Everybody experiences stress. Stress is the body's psychological and biological reaction to a stimulus that is perceived as a threat or to a situation that is considered to be beyond the individual's ability to cope.
Fight or Flight
When faced with a stressor, the body responds by going into a fight-or-flight mode. The hypothalamus, located in the brain, triggers the release of stress hormones that prepare the person to either fight or run. The blood is infused with elevated levels of adrenaline, cortisol and other chemicals that cause rapid breathing, increased heart rate, higher blood pressure, and dilated pupils. Muscles tighten and more acid is secreted in the stomach.
Chronic stress or sporadic exposure to stress can lead to peptic ulcer and disrupt regular bowel movement, causing constipation or irritable bowel syndrome. Symptoms also include frequent headaches, insomnia, fatigue, skin rashes and chest pain. When the stress is too overwhelming, such as with trauma, anxiety disorder may develop and rewire the neural circuitry in the brain. With stress, the way neurons transmit information is altered and brain structures associated with emotionally charged memories may be changed. It is also common for patients with some form of anxiety disorder to be diagnosed with depression.
Marijuana's Effects on the Brain
An animal model study done by the University at Buffalo's Research Institute on Addictions (RIA) showed that chronic stress reduces the production of endocannabinoids, natural chemicals synthesized in the brain that control motor functions, cognition and emotions, as well as regulate anxiety. Endocannabinoids are similar to the compounds found in cannabis, including one of its active ingredient, delta-9-tetrahydrocannabinol (THC).
THC mimics the structurally similar anandamide, a mood-regulating endocannabinoid, by binding to cannabinoid receptors. It also increases the concentration of dopamine, a powerful neurotransmitter that elicits pleasant sensations. Low dopamine levels have been linked to anxiety.
"Using compounds derived from cannabis -- marijuana -- to restore normal endocannabinoid function could potentially help stabilize moods and ease depression," said Samir Haj-Dahmane, Ph.D., who headed the research that was funded by the National Institute of Mental Health and published in the "Journal of Neuroscience."
In another study led by Vanderbilt University, the use of electron microscopy allowed researchers to identify cannabinoid receptors in the amygdala, the part of the brain that is the seat of emotions. The cannabinoids found in marijuana bind to these receptors and inhibit excitatory neurotransmitters. The findings "may help explain why marijuana users say they take the drug mainly to reduce anxiety," said Sachin Patel, M.D., Ph.D., the senior author of Nueron.