| Animals’ adaptive ability is mainly manifested in the ability to adapt to environmental changes, and it is mainly reflected in the distribution of energy: the body will redistribute the limited energy according to the internal resources in order to make the body achieve the best fitness.And energy metabolism is the first change that appears in the physiological reactions caused by cold stress. Fat tissue is an essential energy supply that plays an important role in the body’s energy regulation and stable state.The xinjiang Altay sheep’s cold resistance capablity is strong, so they can adapt to the cold weather conditions in Altay region. The research tried to analysize probable adaptive mechanism of Altay sheep’s cold resistance from the aspects of low temperature’s influences on the synthesis and catabolism of fat tissue of different breeds sheep to study the importance of fat tissue in cold resistance and related physiological functions; this research also tried to study the changes of deposition and metabolism of body fat under the cold stimulation. Then analysize the expression of Hsp70 and concentrations of IL-4, IL-2 in Altay sheep and Hu sheep.The results of the study are as follows:1. Altay sheep tail fat deposition is very significant, how adipose tissue samples after cold stress in their metabolic processes. By adopting the method of real-time fluorescent quantitative PCR to detect the amount of LPL, FAS and SCD m RNA expression of Altay sheep and Hu sheep in their neck, chest, abdomen, leg muscle fat, the tail fat and liver before and after cold stress, it was found that after exposure to the cold stimulation, the expression of LPL and SCD in Altay sheep and Hu sheep had increased, particularly outstanding in Altay sheep, and the expression quantity in the tail was the highest after cold stress; the expression amount of FAS after stress decreased, and the decrease of fat in tail of Altay sheep was particularly significant.These results showed that after cold stress the body needed to constantly adjust the amount of the expression of functional genes to adjust the supply of energy and to adapt to changes in external environment.2. To study of discussing fat metabolic mechanism, we analyzed from the aspects of blood physiological and morphological, this experiment adopted fully automatic biochemical analyzer to test concentration of TC, TG, HDL, VDL of Altay sheep and Hu sheep before and after cold stress; meanwhile, the liver, thyroid and spleen tissues were collected to made paraffin section.Results showed that TG and HDL level in the blood of Altay sheep and Hu sheep increased after cold stress, but the amount of TC, LDL lowered; histological observation found that hyperplasia of epithelial tissue in Hu sheep thyroid gland was severe after cold stress; at the same time, epithelial hyperplasia stretched to lumen, forming a "cushion" phenomenon.Before cold stress, liver cells of Hu sheep significantly turned larger, with mild steatosis and assuming the eosinophilic necrosis; Altay sheep groups had no special pathological changes before and after cold stress, indicating that internal environment was more stable in the body of Altay sheep and that their lipid metabolism ability was better than Hu sheep, so they could better adapt to the climate in the north.3. This research used real-time fluorescent quantitative PCR to test the expression quantity of Hsp70 m RNA in Altay sheep and Hu sheep’s liver, lung, spleen, lymph node tissue before and after cold stress respectively,with a significant increase in the expression of Altay sheep;meanwhile, concentrations of IL-4,IL-2 in serum were detected by ELISA.The results showed that compared with before cold stress, the Hsp70 m RNA expression quantity of Altay sheep and Hu sheep was significantly increased in lung and spleen tissue after cold stress; and the IL-2, IL-4 concentrations in both Altay sheep and Hu sheep serum showed a decreasing trend after cold stress.The results showed that enhanced expression of Hsp70 m RNA after cold stress could improve the animal’s function of self-protection and enhanced resistance to adverse external stimuli, but the decreases in cytokines IL-2 and IL-4 concentrations indicated that cold stress suppressed the body’s immune system. |
PDF Full Text Request