Dataset: Effect of chronic heat stress and inactive Salmonella Enteritidis on the immune-neuroendocrine interface of adult Japanese quail.

Description

Abstract: Birds integrate challenging situations into the Immuno-neuroendocrine (INE) system to maintain homeostasis, but multiple challenges can compromise their response, impairing welfare. Global warming and climate change have created new scenarios increasing the chances for chronic heat stress (CHS) exposures. Although immunosuppression caused by CHS can be reversed when conditions normalize, it may impair abilities to cope with new/successive immune challenges. We evaluated in adult Japanese quail (Coturnix coturnix), the effect of the succession of CHS and an immune challenge on the INE interface. Quails were exposed to 9 days of CHS. Then, we applied an immune challenge with Salmonella ser. Enteritidis antigen (ICH). Ten quail pairs (1 male and 1 female) were used for each combination treatment (non-CHS/non-ICH, non-CHS/ICH, CHS/non-ICH, and CHS/ICH), totalizing n = 80. Inflammatory and humoral immune responses, heterophils/lymphocytes (H/L) ratio, blood glucose concentration, malondialdehyde (MDA) levels, and superoxide dismutase (SOD) activity were assessed 14 days after the challenges ended. No differences were found in inflammatory or humoral immune responses. The H/L ratio was lower in males and, regardless of sex, birds submitted to CHS showed decreased responses. CHS-males exhibited lower glucose levels, while females kept them unchanged. Females showed greater MDA levels than males regardless of treatments. Female antioxidant (SOD) capacity showed higher values when going through CHS or ICH than CHS/Non-ICH males. No differences were found in total blood proteins among treatments. In conclusion, sequential challenges did not negatively affect humoral responses or pro-inflammatory potential in quail. The observed sex disparities in the basal H/L ratio, energy balance/sterile inflammation potential, and oxidative status following the CHS and ICH challenges, suggest that males are more susceptible than females. If confirmed, focus should be primary on males when aiming on strategies to mitigate welfare-related challenges.

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Specific response to SRBC: At 131 DA, 7 days after starting the ICH, an intraperitoneal administration of a non-pathogenic immunogenic antigen, SRBC, was performed. With this purpose, 0.3 ml of 10% SRBC in phosphate-buffered saline (HEMO-G, Rafaela, Santa Fe, Argentina) were injected. One week later (138 DA), the blood samples were taken and the humoral antibody response was analyzed in plasma (Nazar and Marin, 2011) by microtiter agglutination assay using a round bottom microagglutination plate. The microagglutination assay was performed as previously described (Nazar et al., 2018, 2019). Inflammatory response: It was analyzed with an injection of 0.05 ml of a 1 mg/ml phytohemagglutinin (PHA-P) solution in the right-wing web. Before injection, the wing width was measured with a digital caliper (mm), and 24 hours after (immediately after blood sampling) the PHA-P induction was done the day before sampling (137 DA). The variable was determined using the following formula: percentage of inflammation = (wing-width measurement 24 h before sampling day/wing-width measurement on the sampling day) ×100 (Nazar and Marin, 2011). H/L ratio: blood smears previously prepared were stained with May-Grundwal Giemsa. A leukocyte count (Heterophils, Lymphocytes, Monocytes, Eosinophils, and Basophils) was performed (on a total of 100 cells) using a white light optical microscope at 1000 × magnification. The H/L ratio was then calculated for each quail (Shini et al., 2008a, 2010). Glycemia: The plasma obtained after centrifugation was analyzed to determine the glucose concentration as described by Nazar et al. (2018) (Nazar et al., 2018). Total blood proteins: The protein content of blood plasma was analyzed by Bradford’s method using bovine serum albumin as standard (Bradford, 1976). Oxidative stress: oxidative stress indicators were evaluated in accordance with Vanden Braber et al. (2018). Oxidative damage was quantified as μmoles of MDA/mg protein by absorbance measurement at 532 nm of a reaction mixture composed of blood plasma and a 1:1 solution of 10% (w/v) trichloroacetic acid and 0.67% (w/v) Thio-barbituric acid which was exposed for 15 minutes in a water bath at 85 °C. On the other hand, antioxidant activity was evaluated in blood plasma as Superoxide dismutases (SOD) activity against the photochemical reduction of Nitroblue Tetrazolium (NBT) in a solution of 1 μM EDTA, 50 mM Potassium Phosphate Buffer (pH 7.8), 13 mM Methionine, 75 μM NBT and 40 μM Riboflavin. Determinations were performed by spectroscopic measurements at 560 nm. Results were expressed as USOD/mg protein (one SOD unit is defined, in comparison to a control, as the enzyme proportion that inhibits 50% of photochemical reduction of NBT) (Vanden Braber et al., 2018)

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