SOFT 2004 Meeting Abstracts - Society of Forensic Toxicologists
SOFT 2004 Meeting Abstracts - Society of Forensic Toxicologists
SOFT 2004 Meeting Abstracts - Society of Forensic Toxicologists
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B14 <br />
EFFECTS OF OPIOIDS ON METHAMPHETAMINE-INDUCED STEREOTYPICAL<br />
SELF-INJURIOUS BEHAVIOR IN MICE<br />
Tomohisa Mori"', Shinobu Itoh, Toshiko Sawaguchi : Department <strong>of</strong> Legal Medicine, Tokyo Women's<br />
Medical University, Tokyo, Japan<br />
Psychostimulants as well as other abused drugs, such as morphine and heroin, induce several behavioral<br />
effects in rodents, which is believed to be mediated by the activation <strong>of</strong> the dopaminergic system.<br />
Furthermore, relatively high doses <strong>of</strong> psycho stimulants induce stereotypical self-injurious behavior (SIB) in<br />
rodents. The combination <strong>of</strong>psycho stimulants and opioids is quite common and is reportedly used to produce<br />
a more intensely pleasurable "rush". Therefore, some investigators have sought to characterize the<br />
interactions <strong>of</strong> these psychostimulants and opioids. However, the effects <strong>of</strong> opioids on dopamine-related<br />
behavior, especially psychostimulant-induced SIB, remain to be fully elucidated. The present study was<br />
designed to investigate the effects <strong>of</strong> j.l.-, 0- and K-opioid receptor agonists (morphine (5.0 - 20 mg/kg, s.c.),<br />
SNC80 (1.25 - 5.0 mg/kg, s.c.) and U50,488H (1.0 - 10 mg/kg, Lp.), respectively) and buprenorphine (0.125<br />
- 2.0 mg/kg, s.c.) on methamphetamine-induced SIB. After the administration <strong>of</strong> methamphetamine, SIB,<br />
especially skin-picking behavior or self-biting around the chest, was measured for 3 min at 15 min intervals.<br />
A score <strong>of</strong> 0 was given for inactivity <strong>of</strong> SIB-like behavior, 1 for very mild SIB (less than 1 min), 2 for at least<br />
1 min <strong>of</strong> SIB, 3 for continuous SIB through 3 min. Methamphetamine (20 mg/kg) induced SIB in 6 out <strong>of</strong>7<br />
ddY mice, while· in the combination test, the opioid receptor agonists significantly attenuated<br />
methamphetamine-induced SIB. The relative potency <strong>of</strong> these opioids in attenuating<br />
methamphetamine-induced SIB was morphine> buprenorphine > U50,488H » SNC80. These results<br />
suggest that the stimulation <strong>of</strong> j.l.- and K- (particularly j.l.-) opioid receptors exerts an inhibitory effect on<br />
stereotyped high-dose methamphetamine-induced SIB in mice.<br />
Keywords: Self-injurious behavior; Methamphetamine; Opioid<br />
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