Oxidative stress induced by corticosterone administration in broiler chickens (Gallus gallus domesticus)

Baseline glucocorticoids alone do not predict reproductive success across years, but in interaction with enzymatic antioxidants

Glucocorticoids are known to adjust organismal functions, such as metabolism, in response to environmental conditions. Therefore, these hormones are thought to play a key role in regulating the metabolically demanding aspects of reproduction, especially in variable environments. However, support for the hypothesis that variation in glucocorticoid concentrations predicts reproductive success is decidedly mixed. Two explanations may account for this discrepancy: (i) Glucocorticoids might not act independently but could interact with other physiological traits, jointly influencing reproduction, and (ii) such an association could become apparent primarily in challenging environments when glucocorticoid concentrations increase. To address these two possibilities, we determined natural variation in circulating baseline glucocorticoid concentrations in parental great tits (Parus major) alongside two physiological systems known to be related with an individual's metabolism: oxidative status parameters (i.e., concentrations of pro-oxidants, dietary, and enzymatic antioxidants) and body condition. These systems interact with glucocorticoids and can also influence reproductive success. We measured these variables in two breeding seasons that differed in environmental conditions. When accounting for the interaction of baseline glucocorticoids with other physiological traits, we found a positive relationship between baseline glucocorticoids and the number of fledglings in adult great tits. The strength of this relationship was more pronounced for those individuals who also had high concentrations of the enzymatic antioxidant glutathione peroxidase. When studied independently, glucocorticoids were not related to fitness proxies, even in the year with more challenging environmental conditions. Together, our study lend to support the hypothesis that glucocorticoids do not influence fitness alone, but in association with other physiological systems.

Possible role of corticosterone on behavioral, physiological, and immune responses in chicks

Glucocorticoids are one of steroid hormone and have a variety of functions including stress response, carbohydrate metabolism, and modulation of immune system in vertebrates. Corticosterone is the main glucocorticoid in birds, although the precise role of the glucocorticoid during immune challenge is not fully understood. Therefore, the purpose of the present study was to determine if a single subcutaneous injection of corticosterone could affect inflammation-related gene expressions in the spleen and liver of chicks (Gallus gallus). In addition, the effects of corticosterone injection on the food intake, cloacal temperature, formation of conditioned visual aversion, and plasma constituents were also measured. Corticosterone did not affect the food intake or cloacal temperature and did not cause conditioned visual aversion in chicks. The corticosterone injection was associated with a significant decrease in gene expression of several pro-inflammatory cytokines including inducible nitric oxide synthase and cyclooxygenase-2 in the spleen and liver at 1 and 3 h post-injection. Corticosterone increased the plasma glucose and uric acid concentrations and the antioxidant capacity. In summary, the present study suggests that corticosterone is likely not associated with food intake, cloacal temperature or the development of aversive sensation, but suppresses the synthesis of inflammation-associated bioactive molecules and increases the antioxidant capacity in chicks.

A nutrigenomics approach to study the effects of ω-3 fatty acids in laying hens under physiological stress

Supplement of ω-3 fatty acids can decrease the harmful effects of stress. However, the potential molecular mechanisms that are modulated by dietary ω-3 fatty acids in laying hens under stress remain unknown. Hence, RNA-sequencing (RNA-Seq) technology was used to gain new insights into different gene expression profiles and potential pathways involved in response to stress in the liver of 35-week-old Lohmann LSL-Lite laying hens supplemented with ω-3. Three groups including control (non-stress), stress, and stress_ω-3 fatty acids (three layers per each group) were applied. A total of 1,321 genes were detected as differentially expressed genes of which 701, 1,049, and 86 DEGs belonged to stress vs. control, stress_ω-3 vs. control, and stress vs. stress_ω-3 pairwise comparisons, respectively. Gene ontology and KEGG pathway analysis indicated that the DEGs were enriched in particular regulation of steroid and cholesterol biosynthetic process, fatty acid degradation, AMPK signaling pathway, fatty acid biosynthesis, and immune response. Our data represented a promising approach regarding the importance of ω-3 as anxiolytic and anti-stress. In this context, UNC13B and ADRA1B genes were downregulated in the stress_ω-3 group compared to the stress group, which are associated with decreased activity of glutamatergic stimulatory neurons and probably play important role in facilitating the response to stress. This study extends the current understanding of the liver transcriptome response to physiological stress, and provides new insights into the molecular responses to stress in laying hens fed a diet supplemented with ω-3 fatty acids.

Effects of corticosterone administration on the body condition and blood parameters of the house sparrow, Passer domesticus

Glucocorticoids are steroid hormones produced by the adrenal glands and released into the bloodstream in response to stressful situations. In birds, corticosterone (CORT) is the main glucocorticoid released under stress. Throughout their lives, animals in nature are continually exposed to noxious stimuli known as stressful events. Any alteration of homeostatic stability is a stressful situation and this alteration triggers physiological changes to restore homeostasis. Glucocorticoids are one of the components of the complex set of physiological and behavioral responses to stress. In this work, we use CORT supplied in drinking water to evaluate its effect in blood parameters and physiology in house sparrows (Passer domesticus). To accomplish this, P. domesticus were administered three different doses of CORT in drinking water for 72 h. Body mass, organ mass, pectoral muscle mass, leg muscle mass, and blood parameters (CORT, triglycerides, glucose and uric acid, heterophils/lymphocytes ratio, hematocrit, and serum protein profile) were determined before and after CORT treatment. A 15% decrease in body mass with a significant decrease in pectoral mass were observed after the higher CORT treatment, as well as a decrease in the plasma concentration of uric acid. Lastly, we found a reversal of the heterophils/lymphocytes ratio and a decrease in hematocrit. It was possible to establish first data for baseline and CORT-alteration values in serum protein profile for P. domesticus. Baseline and altered values of blood parameters and serum protein profile could be an important tool in field ecology because they provide important data to assess the physiological condition in wild birds.

Stress responses in captive Crocodylus moreletii associated with metal exposure

Environmental pollution by metals has repercussions on wildlife health. It is known that some metals can have an influence on the neuroendocrine stress response, and at the same time, metals have pro-oxidant effects that can overwhelm the antioxidant system and cause oxidative stress. This study evaluates the association of metals with neuroendocrine stress activity and biomarkers of oxidative stress in 42 captive female Morelet's crocodiles (Crocodylus moreletii). We measured five metals of ecotoxicological importance (Hg, Cd, Pb, Cu and Zn), and three biomarkers of the oxidative stress response in the liver: glutathione (GSH) and glutathione disulfide (GSSG) as markers for antioxidant system and thiobarbituric acid reactive substances (TBARS) for oxidative damage. We also measured one biomarker of the neuroendocrine response to stress: corticosterone (B) in blood plasma. The mean ± SD concentrations of metals in the liver expressed in μg/g (dw) were: Cd: 0.004 ± 0.003, Hg: 0.014 ± 0.019, Cu: 0.017 ± 0.013, Zn: 0.043 ± 0.035, Pb: 0.16 ± 0.256. The mean ± SD of GSH was 0.42 ± 0.35 nmol/mg protein, the mean ± SD of GSSG was 0.24 ± 0.20 nmol/mg protein, the mean ± SD concentrations of TBARS were 0.36 ± 0.21 nmol/mg protein, and the mean ± SD of B was 393.57 ± 405.14 pg/mL. Hg presented a significant negative relationship with corticosterone. Cd had a negative relationship with both GSH and GSSG; meanwhile, Zn showed a negative relationship with TBARS levels, could be a protective element against hepatic oxidative damage. Finally, B had negative relationship with oxidative damage. The connection found between Hg and the neuroendocrine stress response, as well as the correlations of Cd and Zn with oxidative damage and antioxidant activity should be studied further, given their toxicological importance and implications for the conservation of C. moreletii and other crocodilians.

