Dexamethasone treatment affects skin mucous cell density in Gyrodactylus derjavini infected Salmo salar

Abstract

Atlantic salmon, Salmo salar, is normally rather refractive to infection with the ectoparasitic monogenean Gyrodactylus derjavini but dexamethasone treatment of the host increases the susceptibility. The causative mechanisms were elucidated in this work. Groups of Atlantic salmon were treated by intra-peritoneal dexamethasone injections and subsequently infected with G. derjavini. It was shown that both the infection level and the mucous cell density of caudal and pelvic fins were affected by the treatment. Significantly higher mucous cell densities were found on infected and treated fish whereas non-infected and treated fish showed no significant elevation of cell density. This suggests that mucous cell discharge elicited by infection is inhibited by the drug. The association with elevated parasite counts in these fish can be explained either by decreased anti-parasitic mucus action or by parasite predilection for intact mucous cells.

Comparative effects of four feed types on white spot disease susceptibility and skin immune parameters in rainbow trout, Oncorhynchus mykiss (Walbaum)

“…In fact, non‐specific responses protecting rainbow trout against Ich may be initiated by ectoparasitic worms such as Gyrodactylus derjavinoides (Buchmann, Lindenstrøm & Sigh 1999). Mucous cell densities in skin seem to act as a sensitive first line of immune defence parameter in fish (Olafsdottir & Buchmann 2004), although statistically significant trends for beta‐glucan feed effects on this parameter were not indicated in the present work. The receptor for beta‐glucan in fish has not been fully characterized, but several candidates have been suggested.…”

Stress response of Salmo salar (Linnaeus 1758) facing low abundance infestation of Caligus rogercresseyi (Boxshall & Bravo 2000), an object in the tank, and handling

“…). The increased number of these cells is an innate host response to parasites (Buchmann & Bresciani ; Olafsdottir & Buchmann ), as well as a good indicator of stress in fish (Vatsos et al . ).…”

Effects of dexamethasone on host innate and adaptive immune responses and parasite development in rainbow trout Oncorhynchus mykiss infected with Loma salmonae

“…The increased ectoparasitic infestations in dex treated fish could be explained by dex inhibiting some innate immune factors in the mucous of fish. Increased infections of G. derjavini caused by dex treatment in Atlantic salmon were thought to be caused by dex inhibiting the mucous cell discharge [40].…”