The human eye expresses high levels of CB1 cannabinoid receptor mRNA and protein

We used reverse transcriptase polymerase chain reaction to detect the expre ssion of the central and peripheral cannabinoid receptors (CB1 and CB2, res pectively) mRNA, and Western blotting to show the presence of the CB1 prote in in subregions of the human eye. CB2 mRNA transcripts were undetectable, while levels of CB1 mRNA were significantly expressed in the human retina ( 25.8 +/- 2.46%), ciliary body (210 +/- 11.55%) and iris (62.7 +/- 5.94%) wh en compared with those of the normalizing reference gene beta(2) microglobu lin. The CB1 gene encodes a functional protein which is detected in its gly cosylated (63 kDa) and unglycosylated (54 kDa) form in the same areas by a specific purified antibody raised against the amino terminus (residues 1-77 ) of the CB1 receptor. These results further support the proposed role of t he CB1 receptor in controlling intraocular pressure, helping to explain the antiglaucoma properties of marijuana.