Establishment and characterization of equine autonomic ganglion cell linesto enable direct testing of candidate toxins involved in equine dysautonomia (grass sickness)

To enable direct testing of a range of potential toxins or pathogens that m ight be involved in grass sickness, equine thoracic sympathetic chain gangl ion cell lines were established from primary cell cultures by retroviral-me diated transduction of the temperature-sensitive mutant of the establishmen t oncogene encoding SV40 large T antigen. Morphological and behavioral feat ures, temperature dependence, and immunocytochemical characteristics of the cell lines were investigated. The majority of cells were noradrenergic neu rons in which dopamine-beta-hydroxylase, the enzyme that catalyzes norepine phrine synthesis, and neuropeptide Y coexisted. Cells treated with plasma from grass sickness cases that had previously bee n shown to induce autonomic nervous system damage when injected into normal horses showed significantly decreased mitochondrial function after 1 day. After 3 days exposure most cells showed severe degeneration in contrast to those treated with normal plasma. Liver and lung cell lines were also susce ptible to plasma, suggesting that the toxin is not specifically neurotoxic.