l-Dopa improves locomotor phenotype but does not lessen dopaminergic neuron loss. A, Negative geotaxis assay of adult flies exposed previously for 7 d to 125 μm rotenone, 1 mm l-dopa, or both, compared with control flies maintained in the absence of drugs. Representation and statistics are the same as in Figure 1 A. B, Quantification of neurons in control brains and in brains of flies exposed for 7 d to 125 μm rotenone (R) with or without 1 mm l-dopa (LD). The number of dopaminergic neurons and the loss of cells as a result of rotenone exposure were not significantly altered by l-dopa. n indicates the number of brain hemispheres examined in each condition. Statistics are the same as in Figure 1C.