Characterization of a novel endocannabinoid, virodhamine, with antagonist activity at the CB1 receptor.
The first endocannabinoid, anandamide, was discovered in 1992. Since then, two other endocannabinoid agonists have been identified, 2-arachidonyl glycerol and, more recently, noladin ether. Here, we report the identification and pharmacological characterization of a novel endocannabinoid, virodhamine, with antagonist properties at the CB1 cannabinoid receptor. Virodhamine is arachidonic acid and ethanolamine joined by an ester linkage. Concentrations of virodhamine measured by liquid chromatography atmospheric pressure chemical ionization-tandem mass spectrometry in rat brain and human hippocampus were similar to anandamide. In peripheral tissues that express the CB2 cannabinoid receptor, virodhamine concentrations were 2- to 9-fold higher than anandamide. In contrast to previously described endocannabinoids, virodhamine was a partial agonist with in vivo antagonist activity at the CB1 receptor. However, at the CB2 receptor, virodhamine acted as a full agonist. Transport of [(14)C]anandamide by RBL-2H3 cells was inhibited by virodhamine. Virodhamine produced hypothermia in the mouse and acted as an antagonist in the presence of anandamide both in vivo and in vitro. As a potential endogenous antagonist at the CB1 receptor, virodhamine adds a new form of regulation to the endocannabinoid system.
Porter
Amy C
AC
Lilly Research Laboratories, Neuroscience Division, Eli Lilly & Co., Lilly Corporate Center, Indianapolis, IN, USA.
Sauer
John-Michael
JM
Knierman
Michael D
MD
Becker
Gerald W
GW
Berna
Michael J
MJ
Bao
Jingqi
J
Nomikos
George G
GG
Carter
Petra
P
Bymaster
Frank P
FP
Leese
Andrea Baker
AB
Felder
Christian C
CC
D000818:Animals; D001095:Arachidonic Acids / Q000737:chemistry* / Q000378:metabolism / Q000494:pharmacology; D001831:Body Temperature / Q000187:drug effects / Q000502:physiology; D001921:Brain / Q000187:drug effects / Q000378:metabolism; D063385:Cannabinoid Receptor Modulators; D002186:Cannabinoids / Q000737:chemistry* / Q000378:metabolism / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D063388:Endocannabinoids; D019856:Ethanolamine / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology; D006624:Hippocampus / Q000737:chemistry / Q000378:metabolism; D008297:Male; D051379:Mice; D053284:Polyunsaturated Alkamides; D051381:Rats; D017208:Rats, Wistar; D043885:Receptor, Cannabinoid, CB2; D043882:Receptors, Cannabinoid; D011955:Receptors, Drug / Q000037:antagonists & inhibitors* / Q000378:metabolism*
D001095:Arachidonic Acids; D063385:Cannabinoid Receptor Modulators; D002186:Cannabinoids; C469526:Cnr2 protein, rat; D063388:Endocannabinoids; D053284:Polyunsaturated Alkamides; D043885:Receptor, Cannabinoid, CB2; D043882:Receptors, Cannabinoid; D011955:Receptors, Drug; C456739:virodhamine; D019856:Ethanolamine; C078814:anandamide