Localization of dopamine receptor subtypes in systemic arteries

Dopamine D1-D5 receptor protein immunoreactivity was investigated in differ ent sized pial, renal and mesenteric artery branches using immunohistochemi cal techniques and anti-dopamine D1-D5 receptor protein antibodies. Faint d opamine D1 receptor protein immunoreactivity was observed in smooth muscle of tunica media of pial, renal and mesenteric artery branches Dopamine D2 r eceptor protein immunoreactivity was located in the adventitia and adventit ia-media border of pial and renal artery branches and to a lesser extent of mesenteric artery branches. No dopamine D3 receptor protein immunoreactivi ty was observed in pial and mesenteric arteries. In renal arteries a modera te dopamine D3 receptor immunoreactivity was detectable in the adventitia a nd adventitia-media border. A strong dopamine D4 receptor protein immunorea ctivity displaying the same localization of dopamine D2 receptor protein wa s observed in pial and mesenteric arteries, but not in renal artery branche s. Moderate dopamine D5 receptor protein immunoreactivity was observed in s mooth muscle of the tunica media of pial, renal and mesenteric artery branc hes. Bilateral removal of superior cervical ganglia, from which sympathetic supp ly to cerebral circulation originate abolished dopamine D2 and D4 receptor protein immunoreactivity in pial arteries but was without effect on dopamin e D1 and D5 receptor protein immunoreactivity. These findings indicate that systemic arteries express dopamine D1-like (D1 and D5) and D2-like (D2, D3 and D4) receptor subtypes displaying respectively a muscular (postjunction al) and prejunctional localization. The specific distribution of dopamine D 2-like receptor subtypes in systemic arteries suggests that they may have a different role in regulating blood flow through the vascular beds investig ated.