The psychoactive ingredient of marijuana induces behavioural sensitization.
Here we describe, for the first time, the occurrence of behavioural sensitization after chronic exposure to Delta9-tetrahydrocannabinol. Rats were treated twice a day, for five days, with increasing doses (5, 10, 20, 40, 40 mg/kg i.p.) of Delta9-tetrahydrocannabinol or its vehicle and after 20 days of withdrawal, animals were challenged with 5 mg/kg (i.p.) of the drug and their behaviour was assessed. Contrary to the motor inhibition induced in control rats, challenge with Delta9-tetrahydrocannabinol in pre-exposed animals elicited a complex behavioural syndrome mainly characterized by oral stereotyped items. Due to the relevance of behavioural sensitization in drug-seeking behaviour that persists long after discontinuation of drug use, our findings suggest that cannabinoids could trigger neurobiological alteration not dissimilar from those observed with more harmful abused drugs.
Rubino
T
T
Department of Structural and Functional Biology, University of Insubria, via Dunant 3, 21100 Varese, Italy.
Viganò
D
D
Massi
P
P
Parolaro
D
D
D000818:Animals; D001522:Behavior, Animal / Q000187:drug effects*; D004305:Dose-Response Relationship, Drug; D013759:Dronabinol / Q000031:analogs & derivatives* / Q000494:pharmacology*; D008297:Male; D002189:Marijuana Abuse / Q000503:physiopathology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D013239:Stereotyped Behavior / Q000187:drug effects; D013375:Substance Withdrawal Syndrome / Q000503:physiopathology
C052413:delta(9-11)-tetrahydrocannabinol; D013759:Dronabinol