Fig. 1.

Electrophysiological properties of dopaminergic neurons and their response to orexins. A, Double stainings of biocytin-filled neuron (red) and TH-immunoreactive neurons (green).Arrows indicate the position of the neuron in the tissue. This biocytin-filled neuron is TH positive. Scale bar, 50 μm.B, Voltage responses to current pulses (−0.4, 0, +0.1 pA). C, Chart recording of membrane potential and spontaneous action potentials before and after application of orexin A (100 nm). Orexin A was applied for 2 min. D, Orexin B (100 nm) caused depolarization in the presence of tetrodotoxin (0.5 μm). E, Example of a TH-positive neuron in which application of orexin B (100 nm) caused burst firing. F, A typical orexin-mediated burst.