Increased CB sub(2) mRNA and anandamide in human blood after cessation of cannabis abuse

In previous studies, long-term cannabis use led to alterations of the endocannabinoid system including an increase in CB sub(1) and/or CB sub(2) receptor messenger RNA (mRNA) in blood cells and an increase in the serum level of the endocannabinoid 2-arachidonoyl glycerol. However, in those studies, cannabis use was stopped only few days before testing or not interrupted at all. Therefore, one cannot decide whether the alterations are due to long-term cannabis abuse or are confounded by acute effects of cannabis. Blood was sampled from donors that had smoked marijuana greater than or equal to 20 times in their lives but had abstained from cannabis for greater than or equal to 6 months (high-frequency users, HFU) and from controls (cannabis use less than or equal to 5 times lifetime). CB sub(1) and CB sub(2) mRNA was determined in peripheral mononuclear blood cells using the reverse transcriptase polymerase chain reaction. Serum anandamide level was assayed using electrospray tandem mass spectrometry. CB sub(2) mRNA was increased by 45 % in HFU when compared to controls, whereas CB sub(1) mRNA did not differ. The anandamide level in HFU exceeded that in controls by 90 %. Tobacco smoking could be excluded as a confounding factor. In conclusion, marijuana users that had smoked marijuana greater than or equal to 20 times in their lives and stopped cannabis use at least 6 months before the study show an increase in CB sub(2) receptor mRNA in the blood and in serum anandamide level. These alterations resemble those obtained for marijuana smokers that had stopped cannabis use only few days before testing and may be implicated in the pathogenesis of disorders associated with long-term cannabis use.