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

The research outlines the creation and study of horse nerve cell lines in order to directly test potential toxins or pathogens that may be involved in a disease known as ‘grass sickness.’ The study uncovered that these cells, when exposed to blood plasma from horses suffering from grass sickness, showed significantly reduced function and severe degeneration.

Background

• Equine dysautonomia, commonly known as ‘grass sickness,’ is a mysterious disease affecting horses, often resulting in death.
• The researchers aimed to learn more about potential causes of this disease by directly testing toxins or pathogens on relevant cell lines established from horses.

Methodology

• Researchers created these horse nerve cell lines from the thoracic sympathetic chain ganglion, a part of the autonomic nervous system that regulates internal organ function.
• The established cell lines were engineered using a temperature-sensitive mutant of the establishment oncogene encoded by SV40 large T antigen. This mutant allows researchers to control cell growth.
• The cell lines’ morphological and behavioral features, temperature dependence, and immunocytochemical characteristics were examined to confirm establishment and characterize the cells.

Findings

• The majority of the established cells were noradrenergic neurons, producing a hormone called norepinephrine and the protein neuropeptide Y.
• When these cells were treated with blood plasma from horses affected by grass sickness, their mitochondrial function significantly declined within a day.
• After three days, most cells demonstrated severe degeneration in compared to cells treated with normal plasma.
• Additionally, liver and lung cell lines were also tested and showed similar susceptibility to plasma from horses affected by grass sickness. This indicates that the suspected toxin may not be exclusively neurotoxic and may also affect other tissues.

Implications

• These findings can contribute to our understanding of the causes of equine dysautonomia, potentially leading to improved treatment options for this disease.
• As the potential toxin seems not to be exclusively neurotoxic, future research could investigate its effects on other tissues and organs in horses, to better understand the disease’s systemic nature.