Structural evidence for the neurotoxicity of methylamphetamine in the frontal cortex of gerbils (Meriones unguiculatus): a light and electron microscopical study.

Morphological alterations in the CNS were investigated in young gerbils treated with two injections of methylamphetamine (Meth) 8 h apart and killed 3, 5 and 7 days after treatment. In gerbils treated with 2 X 35 mg/kg or higher doses of Meth and prepared according to the terminal degeneration method of Gallyas et al. (Stain Technol., 55 (1980) 299-306), silver precipitates occurred in lamina II and III of the frontal cortex. Electron microscopical studies showed degenerated terminals and neurons. After 3 days of survival we found affected but not degenerating pyramidal cells in the same area. Light microscopical observations after 5 and 7 days of survival indicate a recovery of these cells. All described morphological alterations could be suppressed when Meth was administered in combination with haloperidol. These data and the comparison of aminergic projections to the cortex are discussed on the basis of evidence that Meth induces alteration of mesocortical dopamine nerve fibers and their postsynaptic structures in the frontal cortex (FC). Present results indicate that morphological alterations in young gerbils after Meth treatment are limited to the FC. This is in contrast to the literature, which describes neurotoxic effects of Meth in the neostriatum of various adult mammalian species.