The cannabinoid agonist HU 210 modifies rat behavioural responses to novelty and stress.
Experiments were performed on groups of rats after acute and sub-chronic treatment (once daily for 9 days) with the cannabinoid agonist HU 210 (25-100 microg kg(-1), i.p.) as well as 24 h and 7 days after the last drug injection. The animals underwent three behavioural tests in novel environments. In the observation cages (Test 1), rat locomotor activity was found to be dose-dependently reduced after acute and sub-chronic treatment at all doses and virtually unchanged during abstinence; grooming was potently inhibited by acute treatment but potentiated by the sub-chronic one at doses of 50 and 100 microg kg(-1), the effect of the higher dose persisting after 24 h and 7 days abstinence. Vocalization in animals in response to a tactile stimulus was highest after HU 210 at 100 microg kg(-1) in all experimental modes except after 7 days abstinence. In the X-maze (Test 2), sub-chronic HU 210 dose- dependently enhanced rat natural aversion for open arms, and this behaviour persisted during abstinence after the highest dose. Grooming in the X-maze was completely absent in rats acutely injected with HU 210 but potentiated in those sub-chronically treated or abstinent. In the swimming test (Test 3) rats sub-chronically treated at 50 and 100 pg kg(-1) displayed relevant wall-hugging and the same occurred 24 h after last injection. On the whole, our results are indicative of an anxiogenic-like effect of sub-chronic HU 210 at high doses and reflect the persistence of enhanced emotional response to novel environments when the treatment is discontinued.
Giuliani
D
D
Department of Biomedical Sciences, Division of Pharmacology, University of Modena, via G. Campi 287, Modena, I-41100, Italy.
Ferrari
F
F
Ottani
A
A
D000818:Animals; D001007:Anxiety / Q000139:chemically induced*; D001522:Behavior, Animal / Q000187:drug effects*; D004305:Dose-Response Relationship, Drug; D013759:Dronabinol / Q000031:analogs & derivatives* / Q000494:pharmacology; D006120:Grooming / Q000187:drug effects; D008297:Male; D018782:Maze Learning / Q000187:drug effects; D009043:Motor Activity / Q000187:drug effects; D051381:Rats; D017208:Rats, Wistar; D013312:Stress, Physiological / Q000523:psychology*; D013550:Swimming; D014828:Vocalization, Animal / Q000187:drug effects
D013759:Dronabinol; C062018:HU 211