Behavioral and electroencephalographic effects of the adenosine1 agonist, L-PIA.

The effects of N6-(L-2-phenylisopropyl)-adenosine (L-PIA), an A1 agonist, were measured on both spontaneous locomotor activity and electroencephalographic (EEG) measures of sleep in rats. L-PIA strongly inhibited motor activity at 100 micrograms/kg intraperitoneally (IP), a dose which had no statistically significant effects on EEG-defined sleep. A higher dose of L-PIA (200 micrograms/kg) increased the latency to sleep initiation and inhibited later REM sleep. These results demonstrate that L-PIA can produce a state of apparent behavioral quiescence in the presence of EEG-defined arousal.