Drug addiction relapse neurons identified--[which cross posting is inappropriate?]
lancesherman at insightBB.com
Fri Aug 22 11:31:08 EST 2003
hint: maybe the one with the word "science"
"Jasbird" <Jasbirdemail@example.com> wrote in message
news:unr8kv0rlalsm23o9lerqm8nq2els0p2uf at 4ax.com...
> Drug addiction relapse neurons identified
> 21 August 2003, LONDON, By Claire Bennett
> US researchers have linked the behaviour of seeking drugs after a
> period of abstinence to specific nerve cells in a part of the brain
> called the nucleus accumbens.
> Previous studies have shown that drug addiction depends on the
> mesocorticolimbic dopamine system innervating the nucleus accumbens.
> Dr Udi Ghitza and colleagues from Rutgers University tested whether
> the accumbens neurons exhibit responses to external stimuli previously
> associated with self-administration of cocaine by rats.
> The rats learnt that on hearing a tone they could press a lever and
> self-administer cocaine. No cocaine was available if the animal
> pressed the lever in the absence of the tone.
> Microelectrodes were attached to the brains of the animals and these
> recorded the activity of single neurons in the nucleus accumbens.
> After two weeks of self-administration of cocaine, the lever was
> removed and no tone sounds were made. The animals abstained from the
> drug for almost a month.
> When the lever was returned to the cage, the animals ignored it when
> no cocaine and no tone were provided. However, when the original tone
> was made, the animals began to press the lever at a high rate even
> though no cocaine was available.
> During this relapse into drug seeking, the neurons - in an area of
> nucleus accumbens known at the shell - were activated by the tone.
> The rats eventually stopped pressing the lever when the tone was made.
> However, nucleus accumbens neurons still responded to the tone.
> Dr Mark West, one of the co-authors, says, " This activity may reflect
> the processing of memories that persist even after a long abstinence
> and may partially explain why environmental cues can provoke a
> And he adds, "This suggests that the existence of a neuroadaptation
> that may make individuals more vulnerable to assuming drug-taking
> Reference: Ghitza et al, Journal of Neuroscience 2003;23:7239-7245
> © HMG Worldwide 2003
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