Fig.3.

Adenosine attenuates the amplitude of evoked EPSPs in hypocretin/orexin neurons. Whole-cell patch clamp experiments were performed in the presence of bicuculline (30 μM) in all solutions and the stimulating electrode was placed on the medial forebrain bundle (MFB). Evoked EPSPs (eEPSPs) were recorded in hypocretin/orexin neurons under current clamp and presented in A. In order to obtain a stable recording of eEPSP without triggering action potentials, hyperpolarizing current was injected to the recorded neurons to maintain the membrane potential between −60 to −70 mV. The amplitude of eEPSPs declined in the presence of adenosine and recovered after its removal. The time course of a typical experiment is plotted in B. C, pooled data from all experiments show that the amplitude of eEPSPs is significantly decreased by the application of adenosine (**, p<0.01, ANOVA). D, pooled data from all experiments show that the membrane potential of hypocretin/orexin neurons does not change (P>0.05, ANOVA). E-F, the membrane potential of hypocretin/orexin neurons recorded in the presence of TTX (1 μM). E, a sample trace from our experiments is presented (M.P., −68.0 mV). The application of adenosine is indicated with the filled bar and the dotted line represents the baseline of the recording. F, pooled data from all experiments show that adenosine does not cause any changes in membrane potential in the presence of TTX (P>0.05, ANOVA).