ROANOKE TIMES 

                         Roanoke Times
                 Copyright (c) 1995, Landmark Communications, Inc.

DATE: THURSDAY, June 21, 1990                   TAG: 9006210068
SECTION: NATIONAL/INTERNATIONAL                    PAGE: A-5   EDITION: METRO 
SOURCE: Newsday
DATELINE: WASHINGTON                                LENGTH: Short

BRAIN PROCESSES MAY EXPLAIN COCAINE CRAVING

Brookhaven National Laboratory researchers, looking for clues on how cocaine affects the brain, reported Tuesday that chronic users of the drug have fewer receptors for dopamine, a key chemical that transmits neural messages.

Cocaine-induced disturbances in the number of receptor sites and in the amount of dopamine in the brain may help explain the craving a user feels, the researchers found.

The researchers studied how tiny amounts of radioactively tagged cocaine were absorbed in the brains of 10 chronic cocaine users.

The team found that cocaine concentrates in the basal ganglia, a region of the brain that is normally rich in dopamine receptors. Dopamine molecules help transmit messages across gaps - called synapses - between nerve cells. Cocaine causes an acute, temporary increase in dopamine levels in the brain.

Faced with a flood of dopamine, the brain apparently compensates by decreasing the number of available receptor sites. The excess dopamine eventually is destroyed by brain enzymes. 


 by CNB