Equine grass sickness, but not botulism, causes autonomic and enteric neurodegeneration and increases soluble N-ethylmaleimide-sensitive factor attachment receptor protein expression within neuronal perikarya.

This research explores the effects of Equine Grass Sickness and Botulism in horses, specifically focusing on neurodegeneration and the expression of certain proteins called SNARE. The study found that Equine Grass Sickness, but not Botulism, causes neurodegeneration and increases the expression of SNARE proteins. This helps to uncover new insights about the possible causes of Equine Grass Sickness, indicating that it may not be caused by botulinum neurotoxins as previously thought.

Study Objective

• The research aims to determine whether botulism causes autonomic and enteric neurodegeneration (the progressive loss of structure or function of neurons, including death of neurons).
• Another goal is to investigate the effects of Equine Grass Sickness (EGS) on the expression of SNARE proteins within specific areas of the nervous system.

Method

• The study utilised light microscopy to compare the morphology of neurons in stained sections from horses affected by EGS, botulism, and control horses.
• Immunohistochemistry was used to compare the expression of certain proteins (synaptosomal-associated protein-25, synaptobrevin, and syntaxin) within the neurons of these horses.
• Additionally, the concentrations of these SNARE proteins were compared using quantitative fluorescent western blotting, a widely used analytical technique to detect specific proteins in a sample of tissue homogenate or extract.

Findings

• The study found that EGS, but not botulism, was associated with autonomic and enteric neurodegeneration. This means that horses suffering from EGS showed progressive degeneration of their neurons, unlike those affected by botulism.
• EGS was also linked to increased immunoreactivity for SNARE proteins within neuronal perikarya, indicating that EGS affects the expression of these proteins.
• Quantitative fluorescent western blotting confirmed increased concentrations of the studied proteins within extracts from EGS affected horses, supporting the earlier findings.

Conclusion

• The research concludes that the occurrence of autonomic and enteric neurodegeneration, and increased expression of SNARE proteins within neuronal perikarya, in EGS but not botulism, suggests that EGS may not be caused by botulinum neurotoxins.
• This insight disrupts the previous understanding of EGS, and suggests the need for further investigation into its cause.