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

In 22 male Long-Evans hooded rats, focal application of 5 μg of morphine sulfate to the nucleus reticularis tegmenti pontis (NRTP) reversed the akinesia induced by ip haloperidol (5 mg/kg) or morphine (40 mg/kg) and released festinating forward locomotion. GABA (200 μg) applied to this nucleus also reversed such akinesia. Intraventricular naloxone (10 μg) or picrotoxin (0.1 μg) blocked the effects of such focally applied drugs. Thus, morphine and GABA appear to act physiologically on the cells of the NRTP. Results suggest that systemic 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. (10 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)