疫组织化学方法定位了糖皮质激素受体，发现其存在于扁平细胞和丝状细胞的上表皮层以及在这些层中迁移的白细胞中。投喂皮质醇的鱼体内寄生虫数量减少，宿主皮肤的变化可能与此减少有关。因此，轻度的皮质醇应激反应可能有助于排斥这些寄生虫。此外，数据表明皮质醇的这种作用是由皮肤表皮中的糖皮质激素受体介导的，因为这些受体直接位于寄生虫附着和摄食的部位，即上皮肤细胞中，这些细胞会因投喂皮质醇而产生更多的分泌颗粒。
