Locomotion in rats transplanted with noradrenergic neurons.

It is known that catecholaminergic drugs can induce both locomotion and a late flexion reflex in spinalized animals. We studied spinal reflexes and locomotor activity in five adult spinal rats which had received a suspension of fetal noradrenergic (NA) neurons below the transection and in three control spinal rats. A rhythmical activity similar to the one of locomotion was regularly observed in three of the grafted rats held above a moving belt. In two of them, the step frequency was increased when the velocity of the moving belt was increased. This was not observed in control rats. A late flexion reflex was obtained in grafted rats that displayed locomotor activity, as well as in two controls. In the two rats which exhibited locomotor activity, analysis showed numerous immunoreactivite (against NA) cells and processes with terminals concentrated around the perikarya of motoneurones.