The involvement of FATP1 regulating skeletal muscle fat deposition in stressed broilers was affected by fatty acid substrates

Fatty acid transport protein 1 (FATP1), plays a major role in the transport and uptake of fatty acids into cells. The effect of FATP1 on the regulation of skeletal muscle fat uptake and deposition in stressed broiler chickens was investigated both in vivo and in vitro, and the effect of different fatty acid substrates were also included. Dexamethasone (DEX), a synthetic glucocorticoid (GCs), was employed to induce a hyper glucocorticoid milieu and simulate stress. The in vivo results showed that DEX would increase the mRNA expression of FATP1 and fat deposition in muscle tissues (P < 0.05), the very-low-density lipoprotein (VLDL) and insulin (INS) levels were significantly increased in the plasma by DEX (P < 0.05), and the mRNA levels of the glucocorticoid receptor (GR), adiponectin receptor (ADPNR) and peroxisomal proliferator-activated receptor α (PPARα) in thigh were also up-regulated by DEX (P < 0.05). In vitro experiment, DEX did not affect the myoblast fat deposition and PPARα and FATP1 expressions without the external fatty acid (P > 0.05). Under PA pre-treatment, both myoblast fatty acid uptake and fat deposition were promoted by DEX treatment (P < 0.05), and the effects of DEX on the gene expressions of GR, ADPNR, PPARα and FATP1 were upregulated first and then downregulated as the dose of DEX increases; while under OA pre-treatment, the myoblast fat deposition was not affected by DEX (P > 0.05), the fatty acid uptake was decreased by DEX at 500 nM compared to control (P < 0.05). When GR and PPARα were, respectively inhibited by specific inhibitors RU486 and GW6471, the effects of DEX on fatty acid uptake were reversed for PA pre-treated myoblasts (P < 0.05) but not for OA pre-treated myoblasts (P > 0.05). These results indicate that FATP1 regulation by GCs was affected by fatty acid substrate - saturated fatty acids were favorable for fat uptake and deposition, while unsaturated fatty acids were not. GCs may affect the ADPNR-PPARα-FATP1 pathway by binding to its receptors, thus regulating the uptake of saturated fatty acids into myoblasts.

Kidney injury and oxidative damage alleviation by Zingiber officinale: pharmacokinetics and protective approach in a combined murine model of osteoporosis

Ginger (Zingiber officinale) is considered as a nutraceutical spice, which possesses several health promotion and benefits. This study was carried out to investigate the phyto-chemical composition, the antioxidant capacities, the drug-likeness, and pharmacokinetic properties of ginger extract on kidney injury-associated osteoporosis in rats. Phenolic and flavonoid contents were assessed by standard chemical analysis methods and HPLC. In vivo protective effect was based on the use of female rats to evaluate the effect on renal injury as a result of combined osteoporosis using biochemical markers, oxidative status, and histological analyses. Results showed that ZO contained appreciable amounts of phenolics and flavonoids and it exhibited high scavenging activity. Ovariectomy-associated corticotherapy induced severe renal injury marked by altered biochemical markers (creatinine, urea, and uric acid), reduced GFR, significative oxidative damage signs, and disrupted antioxidant status in the combined osteoporotic rats. The histopathological examination revealed structural modifications of kidney tissues. However, all these changes were reversed following the use of ZO. These results confirm the renoprotective and antioxidant potential of ginger against renal injuries in osteoporotic rats.

Physiological Changes in Chicken Embryos Inoculated with Drugs and Viruses Highlight the Need for More Standardization of this Animal Model

Several studies have been developed using the Gallus gallus embryo as an experimental model to study the toxicity of drugs and infections. Studies that seek to standardize the evaluated parameters are needed to better understand and identify the viability of CEs as an experimental model. Therefore, we sought to verify whether macroscopic, histopathological, blood count, metabolites and/or enzymes changes and oxidative stress in CE of different ages are specific to the model. To achieve this goal, in ovo assays were performed by injecting a virus (Gammacoronavirus) and two drugs (filgrastim and dexamethasone) that cause known changes in adult animals. Although congestion and inflammatory infiltrate were visible in the case of viral infections, the white blood cell count and inflammation biomarkers did not change. Filgrastim (FG) testing did not increase granulocytes as we expected. On the other hand, CE weight and red blood cell count were lower with dexamethasone (DX), whereas white blood cell count and biomarkers varied depended on the stage of CE development. Our work reinforces the importance of standardization and correct use of the model so that the results of infection, toxicity and pharmacokinetics are reproducible.

Changes in antioxidant enzyme levels following capture in juvenile American Alligators (Alligator mississippiensis) are tissue dependent

Many parameters used to investigate stress in vertebrates are temporally sensitive. The act of capture and sampling can influence them, hindering their functionality for evaluating the effects of stressors. Consequently, the investigation and subsequent incorporation of less time sensitive parameters are necessary to better evaluate stressors affecting vertebrates. In this study, we investigated how capture stress and handling associated with sampling influences antioxidant status in American Alligators (Alligator mississippiensis, Daudin, 1802; hereafter Alligator), long-lived, top-trophic carnivores found in the southeastern United States, by measuring levels of two antioxidant enzymes in destructive (brain and pancreas) and nondestructive (tail scutes) tissues: superoxide-dismutase-1 (SOD1) and glutathione peroxidase-1 (GPX1). Capture stress had no effect on pancreatic SOD1 and no effect on brain and pancreatic GPX1 (all p > 0.05). However, brain SOD1, scute SOD1, and scute GPX1 were all impacted by capture stress. These disparate results illustrate that the influence of capture stress on antioxidant enzymes in Alligators is tissue and marker dependent, necessitating further investigation. Our results provide a firm foundation to further investigate oxidative status in crocodilians.

Role of steroid growth promoter on growth performance and meat quality traits in broiler

Growth promoters are added with broiler feed to boost the overall feed efficiency and growth rate. The current study investigated the effect of dexamethasone (DEX)—a commonly used growth promoter—on the broiler growth rate, meat quality, and muscle biology. Four homogenous groups (20 chicks/group) of broiler one-day-old chicks were fed commercial broiler feed where the treatment groups received 3, 5, and 7 mg/kg of DEX with their diet for 28 d. Feed consumption and body weight were monitored on a daily basis. Muscle samples were collected on 7, 14, 21, and 28 d of the experiment to investigate meat quality and muscular biology. The residue of DEX in meat was detected using thin-layer chromatography. We observed that DEX had substantially decreased (P < 0.05) feed intake, feed efficiency, and overall weight gain in the broiler. While the weight of breast and thigh meat was decreased, the relative meat weight (meat/body weight) was increased significantly in chicks fed DEX. Simultaneously, body fat decreased while the percentage of fat increased significantly (P < 0.05) in the DEX groups. Contrariwise, DEX improved the investigated meat quality parameters with the potential threat of accumulation of DEX residue in the meat at a high dose (7 mg/kg). We also observed that DEX significantly increased the number of myofibers and decreased the cross-sectional area of myofibers. Based on these findings, we conclude that DEX reduces feed intake, feed efficiency, and growth rate, but might improve meat quality with a potential risk of residual DEX accumulation if fed at a high dose.

Feather pulp: a novel substrate useful for proton nuclear magnetic resonance spectroscopy metabolomics and biomarker discovery

Noninvasive biomarkers of stress that are predictive of poultry health are needed. Feather pulp is highly vascularized and represents a potential source of biomarkers that has not been extensively explored. We investigated the feasibility and use of feather pulp for novel biomarker discovery using ¹H-Nuclear Magnetic Resonance Spectroscopy (NMR)-based metabolomics. To this end, high quality NMR metabolomic spectra were obtained from chicken feather pulp extracted using either ultrafiltration (UF) or Bligh-Dyer methanol-chloroform (BD) methods. In total, 121 and 160 metabolites were identified using the UF and BD extraction methods, respectively, with 71 of these common to both methods. The metabolome of feather pulp differed in broiler breeders that were 1-, 23-, and 45-wk-of-age. Moreover, feather pulp was more difficult to obtain from older birds, indicating that age must be considered when targeting feather pulp as a source of biomarkers. The metabolomic profile of feather pulp obtained from 12-day-old broilers administered corticosterone differed from control birds, indicating that the metabolome of feather pulp was sensitive to induced physiological stress. A comparative examination of feather pulp and serum in broilers revealed that the feather pulp metabolome differed from that of serum but provided more information. The study findings show that metabolite biomarkers in chicken feather pulp may allow producers to effectively monitor stress, and to objectively develop and evaluate on-farm mitigations, including practices that reduce stress and enhance bird health.

