Serotonin may not play major role in depression, new evidence suggests
A study by scientists in the US has cast doubt on the belief that a deficiency in serotonin, a chemical messenger in the brain, is a major trigger for depression.
The team from the John D. Dingell VA Medical Centre and Wayne State University School of Medicine in Michigan developed mice that lacked the ability to produce serotonin in their brains, and found they did NOT show signs of depression-like symptoms.
The results are published in ACS Chemical Neuroscience, and suggest that the majority of today’s antidepressants, which target serotonin, may not be as effective as we had hoped.
According to the World Health Organisation, depression is the leading cause of disability across the globe, affecting more than 350 million people worldwide. Back in the late 1980s, the antidepressant Prozac was developed, which works mainly by increasing the amount of serotonin in the brain. It seemed to be effective, and so other depression treatments that acted on serotonin began to flood the market. However, scientists know that 60 to 70 percent of patients taking such drugs continue to feel depressed.
The team, led by Donald Kuhn, decided to investigate whether serotonin was as involved in the disorder as we expect - if at all.
To do this, they developed “knockout” mice that didn’t have the ability to make serotonin in their brains. According to the current dogma, these mice should have been depressed. But while the mice were compulsive and aggressive, they didn't show signs of depression-like symptoms, the researchers report.
After running a range of behavioural tests, the scientists found that when the knockout mice were put under stress, they behaved in the same way as most normal mice. Most of them also responded to antidepressant medications in a similar way to normal mice.
A press release explains: “These findings further suggest that serotonin is not a major player in the condition, and different factors must be involved.”
The authors conclude in their paper that this research could dramatically alter the creation of antidepressants in the future.
If this research is verified, it could turn out to be quite embarrassing - especially when this seems like it should have been one of the first studies done before the development of antidepressants. But mostly it’s great news, as it’ll give scientists a better indication than ever before of where we should be targeting antidepressant treatments.
Watch this space.
Source: ACS Chemical Neuroscience
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