During a stressful event, the adrenal gland secretes a corticosteroid hormone that acts in the brain to stimulate the production of endocannabinoid within the amygdala.
The endocannabinoid is produced at inhibitory synapses and suppresses inhibition in the amygdala. Synapses are junctions between nerve cells that allow the cells to communicate with each other and form the neural circuits responsible for generating behavior. Neural circuits are controlled by a balance of excitatory and inhibitory synapses, the relative weighting of which determines a given circuit’s state of excitability and output.
“The more excited the circuit, the greater the output of that circuit,” Tasker says. “The endocannabinoid suppresses inhibitory synapses, causing the amygdala to be excited and to increase its output, which leads to a state of anxiety.”