Effects of diclazuril on apoptosis and mitochondrial transmembrane potential in second-generation merozoites of Eimeria tenella

Diclazuril, a benzeneacetonitrile anticoccidial agent, has potent activity against various stages of Eimeria tenella (E. tenella). To study the effects of diclazuril on E. tenella merozoites, purified second-generation merozoites were obtained from infected chicken caecal tissue at 120 h after inoculation by a combination of enzymatic digestion, centrifugation, erythrocytes disruption and percoll density gradient centrifugation. Ultrastructural changes were monitored by transmission electron microscopy (TEM). Apoptosis and mitochondrial transmembrane potential were determined by flow cytometry (FCM). The results showed that diclazuril induced ultrastructural changes and significantly increased the ratio of early apoptosis by 180.75% (P < 0.01) and late apoptosis/necrosis by 86.82% (P < 0.05) in second-generation merozoites, respectively. Compared with the infected/control group, the ratio of second-generation merozoites that lost mitochondrial function was increased by 45.04% (P < 0.01) in the infected/treatment group. In conclusion, diclazuril induced morphological changes and attenuated the activity of mitochondrial transmembrane potential of merozoites, which is involved in mitochondrial-depended apoptosis in second-generation merozoites of E. tenella.