1.   And the treatment the researchers used may hold promise for disorders linked to excessive levels of the brain chemical dopamine.

2.   Addicts given cocaine were found to benefit from isradipine in specific areas of the brain that are rich in the brain chemical dopamine.

3.   Both involve a chemical called dopamine.

4.   Cocaine use causes increased levels of a brain chemical called dopamine, which in turn constricts brain arteries.

5.   In particular, amphetamines act on a brain chemical called dopamine, which scientists believe is responsible for the euphoria the drugs produce and also their potential for abuse.

6.   Moreover, a brain chemical called dopamine regulates this clock.

7.   Nicotine works by stimulating the production of a chemical called dopamine.

8.   Other researchers have found what may be a physical basis for it, in levels of the brain chemical dopamine.

9.   The cells produce a neuron-to-neuron signaling chemical called dopamine.

10.   The disease occurs when nerve cells that produce a crucial brain chemical called dopamine deteriorate and die.