Effects of genetic selection on activity of corticotropic and thyrotropic axes in modern broiler chickens

Commercial selection for meat-type (broiler) chickens has produced economically valuable birds with fast growth rates, enhanced muscle mass, and highly efficient feed utilization. The physiological changes that account for this improvement and unintended consequences associated with them remain largely unexplored, despite their potential to guide further advancements in broiler production efficiency. To identify effects of genetic selection on hormonal signaling in the adrenocorticotropic and thyrotropic axes, gene expression in muscle and liver and post-hatch circulating hormone concentrations were measured in legacy [Athens Canadian Random Bred (ACRB)] and modern (Ross 308) male broilers between embryonic days (e) 10 and e18 and post-hatch days (d) 10 and d40. No interactive effects or main effects of line were observed for adrenocorticotropic gene expression during either developmental period, although age effects appeared for corticosteroid-binding globulin in liver during embryogenesis and post-hatch and glucocorticoid receptor in both tissues post-hatch. There was a main line effect for circulating corticosterone, with levels in ACRB greater than those in Ross. Several thyrotropic genes exhibited line-by-age interactions during embryonic or post-hatch development. In liver, embryonic expression of thyroid hormone receptor beta was greater in ACRB on e12, and deiodinase 3 (DIO3) levels were greater in Ross on e14 and e16. In juvenile liver, deiodinase 2 (DIO2) expression was greater in ACRB on d10 but greater in Ross on d20, while DIO3 was higher in ACRB on d30 and d40. Levels of thyroid hormone receptor alpha mRNA exhibited a main line effect, with levels greater in ACRB juvenile breast muscle. Several thyrotropic genes exhibited main age effects, including DIO2 and DIO3 in embryonic breast muscle, thyroid hormone receptor alpha and thyroid hormone receptor beta in post-hatch liver, and DIO2 in post-hatch breast muscle. Circulating triiodothyronine displayed a main line effect, with levels in Ross significantly reduced as compared to ACRB. These findings suggest that in modern broilers, a decrease in levels of hormones that control basal metabolism triiodothyronine and the stress response circulating corticosterone, as well as altered expression of genes regulating thyroid hormone activity, could contribute to lower heat production, reduced stress response, and altered nutrient partitioning, leading to more efficient feed utilization and faster, more productive growth.

Effect of stocking density and vitamin E or zinc supplementation on growth, physiology, gene expression, and economic efficiency of growing broiler chicks

A total of 636 1-day-old male Cobb chicks were randomly assigned to seven treatments. The chicks were offered feed and water ad libitum throughout the experimental period. The first three groups included different stocking densities of broiler birds (low stocking density, LSD: 23 kg/m²; medium stocking density, MSD: 34 kg birds/m²; and high stocking density HSD: 39 kg birds/m²). The LSD group was considered a control group. The other four groups included MSD or HSD broiler birds supplemented with either Vit E (100 mg/kg DM diet; MSDVE and HSDVE) or Zn (100 mg/kg DM diet; MSDZn and HSDZn) in their basal diet. The main findings indicated that HSD and MSD negatively affected (p < 0.05) all variables under investigation compared with LSD. Compared with LSD, broiler birds in the MSD and HSD groups had lower body weights and higher feed conversion ratios, higher concentrations of blood plasma hormones (triiodothyronine thyroxine and corticosterone), and downregulated expression levels of hepatic growth hormone and insulin-like growth factor-l. In addition, broiler birds stocked at medium or high densities resulted in less economic return and profit. Vit E or Zn supplementation to broiler birds stocked at medium or high densities significantly reversed all adverse effects of HSD (> 23 kg/m²) on growth performance, hormones, and gene expression. It could be recommended that adding Zn at a level of 100 mg/kg per DM diet allows increasing the stocking density of broiler birds from 23 kg/m² to 34 birds/m² while maintaining the birds, welfare and economic profit.

Effects of Dietary Brown Rice on the Growth Performance, Systemic Oxidative Status, and Splenic Inflammatory Responses of Broiler Chickens under Chronic Heat Stress

The aim of this study was to evaluate the effects of dietary brown rice on the growth performance, systemic oxidative status, and splenic inflammatory responses of broiler chickens under both thermo-neutral and chronic heat stress conditions. Forty 12-day-old male broiler chickens (ROSS 308) were randomly assigned to two groups and fed either a control diet (corn-based) or a brown rice-based diet. After seven days (19 days old), both groups were randomly divided into two sub-groups (n=10), one of which was exposed to heat stress (33°C for 14 days), while the other was maintained at 24°C. Heat exposure reduced the body weight gain and feed intake (p<0.01) of both groups. In terms of oxidative plasma states, heat exposure reduced the glutathione peroxidase activity and increased the ceruloplasmin content, while the 2-thiobarbituric acid reactive substance and reduced glutathione levels were not affected adversely. Heat exposure activated the immune responses, as evidenced by increased plasma immunoglobin levels, and altered splenic immune-related gene expressions including heat shock proteins, toll-like receptor 4, and interleukin-12. Under both thermo-neutral and heat stress conditions, dietary brown rice improved the growth performance, decreased the immunoglobulin levels, and down-regulated the expression of splenic immune-related genes of broilers, although their systemic oxidative status was not affected. Dietary brown rice should be considered as a valuable component of broiler chicken feeds subjected to both thermo-neutral and heat stress conditions. The positive effects of brown rice on bird performance may be associated with the modulation of the immune responses, as reflected by the decreased production of immunoglobulins and altered splenic immune-related gene expression.

Effect of temperature manipulation during incubation on body weight, plasma parameters, muscle histology, and expression of myogenic genes in breast muscle of embryos and broiler chickens from two commercial strains

1. This study evaluated the effect of a higher incubation temperature on body weight, plasma profile, histology and expression of myogenin (MYOG), insulin-like growth factor-I (IGF-I) and vascular endothelial growth factor A (VEGFA) genes in breast muscle of embryos and broilers from two commercial strains.2. A total of 784 eggs from Ross 308 and Cobb 500 broiler breeder flocks were used. Half of the eggs per strain were incubated at control temperature (37.8°C), whereas the other half were exposed to heat treatment (HT) of 38.8°C between embryonic day (ED) 10 and 14, for 6 h/day. Embryos and chicks were sampled on ED 19 and at hatch. A total of 480, one-day-old chicks per strain and incubation temperature were reared up to 42 d post-hatch.3. The HT increased hatch weight of Ross chicks and 42-d body weight of broilers from both strains. Lower plasma triacylglycerol levels were measured for HT embryos and broilers on ED 19 and 42 d post-hatch, respectively. HT reduced plasma T₃ levels in Ross embryos and broilers for the same periods. Hepatic TBARS concentrations were elevated by HT compared to the control incubation.4. The HT reduced breast muscle VEGFA gene expression of Cobb embryos on ED 19, whereas expression was stimulated in day-old chicks. At 42 d post-hatch, fibre area was increased by HT regardless of strain. Compared to the control incubation, HT increased the breast yield of Ross broilers and leg yield of Cobb. Ross-HT broilers had a higher pH at 24 h after slaughter and better water holding capacity than Cobb-HT broilers.5. These results suggested that HT increased body weight, fibre area, IGF-I gene expression and lowered plasma triacylglycerol levels of broiler chickens from both strains at 42 d. However, HT influenced the expression of VEGF-A and MYOG genes and meat quality differently between the broiler strains.

