SUB-LETHAL DOSES OF EPSILON TOXIN INDUCES NEURODEGENERATIVE CHANGES, IN THE MOUSE BRAIN

W.E. MORRIS; J. GOLDSTEIN; P. GEOGHEGAN; A. CANGELOSI; C.F. LOIDL; C. CAPELLINO; M. FERNANDEZ-MIYAKAWA

Roma

Conferencia; 6th ClostPath International Conference; 2009

Istituto Superiore di Sanita

Clostridium perfringens type D enterotoxaemia is a disease that affects predominantly sheep and goats . The main histological changes observed in the brain are perivascular oedema which, occasionally, progresses to focal symmetric encephalomalacia. In both, experimental models and spontaneous outbreaks, lethal concentrations of this toxin affects the endothelial cells in the brain vasculature, inducing oedema and sudden death. It has been reported that sublethal doses of this toxin induces neurological changes through a massive neurotransmitter release. However, data on the effects of sub-lethal epsilon toxin doses is still scant. This study characterizes the histological and ultrastructural changes in the brain of rats and mice after sub-lethal doses of epsilon toxin. Groups of 4 mice were inoculated intravenously with sub-lethal doses of epsilon toxin (5, 0.5, 0.25, 0.125, 0.06 LD50) or vehicle and four Sprague Dawley rats were injected via the right lateral ventricle, with either epsilon toxin (0.05 LD50) or vehicle. In mice, the experiments lasted to 96 hours, in which some animals were given a toxin booster. Rats were euthanized 4h after inoculation. All animals were kept under standard housing condition throughout the experiment. In some animals, behaviour parameters were recorded. Animals were either perfused intracardiacally with 10% formalin or 2% glutaraldehyde, and the brains were removed and processed for haematoxylin and eosin stainings, Fluorojade-B, immunohistochemistry to detect active caspase-3 and transmission electron microscopy (TEM). Several toxin-inoculated mice –but no control- exhibited sporadic convulsive episodes after the inoculation until the euthanasia. Both, haematoxylin & eosin and Fluorojade-B stainings revealed shrunken degenerative neurons, with chromatolysis and axon swelling. These changes were seen predominantly in the hippocampus, cortex, striatum, and brain stem. At the ultrastructural level, increased neurofilaments in neurons and glial processes between pre- and post-synapses were observed. These results provide evidences of synaptic disruption observed at the EM level, which are in concordance with previous morphologic observations in CNS after sublethal epsilon toxin doses. The presence of glial processes between pre and post synapses may be an attempt of the CNS to block a massive neurotransmitter release.