POSTNATAL METHADONE EXPOSURE DOES NOT PREVENT PRENATAL METHADONE-INDUCED CHANGES IN STRIATAL CHOLINERGIC NEURONS

On postnatal day 4, rats exposed to methadone prenatally but fostered to control darns, as well as those fostered to darns treated with meth adone, exhibited significant reductions in striatal acetylcholine (ACh ) content. This suggests that neonatal withdrawal from methadone is no t responsible for the effects of prenatal exposure on cholinergic deve lopment in the early perinatal period. The effects of perinatal exposu re to methadone on serotonin (5HT) and dopamine (DA) metabolism do not appear to be strictly related to changes in ACh content. Although pre natal exposure reduces 5-hydroxyindole acetic acid (5HIAA) content, ch anges in SPIT content prevent significant changes in the ratio 5HIAA/5 HT. Pups exposed to methadone only prenatally (withdrawal group) exhib ited a decreased DOPAC/DA ratio, whereas pups in the treatment group e xposed to methadone both pre- and postnatally exhibited an increased D OPAC/DA ratio.