Time-Dependent Effects of Neonatal Methamphetamine Exposure on Catecholamines but Not Oxidative Stress in the Hippocampus and Striatum of Male Rats.

Methamphetamine (MA) is a widely abused psychostimulant known to affect monoaminergic systems, with neurotoxic effects often associated with oxidative stress. The present study investigated the early effects of repeated neonatal MA exposure on dopamine (DA), noradrenaline (NA), and selected markers of oxidative status in the hippocampus and striatum of male rats. MA (5 mg/kg/day, s.c.; PND 1-12) significantly reduced DA levels in both brain regions on PND 12, while lipid peroxidation (TBARS) and antioxidant capacity remained unchanged. By PND 28, the early reduction in DA was no longer detectable, and neonatal MA exposure did not significantly affect body weight within either exposure paradigm. In the indirect-exposure paradigm, post-weaning isolation was associated with increased noradrenaline concentrations, whereas no corresponding housing effect was detected in the direct-injection paradigm; however, treatment × housing interactions were not significantThese findings indicate that early postnatal MA exposure induces transient alterations in dopaminergic neurotransmission without detectable changes in markers of lipid peroxidation, suggesting a normalization of DA levels during early adolescence. Overall, under the present experimental conditions, lipid peroxidation does not appear to be a major contributing mechanism to the observed neurochemical changes.