Long-lasting increased pain sensitivity in rat following exposure to heroin for the first time.
Acute dependence, defined as a precipitation of somatic signs by an antagonist, may occur after a single administration of an opiate drug. Because hyperalgesia is a consistent sign of the withdrawal syndrome, we tested the effectiveness of heroin, an opiate used by addicts, to induce pain facilitation even after a first exposure to the drug. In opiate-naive rats, subcutaneous injection of heroin induced analgesia followed by allodynia, a decrease in pain threshold. This latter phenomenon was observed in the absence of noxious stimuli and lasted several days. An N-methyl-D-aspartate (NMDA) receptor antagonist, MK-801 prevented such long-lasting allodynia. These results suggest that allodynia is an early sign reflecting neural plasticity associated with the development of dependence.
Laulin
J P
JP
INSERM U259, Université Victor Segalen, Bordeaux II, France.
Larcher
A
A
Célèrier
E
E
Le Moal
M
M
Simonnet
G
G
D000818:Animals; D016291:Dizocilpine Maleate / Q000494:pharmacology; D018691:Excitatory Amino Acid Antagonists / Q000494:pharmacology; D003932:Heroin / Q000494:pharmacology*; D008297:Male; D009294:Narcotics / Q000494:pharmacology*; D010146:Pain / Q000523:psychology*; D010147:Pain Measurement / Q000187:drug effects; D017288:Pain Threshold / Q000187:drug effects; D051381:Rats; D017207:Rats, Sprague-Dawley; D016194:Receptors, N-Methyl-D-Aspartate / Q000037:antagonists & inhibitors; D014828:Vocalization, Animal / Q000187:drug effects
D018691:Excitatory Amino Acid Antagonists; D009294:Narcotics; D016194:Receptors, N-Methyl-D-Aspartate; D016291:Dizocilpine Maleate; D003932:Heroin