| Coccidiosis is the major parasitic disease in chickens and causes huge economic losses in poultry industry. Due to the rapid emergence of drug-resistance parasites and the instability of vaccine, the disease is difficult to control. Therefor exploiting new pattern anticoccidial drug will be great practical value. The research finded GSNO could inhibiting the sporulation of E. tenella oocysts.To further confirm the inhibitory characteristics of NO on the sporulation of E.tenella oocysts and discuss the mechanism, this paper will do the following research.1 The inhibiting effect of NO on oocystsTo study the effect of exogenous nitric oxide on E. tenella oocysts, Acidic nitrite, hydrochloric acid and sulfuric acid solution were used to treat freshly isolated oocysts in this experiment, and then the oocysts sporulation were inspected. The results showed acidic sodium nitrite (pH=1) had significant inhibiting roles on the sporulation in E.tenella oocysts, with a high inhibiting rate of 100% in the group treated by 20mmol/L acidic sodium nitrite, but the same concentration sodium nitrite solution without acid and the hydrochloric acid and sulfuric acid solution with equal the pH to acidic nitrite solution had not visible effects on the sporulation. GSNO and SNAP and Hb were used to treat freshly isolated oocysts, and then the oocysts sporulation were detected. The results showed 8mmol/L GSNO and SNAP could inhibit the sporulation of oocysts, however, NO-scavenger, Hb could significantly eliminate the inhibiting effect of GSNO and SNAP on oocysts with a dose-effect relationship. The above-mentioned results indicated No could inhibit the sporulation of E. tenella oocysts.2 The effect of GSNO on sporulated oocysts and sporocystsThe object was to evaluate the effect of NO on the livingness and pathogenicity of sporulated oocysts and sporocysts. The oocysts livingness examination of sporulated oocysts and sporocysts treated by 20mmol/L GSNO were detected by the excystation rate of sporozoites. The results showed the excystation rate of sporozoites of control group, sporulated oocysts and sporocysts treated by GSNO were 95.51%,57.21%,47.67% respectively. To evaluate the effect of NO on the pathogenicity of oocysts according to the clinical symptoms of coccidiosis and the lesion in ceca, the chickens were inoculated the sporulated oocysts or sporocysts. The results showed sporulated oocystes treated by GSNO on chicken's weight gain, lesion scores, OPG and the parasites-burden in ceca were not higher than the sporulated oocystes group (P>0.05); compare with the sporocysts group, sporocysts treated by GSNO on lesion scores, OPG and the parasites-burden in ceca decreased statistically ( P﹤0.05 ) . The above-mentioned results indicated NO could decrease the excystation rate of sporulated oocysts and sporocysts; NO could not obviously inhibit the pathogenicity of sporulated oocystes, nevertheless, the pathogenicity of sporocysts treated by NO decreased significantly.3.The effect of GSNO on the activities of enzymes related to the metabolism of glucide of oocystsIn this study, the effects of GSNO on the activities of LDH, G6PD and ACO related to the metabolism of glucide in oocysts were detected by the PAGE. The substrate special staining results showed that the activities of LDH were similar to those of the control, but the activities of G6PD were less than those of the control, there were the activities of ACO in cytoplasm and mitochondrion of oocystes, whether treated by GSNO or not, the activities of ACO in mitochondrion were higher than those of cytoplasm. The above-mentioned results indicated GSNO had no obviously inhibiting effect on LDH and ACO, or the inhibiting effect was reversible; however GSNO could decrease the activities of G6PD.4 The effect of GSNO on the the recovery system of oocystsThe object was to evaluate the damage effect of NO on the recovery system and the enzyme related to the anti-oxidation ability of E. tenella oocysts. In order to investigate the expression of HSP70 in oocysts treated by GSNO, the ELISA and and the Flow cytometric analysis were used. The results indicated GSNO had no obviously effect on the expression of HSP70, the expression of HSP70 in oocysts sporulating for 6h was more than in the freshly collected oocysts. The PAGE method were used to analyze the effects of GSNO on the activities of SOD, The substrate special staining results showed the activities of SOD in oocystes treated by GSNO were detected respectively, and was initially distinguished as Cu·Zn-SOD. The above-mentioned results indicated GSNO had no obviously effect on the expression of HSP70; so didn't the activities of SOD, or the inhibiting effect was reversible.
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