Marijuana’s Anxiety Relief Effects

Cannabinoid receptors, through which marijuana exerts its effects, have been found in a key emotional hub in the brain involved in regulating anxiety and the flight-or-fight response. This is the first time cannabinoid receptors have been identified in the central nucleus of the amygdala in a mouse model.
An international group led by Vanderbilt University researchers has found cannabinoid receptors, through which marijuana exerts its effects, in a key emotional hub in the brain involved in regulating anxiety and the flight-or-fight response.
The discovery may help explain why marijuana users say they take the drug mainly to reduce anxiety, said Sachin Patel, M.D., Ph.D., the paper’s senior author and professor of Psychiatry and of Molecular Physiology and Biophysics. The paper was published in the journal Neuron.
The researchers also showed for the first time how nerve cells in this part of the brain make and release their own natural “endocannabinoids.” Endocannabinoids are chemicals found in the endocannabinoid system, and are compounds that activate the same receptors as THC, the main active component in marijuana.
The study “could be highly important for understanding how cannabis exerts its behavioral effects,” Patel said. As the legalization of marijuana spreads across America and begins to be discussed in  many regions all across North America, more people — and especially young people whose brains are still developing — are being exposed to the drug.
MarijuanaBrain300 Photo Credit: Johnny Green,
Previous studies in this area both at Vanderbilt University and at other institutions have suggested the following:
  •  The natural endocannabinoid system regulates anxiety and the response to stress by dampening excitatory signals that involve the neurotransmitter glutamate.
  • Chronic stress or acute, severe emotional trauma can cause a reduction in both the production of endocannabinoids and the responsiveness of the receptors. Without their “buffering” effect, anxiety goes up.
  • While marijuana’s “exogenous” cannabinoids also can reduce anxiety, chronic use of the drug down-regulates the receptors, paradoxically increasing anxiety. This can trigger “a vicious cycle” of increasing marijuana use that in some cases leads to addiction.

The researchers at Vanderbilt involved in this study used high-affinity antibodies to label or mark the cannabinoid receptors so that they could be relatively easily seen using the various microscopy techniques utilized, including electron microscopy, which allowed for very detailed visualization at individual synapses between nerve cells.

“We know where the receptors are, we know their function, we know how these neurons make their own cannabinoids,” Patel said. “Now can we see how that system is affected by … stress and chronic (marijuana) use? It might fundamentally change our understanding of cellular communication in the amygdala.”

Sachin Patel, M.D., Ph.D., right, with Teniel Ramikie. The team found cannabinoid receptors in a part of the brain  involved in regulating anxiety. Photo Credit: Joe Howell and Vanderbilt University Press Release.



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