Jan. 13, 1998
                                        Contacts: Jay Hirsh or Colleen McClung
                                                  (804) 982-5608

            STUDY FINDS COCAINE PROMPTS SIMILAR RESPONSES 
            IN FRUIT FLIES AND HUMANS

	University of Virginia biologists Jay Hirsh and Colleen
McClung have spent a year giving cocaine to fruit flies and then
watching what happens.
	The results? The flies were affected much like rodents -- or
humans, for that matter.  That is significant for researchers seeking
to understand the genetics of behavioral, and perhaps even
psychological, responses to cocaine in humans.
	Hirsh, a biology professor, and McClung, a U.Va. doctoral
student, describe the findings of their National Institutes of
Health-sponsored research in the cover story of the Jan. 15 issue of
Current Biology.
	Much is already known about the genetics of the frequently
studied fruit flies, so it should be easier to isolate the genes
involved in their responses to cocaine.  That in turn could make it
easier to clone the corresponding genes in the higher vertebrates.
	"These results suggest that ... this genetically tractable
animal can be used as a new model system to help determine the
biological mechanisms underlying these processes," Hirsh said.
	Among their observations is that the fruit flies (Drosophila
melanogaster) become sensitized to low-dose, intermittent exposures to
cocaine.  "Sensitization" is a phenomenom, previously seen in higher
vertebrates, in which repeated exposures to the same doses of cocaine
elicit greater and greater motor responses.  For other drugs, such as
alcohol or opiates, the opposite is generally true: it takes greater
and greater amounts to induce the same biological responses.
Sensitization is thought to contribute to the psychoses that occur in
long-term cocaine addicts.
	The fruit flies also showed varied responses to increasing
doses of cocaine.  At the lowest doses, the flies moved less, spending
most of their time grooming themselves.  As the dosage increased, the
flies became much more active, exhibiting random, meandering and
ultimately more frenetic movement, some wandering in seemingly aimless
circles.  At the highest doses, the flies suffered from tremors and
paralysis, and in some cases died.
	Rodents also show increased reflexive motor activity --
chewing, scratching, grooming and locomotion -- with increasing doses
of cocaine, Hirsh and McClung said, indicating that the same type of
genes and neural processes are probably at work in both fruit flies
and higher vertebrates.
	"We really don't understand the basic biology of the changes
in response to the differences in doses or to repeated doses," Hirsh
said.
	"Basically, we want to find the genes involved," McClung
added.
	The researchers also refined their methods of studying the
responses.  In the Hirsh lab's previous studies of the behavioral
responses of Drosophila melanogaster, they removed the flies' heads
and administered stimulants directly to the exposed nerve cords.
Amazingly, the flies can live for up to three days without their
heads, Hirsh said.
	In studying fruit flies' response to cocaine, Hirsh and
McClung administered the drug differently: basically, they gave the
flies tiny amounts of crack cocaine as an aerosol.
	The process involves mixing the cocaine with ethanol, then
allowing the ethanol to evaporate on a filament, leaving tiny crystals
of crack.  The filament is placed inside a sealed test tube with
several fruit flies, then heated, releasing the drug in a vapor form,
which is absorbed by the flies.
	Their flies were then videotaped to allow analysis of the
responses.
	The government-supplied cocaine is carefully monitored.  The
researchers' work is supported by the National Institute on Drug Abuse
and the National Institute of General Medicine Sciences, both agencies
of the National Institutes of Health.
	The research requires very small quantities of the drug, Hirsh
said.  A year's supply only amounts to about 15 percent of what is
used in one day by a human addict.
	"There is not a lot of cocaine stored in the Hirsh lab," he
said.
                                 ###
	For more information, contact Dan Heuchert of the University
News Office, (804) 924-7676, or via e-mail at dnh6n@virginia.edu.
Hirsh's website is located at
http://minerva.acc.virginia.edu/~biology/Fac/Hirsh.html
	Journalists may obtain the journal article from Current
Biology at http://biomednet.com/cbiology/cubsamp2.htm.
	Michael Sesma, scientific review administrator at the National
Institute of General Medical Sciences, NIH, is available for comment
at (301) 594-2048, or via e-mail at sesmam@nigms.nih.gov
	Television reporters should call our TV News Office at (804)
924-7550.
	


            U.Va. news online: http://www.virginia.edu/topnews/