Peri-response pharmacokinetics of remifentanil during a self-administration session indicates that neither blood nor brain levels are titrated.
An individual's drug abuse pattern is determined by a multitude of factors. Among these, simple pharmacological determinants of within-binge drug consumption are sorely underinvestigated. We therefore determined if within-session operant responsing to the ultra-short-acting mu opioid agonist remifentanil (RMF) was determined by blood or brain RMF levels or changes thereof. Our peri-response analysis did not detect any "threshold" RMF level, either in blood or in the nucleus accumbens (NAc) core as a deep brain region that might determine a rat's "decision" to re-emit a response during a multiple-injection drug self-administration session. The peri-response analysis also failed to find any peak RMF level, either in blood or in the NAc core, which could serve as a "ceiling" level. Thus, our findings strongly suggest that titration of blood or brain RMF levels does not determine a rat's intra-session operant response.
Crespo
Jose A
JA
Division of Neurochemistry, Department of Psychiatry, Medical University Innsbruck, Anichstrasse 35, A-6020 Innsbruck, Austria.
Panlilio
Leigh V
LV
Schindler
Charles W
CW
Sturm
Katja
K
Saria
Alois
A
Zernig
Gerald
G
D000818:Animals; D001921:Brain / Q000378:metabolism*; D009714:Nucleus Accumbens / Q000378:metabolism*; D010880:Piperidines / Q000097:blood* / Q000493:pharmacokinetics*; D051381:Rats; D000077208:Remifentanil; D012646:Self Administration; D013997:Time Factors
D010880:Piperidines; D000077208:Remifentanil