褪黑激素(MT)是由身体分泌的具有抗氧化和抗炎特性的胺激素。本研究的目的是研究MT对热应激鸡的病理生理保护作用。通过对热应激鸡建模并用MT处理。给药21天后,血清抗氧化酶,生化指标,检测炎性细胞因子和热应激指标,以及鸡的心肺功能指标和组织学观察。结果表明,热应激引起的体重下降(P<0.05)和体温升高,在MT干预后被逆转。MT治疗可抑制促炎因子白细胞介素-1β的分泌(P<0.05),白细胞介素-6,肿瘤坏死因子α,血清热休克蛋白70,皮质酮,生化因子总蛋白水平升高(P<0.05),白蛋白,球蛋白,并增加了抗氧化酶超氧化物歧化酶的活性(P<0.05),热应激引起的鸡血清中的谷胱甘肽过氧化物酶和过氧化氢酶,中剂量MT效果最佳。热应激导致心脏萎缩和肺充血,肌酸激酶同工酶降低(P<0.05),心肌肌钙蛋白I,血管紧张素受体I,肌酸激酶和肺功能指标髓过氧化物酶,血管紧张素II,热冲击因子I,并升高(P<0.05)肺血管内皮生长因子Ⅱ。观察到施用MT后心脏和肺的切片更完整,组织指数更正常。同时,与热应激相比,MT给药后,分级鸡的心肺功能指标显著降低(P<0.05),趋于正常水平,中剂量MT效果最佳。总之,热应激可引起鸡的病理生理损伤,1mg/kg/d的外源性褪黑素可以减轻这种不良作用。
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.