The perifornical (PF) region of the posterior hypothalamus contains many GABAergic neurons and axon terminals; some of them inhibit cells that synthesize orexins (ORX), peptides important for the regulation of sleep-wake behavior, motor activity and energy balance. We previously reported (Kubin et al., SFN Abstr. 2002) that microinjections of bicuculline (BIC) into the PF region to antagonize the endogenous inhibition mediated by GABAA receptors reduce sleep, increase motor activity and stimulate c-fos expression in ORX neurons. To test whether the wake-promoting effects of BIC can occur without motor activation, we have now used unilateral microdialysis perfusion of the PF region with a low concentration of BIC (20 μM). Five rats were chronically instrumented (cortical, hippocampal and nuchal EMG activity). Sleep-wake and motor activity were recorded for 4 h of either a continuous perfusion with artificial csf or with BIC substituting for csf during the middle two hours. During the test period, BIC increa...