Observations on the interstitial cells of Cajal and neurons in a recovered case of equine dysautonomia (grass sickness).

The research study details the changes that occur in the nervous system of a horse that has recovered from equine dysautonomia, a disease affecting the digestive system, with the particular focus on a specialized cell type, the interstitial cells of Cajal, in the intestinal tract.

Context and Research Objectives

• The study investigates a known case of equine dysautonomia (ED), which is a neurological disease affecting horses that majorly perturbs the functioning of their digestive systems.
• The main focus is to understand the pathological changes in the horse’s central, autonomic, and enteric nervous system post-recovery from ED, without any significant residual clinical signs.

Research Findings

• The research did not find evidence of neuronal degeneration, like neuronal chromatolysis, glial scars, or a drop in neuron density in the the midbrain, pons, medulla oblongata or the spinal cord. This also included the nuclei of certain cranial nerves, indicating that neurons affected in ED may not undergo cell death. This finding challenges previous assumptions on destructive diseases like ED.
• The autonomic ganglia showed evidence of previous neuronal loss indicating disease incidence. Moreover, in the ileum’s myenteric and submucosal plexuses, there was a significant loss of enteric neurons, which substantiates the impact of ED on the enteric nervous system.
• However, the researchers also found a continuous network of interstitial cells of Cajal (ICCs) in the ileum via immunohistochemical techniques. ICCs perform a critical pacemaker function in the gastrointestinal tract, regulate smooth muscle contraction, and facilitate digestion.

Conclusions

• The study suggests that the recovery seen in this ED case, without significant residual clinical signs, could very likely be linked to the lack of extensive damage to, or the likelihood of recovery of the interstitial cells of Cajal (ICCs) in the ileum. This protective or resilient feature of the ICCs is a novel finding that opens up potential avenues in the treatment and management of diseases like ED.