Effects Of Simulated Transport Stress On Immune Function And TLR4-NF-κB Signaling Pathway Of Lung In Rat

Intensification of modern breeding continues to increase, causes the long-distance transport of animals more common. Because of the comprehensive effect of fasting or restriction, noise, high temperature, turbulence, psychological pressure and other environmental factors during the transportation, generally causes animal transport stress reactin, which decreased animal production performance, immune function and meat quality, resulting in significant economic losses and potential health risks. Therefore, this study used rats as experimental animals, made rat simulated transport stress model, aimed to study the effects of transport stress on immune function of inherent lung tissue and alveolar macrophage.1. SD rats adaptive feeded 7 days, then during 9:00-11:00, the rats were placed in simulated transport 35℃,60r/min horizontal shaker shaking for 3 consecutive days, to simulate the transport process of shaking, temperature, noise, congestion and other factors, to build rat transport street model, purpose to observe the impact of transport stress on rats clinical symptoms, body weigh, serum corticosterone and damage of lung tissue structure. The results show that:(1) Simulated transprot stress ccould induce rat nervous, slow, body trembling, hair messy, tachypnea, urine volume decreased and the yellow, dungs dry and shrinked. (2) Simulated transport stress could cause the body weight of rat significantly lower than the control group (P<0.05). (3) Simulated transport stress could increase the concentration of serum TNF-α、IL-6 of rats, and the latter significantly higher than the control group (P<0.05). (4) Simulated transport stress could cause the concentration of serum corticosterone of rats significantly higher than the control group (P<0.05). (5) Simulated transport stress could cause uneven alveolar expansion, part of alveolar septal rupture; Venules dilatation and congestion, inflammatory cell infiltration, and some alveolar edema visible. Therefore, the daily shaking on the condition of 35℃,60r/min for two hours for three consecutive days, could induce severe transport stress and lung tissue damage.2. By extracting the total RNA of rat lung tissue, amplified by reverse transcription, then amplified the relative immune parameters gene, final detected the mRNA expression of IL-1β、IL-6、TNF-α、IFN-γ、TLR4、β-actin, the results show: simulated transport stress could significantly reduce the mRNA expression of TNF-α、 IFN-γ of rat lung tissue (P<0.05); TLR4, IL-1β and IL-6 increased slightly, but not significantly compared with control group, indicating that simulated transport stress inhibits the immune function in rat’s lung.3. After the rat model of simulated transport stress was made, collected alveolar macrophages by repeated washing, extracted the total protein of alveolar macrophages, then determined the concentration, detected the expression of NF-κB p65, Phospho-NF-κB p65, IκBα, and Actin by Western Blot. The results show that: simulated transport stress improved phosphorylation of NF-κB p65, reduced the expression of inhibit protein IκBα significantly (P<0.05), explained that simulated transport stress activated NF-κB signaling pathways in alveolar macrophages, and induced the expression and secretion of downstream proinflammatory cytokine.Above all, simulated transport stress could induce a sharp rise in blood corticosterone levels, damage lung tissue structure and inhibit lung immune function, activated NF-kB signaling pathway in alveolar macrophages, and induced the secretion and expression of proinflammatory cytokines.