5-Hydroxytryptamine-induced locomotor rhythm in the neonatal mouse spinal cord in vitro

We examined the 5-hydroxytryptamine (5-HT)-induced locomotor rhythm in isol ated spinal cord preparations taken from neonatal mice on postnatal day (P) 0-3. Motor activity was recorded from L2 and L5 ventral roots. Bath applic ation of 5-HT (15-100 mu M) evoked rhythmic bursts that alternated between the two sides, and the bursts in the L2 ventral root alternated with those in the ipsilateral L5 ventral root. After transection of the mid-lumbar cor d, the locomotor rhythm in L2 persisted, while that in the L5 ventral root was abolished. This suggests that the upper lumbar region has a greater abi lity to generate a locomotor rhythm than the lower lumbar spinal cord. Kynu renate, a broad-spectrum glutamate receptor antagonist, blocked the 5-HT-in duced locomotor rhythm indicating that ionotropic glutamate receptors are r equired for the rhythm to be generated. (C) 2000 Elsevier Science Ireland L td. All rights reserved.