Fig. 1. Clinically relevant concentrations of propofol do not induce cell death but alter dendritic differentiation of developing γ-aminobutyric acid–positive neurons. ( A ) Forty-eight hours after seeding, isolated neuroblasts survive and differentiate under serum-free conditions. ( B ) These cells develop a highly complex arborization pattern by the end of the first week in vitro . ( C ) The presence of propofol (5 μg/ml) in the culture medium reduces dendritic arbor development, and ( D ) this effect is even more pronounced at higher concentrations (50 μg/ml) of propofol. ( E ) In contrast to propofol, midazolam (2.5 μg/ml) does not affect development of γ-aminobutyric acid–positive neurons. ( F ) Quantitative assessment of cell survival shows that, similar to control conditions, midazolam (2.5 μg/ml) as well as propofol at a concentration of 5 μg/ml does not induce cell death. In contrast, significant cell loss is observed when propofol is applied at 50 μg/ml. In A–E , cells were stained with an anti–γ-aminobutyric acid antibody. Correction bar ( A–I ): 150 μm. In E , results are presented as mean ± SEM; n = 3 independent experiences for each time point and each treatment expressed. Values are expressed as the number neurons/mm2. * P < 0.05 compared with the untreated control group.