Cortisol Induces Stress-Related Changes in the Skin of Rainbow Trout (Oncorhynchus mykiss)

Abstract

The ultrastructure of the skin of rainbow trout, Oncorlixnchus mykiss, was studied over a 7-day period after a single meal containing cortisol. The fish experienced increased plasma cortisol levels for I day. Pavement cells contained significantly more vesicles of high elec tron density, which were also numerous in deeper filament cells, and displayed peroxidase activity. Mitotic cells were common after 4 and 7 days. Increased apoptosis, taken to indicate accelerated ageing, was detected in both pavement and mucous cells. Newly dif ferentiated mucous cells were found close to skin surface, and many mucous cells contained mucosomes of high electron density. The basal lamina became highly folded. The low numbers of leukocytes present in the skin did not change noticeably, but substantially more lymphocytes were apoptotic. The melanosomes in the pigment initially dispersed and sub sequently reaggregated in the cell bodies of these cells. The reaggregation was accompanied by apoptosis of melanocyte extensions. The results demonstrate the ability of the hormone to regulate several of the effects observed in the skin of fish challenged by stressors. Other phenomena generally observed in stressed fish, such as pavement cell necrosis and massive leucocyte infiltration, were not found after cortisol treatment. The latter observation indi cates that regulatory factors in addition to cortisol must be operative during stress.

Effects of water temperature on mucous cell distribution in channel catfish epidermis: a factor in winter saprolegniasis

“…However, Pickering & Duston (1983) indicated that oral administration of physiological doses of cortisol to brown trout (Salmo trutta) markedly increased their susceptibility to Saprolegnia infection. Furthermore, Iger et al (1995) demonstrated that increased levels of cortisol in rainbow trout (Oncorhynchus mykiss) induced mucous cell changes similar to those induced by other stressors, i.e. increased mucus release and/or mucous cell apoptosis.…”

Morphological color changes in fish: Regulation of pigment cell density and morphology

“…Later, the ability of fish chromatophores to migrate or to transdifferentiate was also shown (Iwata et al, 1984;Matsumoto et al, 1984). In addition, Iger et al (1995) reported that the dendritic extensions of melanophores can be engulfed and removed without killing the melanophore. Thus, these reports showed other possible mechanisms for decreases in melanophores.…”

Nonylphenol Affects the Granulation Pattern of Epidermal Mucous Cells in Rainbow Trout, Oncorhynchus mykiss

“…The epidermis, composed mainly of mucous and "lament cells covered with a mucous layer, protects the animal against external e!ects. Several studies demonstrated the high susceptibility of the skin to environmental in#uences (Burkhardt-Holm et al, 1997;Iger et al, 1995;Shephard, 1994). As a target organ for steroids, biological e!ects can be assumed.…”