Effect of parenteral endotoxin administration on the immuno-haematological responses of catfish , Heteropneustes fossilis

Abstract

Endotoxin, the outer cell wall membrane lipopolysaccharide component of the Gram-negative bacteria is a factor responsible for a number of complications/disorders and plays important role in the associated with pathophysiological complications and pathogenesis of many diseases in animals. Unlike higher animals which are extremely sensitive to endotoxin, fish are found to be resistant to endotoxic shock and earlier studies though limited have demonstrated the patho-physiological, immuno-endocrinological and immuno-neurological effects of LPS/endotoxin in aquatic animals including fish. Herein in the present investigation, the effect of pure endotoxin on immuno-haematological parameters of stinging catfish, Heteropneustes fossilis ranging from 50-60 g was studied by intraperitoneally injecting 0.1, 0.05 and 0.01 mg endotoxin per fish. H. fossilis yearlings were found to resist the endotoxin concentration up to 0.1 mg without any mortality. While, no change in immune parameters was recorded in stinging catfish injected with low dose of endotoxin (0.01 mg), most of the immune parameters were found to be significantly elevated in catfish injected with 0.05 mg endotoxin. Different serum and immune parameters like protein, globulin, lysozyme, respiratory burst activity, myeloperoxidase activity, natural agglutination titre were found to be significantly high (p < 0.01) at a dose of 0.05 mg endotoxin per fish. On the contrary, most of these parameters were decreased at high dose i.e., 0.1 mg endotoxin per fish, thereby indicating the immuno-suppressive effect of the endotoxin. The findings of the modulation of innate immunity also corroborated with the results of Aeromonas hydrophila pathogen challenge study with highest percent of mortality in group injected with 0.1 mg endotoxin per fish and least percentage in group injected with 0.05 mg endotoxin per fish.

Keywords: Endotoxin; Haematology; Heteropneustes fossilis; Immunity; Lipopolysachharide.

Fig. 1

(a–c). Effect of different endotoxin concentrations on various serum enzyme parameters of Heteropneustes fossilis at 7th and 15th days post injection (dpi) a) Alkaline phosphatase activity; b) SGOT level; c) SGPT level *: superscripts indicate significant difference in the mean (± SD) values of individual enzyme content at P < 0.01 among different endotoxin injected and control groups at specific sampling period.

Fig. 2

(a–c). Effect of different endotoxin concentrations on various non-specific immune parameters of Heteropneustes fossilis at 7th and 15th days post injection (dpi); (a) Respiratory burst activity; (b) Myeloperoxidase activity; (c) Lysozyme content *: superscripts indicate significant difference in the mean (± SD) values of individual non-specific immune parameters at P < 0.01 among the different endotoxin injected and control groups at specific sampling period.

Fig. 3

The mortality percentage of Heteropneustes fossilis injected with various doses of endotoxin challenged after 15th days post injection with virulent Aeromonas hydrophila @ 10⁶ CFU ml⁻¹ *: Superscript indicates significance difference (p ≤ 0.01) in the mortality percentage from other groups.