Melatonin (MT) is an amine hormone secreted by the body that has antioxidant and anti-inflammatory properties. The aim of this study was to investigate pathophysiological protection of MT in heat-stressed chickens. By modelling heat-stressed chickens and treating them with MT. After 21 days of administration, serum antioxidant enzymes, biochemical indices, inflammatory cytokine and heat-stress indices were detected, along with cardiopulmonary function indices and histological observations in chickens. The results show heat-stress induced a decrease (P < 0.05) in body weight and an increase in body temperature, which was reversed after MT intervention. Treatment with MT inhibited (P < 0.05) the secretion of pro-inflammatory factors interleukin-1β, interleukin-6, tumor necrosis factor α, serum heat shock protein 70, corticosterone, and elevated (P < 0.05) the levels of biochemical factors total protein, albumin, globulin, and increased (P < 0.05) the activities of antioxidant enzymes superoxide dismutase, glutathione peroxidase and catalase in chicken serum caused by heat stress, and the best effect was observed with the medium dose of MT. The heat-stress caused cardiac atrophy and pulmonary congestion, decreased (P < 0.05) the cardiac function indices creatine kinase isoenzyme, cardiac troponin I, angiotensin receptor I, creatine kinase and lung function indices myeloperoxidase, angiotensin-II, heat shock factor I, and increased (P < 0.05) the lung vascular endothelial growth factor II. Sections of the heart and lungs after administration of MT were observed to be more complete with more normal tissue indices. At the same time, compared with heat stress, heart and lung function indices of grade chickens after MT administration were significantly (P < 0.05)reduced and tended to normal levels, and the best effect was observed in the medium-dose MT. In conclusion, heat stress can cause pathophysiological damage in chickens, and 1 mg/kg/d of exogenous melatonin can attenuate this adverse effect.

暂无摘要。

As global warming intensifies, extreme heat is becoming increasingly frequent. These extreme heatwaves have decreased the milk production of dairy animals such as cows and goats and have caused significant damage to the entire dairy industry. It is known that heat stress (HS) can induce the apoptosis and autophagy of mammary epithelial cells (MECs), leading to a decrease in lactating MECs. L-arginine can effectively attenuate HS-induced decreases in milk yield, but the exact mechanisms are not fully understood. In this study, we found that HS upregulated the arginine sensor CASTOR1 in mouse MECs. Arginine activated mTORC1 activity through CASTOR1 and promoted mitochondrial biogenesis through the mTORC1/PGC-1α/NRF1 pathway. Moreover, arginine inhibited mitophagy through the CASTOR1/PINK1/Parkin pathway. Mitochondrial homeostasis ensures ATP synthesis and a stable cellular redox state for MECs under HS, further alleviating HS-induced damage and improving the lactation performance of MECs. In conclusion, these findings reveal the molecular mechanisms by which L-arginine relieves HS-induced mammary gland injury, and suggest that the intake of arginine-based feeds or feed additives is a promising method to increase the milk yield of dairy animals in extreme heat conditions.

Cross-adaptation (CA) refers to the successful induction of physiological adaptation under one environmental stressor (e.g., heat), to enable subsequent benefit in another (e.g., hypoxia). This systematic review and exploratory meta-analysis investigated the effect of heat acclimation (HA) on physiological, perceptual and physical performance outcome measures during rest, and submaximal and maximal intensity exercise in hypoxia. Database searches in Scopus and MEDLINE were performed. Studies were included when they met the Population, Intervention, Comparison, and Outcome criteria, were of English-language, peer-reviewed, full-text original articles, using human participants. Risk of bias and study quality were assessed using the COnsensus based Standards for the selection of health status Measurement INstruments checklist. Nine studies were included, totalling 79 participants (100 % recreationally trained males). The most common method of HA included fixed-intensity exercise comprising 9 ± 3 sessions, 89 ± 24-min in duration and occurred within 39 ± 2 °C and 32 ± 13 % relative humidity. CA induced a moderate, beneficial effect on physiological measures at rest (oxygen saturation: g = 0.60) and during submaximal exercise (heart rate: g = -0.65, core temperature: g = -0.68 and skin temperature: g = -0.72). A small effect was found for ventilation (g = 0.24) and performance measures (peak power: g = 0.32 and time trial time: g = -0.43) during maximal intensity exercise. No effect was observed for perceptual outcome measures. CA may be appropriate for individuals, such as occupational or military workers, whose access to altitude exposure prior to undertaking submaximal activity in hypoxic conditions is restricted. Methodological variances exist within the current literature, and females and well-trained individuals have yet to be investigated. Future research should focus on these cohorts and explore the mechanistic underpinnings of CA.