Effects of Scopoletin Supplementation and Stocking Density on Growth Performance, Antioxidant Activity, and Meat Quality of Korean Native Broiler Chickens

Stocking density stress is one of the most common management stressors in the poultry industry. The present study was designed to investigate the effect of dietary Sophora koreensis (SK; 0 and 20 mg/kg diet) and stocking density (SD; 14 and 16 chickens/m²) on the antioxidant status, meat quality, and growth performance of native Korean chickens. There was a lower concentration of malondialdehyde (MDA) and a higher concentration of catalase, superoxide dismutase (SOD), and total antioxidant capacity in the serum and leg muscle with the supplementation of SK. The concentration of MDA was increased and concentrations of SOD were decreased in the leg muscle of chickens in low SD treatments. The SK-supplemented treatments showed an increased 3-ethylbenzothiazoline-6-sulfonate-reducing activity of leg muscles. The higher water holding capacity of breast muscle and a lower cooking loss and pH were shown in the SK-supplemented treatments. The addition of dietary SK resulted in a greater body weight gain and greater spleen and bursa Fabricius weight, as well as lower feed intake and abdominal fat. The low SD and supplementation of SK increased the concentrations of cholesterol. The concentration of glucose was increased in the low SD treatment. Corticosterone level was decreased in the SK-supplemented and low SD treatments. In conclusion, SK supplementation reduced the oxidative stress and increased meat quality and antioxidant status of chickens apart from the SD stress.

Glucocorticoid Receptor Alpha Targets SLC2A4 to Regulate Protein Synthesis and Breakdown in Porcine Skeletal Muscle Cells

In the presence of stress, the hypothalamic-pituitary-adrenal (HPA) axis activity can be enhanced to promote the secretion of a large amount of glucocorticoids (GCs), which play an important role in the anabolism and catabolism of skeletal muscle. When the endogenous and exogenous glucocorticoids are deficient or excessive, the body will produce stress-related resistance and change the protein metabolism. In this study, we investigated the effect of GC receptor GRα on protein breakdown and synthesis in porcine skeletal muscle cells (PSCs). Overexpression of GRα was shown to increase the expression of protein degradation-related genes, while knockdown of GRα decreased the expression of these genes. Additionally, we found a relationship between GRα and solute carrier family 2 member 4 (SLC2A4), SLC2A4 expression level increases when stress occurs, suggesting that increasing SLC2A4 expression can partially alleviate stress-induced damage, and we found that there is a combination between them via luciferase reporter assays, which still needs to be confirmed in further studies.

Identification and expression analysis of MicroRNAs in chicken spleen in a corticosterone-induced stress model

For investigating the effects of stress on the immune response of chickens, we established a corticosterone (CORT)-induced stress model by exogenous intake of CORT. Control group was fed with a basal diet and the stress model group was fed with a 30 mg/Kg CORT-treated diet in ad libitum conditions for 7 days. Then, we used RNA-seq technology to identify the expression pattern of miRNAs, target genes, and relevant pathways in chicken spleen. Results showed that 71 differentially expressed miRNAs (DEMs) were determined, 9 of which were significantly differentially expressed miRNAs (SDEMs), and 241 target genes of DEMs were predicted. GO annotation and KEGG pathway analysis were carried out to understand the role of the DEMs. Out of 287 significantly enriched GO terms, 37 were stress- or immune-related, such as response to light stimulus, detection of oxidative stress, and immune response in mucosal-associated lymphoid tissue. Out of 85 KEGG pathways, 8 were related to stress or immunity, such as cytokine-cytokine receptor interaction, JAK-STAT signaling pathway, and RLR signaling pathway. We then constructed the interaction networks between target genes from immune-related pathways and their DEMs. The analysis results suggested that some DEMs (gga-miR-17 family, gga-miR-15/16 family, gga-miR-2954 and gga-miR-34b-5p) and target genes (SIKE1, CX3CL1, IL11Ra, PIGR, and CDKN1A) were core miRNAs and genes. This study revealed the dynamic miRNA transcriptome, target genes and related pathways in chicken spleen under CORT-induced stress model, which provided a basis for studying the molecular mechanism of stress affecting immune function.

Synergetic effects of immune challenge and stress depress cortisol, inflammatory response and antioxidant activity in fish-eating Myotis

One of the most common tools in conservation physiology is the assessment of environmental stress via glucocorticoid measurement. However, little is known of its relationship with other stress-related biomarkers, and how the incidence of an immune challenge during long-term stress could affect an individual's overall stress response. We investigated here the relationship between basal and post-acute stress fecal cortisol metabolite (FC) with different antioxidant enzymes, oxidative damage and immune parameters in the fish-eating bat, Myotis vivesi We found that in both basal and post-stress conditions, FC was highly related with a number of antioxidant enzymes and immune parameters, but not to oxidative damage. We also assessed changes of FC through the seasons. Basal FC samples and stress reactivity after short-duration stress displayed similar levels during summer, autumn and early winter, but lower concentrations in late winter. Stress reactivity after long-duration stress was greater in summer and early winter. Finally, we tested the effect of a simultaneous exposure to a long, strong stress stimulus with an immune response stimulation by administrating adrenocorticotropic hormone (ACTH) and phytohemagglutinin (PHA) after 42 h. Results showed that when both stimuli were administrated, FC concentrations, inflammation and some antioxidant activity were lowered in comparison with the control and individual administration of the challenges. Our findings support the idea that animals maintain constant basal glucocorticoid levels when living in challenging environments, but response to acute stress differs seasonally and immune defense mechanisms and stress responses might be compromised when confronted with multiple challenges.

Rule of UA on Cardiac Myocytes Uric Acid Differently Influence the Oxidative Damage Induced by Acute Exposure of High Level of Glucose in Chicken Cardiac Myocytes

Background: Uric acid (UA) is a potent scavenger of oxidants in mammalian and avian species. In humans, hyperglycemia with simultaneous hyperuricemia may exert additional damage to the cardiovascular system. Chickens naturally have hyperglycemia (10.1–11.0 mmol/L) and hyperuricemia (100–900 μmol/L), which makes them an interesting model.

Methods: The aim of this study was to investigate the effects of UA on the oxidative damage induced by acute exposure of high level of glucose in chicken cardiac myocytes.

Results: Cell viability and the concentrations of thiobarbituric acid reactive substance (TBARS) were decreased by glucose treatment in a dose- and time-dependent manner. After acute exposure to high level of glucose (300 mM), a moderate level of UA (300 μM) increased cell viability and reduced TBARS and glutathione (GSH) content. Compared to the control or to independent high glucose (300 mM) or UA (1,200 μM) treatment, the concurrent treatment of high glucose and high UA significantly increased the TBARS, protein carbonyl contents, and ROS concentration, whereas it decreased the cell viability, superoxide dismutase (SOD) activity, and GSH content. In the presence of high glucose and UA, the nucleic protein expression of nuclear factor erythroid 2-related factor 2 (Nrf2) was decreased and the mRNA levels of the genes cat, sod1, sod2, gss, and gclc were downregulated.

Conclusion: In conclusion, acute exposure of high level of glucose induced oxidative damage in the cardiac myocytes of chicken. The present result suggests that an adequate level of uric acid is helpful in alleviating the acute oxidative damage that is induced by high glucose, whereas the inhibition of the Nrf2 pathway by a high level of uric acid may render the cardiac myocytes more vulnerable to suffering from oxidative damage.

