This study evaluated the effects of resveratrol on locomotor behaviors, neuronal and glial densities, and tyrosine hydroxylase immunoreactivity in the substantia nigra pars compacta of rats with streptozotocin-induced diabetes. Animals were divided into four groups: non-diabetic rats treated with saline (SAL), non-diabetic rats treated with resveratrol (RSV), diabetic rats treated with saline (DM) and diabetic rats treated with resveratrol (DM+RSV). The animals received oral gavage with resveratrol (20 mg/kg) for 35 days. The open field test and the bar test were performed to evaluate bradykinesia and akinesia, respectively. The Nissl-stained neuronal and glial densities and the dopaminergic neuronal density were estimated using planar morphometry. Tyrosine hydroxylase immunoreactivity was evaluated using regional and cellular optical densitometry. In relation to the locomotor behaviors, it was observed that the DM group developed akinesia, which was attenuated by resveratrol in the DM+RSV group, while the DM and DM+RSV groups showed bradykinesia. Our main morpho-physiological results demonstrated: a decrease in the cellular tyrosine hydroxylase immunoreactivity in the DM group, which was attenuated by resveratrol in the DM+RSV group; a higher neuronal density in the RSV group, when compared to the DM and DM+RSV groups; an increase in the glial density in the DM group, which was also reversed by resveratrol in the DM+RSV group. Resveratrol treatment prevents akinesia development and restores neuronal tyrosine hydroxylase immunoreactivity and glial density in the substantia nigra pars compacta of diabetic rats, suggesting that this polyphenol could be a potential therapeutic option against diabetes-induced nigrostriatal dysfunctions. [ABSTRACT FROM AUTHOR]