The present study was conducted 1) to investigate the effects of gender and temperature on growth performance in broiler chickens and 2) to establish body protein and fat deposition curves and amino acid patterns for broilers of both genders at different ambient temperatures. A total of 432 1-day-old (d) Arbor Acres chickens with a male/female ratio of 1:1 were randomly divided into the following 4 treatment groups: the male thermoneutral group, the female thermoneutral group, the male heat stress group, and the female heat stress group. The chickens in the thermoneutral groups were kept at a comfortable temperature from 1 to 42 d, while chickens in the heat stress groups were kept at a comfortable temperature from 1 to 28 d and at a high ambient temperature from d 29 to 42. The body composition retention data were obtained by comparative slaughter method, and the models were constructed by the Gompertz model. The results revealed significant variation in body protein content (BPC) and body fat deposition efficiency (BFE) between both genders and the 2 temperatures. Moreover, a noteworthy interaction between gender and temperature was observed in terms of the BPC and protein deposition efficiency (BPE). The following equations for body protein and body fat deposition in the thermoneutral groups were obtained: Body protein weight of male broilers: [Formula: see text] ; Body protein weight of female broilers: [Formula: see text] ; Body fat weight of male broilers: [Formula: see text] ; Body fat weight of female broilers: [Formula: see text] . Where t means age (d). The following equations for body protein and body fat deposition in the heat stress groups were obtained: Body protein weight of male broilers: [Formula: see text] ; Body protein weight of female broilers: [Formula: see text] ; Body fat weight of male broilers: [Formula: see text] ; Body fat weight of female broilers: [Formula: see text] . Where t means age (d). In addition, no significant difference in amino acid content was found between different genders and temperatures. The amino acid pattern could be divided into 2 stages: 0 to 14 d and 15 to 42 d. Our equations and patterns enable a deeper understanding of the nutritional requirements in broiler chickens under various temperature conditions. This enables researchers to develop more accurate feeding programs to fulfill the growth and health requirements of broiler chickens.

Objective: Through the analysis of five cases of occupational heat illness caused by high temperature, we expounded the pathogenesis and summarized the clinical characteristics of heat cramp and heat exhaustion of the newly revised diagnostic criteria for occupational heat illness (GBZ41-2019), in order to prevent the occurrence of occupational heat illness to put forward controllable countermeasures. Methods: According to the occupational history, clinical diagnosis and treatment and the other relevant data submitted by five patients, the diagnosis process was analyzed and summarized. Results: Five patients developed symptoms from July to August in summer, belonging to high-temperature operation. They improved by timely treatment. The symptoms, signs and laboratory tests of the five patients were different, but they were diagnosed as occupational heat illness. Conclusion: Employers should pay attention to the high temperature protection and cooling work, and strengthen the labor protection. If patients with heat cramp and heat exhaustion were timely treated, they could basically recover. Occupational disease diagnosticians should seriously study the new diagnostic criteria of occupational disease and constantly improve their diagnostic ability.
目的： 通过对5例因高温导致的职业性中暑病例分析，阐述发病机制，总结新修订GBZ 41-2019《职业性中暑诊断标准》热痉挛、热衰竭的临床特点，为预防职业性中暑疾病的发生提出可控对策。 方法： 于2021年11月，以2020年9月10日至2021年9月30日期间苏州市疾病预防控制中心职业卫生科收治并诊断的5例职业性中暑患者作为研究对象，调查职业史、临床诊疗等相关资料，并对诊断过程加以分析与总结。 结果： 5例患者发病于夏季7~8月份，属于高温作业，经及时治疗后好转而出院。5例患者自身的症状、体征及实验室检查存在差异性，但均被诊断为职业性中暑。 结论： 用人单位应重视夏季高温防护降温工作，加强劳动保护。热痉挛、热衰竭患者若及时救治，基本能康复痊愈。职业病诊断医师应认真学习新的职业病诊断标准，不断提升诊断能力。.

Studies have demonstrated that chronic heat stress can accelerate glycolysis, decrease glycogen content in muscle, and affect muscle quality. However, the consequences of chronic heat stress on glycogen synthesis, miRNA expression in pectoralis major (PM) muscle, and its regulatory functions remain unknown. In this study, high-throughput sequencing and cell experiments were used to explore the effects of chronic heat stress on miRNA expression profiles and the regulatory mechanisms of miRNAs in glycogen synthesis under chronic heat stress. In total, 144 cocks were allocated into 3 groups: the normal control (NC) group, the heat stress (HS) group, and the pair-fed (PF) group. In total, 30 differently expressed (DE) miRNAs were screened after excluding the effect of feed intake, which were mainly related to metabolism, signal transduction, cell growth and death. Furthermore, the gga-miR-212-5p/GYS1 axis was predicted to participate in glycogen synthesis through the miRNA-mRNA analysis, and a dual-luciferase reporter test assay confirmed the target relationship. Mechanistically, chronic heat stress up-regulated gga-miR-212-5p, which could inhibit the expression of GYS1 in the PM muscle. Knocking down gga-miR-212-5p alleviates the reduction of glycogen content caused by chronic heat stress; overexpression of gga-miR-212-5p can reduce glycogen content. This study provided another important mechanism for the decreased glycogen contents within the PM muscle of broilers under heat stress, which might contribute to impaired meat quality.