Effects of plant-derived isoquinoline alkaloids on growth performance and intestinal function of broiler chickens under heat stress

Broiler chickens reared under heat stress (HS) conditions have decreased growth performance and show metabolic and immunologic alterations. This study aimed to evaluate the effect of supplementation with a standardized blend of plant-derived isoquinoline alkaloids (IQ) on the growth performance, protein catabolism, intestinal barrier function, and inflammatory status of HS-treated chickens. Three hundred sixty 0-day-old Ross 308 male broiler chickens were randomly distributed into 2 treatment groups: control diet (no additives) or diet supplemented with 100 ppm IQ. At day 14, the chicks in each diet group were further divided into 2 groups, each of which was reared under thermoneutral (TN) (22.4°C) or constant HS (33.0°C) conditions until day 42. Each group consisted of 6 replicates with 15 birds per replicate, and chickens were provided ad libitum access to water and feed. During days 15–21, the body weight gain (BWG) and feed intake (FI) were significantly lower in the HS treatment group than in the TN group, and feed conversion ratio was higher (P < 0.05); these factors were not alleviated by IQ supplementation. During days 22–42, the final BW, BWG, and FI of the HS birds were better among those administered IQ than those that were not (P < 0.05). HS treatment increased plasma lipid peroxide, corticosterone, and uric acid concentrations as well as serum fluorescein isothiocyanate–dextran, a marker of intestinal barrier function, and decreased plasma total protein content (P < 0.05). These changes were not observed in the IQ group, suggesting that IQ supplementation improved oxidative damage, protein catabolism, and intestinal barrier function of chickens under HS. Isoquinoline alkaloid supplementation inhibited the expression of intestinal inflammatory factors, IL-6, tumor necrosis factor–like factor 1A, and inducible nitric oxide synthase under HS treatment (P < 0.05). These results suggest that IQ supplementation can improve the growth performance of broiler chickens under HS conditions, which may be associated with amelioration of oxidative damage, protein catabolism, intestinal barrier function, and inflammation.

Spontaneous intake of essential oils after a negative postnatal experience has long-term effects on blood transcriptome in chickens

Chicks subjected to early stressful factors could develop long-lasting effects on their performances, welfare and health. Free access to essential oils (EO) in poultry farming could mitigate these effects and potentially reduce use of antimicrobial drugs. This study on chicken analyzed long-lasting effects of post-hatch adverse conditions (Delayed group), and the impact of EO intake on blood physiological parameters and transcriptome. Half of the Control and Delayed groups had free access to EO, while the other half had only water for the first 13 days post-hatching. Blood analyses of metabolites, inflammation and oxidative stress biomarkers, and mRNA expression showed sex differences. Long-lasting effects of postnatal experience and EO intake persisted in blood transcriptome at D34. The early adverse conditions modified 68 genes in males and 83 genes in females. In Delayed males six transcription factors were over-represented (NFE2L2, MEF2A, FOXI1, Foxd3, Sox2 and TEAD1). In females only one factor was over-represented (PLAG1) and four under-represented (NFIL3, Foxd3, ESR2 and TAL1::TCF3). The genes showing modified expression are involved in oxidative stress, growth, bone metabolism and reproduction. Remarkably, spontaneous EO intake restored the expression levels of some genes affected by the postnatal adverse conditions suggesting a mitigating effect of EO intake.

Effects of dietary corticosterone on the central adenosine monophosphate-activated protein kinase (AMPK) signaling pathway in broiler chickens

Glucocorticoids (GCs) induce the activation of the central adenosine 5'-monophosphate-activated protein kinase (AMPK) signaling pathway in birds. In this study, we aimed to investigate the effects of corticosterone (CORT) supplemented in diet on the central AMPK signaling pathway in broilers. The average daily gain was reduced by CORT treatment, and the average daily feed intake remained unchanged. Plasma glucose, triglyceride, total cholesterol, and CORT contents were increased by CORT administration. In addition, CORT treatment decreased the relative weights of heart, spleen, and bursa and increased the relative weights of liver and abdominal fat. The glycogen contents in the liver and breast muscle were higher in the chicks treated with CORT. CORT treatment upregulated the gene expression of mammalian target of rapamycin, glucocorticoid receptor, AMPKα2, neuropeptide Y(NPY), liver kinase B1 (LKB1), AMPKα1, and fatty acid synthase in the hypothalamus. Moreover, CORT treatment increased the protein levels of acetyl-coenzyme A carboxylase (ACC) phosphorylation and total AMPK and phosphorylated AMPK in the hypothalamus. Hence, CORT administration in the diet activated the LKB1-AMPK-NPY/ACC signaling pathway in the hypothalamus of broiler.

Effects of chronic heat stress and ammonia concentration on blood parameters of laying hens

Less evidence is available currently to reveal whether the immune system and productivity of laying hens change under long periods of ammonia exposure in hot climate. The present study was conducted to determine the effects of chronic exposure to high temperature and ammonia concentrations on health, immune response, and reproductive hormones of commercial laying hens. A total of five hundred and seventy six 20-week-old laying hens (Hy-Line Brown) were used in this study. Birds were housed in cages (4 birds per cage) and received 16-wk treatments in 6 artificial environmental chambers. Hens were allocated to 6 treatments: treatment 1 (T1, 20°C, ≤5 ppm, control group), treatment 2 (T2, 20°C, 20 ppm), treatment 3 (T3, 20°C, 45 ppm), treatment 4 (T4, 35°C, ≤5 ppm), treatment 5 (T5, 35°C, 20 ppm), and treatment 6 (T6, 35°C, 45 ppm). Blood samples were collected at 22, 26, 30, 34, and 38 wk of age and plasma IgG, IgM, IgA, corticosterone (CORT), total antioxidant capacity (T-AOC), luteinizing hormone (LH), estradiol (E2), and follicular stimulating hormone (FSH) were measured. The results of this study showed that high ambient temperature and excessive ammonia increased the concentration of IgG but decreased the concentration of IgA, T-AOC, LH, FSH, and E2 of hens compared with those of the control birds. From the age of 34 wk, significantly increased concentrations of IgG were observed in hens exposed to moderate and high levels of ammonia. CORT level showed marked differences between the treatments only at the age of 26 wk. In addition, LH and E2 of hens demonstrated significant differences among the treatments in the middle and later stages of the experiment, while FSH levels of the control birds were significantly higher than the others at the age of 38 wk. Excessive ammonia in high temperature was a physiological stress factor that had a negative effect, which inhibited immune function and impacted the reproductive hormones.

Evaluation of copper nanoparticles and copper sulfate effect on immune status, behavior, and productive performance of broilers

Objective:

This study was conducted to compare between the nanoparticles of copper (Cu-NP) and copper sulfate (CuSO₄) effect on immunity, pro-inflammatory cytokine, oxidant/antioxidant balance, different behavioral patterns, growth rate, and weight gain by adding them in drinking water of broilers.

Materials and Methods:

One hundred and fifty broiler chicks of 1-day-old were randomly divided into three groups: the first group was the control, the second group received CuSO₄ in drinking water (10 mg/l), and the third group received Cu-NP in drinking water (10 mg/l) with replicates (n = 25) for 5 weeks of age. Blood samples collected for estimating immunoglobulins (A, G, and M), superoxide dismutase, pro-inflammatory (IL-6), erythrocyte sedimentation rate, heterophil/lymphocyte (H/L) ratio, malondialdehyde (MDA), corticosterone hormone, and lymphoid organs index weight. Moreover, behavioral observations were undertaken from the 2nd week until the 5th week of age for measuring different behavioral patterns (feeding, drinking, crouching, body care, and comfort behaviors). Chicks were individually weighed weekly (gm); also, the weight gain, the intake of food, and the ratio of feed conversion were calculated.

Results:

Cu-NP administration has improved the blood profile, lymphoid organs index weight in Cu-NP treated broilers in relation to control and CuSO₄ treated groups. Conversely, erythrocyte sedimentation rate, H/L ratio, MDA, and corticosterone hormone were reduced by Cu-NP treatment. Moreover, Cu-NP has a positive effect on all behavioral patterns more than other groups which significantly reflect on the weight of the body, gaining of weight, and the intake of food in the Cu-NP treated group of birds.

Conclusion:

The findings in this study stated that when the drinking water of broilers was supplemented with Cu-NP, there might be an improvement in the immunity, behavior, and productive performance more efficiently than CuSO₄.

