PERINATAL MORPHINE .2. CHANGES IN CORTICAL PLASTICITY

We have previously shown that perinatal exposure to morphine impairs r eactive plasticity of serotonin (5-HT) neurons following selective neo natal lesion (Gorio et al., J Neurosci Res 34:462-471, 1993), This stu dy shows that morphine inhibits also that the compensatory sprouting o f intact axons after partial denervation, Neonatal 6-OHDA injection ca uses norepinephrine (NE) depletion in the frontal cortex, which trigge rs a compensatory increase of dopamine, serotonin (5-HT), and met-enke phalin content correlated by the increased density of tyrosine hydroxy lase- and 5-HT-positive axons, In perinatal morphine-treated rats, no compensatory changes are observed after neonatal 6-OHDA depletion of N E in the frontal cortex. (C) 1995 Wiley-Liss, Inc.