A study in mice shows that anorexia hijacks the same 'reward' signalling pathway as MDMA
Researchers in France have discovered that anorexia and MDMA share a common signaling pathway in the brain - both reducing the drive to eat by stimulating the same subset of receptors for the neurotransmitter serotonin. The team believe the work could help explain the addictive nature of eating disorders.
In mouse studies, Valerie Compan from the University of Montpellier, and her colleagues, found that by directly stimulating so-called 5HT-4 receptors in the nucleus accumbens, an area of the brain associated with feelings of reward, they could mimic the effects of anorexia - reducing the animals’ desire to eat.
This reduction in appetite is also a well-recognised side effect of ecstasy or MDMA. When the researchers injected MDMA into mice genetically engineered to lack 5HT-4 receptors, it did not cause the reduction in appetite seen in normal mice - suggesting ecstasy’s appetite-suppressing effect is mediated by the same receptors.
’This is a starting point showing us that it is likely that anorexia is addictive, as anorexia-like behaviour in mice shares the same pathway with drugs that are commonly abused,’ Compan told Chemistry World.
She stressed the importance of uncovering the neuronal mechanisms involved in anorexia, to complete the ’biological picture’ of the disease. ’The 5HT-4 receptor could represent an important therapeutic target,’ she said.
Ursula Bailer from the Medical University of Vienna, Austria, collaborated in the first study that showed the link between anorexia and serotonin signaling in humans. ’This same pathway is associated with stress and anxiety, so this study helps to explain the underlying anxiety of associated with anorexia, which we need to find ways to reduce,’ she explained. ’But these disorders involve more than one pathway, and more than one neurotransmitter.’
As yet, there is no proven medical treatment for anorexia, Bailer says. The next important step on the way to finding a cure will be collaboration between groups carrying out this work. ’We are still right at the beginning of uncovering the neurobiology of eating disorders,’ she told Chemistry World. ’I really like this study as it presents a new aspect of the disease, but we now need to bring all of these pieces together.’
et al, PNAS, 2007, Doi: 10.1073/pnas.0701471104
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