Recovery from repeated stressors: Physiology and behavior are affected on different timescales in house sparrows

For decades, researchers across disciplines have been captivated by classifying, diagnosing, and avoiding the consequences of chronic stress. Despite the vast body of literature this has generated, we still lack the ability to predict which individuals or populations may be susceptible to stress-related pathologies. One critical unanswered question is whether the impacts of repeated stressors are reversible, or if instead they permanently alter an individual. In this study, we exposed house sparrows (Passer domesticus) to 6 days of random, repeated stressors, permitted them 0, 1, 3, or 6 days to recover, and then assessed changes in their body mass, hypothalamic-pituitaryadrenal (HPA) axis (baseline, stress-induced corticosterone, negative feedback strength), immune function, uric acid concentrations, DNA damage levels, and perch hopping activity. Body mass did not vary between groups after recovery. We found that the HPA axis and perch hopping were not significantly impacted by the 6 days of stressors, but that uric acid and DNA damage increased. Short recovery periods tended to negatively affect the HPA axis and reduced uric acid levels, but these were reversed with longer recovery periods. Following the recovery periods, the birds experienced an additional 6 days of random stressors and their responses were assessed again. All recovery times reduced perch hopping and immune function, but paradoxically, DNA damage was highest in the birds that had the longest amount of time to recover. These results show that recovery time affects responses to subsequent chronic stress in complex ways, and highlight the importance of multimodal, interdisciplinary approaches to studying stress physiology.

A Discovery of Relevant Hepatoprotective Effects and Underlying Mechanisms of Dietary Clostridium butyricum Against Corticosterone-Induced Liver Injury in Pekin Ducks

Clostridium butyricum (C. butyricum) can attenuate oxidative stress, inflammation, and hepatic fatty deposition in poultry, however, the underlying mechanisms for this in Pekin ducks remain unclear. This study evaluated these hepatoprotective effects and the underlying mechanisms in a corticosterone (CORT)-induced liver injury model in Pekin ducks fed a C. butyricum intervention diet. A total of 500 Pekin ducks were randomly divided into five groups: one group (CON group) was only provided with a basal diet, three groups were provided a basal diet with 200 mg/kg (LCB group), 400 mg/kg (MCB group), or 600 mg/kg (HCB group) C. butyricum, respectively, and one group was provided a basal diet with 150 mg/kg aureomycin (ANT group) for 42 d. At 37 days-old, all ducks received daily intraperitoneal injections of CORT for five days to establish a liver injury model. C. butyricum intervention alleviated liver injury by decreasing the liver organ indices, hepatic steatosis and hepatocyte necrosis, and improving liver function, antioxidant capacity, and inflammatory factors. Hepatic RNA-seq revealed 365 differentially expressed genes (DEGs) between the MCB and CON groups, with 229 up- and 136 down-regulated DEGs in the MCB group. Between the MCB and ANT groups, 407 DEGs were identified, including 299 up- and 108 down-regulated genes in MCB group. Some DEGs in the MCB group related to oxidative stress and inflammatory responses such as Sod3, Tlr2a/b, and Il10, which were up-regulated, while Apoa1, Cyp7a1, Acsl1/5, Fasn, Ppar-γ, and Scd, which are involved in lipid metabolism, were down-regulated, indicating that these genes were responsive to dietary C. butyricum for the alleviation of corticosterone-induced hepatic injury. Toll-like receptor signaling, PI3K-Akt signaling pathway, cytokine-cytokine receptor interaction, peroxisome proliferator-activated receptor (PPAR) signaling pathway, adipocytokine and glycerophospholipid metabolism signaling pathway were significantly enriched in the MCB group. These findings indicate that C. butyricum intervention can protect Pekin ducks from corticosterone-induced liver injury by the modulation of immunoregulatory- and lipid metabolism-related genes and pathways.

Effects of Cassia abbreviata extract and stocking density on growth performance, oxidative stress and liver function of indigenous chickens

The objective of the study was to investigate the effect of stocking density and extract from Cassia abbreviata stem bark on growth performance, oxidative stress and liver function of indigenous chickens. A total of 420 1-day-old female Ovambo chicks with initial body weight of 0.32 ± 0.036 kg (mean ± SD) were used in the study. Birds, which were cooped in stocking densities consisting 5, 10 and 20 birds/m², were orally administered with 0, 50, 200 and 500 mg/kg of extract from C. abbreviata stem bark. Each stocking density per dosage level of extract was repeated three times. Average feed intake was lower (P < 0.05) in birds housed at 20 birds/m². There was a low (P < 0.05) average daily gain in birds housed at 20 birds/m². Malondialdehyde was higher (P < 0.05) in 20 birds/m². Average daily gain was high (P < 0.05) in birds administered with 0 and 50 mg/kg of C. abbreviata stem bark extract. Birds administered with 0 and 50 mg/kg of C. abbreviata stem bark extract had a higher (P < 0.05) gain to feed ratio. Birds dosed with 500 and 200 mg/kg had high (P < 0.05) superoxide dismutase activity. Birds administered with 500 mg/kg of C. abbreviata stem bark extract had the lowest (P < 0.05) malondialdehyde. A 500 mg/kg of stem bark extract from C. abbreviata resulted to higher (P < 0.05) activities of aspartate transaminase and alanine transaminase. There was a significant (P < 0.05) interaction between the stocking density and C. abbreviata extract on catalase activity. High stocking density of 20 birds/m² reduced growth performance and induced stress in indigenous chickens. High dosage of level 500 mg/kg of stem bark extract of C. abbreviata reduced oxidative stress while depressing growth performance and causing hepatotoxicity in birds. There is a need to precisely determine the maximum dosage level of C. abbreviata extract to improve growth performance and reduce oxidative stress and hepatotoxicity in indigenous chickens in high stocking density.

Effect of temperature on antioxidant defense and innate immunity in Brandt's voles

Ambient temperature is an important factor influencing many physiological processes, including antioxidant defense and immunity. In the present study, we tested the hypothesis that antioxidant defense and immunity are suppressed by high and low temperature treatment in Brandt’s voles (Lasiopodomys brandtii). Thirty male voles were randomly assigned into different temperature groups (4, 23, and 32 °C, n=10 for each group), with the treatment course lasting for 27 d. Results showed that low temperature increased gross energy intake (GEI) and liver, heart, and kidney mass, but decreased body fat mass and dry carcass mass. With the decline in temperature, hydrogen peroxide (H₂O₂) concentration, which is indicative of reactive oxygen species (ROS) levels, increased in the liver, decreased in the heart, and was unchanged in the kidney, testis, and small intestine. Lipid peroxidation indicated by malonaldehyde (MDA) content in the liver, heart, kidney, testis, and small intestine did not differ among groups, implying that high and low temperature did not cause oxidative damage. Similarly, superoxide dismutase (SOD) and catalase (CAT) activities and total antioxidant capacity (T-AOC) in the five tissues did not respond to low or high temperature, except for elevation of CAT activity in the testis upon cold exposure. Bacteria killing capacity, which is indicative of innate immunity, was nearly suppressed in the 4 °C group in contrast to the 23 °C group, whereas spleen mass and white blood cells were unaffected by temperature treatment. The levels of testosterone, but not corticosterone, were influenced by temperature treatment, though neither were correlated with innate immunity, H₂O₂ and MDA levels, or SOD, CAT, and T-AOC activity in any detected tissues. Overall, these results showed that temperature had different influences on oxidative stress, antioxidant enzymes, and immunity, which depended on the tissues and parameters tested. Up-regulation or maintenance of antioxidant defense might be an important mechanism for voles to survive highly variable environmental temperatures.

Effects of glucocorticoids on lipid metabolism and AMPK in broiler chickens' liver

Adenosine monophosphate-activated protein kinase (AMPK) plays a pivotal role in the regulation of carbohydrate, lipid, and protein metabolism in animals. In this study, we examined whether any cross talk exists between glucocorticoids and AMPK in the regulation of the liver bile acid biosynthesis pathway. Dexamethasone treatment decreased the growth performance of broiler chickens. The liver mRNA levels of fatty acid transport protein (FATP-1), farnesoid X receptor (FXR), AMPK alpha 1 subunit (AMPKα1), and glucocorticoid receptor were significantly upregulated in DEX-treated broilers; the gene expression of liver cholesterol 7 alpha-hydroxylase (CYP7A1) was significantly downregulated. The protein level of liver CYP7A1 was significantly decreased by DEX treatment at both 24 and 72 h, while the protein level of p-AMPK/ t-AMPK stayed unchanged. In the in vitro cultured hepatocytes, compound C pretreatment blocked the increase in CYP7A1 protein level by DEX and significantly suppressed FATP-1, SREBP-1c, FXR, and CYP7A1 gene expression stimulated by DEX. Compound C treatment significantly reduces the protein level of p-AMPK, and the combination of compound C and DEX significantly reduces the protein level of t-AMPK. Thus, glucocorticoids affected liver AMPK and the bile acid synthesis signal pathway, and AMPK might be involved in the glucocorticoid effect of liver bile acid synthesis.

