Dynamic Changes Of Serum Nitric Oxide In Mice Infected With Schistosma Japonicum

Objective: To observe on the dynamic changes of serum nitric oxide in mice infected with Schistosoma japonicum, and investigate the role of nitric oxide in the infection.Methods: Kunming strain Mice were lightly (20±2)or heavily (50±2)infected with cercariae of Schistosma japonicum through the skin of abdomen. On the 42nd day of post-infection, the mice were treated ip with praziquantel of 600mg/kg.d-1. The change of serum nitric oxide in the mice was examined at different time with the means of nitrate reductase, in comparison with that of normal mice. Meanwhile the pathological changes of liver were observed and the organ ratio of liver and spleen (defined as a ratio of the weight of organs to that of bodies of mice) of these mice was recorded.Results: 1.On the 30th day of post-infection, the worm recovery rate from lightly infected mice was 84% and 59.2% for the heavily infected group. After praziquantel treatment, the recovery rate decreased significantly.2. The organ ratio of liver and spleen of infected group increased more significantly than that of the normal group. After praziquantel early treatment there was no significant difference in the result between the infected group and the control group except spleen ratio in the 60th day of post-infection.3. At different time the serum nitric oxide of both lightly and heavily infected groups was significantly higher than that of the control group (P<0.01). On the 30th and 45th days of post-infection, nitric oxide of heavily infected group was much higher than that of lightly infected group (P<0.05), on the 60th day there was no significant difference between these two infected groups (P>0.05). Nitric oxide of lightly infected group examined on the 30th, 45th and 60th day was significantly higher than the 75th day of post-infection(P<0.05). There was significant difference in NO at different check point time of the heavily infected groups, and the highest was detected on the 30th day. After praziquantel treatment the level of nitric oxide of these two infected groups was significantly lower than that of untreated group on the 45th day and 60th day, moreover there was significantly higher than that of the normal group. However those were no difference between the treated and untreated groups on the 75th day.4.No significant difference in size of egg granuloma of liver between the lightly and heavily infected groups was found at the same examination time. The size of egg granuloma of liver of the infected group reached the summit on the 60th day then decreased gradually. The size of egg granuloma of liver of treated group on the 75th day was significantly lower than that of untreated group in lightly infected mice.Conclusions : The infection with Schistosma japonicum resulted in a significant increase in the serum nitric oxide in the infected mice but with the extension of the infection, then the serum nitric oxide decreased gradually. Praziquantel treatment significantly reduced the amount of serum nitric oxide in the infected mice. The results suggested that nitric oxide should be correlated to the formation of the egg granuloma and to the modulation of immune system of mice to the granuloma.