RESUMO
Here we show that selected nutritional feed additives reduce the adverse effects of transport stress on the immune system and hematology of tambaqui. We formulated a control diet to contain normal dietary levels of vitamin E (21.6 mg/ kg diet) and C (143 mg/kg), then we added supra levels of these vitamins (vit E - 264 mg/kg and vit C - 1000 mg/kg) to a second diet. Finally, a third diet was produced to contain similar levels of vitamins from diet 2 with 0.1% beta-glucan supplementation. Four hundred thirty-two tambaquis (20.91 g ± 0.27 g) were randomly assigned to 12 aquaria and fed the diets for 15 days; then, all fish were transported for five h and then returned to the aquaria. Blood samples were collected before and after the transport and at the end of the trial (60 days). Transportation significantly increased blood glucose that returned to baseline levels at the end of the trial. However, cortisol seemed to be unresponsive to the stress. Surprisingly, the stress significantly increased the immunoglobulin level after transport. Additionally, the transport markedly reduced the red blood cell count and leukocyte and lymphocytes counts while increasing the control group's neutrophil number. These effects lasted until the end of the trial in the control group. Supra levels of the vitamins and glucan supplementation prevented the decrease in red blood cell and leukocyte count after the stress. Additionally, beta-glucan supplementation induced lower cortisol levels in all the sampling points. However, the effect on the immune parameters was limited, increasing only the lysozyme activity and serum protein levels in the beta-glucan supplemented group and the group fed only the supra levels of vitamins, respectively. In sum, our results indicated that transport for five h induced a limited effect on stress biomarkers. The use of supra levels of antioxidant vitamins alone or in combination with beta-glucan could restore or prevent the adverse effects of stress on hematology and the immune system.
RESUMO
In aquaculture production, studies of salmon health and interaction between pathogens and nutrition are of high importance. This study aimed to compare genes and pathways involved in salmon head kidney cells and liver cells, isolated from the same fish, towards polyinosinic acid: polycytidylic acid (poly I:C) and lipopolysaccharide (LPS), with and without addition of surplus arginine. Selected transcriptional responses of genes involved in inflammation, polyamine synthesis, oxidation and apoptosis were elucidated. For the genes related to inflammation, viperin, Mx and Toll like receptor 3 (TLR3), transcription were significantly upregulated by poly I:C in head kidney cells, while viperin was upregulated in liver cells. Surplus arginine did not affect poly I:C induced responses with the exception of reducing poly I:C induced Mx transcription in head kidney cells. Gene transcription of Interleukin 1ß (IL-1ß), Interleukin-8 (IL-8) and cyclooxygenase 2 (Cox2) were elevated during LPS treatment in all liver and head kidney cell cultures. In addition, LPS induced significantly, CD83 transcription in liver cells and TNF-α transcription in head kidney cells. Surplus arginine significantly reduced IL-8, Cox2 and TNF-α transcription in head kidney cells. LPS upregulated arginase in head kidney cells while poly I:C upregulated S-adenosyl methionine decarboxylase (SAMdc) transcription in liver cells. This suggests that LPS and poly I:C modulates genes involved in polyamine synthesis. In addition, in head kidney cells, surplus arginine, when cultured together with LPS, increased the transcription of ornithine decarboxylase (ODC) the limiting enzyme of polyamine synthesis. The genes involved with oxidation and apoptosis were not affect by any of the treatments in liver cells, while LPS decreased caspase 3 transcription in head kidney cells. In liver cells, protein expression of catalase was reduced by surplus arginine alone and when challenged with poly I:C. Both liver cells and head kidney cells isolated from the same individual fish responded to LPS and poly I:C, depending on the gene analyzed. Additionally, arginine could modulate transcription of pro-inflammatory genes induced by LPS in salmon immune cells, thus affecting salmon immunity.
