Genetic factors linked to drug addiction - study

12:23 PM ET 05/13/98

	    LONDON (Reuters) - Genetic factors may influence a person's
vulnerability to drug addiction, U.S. researchers said
Wednesday.
	    Dr Rene Hen and colleagues at Columbia University in New
York found that mice lacking an important brain protein had a
stronger response and sensitivity to cocaine than normal mice.
	    The finding could help scientists better understand the
molecular basis of human drug addiction and how to counteract
it.
	    In a report in the scientific journal Nature, Hen described
how mice without the 1-B receptor for the neurotransmitter
serotonin were more susceptible to the addictive properties of
cocaine.
	    The loss of the receptor seemed to have caused long-term
changes in the brains of the mutant mice that were similar to
changes in normal mice that had become sensitized to cocaine.
	    ``These results provide the first definitive evidence for
the involvement of a specific serotonin receptor in processes
that may underlie cocaine addiction,'' Francis White of Finch
University of Health Sciences in Chicago said in an accompanying
commentary.
	    The addictive elements of cocaine and other drugs are
connected with the release of another neurotransmitter, called
dopamine, which controls motivation and feelings of pleasure in
the brain.
	    Serotonin influences mood and appetite and can interfere
with dopamine to modify the effects of drugs.
	    ``Results from these experiments indicated that certain
effects of cocaine could be mimicked by stimulating the
serotonin-1B receptors, and that blocking the receptors might
reduce the effects of cocaine,'' White said.
	    During the experiments, the mice were trained to
self-administer cocaine by pressing on a lever. The researchers
found that mice lacking the 1-B receptor took twice as much
cocaine as the normal mice.
	    Hen also noted that the mutant mice were more impulsive, a
characteristic that is often associated with drug abuse.