Localisation of dopamine D2-like receptors in pulmonary artery of the human and rabbit but not of the rat.
The present study was designed to investigate the presence of dopamine D2-like receptor sites in the main trunk of the human, rabbit and rat pulmonary artery using combined radioligand binding and light microscope autoradiography techniques. [3H]Spiroperidol was used as a ligand. The presence and the localisation of the sympathetic neuroeffector plexus were also studied using catecholamine histofluorescence techniques. Radioligand binding experiments demonstrated the labelling of a population of dopamine D2-like receptors in sections of human and rabbit pulmonary arteries by [3H]spiroperidol. No specific binding occurred in sections of the rat pulmonary artery. Light microscope autoradiography showed the development of specific silver grains within the tunica adventitia, including the adventitia-media border, of the human and rabbit pulmonary arteries. No specific silver grains were found in sections of the rat pulmonary artery. Studies on the pharmacological characterisation of [3H]spiroperidol binding sites in the human and rabbit pulmonary arteries showed that they are sensitive primarily to domperidone, haloperidol, (-)-sulpiride or bromocriptine, and to a lesser extent to n-propylnorapomorphine, quinpirole or clozapine displacement. This suggests that [3H]spiroperidol binding sites in the pulmonary artery probably belong to the dopamine D2 receptor subtype. Catecholamine histofluorescence techniques revealed a rich plexus of fluorescent adventitial and adventitial-medial nerve fibres in the human and to a lesser extent in the rabbit pulmonary artery. Comparison of the localisation of dopamine D2-like receptor sites and of the sympathetic neuroeffector plexus in the pulmonary artery, suggests a possible prejunctional localisation of these sites.
Kobayashi
Y
Y
Sezione di Anatomia Umana, Università di Camerino, Italy.
Cavallotti
D
D
Ricci
A
A
Amenta
F
F
D000368:Aged; D000818:Animals; D001345:Autoradiography; D002395:Catecholamines / Q000378:metabolism; D005455:Fluorescent Antibody Technique; D006651:Histocytochemistry; D006801:Humans; D008297:Male; D009451:Neuroeffector Junction / Q000187:drug effects; D011651:Pulmonary Artery / Q000033:anatomy & histology / Q000294:innervation / Q000378:metabolism*; D011817:Rabbits; D011869:Radioligand Assay; D051381:Rats; D017208:Rats, Wistar; D017448:Receptors, Dopamine D2 / Q000378:metabolism*; D013045:Species Specificity; D013134:Spiperone
D002395:Catecholamines; D017448:Receptors, Dopamine D2; D013134:Spiperone