In vivo microdialysis and conditioned place preference studies in rats are consistent with abuse potential of tramadol.
The abuse potential of tramadol was investigated using both in vivo microdialysis measures of dopamine (DA) release within the nucleus accumbens (NAc) shell and the conditioned place preference (CPP) paradigm in rats. Tramadol (75 mg/kg, i.p.) induced a statistically significant increase (starting 80 min posttreatment) in DA release within the NAc shell, which was maintained for at least 120 min posttreatment. Tramadol (18.75, 37.5, and 75 mg/kg i.p.) produced a statistically significant CPP, with the effects of the two highest doses comparable to those induced by morphine (5 mg/kg, s.c.). The release of DA within the NAc shell may be responsible for the rewarding properties of tramadol and, together with the CPP results, provide evidence that tramadol may possess greater abuse potential than originally believed.
Sprague
Jon E
JE
The Department of Pharmaceutical & Biomedical Sciences, The Raabe College of Pharmacy, Ohio Northern University, Ada, Ohio 45810, USA. j-sprague@onu.edu
Leifheit
Michael
M
Selken
Jennifer
J
Milks
Michael M
MM
Kinder
David H
DH
Nichols
David E
DE
D000701:Analgesics, Opioid / Q000494:pharmacology*; D000818:Animals; D001522:Behavior, Animal / Q000187:drug effects / Q000502:physiology; D003213:Conditioning, Psychological / Q000187:drug effects* / Q000502:physiology; D004298:Dopamine / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D005110:Extracellular Space / Q000187:drug effects / Q000378:metabolism; D008297:Male; D017551:Microdialysis; D009474:Neurons / Q000187:drug effects* / Q000378:metabolism; D009714:Nucleus Accumbens / Q000187:drug effects* / Q000378:metabolism; D009293:Opioid-Related Disorders / Q000378:metabolism* / Q000473:pathology / Q000503:physiopathology; D051381:Rats; D017207:Rats, Sprague-Dawley; D014147:Tramadol / Q000494:pharmacology*
D000701:Analgesics, Opioid; D014147:Tramadol; D004298:Dopamine