Cannabidiol (CBD), one of the chemical components found in marijuana, may have fast-acting antidepressant effects, according to a study published in Neuropharmacology.

Marijuana has long been valued in many cultures for its mood-altering effects. Neuroscientists have identified several ways CBD influences neurochemical processes, especially by affecting production of the neurotransmitters serotonin and glutamate. Because the same brain systems are known to be related to depression, it has been suggested that CBD has the potential to impact depression through these pathways.

In a study led by Raquel Linge, of the Universidad de Cantabria, neuroscientists examined the action of CBD in the brains of 40 mice to determine whether the chemical was effective at reducing depression, and the neural pathways by which it operates. Researchers performed surgery on some of the mice to remove a region of the brain called the olfactory bulb.

Removing this part of the brain causes symptoms including hyperactivity, memory impairment, and decreased interest in being rewarded with sugar, which can be effectively treated using compounds that act as antidepressants in humans. Because of this, the “olfactory bulbectomy mouse model of depression” (OBX) is widely used to perform research related to the biological causes of depression and potential treatments.

Mice with the OBX surgery showed significantly reduced symptoms of hyperactivity 30 minutes after CBD was administered, in comparison to mice that were given a placebo. Continued daily administration of CBD was found to completely reverse the effects of OBX surgery on the mice’s loss of interest in sugar after one week. Examination of chemical activity within the mice’s brains indicated that CBD caused increased release of serotonin and glutamate.

Glutamate release was affected dramatically in all mice who received CBD, both immediately after the first dose and after weeks of repeated administration. The impact on serotonin was more subtle after the first dose, and it persisted over time only in mice who had OBX surgery, suggesting that this change may have occurred only in response to the depression-like conditions in the mice’s brains.

Because OBX has proven to be an accurate model for human depression in numerous previous studies, these findings suggest that CBD may one day serve as the basis for a new treatment for depression. It may be especially promising because it appears to both act rapidly to reduce symptoms and to lead to sustained recovery over time.

These findings stop short of directly supporting the effectiveness of CBD, delivered either through use of marijuana or as an isolated compound, as a treatment for depression in humans. However, they are likely to add weight to the argument that marijuana and its chemical components have strong potential as sources of future breakthroughs in the treatment of mental as well as physical illness.

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