Investigation of the susceptibility of equine autonomic neuronal cell lines, clonally derived from the same paravertebral ganglion, to toxic plasma from equine dysautonomia (grass sickness) cases.

This research investigates the varying susceptibility of certain horse autonomic nervous system neurons, derived from the same ganglion, to a toxic substance found in cases of equine grass sickness. The study advocates that despite originating from the same source, these neurons displayed varied reactions when exposed to the toxin, ultimately leading to their demise.

Autonomic Nervous System and Grass Sickness

• The research focuses on the reactions within the autonomic nervous system (ANS) of horses afflicted with grass sickness (GS), a debilitating condition with currently unknown cause(s).
• This study uses as its basis, observations from affected horses where some neurons displayed abnormal changes whereas adjacent neurons remained unaffected.
• The examination zeroes in on noradrenergic neurons due to their varied susceptibility to the GS toxin when studied in culture.

Study & Findings

• The researchers utilised clonally-derived populations (cells cloned from a single parent cell, thus being genetically identical) which were isolated from the same fetal thoracic sympathetic chain ganglion – a group of nerve cells located near the spinal cord.
• These cloned populations were then exposed to plasma (the straw-coloured liquid component of blood) from equine sufferers of GS. It was previously determined that this plasma has been shown to induce ANS damage when injected into healthy horses.
• The report states that varying degrees of susceptibility were noticed within the cloned cell population. This ranged from insignificant impact to distinct patterns of pathological changes.
• However, the study revealed that prolonged exposure to the toxic plasma resulted in the death of all tested cells after three days.

Dose-Response Analysis

• A dose-response analysis was conducted on selected clonal populations. This process involves assessing the proportionate change in an outcome (in this case, neuron damage/death) with varying levels of exposure to the toxin.
• This analysis found no significant discrepancy in TD(50) values. In pharmacology, TD(50) refers to the dose of a toxin at which 50% of the population is theoretically negatively impacted.
• Despite cells originating from the same ganglion (and thus, expected to have similar genetic ability to resist the toxic impact), they did not show any significant difference in their ability to withstand GS plasma toxins.