Morphological, biochemical and molecular effects of cocaine on mouse neuroblastoma cells culture in vitro

In order to compare the effects of cocaine at morphological, basal cytotoxicity, biochemical and molecular levels, cultured mouse neuroblastoma cells (Neuro-2a) were exposed to a range of concentrations of cocaine hydrochloride. Neuroblastoma cell proliferation, evaluated by quantification of total protein content, was very sensitive to cocaine, being increasingly inhibited from 12 to 72 hr of exposure (EC(50) = 3.1 mm at 24 hr). Cytoplasmic membrane permeability to lactate dehydrogenase was not particularly increased and lysosomal function was stimulated from 0.05 to 1.5 mm, and inhibited from 2.5 mm. A shift to anaerobiosis was detected as intracellular lactate dehydrogenase (LDH) activity was increased and mitochondrial succinate dehydrogenase (SDH) activity decreased. Hexosaminidase (HEX), a lysosomal enzyme involved in sphingolipid degradation, was stimulated only at 1 mm and neural acetylcholinesterase (AChE) activity was stimulated from 2.5 mm. Morphological examination of exposed cultures revealed that most cells became bipolar and multipolar neurons by extension of neurites, but also suffered cytoplasmic vacuolization, hydropic degeneration and nuclear pyknosis. Although cells developing apoptosis were observed, no DNA oligonucleosomal fragmentation was detected by agarose gel electrophoresis of DNA from cells exposed to cocaine. In conclusion, in addition to predominance of anaerobiosis, little disruption of membranes and severe morphologic injury, biochemical and morphological differentiation-like effects were the most prominent alterations produced by cocaine on mouse neuroblastoma cells.