Nigrostriatal dopamine system mediates baroreflex sensitivity in rats.

Both sham-operated rats and rats with lesions of the nigrostriatal dopamine (DA) pathway were subjected to increasing or decreasing carotid sinus pressure (respectively produced by phenylephrine injection or bilateral carotid occlusion) and their striatal DA release and baroreflex responses were compared. In sham-operated rats, phenylephrine produced both increased striatal DA release and decreased heart rate, while bilateral carotid occlusion produced the opposite effects. Both the striatal DA release and baroreflex responses produced by phenylephrine or carotid occlusion were attenuated by lesions of the nigrostriatal DA pathway induced by intramedial forebrain bundle injection of 6-hydroxydopamine. The data indicate that the nigrostriatal DA pathway mediates baroreflex sensitivity in rats.