Tocotrienol-rich fraction supplementation prevents foetal loss in females mated with corticosterone-treated male Sprague-Dawley rats

This study examined whether tocotrienol supplementation to corticosterone-treated male rats could prevent foetal loss in females upon their mating. Epididymides of adult male Sprague-Dawley (SD) rats with proven fertility were surgically separated at the testis-caput junction. Twenty-four hours post-surgery, these animals received for 7 days either: tocopherol-stripped corn oil (Control), corticosterone 25 mg/kg s.c. (CORT), CORT 25 mg/kg s.c. and tocotrienol-rich fraction (TRF) 100 mg/kg orally (CORT + TRF) or TRF 100 mg/kg orally (TRF). On day 8, males were cohabited with proestrus females. A spermatozoa-positive vaginal smear indicated pregnancy. Males were euthanised for analysis of testosterone and antioxidant activities. Reproductive organs were weighed. On day 8 of pregnancy, females were laparotomised to count the number of implantation sites. Pregnancy was continued until term. Number of pups delivered and their weights were determined. Data were analysed using ANOVA. Malondialdehyde levels were significantly lower in CORT + TRF group compared with CORT group. Enzymatic antioxidant activities, testosterone level and reproductive organ weights were significantly higher in CORT + TRF group compared with CORT group. Number of implantation sites and live pups delivered, and their birth weights from females mated with CORT + TRF males were significantly higher compared to CORT group. Therefore, TRF prevents foetal loss in females mated with CORT + TRF-treated males.

DNA damage as an indicator of chronic stress: Correlations with corticosterone and uric acid

Corticosterone does not change in consistent ways across species and contexts, making it challenging to use as an indicator of chronic stress. We assessed DNA damage as a potential metric that could be a more integrative stress measurement with direct links to health. We captured free-living house sparrows, took an immediate blood sample, and transferred them to the laboratory, exposing them to the chronic stress of captivity. Biweekly blood and weight samples were then taken for 4 weeks. We immediately assessed DNA damage in red blood cells using the comet assay and later quantified corticosterone. Uric acid was analyzed in a separate group of birds. We found that birds initially lost, but began to regain weight over the course of captivity. DNA damage peaked within the first 10 days of captivity, and mostly remained elevated. However, the cellular distribution of damage changed considerably over time; most cells showed low levels of damage early, a bimodal distribution of high and low DNA damage during the peak of damage, and a wide unimodal distribution of damage at the end of the 4 weeks. Furthermore, corticosterone increased and remained elevated and uric acid decreased and remained depleted over the same period. Although both a molecular (DNA damage) and an endocrine (corticosterone) marker showed similar response profiles over the 4 weeks, they were not correlated, suggesting they reflect different aspects of the underlying physiology. These data provide convincing preliminary evidence that DNA damage has potential to be an additional indicator of chronic stress.

Forsythia suspensa extract protects broilers against breast muscle oxidative injury induced by corticosterone mimicked pre-slaughter acute stress

Broilers were used to determine the protective effects of Forsythia suspensa extract (FSE) against breast muscle oxidative injury induced by corticosterone (CS) mimicking pre-slaughter acute stress. A total of 144 male Arbor Acre broilers was randomly allotted to one of 4 treatments in a 2 × 2 factorial arrangement that included FSE supplementation (0 or 100 mg/kg) and subcutaneous injection of CS (0 or 4 mg/kg) at 3 h before slaughter. Corticosterone increased live BW loss, and the adverse effect was attenuated by FSE in broilers subjected to CS (P < 0.05). Serum levels of CS, uric acid, and glucose were increased, and postmortem breast muscle pH values at 45 min and 24 h were decreased for CS-challenged broilers (P < 0.05). Corticosterone increased lightness and yellowness values and decreased redness of breast muscle (P < 0.05), and FSE decreased yellowness and increased redness of breast muscle (P < 0.05). Drip loss was increased by CS for birds supplemented without FSE (P < 0.05) and decreased by FSE for birds under CS challenge (P < 0.05). Corticosterone increased monounsaturated fatty acid (FA) and decreased polyunsaturated FA in breast muscle (P < 0.05), and saturated FA was decreased and polyunsaturated FA was increased by FSE (P < 0.05). Malondialdehyde and carbonyl contents in breast muscle were increased by CS and decreased by FSE (P < 0.05). Inhibition of 1,1-diphenyl-2-picryl-hydrazyl was decreased by CS and increased by FSE (P < 0.05). The activities of total-antioxidant capacity, glutathione peroxidase, and superoxide dismutase in breast muscle were lower in birds subjected to CS (P < 0.05) and were greater in birds supplemented with FSE (P < 0.05). Collectively, live BW loss and breast muscle oxidative injury were increased by CS in broilers, and these stress-related adverse effects could be attenuated by FSE supplementation via enhanced scavenging ability of free radicals and antioxidant capacity. Therefore, FSE could protect broilers against breast muscle oxidative injury when acute stress happens.

Sex and species differences of stress markers in sympatric cheetahs and leopards in Namibia

Physiological stress markers may provide valuable insight for our understanding of costs of given life-history strategies or of wildlife health condition, most importantly in case of threatened species. In the last decade, there has been growing interest in the ecological relevance of cellular oxidative stress, which would provide complimentary information to that obtained by the classic analyses of glucocorticoid hormones. In this study, we analysed the sex and species variation of five blood-based markers of oxidative status, both molecular oxidative damage and antioxidant protection, in sympatric cheetahs (Acinonyx jubatus) and leopards (Panthera pardus) living on Namibian farmlands. Both these terrestrial carnivores are classified as vulnerable by the International Union for Conservation of Nature. We found that female cheetahs had significantly higher serum reactive oxygen metabolites of non-protein origin and lower glutathione peroxidase activity in whole blood than both male and female leopards and male cheetahs. We also found that cheetahs and leopards differed in the association between the two antioxidant enzymes glutathione peroxidase and superoxide dismutase. Correlations among oxidative status markers were stronger in female cheetahs than leopards or male cheetahs. Our results suggest that female cheetahs are more sensitive to local sources of stress. Our work did not corroborate the assumption that two species with different life histories consistently differ in key physiological traits.

Heat stress-induced renal damage in poultry and the protective effects of HSP60 and HSP47

The present study investigates the effects of heat stress on the kidney in broilers, based on previous findings which showed that heat stress caused cardiac damage in broilers. Further, the possible renoprotective role of aspirin and the heat shock proteins HSP60 and HSP47 was also investigated. The enzyme levels of urea and uric acid, which are indicators of renal damage, and lactate dehydrogenase, an indicator of oxidative damage, were measured in chickens that were only exposed to heat stress, chickens that were pretreated with aspirin before heat stress, and chickens that were only treated with aspirin. Further, histological examination of renal tissue from the three groups was also performed. Finally, expression of HSP60 and HSP47 was also examined. In the heat stress group, the enzyme measurements were indicative of renal dysfunction and oxidative damage, and the histological findings were indicative of renal ischemia and damage. Aspirin seemed to have a protective effect against the renal damage caused by the stress, based on the enzyme measurements and histopathological findings in the aspirin-treated group. The findings also indicate that aspirin may induce HSP60 and HSP47 expression in renal cells. Finally, the expression patterns of HSP60 and HSP47 indicated that they may play a renoprotective role, as their expression was higher in the aspirin-treated groups. In conclusion, the present findings show that heat stress causes renal damage in poultry and that aspirin may play a protective role against this damage via pathways that involve HSP60 and HSP47.

