title: Differential effects of THC- or CBD-rich cannabis extracts on working memory in rats.
abstract: Cannabinoid receptors in the brain (CB(1)) take part in modulation of learning, and are particularly important for working and short-term memory. Here, we employed a delayed-matching-to-place (DMTP) task in the open-field water maze and examined the effects of cannabis plant extracts rich in either Delta(9)-tetrahydrocannabinol (Delta(9)-THC), or rich in cannabidiol (CBD), on spatial working and short-term memory formation in rats. Delta(9)-THC-rich extracts impaired performance in the memory trial (trial 2) of the DMTP task in a dose-dependent but delay-independent manner. Deficits appeared at doses of 2 or 5 mg/kg (i.p.) at both 30 s and 4 h delays and were similar in severity compared with synthetic Delta(9)-THC. Despite considerable amounts of Delta(9)-THC present, CBD-rich extracts had no effect on spatial working/short-term memory, even at doses of up to 50 mg/kg. When given concomitantly, CBD-rich extracts did not reverse memory deficits of the additional Delta(9)-THC-rich extract. CBD-rich extracts also did not alter Delta(9)-THC-rich extract-induced catalepsy as revealed by the bar test. It appears that spatial working/short-term memory is not sensitive to CBD-rich extracts and that potentiation and antagonism of Delta(9)-THC-induced spatial memory deficits is dependent on the ratio between CBD and Delta(9)-THC.
authors.affiliation: Department of Biomedical Science, College of Life Sciences and Medicine, University of Aberdeen, Foresterhill, Aberdeen AB25 2ZD, UK.
authors.forename: Paola
authors.initials: P
authors.lastname: Fadda
authors.forename: Lianne
authors.initials: L
authors.lastname: Robinson
authors.forename: Walter
authors.initials: W
authors.lastname: Fratta
authors.forename: Roger G
authors.initials: RG
authors.lastname: Pertwee
authors.forename: Gernot
authors.initials: G
authors.lastname: Riedel
mesh_terms: D000818:Animals; D002185:Cannabidiol / Q000302:isolation & purification / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D013759:Dronabinol / Q000302:isolation & purification / Q000494:pharmacology*; D008297:Male; D018782:Maze Learning / Q000187:drug effects / Q000502:physiology; D008568:Memory / Q000187:drug effects* / Q000502:physiology; D010936:Plant Extracts / Q000302:isolation & purification / Q000494:pharmacology; D051381:Rats; D043884:Receptor, Cannabinoid, CB1 / Q000819:agonists / Q000502:physiology
chemical_list: D010936:Plant Extracts; D043884:Receptor, Cannabinoid, CB1; D002185:Cannabidiol; D013759:Dronabinol