Brain Reaggregate Cultures in Neurotoxicological Investigations: Studies with Cholinergic Neurotoxins

Abstract

The number of neurotoxicants which produce ‘lesions’ in organotypic brain reaggregate cultures in vitro, which correlate with known in vivo actions, is growing. With respect to cholinergic neurones, this includes kainic acid, organophosphorus compounds and, in our hands, ethylcholine mustard aziridinium (ECMA) and aluminium. We have demonstrated that in vitro exposure to low concentrations of ECMA (12.5μM) produces a two-stage lesion in rat whole-brain reaggregate cultures, corresponding to initial direct inhibition of choline acetyltransferase (ChAT), followed by a later loss of cholinergic neurones. Higher concentrations of ECMA (25–50μM) are more generally cytotoxic and also cause lesions in non-cholinergic cerebellar granule neurones in monolayer culture. Aluminium (0.1–0.01mM) similarly reduces ChAT activity in rat whole-brain reaggregate cultures. Both agents may be useful in providing brain cholinergic lesions in vitro analagous to those occurring in types of dementia in vivo. The use of brain reaggregates in a ‘stepwise’ procedure for testing potential neurotoxicants is also described.