Vidyya Medical News Service
Volume 6 Issue 199 Published - 14:00 UTC 08:00 EST 17-Jul-2004 Next Update - 14:00 UTC 08:00 EST 18-Jul-2004
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The timecourse of addiction

Anne-Noël Samaha, Nicolas Mallet, Susan M. Ferguson, François Gonon, and Terry E. Robinson

Rapid cocaine delivery, such as smoking "crack" rather than snorting powder, produces an intensely pleasurable and reinforcing high. However, rapid delivery comes with a high price, a greater likelihood of addiction and compulsive drug-seeking behavior.

This week, in the Journal of Neuroscience, Samaha et al. attack possible adaptations underlying the addictive state, including psychomotor sensitization, dopamine uptake, and induction of immediate early genes (IEGs).

Only rats that received rapid cocaine delivery (the same dose given over 5 sec rather than 100 sec) displayed psychomotor sensitization on the second day of drug delivery. In the orbitofrontal and medial pre-frontal cortex, nucleus accumbens, and caudate-putamen, c-fos and arc mRNAs were increased to a greater extent by fast drug delivery.

Finally, rapid delivery resulted in a faster onset and larger block of dopamine reuptake.

Such kinetic data may also be important in designing anti-addictive treatment strategies.

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