Distinct β-glucan molecules modulates differently the circulating cortisol levels and innate immune responses in matrinxã (Brycon amazonicus)

Abstract

This study investigated the effects of two β-glucan molecules with different purities and isolated by different biotechnological processes on the immune response of matrinxã (Brycon amazonicus) prior and after challenge with Aeromonas hydrophila. In this sense, we evaluated serum cortisol and plasma glucose levels, the number of leukocytes (lymphocytes, neutrophils and monocytes), as well as the respiratory activity of leukocytes prior to, 6 and 24 h post infection (hpi). During 15 days, fish were fed with diets containing 0.1% of two β-glucans (β-G 1 and β-G 2, with 71 and 62% of purity, respectively) and then submitted to challenge. Results were compared with a positive control group fed with a β-glucan-free diet. A negative control group, also fed with β-glucan-free diet but inoculated with PBS, was established to evaluate the effect of handling during injection. Our results showed that different β-glucans affected differently the biological responses of matrinxã. The βG 2 modulated the cortisol profile prior to and after the acute infection with A. hydrophila, and increased the mobilization and activity of leukocytes. The infection promoted lymphopenia at 6 hpi and both β-glucans increased the circulating lymphocyte population 24 hpi. Moreover, the β-G 2 prevented the infection-induced neutrophilia at 6 and 24 hpi. Finally, the β-G 2 caused a marked increase in the circulating monocytes prior to infection, and a reduction at 6 hpi that was reversed at 24 hpi. In summary, our study demonstrates that β-G 2 was more efficient on the induction of the cell-mediate immunity in matrinxã.

The Effects of Silkworm-Derived Polysaccharide (Silkrose) on Ectoparasitic Infestations in Yellowtail (Seriola quinqueradiata) and White Trevally (Pseudocaranx dentex)

“…However, it is also possible that the silkrose treatment itself causes a decrease in serum cortisol levels, as the treatment induced a significant decrease in serum cortisol levels even in yellowtail that had not been infected with many parasites. In agreement with the current result, naturally derived polysaccharides, such as those from Astralagus propinquus [53], Ulva intestinalis [54], Gracilariopsis persica [54], as well as β-glucan [55,56], have also been found to be associated with the reduction of serum cortisol level in various teleost species. These previous studies, however, did not establish the underlying mechanism of this cortisol-lowering effect.…”

Development of Fish Immunity and the Role of β-Glucan in Immune Responses

“…Douxfils, Fierro-Castro, Mandiki, Emile, Tort and Kestemont [174] Matrinxã (Brycon amazonicus) 0.1% on feed 15 Inclusion of β-glucan in fish diet may help to prepare them to face stressful practices in fish farming. Montoya, et al [195] Carp (Cyprinus carpio) 0.1; 1.0; 2.0% of feed 14 and 28…”