Neuronal Cell Cultures and Digitized Fluorescent Imaging of Intracellular Calcium as Tools for in Vitro Drug Screening

Isolated cultures of neonatal mouse brain cortex grown on coverslips offer an unique opportunity to apply optical recording techniques to clarify the neurotoxic or neuroprotective potential of drugs. Being a key modulator of neuronal function, excessive or sustained intracellular calcium accumulation has been implicated as a trigger for neuronal degeneration and therefore be termed the final common pathway of cell death. This discovery_has opened up new avenues of therapeutic intervention in a variety of acute and progressive neurodegenerative diseases and for the development of new in vitro screening models. The purpose of the study was to develop an in vitro assay in which individual neurons can be analysed quantitatively with respect to their calcium dynamics upon the action of agonistic or antagonistic test substances and the temporal relationship between ion deregulation and cell death. To measure cytosolic free calcium with high spatial and temporal resolution in living neurons we used the fluorescent calcium indicator fora-2 in combination with low light level TV camera and digital imaging. It is anticipated that the described in vitro assay may supplement currently used animal tests for drug development.