Actions of a tremorgenic mycotoxin on amino acid transmitter release in vivo

The tremorgenic mycotoxin verruculogen was administered directly into the brain of freely moving rats by the use of cannula systems that superfused either the cortical surface or the lateral ventricular space. The tremor produced by these CNS routes was compared with that produced by i.p. administration of the toxin or the dried mycelium of the fungus that synthesizes the verruculogen. The nature and degree of tremor produced by the central vs peripheral routes suggest that the site of action of verruculogen is not immediately adjacent to the cannula sites in the brain. Measures of the amino acids in the superfusates collected during the verruculogen-induced tremor showed an increase in the excitatory neurotransmitters, glutamate and aspartate in superfusates from the lateral ventricle but not in superfusates from the cortical surface. The differential effect on transmitter release suggests that a subcortical action of verruculogen is responsible for its tremorgenic activity.