No abstract

(+/-)3,4-Methylenedioxymethamphetamine (MDMA) is a popular recreational drug that has been proposed to be useful as an adjunct to psychotherapy. This study assessed the neurotoxic potential of MDMA in nonhuman primates. Monkeys were repeatedly administered doses (2.50, 3.75, and 5.00 mg/kg) of MDMA subcutaneously and analyzed for regional brain content of serotonin and 5-hydroxyindoleacetic acid two weeks later. In all regions of the monkey brain examined, MDMA produced a selective dose-related depletion of serotonin and 5-hydroxyindoleacetic acid. These neurochemical deficits were associated with evidence of structural damage to serotonergic nerve fibers. In addition, MDMA produced pathological changes in nerve cell bodies in the dorsal, but not median, raphe nucleus. These results indicate that MDMA is a selective serotonergic neurotoxin in nonhuman primates and that humans using this drug may be at risk for incurring central serotonergic neuronal damage.

Systemic administration of the recently discovered neurotoxin 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) produces severe clinical parkinsonism and degeneration of the substantia nigra in humans and monkeys. In previous studies, no convincing structural damage to nerve cells outside the substantia nigra could be demonstrated in subhuman primates. Using a protracted MPTP regimen and older animals, we now report locus ceruleus lesions and eosinophilic inclusion bodies in squirrel monkeys. The inclusions were seen only in areas where Lewy bodies are found in human Parkinson's disease. No such abnormalities were seen in control animals. These findings suggest that similarities between the neuropathology of MPTP-induced parkinsonism in the monkey and human Parkinson's disease are greater than first thought and increase the usefulness of the MPTP monkey model for research in Parkinson's disease.

The effects of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) on ATP levels in different areas of mouse brain were studied after rapid fixation of cerebral tissue in situ by microwave irradiation. ATP levels in the striatum, ventral mesencephalon, and cerebellum of untreated C57BL/6 mice killed by microwave irradiation were 2-3 times greater than values measured in the brains of animals killed by cervical dislocation. In microwaved mice, administration of MPTP (40 mg/kg s.c.) caused a 10-20% decrease in ATP concentrations as compared to control animals injected with saline. This decrease was relatively rapid and selective because it occurred in both the striatum and ventral mesencephalon, but not in the cerebellar and frontal cortex, at 30, 60, 120, and 240 min after MPTP exposure. Furthermore, ATP loss in the striatum was prevented by mazindol, a catecholamine uptake blocker, indicating a rather selective effect of MPTP on the ATP content of dopaminergic terminals. Results of this study are consistent with mitochondrial damage in the MPTP model of parkinsonism and provide the first direct experimental evidence in vivo that a decrease in ATP may play a role in MPTP-induced neurotoxicity.