Lafora Disease and Alpha-Synucleinopathy in Two Adult Free-Ranging Moose (Alces alces) Presenting with Signs of Blindness and Circling

Abstract

Lafora disease is an autosomal recessive glycogen-storage disorder resulting from an accumulation of toxic polyglucosan bodies (PGBs) in the central nervous system, which causes behavioral and neurologic symptoms in humans and other animals. In this case study, brains collected from two young adult free-ranging moose (Alces alces) cows that were seemingly blind and found walking in circles were examined by light and electron microscopy. Microscopic analysis of the hippocampus of the brain revealed inclusion bodies resembling PGBs in the neuronal perikaryon, neuronal processes, and neuropil. These round inclusions measuring up to 30 microns in diameter were predominantly confined to the hippocampus region of the brain in both animals. The inclusions tested α-synuclein-negative by immunohistochemistry, α-synuclein-positive with PAS, GMS, and Bielschowsky's staining; and diastase-resistant with central basophilic cores and faintly radiating peripheral lines. Ultrastructural examination of the affected areas of the hippocampus showed non-membrane-bound aggregates of asymmetrically branching filaments that bifurcated regularly, consistent with PGBs in both animals. Additionally, α-synuclein immunopositivity was noted in the different regions of the hippocampus with accumulations of small granules ultrastructurally distinct from PGBs and morphologically compatible with alpha-synucleinopathy (Lewy body). The apparent blindness found in these moose could be related to an injury associated with secondary bacterial invasion; however, an accumulation of neurotoxicants (PGBs and α-synuclein) in retinal ganglions cells could also be the cause. This is the first report demonstrating Lafora disease with concurrent alpha-synucleinopathy (Lewy body neuropathy) in a non-domesticated animal.

Keywords: Lafora disease; Lewy body; blindness; circling; moose; polyglucosan bodies; synucleinopathies; α-Synuclein.

Figure 1

Hematoxylin and eosin (H&E)-stained section of hippocampus region of the brain of a moose showing round polyglucosan bodies (PGBs) in the perikaryon, neuronal processes, and neuropil. Note the outer pale layer and basophilic core.

Figure 2

Periodic acid-Schiff (PAS)-stained section of the hippocampus region of the brain of the same moose showing round polyglucosan (Lafora) bodies.

Figure 3

Grocott’s methenamine silver (GMS)-stained section of the hippocampus of the same moose showing dark-stained polyglucosan (Lafora) bodies.

Figure 4

(a) Low magnification (2x) showing a diastase-digested periodic acid-Schiff (PASD) section of the hippocampus of the same moose showing polyglucosan (Lafora) bodies; (b) higher magnification showing a diastase-digested periodic acid-Schiff (PASD) section of the hippocampus of the same moose showing polyglucosan (Lafora) bodies.

Figure 5

Bielschowsky’s silver-stained section of the hippocampus of the same moose showing dark-stained polyglucosan (Lafora) bodies.

Figure 6

Low-power electron micrograph of the perikaryon with polyglucosan bodies (PGBs) in neurons of the hippocampus of the same moose. Electron-dense core is the equivalent of the basophilic core seen in H&E-stained material.

Figure 7

Ultrastructure image showing branched filamentous material in a non-membrane-bound polyglucosan body (PGB).

Figure 8

IHC labeling using α-synuclein monoclonal antibodies to label α-synucleins in the neuropil of the hippocampus.

Figure 9

Ultrastructure image from the positively labeled area of the hippocampus with α-synuclein monoclonal antibodies showing electro- dense membranous inclusions (white arrows). Vesicles, lipid bodies (stars), and distorted mitochondria are also interspersed with the inclusions (black arrows).