Case Report: Synucleinopathy Associated WithNeurotoxicity in Sheep.

Abstract

Chronic intoxication with tryptamine-alkaloid-richspecies (spp.) pasture plants is known colloquially asstaggers syndrome, a widely occurring neurological disorder of sheep, cattle, horses, and kangaroos. Of comparative interest, structurally analogous tryptamine-alkaloids cause experimental parkinsonism in primates. This study aimed to investigate the neuropathological changes associated with spontaneous cases ofstaggers in sheep with respect to those encountered in human synucleinopathy. In sheep affected withstaggers, histological, immunohistochemical, and immunofluorescence analysis revealed significant accumulation of neuromelanin and aggregated α-synuclein in the perikaryon of neurons in the cerebral cortex, thalamus, brainstem, and spinal cord. Neuronal intracytoplasmic Lewy bodies inclusions were not observed in these cases of ovinestaggers. These important findings established a clear link between synucleinopathy and the neurologic form ofplant poisoning in sheep, demonstrated in six of six affected sheep. Synucleinopathy is a feature of a number of progressive and fatal neurodegenerative disorders of man and may be a common endpoint of such disorders, which in a variety of ways perturb neuronal function. However, whether primary to the degenerative process or a consequence of it awaits clarification in an appropriate model system.