Blocking the hormone GLP-1 can make the brain not reward you for smoking nicotine. An article in NordicScience says that this hormone is used to provide the feeling of reward when smoking, and other things. Blocking this hormone should make it easier to quit smoking. They used the drug Ex-4 (Exendin-4) which simulates GLP-1, and found that it reduced the effects of nicotine.
The researchers concluded that GLP-1 receptors regulated the effect of nicotine on the reward functions in the brains of mice, and that Ex4 diminished the effect of nicotine.
This can also be used for alcohol, cocaine, and amphetamines. Hopefully this new approach can help people quit.
However, there are many things that need to be tested before this can become a medicine to help people. Does it work in people as well as in mice? Doing trials. Getting regulatory approval. If it works as hoped, it will take years for this to be available.