Immunohistochemical localization of cerebrovascular cannabinoid CB1 receptor protein.
Cannabinoids are powerful hypotensives and vasodilators. However, their mode of action is controversial. This study is the first to investigate the distribution of vascular CB1 receptor protein expression in situ. We used double-fluorescence and chromogenic immunohistochemistry to investigate patterns of CB1 protein expression in cerebrovascular tissue in rat brain sections. We found a layer of intense CB1 labeling immediately adjacent to the internal elastic lamina, consistent with myointimal and vascular smooth muscle cells, and diffuse labeling adventitial to this layer. We concluded that CB1 receptor are most intensely expressed in the vascular smooth muscle layer in cerebral arteries, and are likely to be chiefly responsible for the potent vasodilatory effect of cannabinoids.
Ashton
John C
JC
Department of Pharmacology and Toxicology, School of Medical Sciences, University of Otago Medical School, University of Otago, Dunedin, New Zealand. john.ashton@stonebow.otago.ac.nz
Appleton
Ian
I
Darlington
Cynthia L
CL
Smith
Paul F
PF
D015100:3,3'-Diaminobenzidine / Q000737:chemistry; D000818:Animals; D000918:Antibody Specificity / Q000276:immunology; D002536:Cerebral Arteries / Q000737:chemistry* / Q000187:drug effects; D002863:Chromogenic Compounds / Q000737:chemistry; D004547:Elastic Tissue / Q000276:immunology / Q000473:pathology; D005455:Fluorescent Antibody Technique / Q000379:methods; D005456:Fluorescent Dyes / Q000737:chemistry; D007150:Immunohistochemistry / Q000379:methods*; D009131:Muscle, Smooth, Vascular / Q000276:immunology / Q000473:pathology; D009520:New Zealand; D051381:Rats; D017208:Rats, Wistar; D043884:Receptor, Cannabinoid, CB1 / Q000032:analysis*; D013194:Staining and Labeling / Q000379:methods; D017539:Tunica Intima / Q000276:immunology / Q000473:pathology
D002863:Chromogenic Compounds; D005456:Fluorescent Dyes; D043884:Receptor, Cannabinoid, CB1; D015100:3,3'-Diaminobenzidine