Hassan Malekinejad - Department of Basic Sciences, Faculty of Veterinary Medicine, Urmia University, Urmia, Iran
Nazli Alizadeh-Tabrizi - Department of Basic Sciences, Faculty of Veterinary Medicine, Urmia University, Urmia, Iran
Araz Ostadi - Department of Basic Sciences, Faculty of Veterinary Medicine, Urmia University, Urmia, Iran
Johanna Fink-Gremmels - Department for Veterinary Pharmacology and Toxicology, Faculty of Veterinary Medicine, Utrecht University, Utrecht, The Netherlands

The pathogenesis of equine grass sickness (EGS) has not fully understood. A better understanding of the exact pathogenesis of diseases can help to make an accurate diagnosis. Previous studies reported some pathological damage of neuronal cells in EGS patients. In this study, primarily cytotoxicity of serum from three clinically EGS-diagnosed horses on PC۱۲ Tet-off (PTO) cells was assessed. Subsequently, the apoptotic tests including cytochrome C release, caspase-۳/۷ activity measurement and DNA fragmentation assay were conducted to clarify the apoptotic effect of serum from EGS patients. Addition of serum from EGS patients at concentrations higher than ۲۵% on PTO cells resulted in a significant cytotoxicity in Alamar blue reduction assay compared with serum from healthy horses. All three apoptotic endpoints showed that the serum from EGS patients does have capability to induce apoptosis. A remarkable up regulation of cytochrome C release accompanied with concentration- and time-dependent augmentation in caspase-۳/۷ activity and ultimately DNA fragmentation were observed. Our data suggest that serum from EGS patients might have potentially neurotoxic compounds, which exerts cytotoxic and apoptotic effects on neuronal cells. Moreover, the EGS serum-induced apoptosis attributes to augmentation of cytochrome C release and caspase-۳/۷ activity.

Caspase-۳/۷, cytochrome c, DNA fragmentation, P۵۳ cells, PC۱۲ Tet-off