To overcome addiction, scientists have found that if a hormone related to hunger regulation is blocked in the brain's "pleasure center", it can suppress craving for drugs like cocaine.
The study, led by Shinjae Chung and Olivier Civelli, discovered how the melanin-concentrating hormone works with dopamine in the brain's "pleasure centre" to create an addictive response to cocaine use.
The researchers have also found that blocking MCH in these brain cells limits cocaine cravings.
Dopamine is a neurotransmitter essential to the normal functioning of the central nervous system. It is also linked with feelings of pleasure and is released in the brain during eating, sex and drug use.
Scientists have discovered increased levels of the neurotransmitter in the nucleus accumbens of drug addicts.
This is the first study to detail the interaction of MCH and dopamine in cocaine addiction and show that it occurs in the nucleus accumbens-a portion of the forebrain believed to play an important role in addiction and feelings of pleasure and fear.
"This discovery indicates that MCH is a key regulator of dopamine in a brain area associated with both pleasure and addiction. We believe that efforts to target MCH may lead to new treatments to break addiction to cocaine and, possibly, other drugs, like amphetamines and nicotine," said Civelli.
High levels of MCH are known to intensify feelings of hunger and researchers believe that MCH works in the nucleus accumbens to increase the pleasure of eating.
The study showed that dopamine signalling rose when MCH amounts increased in those brain cells.
The researchers also observed that test mice conditioned to develop cocaine cravings had increased amounts of MCH and dopamine in their nucleus accumbens.
However, the cravings disappeared when experimental compounds blocking MCH proteins were administered to the mice.
The researchers also found that mice lacking key receptors for MCH exhibited significantly fewer cocaine cravings.
They next plan to study whether MCH modulation is beneficial in treating other dopamine-related disorders as well.
The study has been published in the online edition of the Proceedings of the National Academy of Sciences.