The Effect Of Heat Stress On Liver Gluconeogenesis Of Goat And Its Mechanism With RT-PCR And AVF

By studying the effect of thermal stress and mechanisms on ruminant gluconeogenesis to provide a theoretical guidance for the rationally developing regulating measures easing heat stress.Selecting eight similar weight, good body condition health Macheng black goat were randomly divided into two groups of four sheep, the first group to keep the air conditioning temperature and humidity index ≤72; the second group THI ≥72. Pre-trial period seven days, followed by three days to digest tests. After 1 day of fasting installating hepatic vein, portal vein, mesenteric proximal, distal mesenteric, carotid artery cannula.Taking Jugular venous blood before surgery, postoperative continuous feeding. The first five days after infusion of PAH(PAH), and point to take blood samples, the serum was separated measurement equipment. 30 days later conducting slaughter test.Taking sampling. To carry out the following research: The first part we mensurate digestibility of nutrients and deposition rate of Nitrogen with total feces collection. The result show that digestibility of NDF and ADF are decreased significantly(P<0.05),CP and DM and deposition rate of Nitrogen have no significant decrease(P>0.05). The second part we install Arteriovenous vascular intubation to measure the change of plasmaflux and blood sugar concentration in hepatic vein, portal vein, mesenteric vein, arteria carotis. The result show that blood sugar concentration of control group is higher than heat stress group, the blood sugar concentration of hepatic vein is significantly higher at 9:00,13:00. Each group blood sugar concentration high to low are hepatic vein, portal vein, mesenteric vein, arteria carotis. Stress group plasmaflux of hepatic vein,mesenteric vein is higher than control group, portal vein is lower. The third part we research the effect of heat stress on flux and level of portal propionic acid routine blood test, level of insulin, glucagon and glucocorticoid. The result reflect that heat stress has no significantly effect on level of TG and ALP(P>0.05), CK and TCHO significantly decreased(P<0.05).Heat stress group level of insulin and glucagon have no difference(P>0.05), glucocorticoid significantly higher(P<0.05), level of portal propionic acid has no difference(P>0.05), but propionic acid flux of heat stress is up-regulated significantly(P<0.05). The forth part we research the effect of heat stress on organ index, Organization form of liver, kidney and alimentary canal. The result show that heart, hepatic, lungs,kidney, splenic organ indexes are decreased by heat stress(P>0.05).In heat stress group goat hepatic, cell denaturation and swelling. Glomeruli of kidney is denaturated,thanatosis. Rumen epithelium nipple width is significantly reduced(P<0.05). Heat stress has no effect on villus height, crypt depth and the ratio of villus height with crypt depth of duodenum, jejunum, ileum(P>0.05).Mucosal thickness of jejunum are increased significantly in heat stress group(P<0.05); muscular coat thickness of jejunum and ileum is significantly decreased(P<0.05). The fifth part we study the effect of heat stress on expression of gene regulating gluconeogenesis. The result show that expression of PEPCK, G-6-P, PGC-1α are increased significantly(P<0.05). The sixth part we study the effect of heat stress on diversity of rumen microorganism. The result show that heat stress group has more microorganism(P>0.05); the similarity of microorganism in heat stress and control group microorganism is lower than 50% which reflect that heat stress do have an effect on diversity of rumen microorganism. To sum up, the conclusion of this experiment is: when the environment temperature and humidity index is greater than or equal to 72, nutrient digestibility rate is reduced, the portal vein propionic acid flow is decreased, rumen epithelial papilla width is reduced, microbial diversity of the rumen has changed, Mucosal thickness of jejunum are increased significantly in heat stress group; muscular coat thickness of jejunum and ileum is significantly decreased.G-6P, PEPCK and PGC-1α mRNA expression decreased in hepatic. It is suggested that heat stress may through reducing mRNA expression of the rate-limiting enzyme participating in gluconeogenesis process and PGC-1-α a important factor regulating process of gluconeogenesis to affect gluconeogenesis.