Mechanical and enzymatic isolation of mammalian CNS neurons

Neurons were isolated from various regions of the central nervous system (CNS), by both enzymatic and mechanical isolation. These neurons were isolated from the brains of 3-21-day-old and adult rats, guinea pigs and kittens. Particular attention was directed to the thickness of the slice, the enzymes used and the treatment time, the ionic composition, pH and buffer of the bathing medium, the pipetting of brain slices after enzyme treatment, and the preservation of the isolated cells. The isolated neurons had long dendrites with numerous branchings and a typical morphological shape: e.g. the pyramidal neurons of the rat hippocampus had apical dendrites over 250 micron long; those of the rat neocortex had apical dendrites longer than 300 micron; the Purkinje cells of the rat and kitten also maintained dendrites with fifth branchings. All isolated neurons had well-preserved electrical and chemical membrane properties of the voltage-dependent channels and the receptor-ionophore complexes respectively, even after the enzyme treatment. Thus, these isolated CNS neurons having a well-preserved morphological state can be used extensively for electrophysiological and pharmacological studies on voltage-dependent and drug-gated ionic channels.