Heat stress (HS) is a critical challenge in broilers due to the high metabolic rate and lack of sweat glands. Results from this study show that implementing a cyclic chronic HS (34 °C for 7 h/d) to finisher broilers decreased the diversity of cecal microbiota and impaired intestinal barrier, resulting in gut leak and decreased body weight (both P < 0.05). These alterations might be related to inflammatory outbursts and the retarded proliferation of intestinal epithelial cells (IECs) according to the transcriptome analysis. Considering the potential beneficial properties of Lactobacillus on intestinal development and function, the protective effects of Lactobacillus rhamnosus (L. rhamnosus) on the intestine were investigated under HS conditions in this study. Orally supplemented L. rhamnosus improved the composition of cecal microbiota and upregulated the transcription of tight junction proteins in both duodenum and jejunum, with a consequent suppression in intestinal gene expressions of pro-inflammatory cytokines and facilitation in digestive capability. Meanwhile, the jejunal villus height of the birds that received L. rhamnosus was significantly higher compared with those treated with the broth (P < 0.05). The expression abundances of genes related to IECs proliferation and differentiation were increased by L. rhamnosus, along with upregulated mRNA levels of Wnt3a and β-catenin in jejunum. In addition, L. rhamnosus attenuated enterocyte apoptosis as indicated by decreased caspase-3 and caspase-9 gene expressions. The results indicated that oral administration with L. rhamnosus mitigated HS-induced dysfunction by promoting intestinal development and epithelial maturation in broilers and that the effects of L. rhamnosus might be dependent of Wnt/β-catenin signaling.

Zinc (Zn), an essential trace element for poultry, plays a crucial role in promoting growth, improving feed conversion efficiency, enhancing antioxidant activity, and preventing disease. This study investigated the impact of different levels and sources of dietary Zn supplementation on the growth performance, intestinal morphology and antioxidant activity of broiler chickens under heat stress conditions. In this experiment, 1024 Xueshan chickens were divided into eight groups and subjected to heat stress conditions with different levels of Zn supplementation (30 mg/kg, 60 mg/kg, and 90 mg/kg) using organic or inorganic sources. Our findings indicated that dietary Zn supplementation significantly increased the feed-to-weight ratio of broilers during the experimental period under heat stress. Moreover, Zn supplementation positively increased the villus height and villus width in the jejunum and ileum at 74 and 88 days old, with the 60 and 90 mg/kg groups outperforming other groups, and organic Zn was more effective than inorganic Zn. Furthermore, Zn supplementation significantly increased serum antioxidant levels, with higher superoxide dismutase (SOD), malondialdehyde (MDA), and glutathione peroxidase (GSH-px) activities, and organic Zn was more effective than inorganic Zn. This study concludes that Zn supplementation is beneficial in mitigating the detrimental impacts of heat stress on broilers. The findings suggest that employing Zn as a strategy can enhance productivity in the poultry industry by positively influencing intestinal morphology and bolstering antioxidant activity to counteract potential stress.

Elephantopus scaber L. (ESL) is a Chinese herb that is used both as a food and medicine, often being added to soups in summer in south China to relieve heat stress (HS), but its exact mechanism of action is unknown. In this study, heat-stressed mice were gavaged with ESL polysaccharides (ESLP) at 0, 150, 300, and 450 mg/kg/d-1 (n = 5) for seven days. The gut microbiota composition, short-chain fatty acids (SCFAs), seven neurotransmitters in faeces, expression of intestinal epithelial tight junction (TJ) proteins (Claudin-1, Occludin), and serum inflammatory cytokines were measured. The low dose of ESLP (ESLL) improved the adverse physiological conditions; significantly reduced the cytokines (TNF-α, IL-1β, IL-6) and lipopolysaccharide (LPS) levels (p < 0.05); upregulated the expression of Claudin-1; restored the gut microbiota composition including Achromobacter and Oscillospira, which were at similar levels to those in the normal control group; significantly increased beneficial SCFAs like butyric acid and 5-HT levels in the faeces of heat-stressed mice; and significantly decreased the valeric acid and glutamic acid level. The level of inflammatory markers significantly correlated with the above-mentioned indicators (p < 0.05). Thus, ESLL reduced the HS-induced systemic inflammation by optimizing gut microbiota (Achromobacter, Oscillospira) abundance, increasing gut beneficial SCFAs like butyric acid and 5-HT levels, and reducing gut valeric and glutamic acid levels.