Physiological and behavioral responses of house sparrows to repeated stressors

Despite decades of research, we still lack a complete understanding of what factors influence the transition of the necessary and adaptive acute stress response to what has become known as chronic stress. This gap in knowledge has illuminated the necessity for studies that examine the thresholds between these two sides of the stress response. Here, we determine how repeated exposure to acute stressors influences physiological and behavioral responses. In this repeated measures study, house sparrows (Passer domesticus) were exposed to a chronic stress protocol. We took physiological and behavioral measurements before, during, and after the protocol. Blood samples were used to assess four aspects of hypothalamic-pituitary-adrenal (HPA) axis function: baseline corticosterone, stress-induced corticosterone, negative feedback, and the maximal capacity to secrete corticosterone. We also assessed bacterial killing capacity and changes in uric acid concentration. Neophobia trials were used to assess behavioral changes throughout the protocol. We found no significant changes in HPA axis regulation in any of the four aspects we tested. However, we found that uric acid concentrations and neophobia significantly decreased after only four days of the chronic stress protocol, while bacterial killing capacity did not decrease until after eight days of exposure. These results indicate that different components of the stress response can be impacted by chronic stress on different timescales. Our results further indicate the importance of assessing multiple aspects of both physiology and behavior in order to understand how exposure to chronic stress may influence ability to cope with future challenges.

Experimental increase in baseline corticosterone level reduces oxidative damage and enhances innate immune response

Glucocorticoid (GC) hormones are significant regulators of homeostasis. The physiological effects of GCs critically depend on the time of exposure (short vs. long) as well as on their circulating levels (baseline vs. stress-induced). Previous experiments, in which chronic and high elevation of GC levels was induced, indicate that GCs impair both the activity of the immune system and the oxidative balance. Nonetheless, our knowledge on how mildly elevated GC levels, a situation much more common in nature, might influence homeostasis is limited. Therefore, we studied whether an increase in GC level within the baseline range suppresses or enhances condition (body mass, hematocrit and coccidian infestation) and physiological state (humoral innate immune system activity and oxidative balance). We implanted captive house sparrows Passer domesticus with either 60 days release corticosterone (CORT) or control pellets. CORT-treated birds had elevated baseline CORT levels one week after the implantation, but following this CORT returned to its pre-treatment level and the experimental groups had similar CORT levels one and two months following the implantation. The mass of tail feathers grown during the initial phase of treatment was smaller in treated than in control birds. CORT implantation had a transient negative effect on body mass and hematocrit, but both of these traits resumed the pre-treatment values by one month post-treatment. CORT treatment lowered oxidative damage to lipids (malondialdehyde) and enhanced constitutive innate immunity at one week and one month post-implantation. Our findings suggest that a relatively short-term (i.e. few days) elevation of baseline CORT might have a positive and stimulatory effect on animal physiology.

Effect of fermented total mixed rations on the growth performance, carcass and meat quality characteristics of Hanwoo steers

This study was conducted to assess the effects of fermented total mixed ration (FTMR) on the growth performance, carcass and meat quality traits of Hanwoo steers. The present study evidenced that the FTMR had a strong effect on dry matter intake, body weight, daily gain, slaughter weight and carcass characteristics compared with control animals. The results showed that the dry matter intake (7.17 ± 0.13 kg), average body weight (615.20 ± 112.82 kg), and daily gain (0.56 ± 0.16 kg) were greater in animals receiving FTMR than in control animals (P < 0.05). The meat quality characteristics indicated that cooking loss and the pH values did not vary between control and FTMR treated animals; however, animals in the treated groups (FTMR) had higher meat quality grades, carcass weight (396.13 ± 18.35), fat thickness (13.25 ± 1.75), marbling score (5.63 ± 0.56), meat color (40.06 ± 1.23), crude fat (18.39 ± 1.32) and sensory characteristics (flavor 5.03 ± 0.17; tenderness 4.42 ± 0.33; juiciness 5.10 ± 0.16). Nevertheless, the shear force values decreased significantly in FTMR-treated animals compared with control group steers. Overall, FTMR may not only improve the growth performance, biochemical metabolites, and fatty and acetic acid profiles of steers, but may also enhance the carcass and meat quality characteristics of Hanwoo steers. Regarding economics, our research findings suggest that FTMR-based feeds may enhance Hanwoo steer meat quality at a low cost.

A high-caloric diet rich in soy oil alleviates oxidative damage of skeletal muscles induced by dexamethasone in chickens

Objective: Glucocorticoids (GCs) can induce oxidative damage in skeletal muscles. The purpose of this study was to demonstrate a high caloric (HC) diet rich in soy oil would change the oxidative stress induced by a GC.

Methods: The effect of dexamethasone (DEX) and HC diet on oxidative stress in plasma, skeletal muscles (M. pectoralis major, PM; M. biceps femoris, BF), and mitochondria were determined. The biomarkers of oxidative damage and antioxidative enzyme activity were determined. The fatty acid profile of muscles and the activities of complex I and II in mitochondria were measured.

Results: The results showed that DEX increased the concentrations of oxidative damage markers in plasma, muscles, and mitochondria. The activity of complex I was significantly suppressed by DEX. DEX-chickens had higher proportions of polyunsaturated fatty acids and lower proportions of monounsaturated fatty acids in the PM. A HC diet decreased the levels of oxidative damage biomarkers in plasma, muscles, and mitochondria. The interaction between DEX and diet suppressed the activities of complex I and II in HC-chickens.

Discussion: Oxidative damage in skeletal muscles and mitochondria was the result of GC-induced suppression of the activity of mitochondrial complex I. A HC diet improved the antioxidative capacity and reduced the oxidative damage induced by the GC.

Impact of transportation duration on stress responses in day-old chicks from young and old breeders

The aim of this study was to assess the interaction effect of transportation duration and parental age on physiological stress responses and quality in day-old chicks. After hatch, 3240 chicks from either 29-week old (young) or 60-week old (old) broiler breeders were transported for 1.5h (short) or 11h (long). Thereafter, 228 chicks were assessed for quality and blood plasma was assayed for corticosterone (CORT), lactate, glucose, and thiobarbituric acid-reactive substances (TBARS, increased concentrations can indicate oxidative stress). No interaction effects of parental age and transportation duration were found (all P>0.10). Chicks from young breeders showed higher CORT levels (P=0.007) and were of higher quality (Tona method, P<0.001) than those from old breeders. After long transportation, chicks showed increased CORT (P<0.001) and lower TBARS levels (P<0.001) compared to after short transportation. No evidence was provided that long transportation differently affected the quality or stress responses of chicks from breeder flocks of two ages.

Endocrine, metabolic, and behavioral effects of and recovery from acute stress in a free-ranging bird

Acute stress in vertebrates generally stimulates the hypothalamo-pituitary-adrenal axis and is often associated with multiple metabolic changes, such as increased gluconeogenesis, and with behavioral alterations. Little information is available, especially in free-ranging organisms, on the duration of these reversible effects once animals are no longer exposed to the stressor. To investigate this question, we exposed free-ranging adult male Rufous-winged Sparrows, Peucaea carpalis, in breeding condition to a standard protocol consisting of a social challenge (conspecific song playback) followed with capture and restraint for 30min, after which birds were released on site. Capture and restraint increased plasma corticosterone (CORT) and decreased plasma testosterone (T), glucose (GLU), and uric acid (UA). In birds that we recaptured the next day after exposure to conspecific song playback, plasma CORT and UA levels no longer differed from levels immediately after capture the preceding day. However, plasma T was similar to that measured after stress exposure the preceding day, and plasma GLU was markedly elevated. Thus, exposure to social challenge and acute stress resulted in persistent (⩾24h) parameter-specific effects. In recaptured sparrows, the territorial aggressive response to conspecific song playback, as measured by song rate and the number of flights over the song-broadcasting speakers, did not, however, differ between the first capture and the recapture, suggesting no proximate functional association between plasma T and conspecific territorial aggression. The study is the first in free-ranging birds to report the endocrine, metabolic, and behavioral recovery from the effects of combined social challenge and acute stress.