Sagittal section of an Nr4a1-eGFP transgenic mouse stained for the CB1 cannabinoid receptor and DAPI to show nucleiWIKIMEDIA, NIHThe mammalian central nervous system is studded with receptors that bind with a small number of endogenous cannabinoids, as well as those found in marijuana. Marijuana is known to promote heightened social connection, but the mechanism for this phenomenon was not well understood. According to a paper published today (October 26) in PNAS, it is social interaction between mice plus oxytocin—the hormone involved in social bonding—that drive cannabinoid activity in the animals’ brains.
“It was a great surprise to see how powerful the effects of social contact are on production of anandamide in select regions of the brain,” said study coauthor Daniele Piomelli, a neuroscientist at the University of California, Irvine.
The brain has two known cannabinoid receptors, types 1 and 2 (CB1 and CB2). Two main endocannabinoids bind with CB1, anandamide and 2-Arachidonoylglycerol (2-AG), as do plant cannabinoids such as tetrahydrocannabinol (THC), the main psychoactive compound in marijuana.
To study the behavioral effects of oxytocin, endocannabinoids, and social interaction, Poimelli and his colleagues isolated mice for 24 hours, then allowed them to either socialize with other mice or remain in isolation for another three hours. The researchers found that the mice that were allowed to socialize had ...
