Dynamic Study On Levels Of NO And Antioxidant System In Ducklings With New Duck Viral Hepatitis

180 one-day old healthy ducklings were divided into two groups randomly after feeding a week, 120 in tested group and 60 in control. Every duckling in tested group was infected with 0.2ml New duck hepatitis virus (NDHV) in the muscle of right leg, and control group was processed with PBS. The pathological model of New duck viral hepatitis (NDVH) was duplicated successfully after inoculation of virus. The clinical signs and histopathological changes of inoculated ducklings were observed. Meantime, the content of MDA, NO and the activity of SOD, GSH-Px, CAT were determined in liver, brain and serum at 12h, 24h, 48h, 72h, 96h, 168h and 336h post inoculation.The clinical signs showed that: affected ducklings at first stop moving and squat down, then kick spasmodically with both legs, and die with heads drawn back. Death occurs shortly after signs are noted. The death focus on 24-48h post inoculation and the total mortality was 21.7%. The gross anatomy showed that: liver swelled apparently and appeared hemorrhagic lesions, frequent redish discoloration or motting is seen in the surface; gall bladder is full of gall; pancreas occurs necrosis as large as a needle tip; spleen swell with white and red disturbing dispersely; kidney appears congestion; brain occurs hyperemia.The microscopic changes showed that: liver appeared abroad and severe hydropic degeneration , small bile ducts around portal area are proliferated, tissue with infiltration of inflammatory cell is seen; Brain occurred cerebrum, satellitosis, neuronophagia and forming of glial nodule.The SOD showed that: the activity of serum SOD rise to the maximum at 24h after injection then decrease apparently at 96h, the activity of liver SOD in tested group is lower than that in control group at 24 and 48h, there are no changes in the activities of brain SOD.The GSH-Px showed that: the activity of serum GSH-Px is apparent lower than that of control group at 48h, lower than the control group at 96h, recover to the normal at 7d after infection.The CAT showed that: the activity of liver CAT decrease at 48h and apparent lower at 96h.The MDA showed that: the content of MDA in liver and serum is apparent higher than that of control group at 24h post inoculation there are no changes in the brain.The NO showed that: the content of serum NO rise at 48h after infection, continues to 96h. the content of liver NO rise at 24h.in brain, there are no apparent change.The study indicated that ducklings infected with NDHV could not eliminate free radicals, the free radicals participated in the pathological course of NDVH.