71.   Gene controls brain chemical that affects stress.

72.   Henriksen said the sleep potion is a natural brain chemical that apparently plays a key role in causing slumber.

73.   Howard Hughes Medical Institute researchers at Duke University discovered the serotonin action of Ritalin by eliminating the possibility that the drug was acting on other brain chemicals.

74.   It modestly slows cognitive decline by inhibiting the breakdown of acetylcholine, a brain chemical vital for nerve cells to communicate.

75.   Previous studies have suggested the drug can cause a long-term decrease in a brain chemical involved with thought and memory.

76.   Seizure-controlling drugs and the tricyclics all modify brain chemicals that regulate pain signals from nerves, Low and Dotson said.

77.   Sibutramine, known as Meridia in the United States and as Reductil elsewhere, acts on the brain chemicals which regulate food intake and energy burning.

78.   The discovery that a specific brain chemical is involved in narcolepsy could point the way for researchers to seek new treatments for the disease.

79.   The researchers then blocked the effects of norepinephrine, another brain chemical, but this had no effect on the ADHD symptoms.

80.   They inhibit the breakdown of acetylcholine, a brain chemical vital for nerve cells to communicate with each other.