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

To evaluate the involvement of the mesolimbic and nigrostriatal dopami nergic systems in hyperactivity in offspring of nicotine-treated dams, timed-pregnant Sprague-Dawley rats were implanted SC on gestational d ay 4 with osmotic minipumps to receive saline or nicotine (3 or 6 mg/k g/day) for 16 days. Hyperactive and nonhyperactive male offspring of n icotine-treated dams as well as nonhyperactive offspring of saline-tre ated darns were selected and sacrificed at day 22 postnatally. Discret e brain areas (the nucleus accumbens [NAcc], striatum [STR], frontal c ortex [FC], ventral tegmental area [VTA], and substantia nigra [SN]) w ere microdissected for the evaluation of dopamine (DA) concentration a nd/or the D-2 receptor subtype. Dopamine concentration was decreased i n the VTA and STR but was increased in the SN of the hyperactive offsp ring. The reduction in striatal DA level was associated with a reducti on in the number of D-2 receptors in that area. The data suggest a rol e for the VTA and striatal dopaminergic system in offspring hyperactiv ity.