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Induction of Metallothionein in Broiler Chickens under Heat Stress and the Mediation by Corticosterone

Author: YangLiRong
Tutor: ZhangMinHong
School: Chinese Academy of Agricultural Sciences
Course: Animal Nutrition and Feed Science
Keywords: Heat stress Broiler Metallothionein Corticosterone Superoxide dismutase
CLC: S858.31
Type: Master's thesis
Year: 2011
Downloads: 43
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Abstract

This thesis, broiler study, two models of acute and continuous heat stress system to study the variation of heat stress in broilers metallothionein (MT), explore the corticosterone-mediated effects by regulating MT for the future provide a theoretical basis to ease the poultry heat stress. This thesis from the following three aspects: 1. Acute heat stress the broiler metallothionein change and corticosterone-mediated role in growth and development of good, considerable weight 35-day-old AA meat cock 192 randomly as follows four treatments: 23 ° C normothermia group (Normal Temperature, NT): injection of corn oil; 23 ℃ room temperature CORT (NT CORT): intramuscular injection of corticosterone (CORT) 4mg/kg body weight; 35 ° C hyperthermia group (High Temperature, HT) : injecting corn oil; 35 ℃ high temperature sugar glucocorticoid receptor blocker RU486 (HT RU486): subcutaneous injection of 50mg/kg body weight. Groups of six replicates of 8 birds. The beginning of the test, rapid hyperthermia and high temperature blocker group temperature rose from 23 ℃ to 35 ℃, and continued to 3h. Were treated 0h, 0.5h, 1h, 1.5h, 3h, 6h, 9h and 12h samples. Dynamic variation of heat stress the broiler MT and corticosterone-mediated effects. The results showed: acute heat stress causes the broiler liver MT and MTmRNA significant changes: MT protein levels the 0.5h significantly decreased (P lt; 0.05), 1h, 1.5h, 3h increased significantly (P lt; 0.05), and 1.5 h peak point; the liver MTmRNA in within 0-3h significant rise (P lt; 0.05) and in 3h at peak point, both highly consistent trends. MT synthesis was significantly increased (P lt; 0.05), consistent trend of high-temperature group hepatic MT and plasma corticosterone, high-temperature injection of glucocorticoid receptor blocker RU486 significantly reduced the hyperthermia group MT synthesis and injection at room temperature exogenous CORT lead MTmRNA expression (P lt; 0.05). The above results show that the liver MT in the case of broiler heat stress occurs a significant change, and the liver MT biological synthesis is regulated by the transcriptional level, the same time, corticosterone mediated acute heat stress liver MT Synthesis. Constant heat stress the broiler metallothionein changes and corticosterone-mediated effects to choose good growth, and weight of 35-day-old AA meat cock 120 randomly following four treatments: 23 ° C normothermia group (Normal Temperature, NT); 23 ° C room temperature pairing group (Paired-Feeding, PF): 1 day prior to hyperthermia group fed feed intake; 33 ° C hyperthermia group (High Temperature, HT): day variable cycle high temperature mode; 23 ℃ normal temperature CORT (NT CORT) group: CORT 30mg/kg feed added. Groups of six replicates of five chickens. Day variable cycle high temperature 23-33-23 ℃ changing pattern of the daily cycle, repeated one week. Respectively, after treatment 0d, 1d, 3d, 5d and 7d samples. The study continuous variation of the heat stress the broiler MT and corticosterone-mediated effect. The results showed: high temperature group broiler liver MT and MTmRNA of 0-3 days of constant heat stress significantly elevated (P lt; 0.05) ,5-7 days significantly decreased (P lt; 0.05), plasma corticosterone trend while the paired group the MT and MTmRNA and normothermia group had no significant difference (P gt; 0.05); room temperature, feed additive corticosterone liver MT protein levels and the MTmRNA expression and plasma corticosterone highly consistent trend in 1d , 3d, 5d was significantly higher (P lt; 0.05). That constant heat stress can lead to increased synthesis of liver MT protein pre-, post-synthesis to reduce this phenomenon caused by heat stress independent of the decline in feed intake, corticosterone-mediated generation of constant heat stress under the broiler liver MT. 3. Metallothionein and superoxide dismutase (SOD) in the comparison of heat stress regulation in acute and continuous heat stress model has been established based on liver antioxidant enzymes SOD reference object to the liver malondialdehyde (MDA) as a measure of the degree of oxidative damage in liver tissue indicators preliminary inquiry MT and SOD whether the differences in heat stress regulation. The results showed: acute heat stress cases, MT 1h, 1.5h significantly increased, while SOD 1h, 1.5h almost no change, 3h, 6h was significantly higher (P lt; 0.05); glucocorticoid injection receptor antagonist RU486, MT protein levels in 1h, 1.5h significantly reduce SOD 1h, 1.5h, 3h, 6h are significantly elevated (P lt; 0.05). Similar to the acute test results, MT constant heat stress 1d, 3d significantly increased SOD continues to heat stress 5d 7d significantly higher. The above results show that the MT and SOD may differ heat stress regulation time. Based on the results of the above studies, it can be drawn, the MT protein level in thermal stress situations, broiler liver has undergone a significant change, the hepatic MT biological synthesis transcriptional level regulation; corticosterone mediated synthesis of heat stress under broiler liver MT; MT and SOD in heat stress regulation may differ.

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CLC: > Agricultural Sciences > Livestock, animal medicine,hunting,silkworm,bee > Animal Medicine ( Veterinary Medicine) > Livestock, poultry, wildlife diseases > Poultry > Chicken
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