For the first time, cannabinoid receptors, with which the active compounds in cannabis interact, have been shown to be present in a part of the brain involved in emotional reactions. Published in the journal Neuron, the research may offer new insight into how the effects of cannabis are exerted, according to Sachin Patel at Vanderbilt University, Tennessee.
Patel and his group have been looking at the body’s own production of cannabinoids – the large class of compounds that act on these receptors. Although first discovered in cannabis plants, subsequent studies found that humans and other animals produce their own set of cannabinoids – known as endocannabinoids.
Teniel Ramikie, a postgraduate student in Patel’s lab, used antibodies to target cannabinoid receptors in the brains of mice. This allowed her to locate them very precisely using a microscope. She was able to find them in nuclei in the brain called amygdalae. These small regions have been shown to have increased activity in people with some anxiety disorders. They may also be involved in fear response, with increased function leading to paranoia.
The endocannabinoid system is thought to play a role in regulating anxiety. When we become stressed or experience emotional trauma, production of these compounds slows down. The cannabinoids in cannabis have a similar effect on reducing feelings of anxiety. However, Patel believes that chronic cannabis use may make the cannabinoid receptors less responsive. This could mean that long term use has the effect of increasing anxiety.
“We know where the receptors are, we know their function, we know how these neurons make their own cannabinoids,” Patel added. “Now can we see how that system is affected by … stress and chronic [cannabis] use.”