Involvement of neuronal cell bodies of the mesencephalic locomotor region in the initiation of locomotor activity of freely behaving rats.

The locomotor activity of freely-moving rats was increased substantially by injections of L-sodium glutamate or of picrotoxin, a GABA antagonist, into the region of the tegmental pedunculopontine nucleus. The onset of hyper-motility was more rapid with L-glutamate than with picrotoxin and the duration shorter. Locomotor activity from injecting amphetamine unilaterally into the nucleus accumbens was reduced by injections of GABA into the ipsilateral pedunculopontine nucleus. These observations provide additional evidence implicating neurons of the MLR and possibly GABA synaptic inputs to these neurons in locomotor activity and suggest that they may mediate indirect inputs from the nucleus accumbens.