快猫短视频

THE function of brain receptors to which cannabinoid drugs bind is at last
being uncovered. Neuroscientists have shown that a brain chemical that binds to
the receptors modifies the effect of the neurotransmitter dopamine and so helps
us to control our movements.

The chemical, called anandamide, is released from a brain structure called
the striatum. This also makes dopamine, and researchers led by Daniele Piomelli
of the University of California at Irvine have shown that the two are released
simultaneously.

To find out why, Piomelli and his colleagues gave mice a chemical known to
block the brain鈥檚 cannabinoid receptors. At the same time, they simulated a
surge in dopamine levels using a drug called quinpirole, which mimics the
neurotransmitter. The mice developed nervous ticks and poorly controlled
movements (Nature Neuroscience, vol 2, p 358).

These symptoms are similar to those of Tourette鈥檚 syndrome and Parkinson鈥檚
disease, which are thought to be linked to problems in the dopamine system. The
involvement of anandamide may explain why some people claim marijuana can help
ease the symptoms of Parkinson鈥檚. The discovery could also lead to the
development of drugs to treat the disease by slowing the breakdown of
anandamide.

Leslie Iverson of Oxford University describes the new study as a 鈥渓andmark鈥�.
But Piomelli suspects the brain鈥檚 cannabinoid system has several other functions
still waiting to be discovered.