A single dose of cannabidiol -- a non-intoxicating compound of marijuana -- was found highly effective in eliminating the symptoms of depression in rats, finds a study.
The findings showed that as compared to the commercial anti-depressants that typically take two to four weeks to have a significant effect, cannabidiol's first results appear in 24 hours after a single dose.
Moreover, the beneficial effects were fast acting and sustained, persisting for seven days.
It could be because cannabidiol activates mechanisms which repair neuronal circuitry in patients' prefrontal cortex and hippocampus, the researchers said.
"In light of the study, we believe cannabidiol rapidly triggers neuroplastic mechanisms that help repair the neuronal circuitry that gets damaged in depression," said lead author Samia Regiane Lourenco Joca, Professor at the University of Sao Paulo in Brazil.
For the study, published in the journal Molecular Neurobiology, the team performed tests using rat and mouse lines selected by cross-breeding to develop symptoms of depression. The tests and behavioural analysis involved a total of 367 animals.
Before the test, some of the animals were given an injection of cannabidiol with doses of 7, 10 and 30 mg/kg in saline solution, and the rest, which were the control group, received only saline.
After 30 minutes, the animals were placed for five minutes in cylinders with a height of 25 cm and a diameter of 17 cm, containing 10 cm of water for mice and 30 cm of water for rats.
The team found that cannabidiol induced acute and sustained antidepressant-like effects in mice submitted to the forced swim test.
According to Joca, if studies in humans also find cannabidiol to be beneficial in treating depression, given that cannabidiol is already used in humans to treat other diseases or disorders, "they could result in an important advance in the treatment of depression, potentially helping patients who suffer for weeks, often with a risk of suicide, until the treatment starts working."