Reversal of akinesia and release of festination by morphine or GABA applied focally to the nucleus reticularis tegmenti pontis

Focal application of 5 μg of morphine sulfate to the nucleus reticularis tegmenti pontis (NRTP) in rats reversed the akinesia induced by 5 mg/kg systemic haloperidol or 40 mg/kg systemic morphine and released festinating forward locomotion. γ-Aminobutyric acid (200 μg) applied to this nucleus also reversed such kinesia. Intraventricular naloxone (10μg) or picrotoxin (0.1μg), respectively, blocked the effects of such focally applied drugs. Thus, morphine and γ-aminobutyric acid appear to act physiologically on the cells of the NRTP. The results suggest that suystemic morphine, in addition to producing immobility, simultaneously facilitates a readiness for locomotion by inactivating a final common inhibitory system in the region of the NRTP.