HYPERACTIVITY IN THE OFFSPRING OF NICOTINE-TREATED RATS - ROLE OF THE MESOLIMBIC AND NIGROSTRIATAL DOPAMINERGIC PATHWAYS

To evaluate the involvement of the mesolimbic and nigrostriatal dopaminergic systems in hyperactivity in offspring of nicotine-treated dams, timed-pregnant Sprague-Dawley rats were implanted SC on gestational day 4 with osmotic minipumps to receive saline or nicotine (3 or 6 mg/kg/day) for 16 days. Hyperactive and nonhyperactive male offspring of nicotine-treated dams as well as nonhyperactive offspring of saline-treated darns were selected and sacrificed at day 22 postnatally. Discrete brain areas (the nucleus accumbens [NAcc], striatum [STR], frontal cortex [FC], ventral tegmental area [VTA], and substantia nigra [SN]) were microdissected for the evaluation of dopamine (DA) concentration and/or the D-2 receptor subtype. Dopamine concentration was decreased in the VTA and STR but was increased in the SN of the hyperactive offspring. The reduction in striatal DA level was associated with a reduction in the number of D-2 receptors in that area. The data suggest a role for the VTA and striatal dopaminergic system in offspring hyperactivity.