Chronic treatment of haloperidol causes vasoconstriction on basilar arteries of rats, dose dependently.

Haloperidol is a widely used antipsychotic drug, which exerts its effects via antagonizing the dopaminergic D2 receptors. Also it affects a number of receptors on vascular bed and other tissues. The impact of haloperidol on vascular bed seems still debatable and not clear. In the present study, haloperidol was given to adult rats in 0.5, 1, 2.5 and 5 mg kg(-1) doses, once a day, intraperitoneally in 1 ml volumes, for 9 weeks. After decapitation under Pentothal anesthesia, brains and basilar arteries were dissected out at midpontine level immediately. Conventional histopathology and morphometric analysis were carried out on the dissected artery branches. Medial and adventitial layers, endothelial cells and internal elastic membranes were observed as normal in the control group. It was determined clearly that the lumen of basilar artery in the control group was larger than in the other groups and also it was observed that is more regular the lumen contours of basilar artery in control group compared with other groups. Finally, wall thickness of basilar artery in all experimental groups decreased significantly due to the vasoconstriction. Regarding the total, lumen and wall volumes, 1 mg kg(-1) haloperidol induces vasoconstriction more than the other groups.