title: Part II: Strain- and sex-specific effects of adolescent exposure to THC on adult brain and behaviour: Variants of learning, anxiety and volumetric estimates.
abstract: Marijuana is one of the most highly used psychoactive substances in the world, and its use typically begins during adolescence, a period of substantial brain development. Females across species appear to be more susceptible to the long-term consequences of marijuana use. Despite the identification of inherent differences between rat strains including measures of anatomy, genetics and behaviour, no studies to our knowledge have examined the long-term consequences of adolescent exposure to marijuana or its main psychoactive component, Δ(9)-tetrahydrocannabinol (THC), in males and females of two widely used rat strains: Long-Evans hooded (LER) and Wistar (WR) rats. THC was administered for 14 consecutive days following puberty onset, and once they reached adulthood, changes in behaviour and in the volume of associated brain areas were quantified. Rats were assessed in behavioural tests of motor, spatial and contextual learning, and anxiety. Some tasks showed effects of injection, since handled and vehicle groups were included as controls. Performance on all tasks, except motor learning, and the volume of associated brain areas were altered with injection or THC administration, although these effects varied by strain and sex group. Finally, analysis revealed treatment-specific correlations between performance and brain volumes. This study is the first of its kind to directly compare males and females of two rat strains for the long-term consequences of adolescent THC exposure. It highlights the importance of considering strain and identifies certain rat strains as susceptible or resilient to the effects of THC.
authors.affiliation: University of Lethbridge, 4401 University Drive, Lethbridge, AB T1K 4N8, Canada. Electronic address: rj.keeley@uleth.ca.
authors.forename: R J
authors.initials: RJ
authors.lastname: Keeley
authors.affiliation: University of Lethbridge, 4401 University Drive, Lethbridge, AB T1K 4N8, Canada.
authors.forename: J
authors.initials: J
authors.lastname: Trow
authors.affiliation: University of Lethbridge, 4401 University Drive, Lethbridge, AB T1K 4N8, Canada.
authors.forename: C
authors.initials: C
authors.lastname: Bye
authors.affiliation: University of Lethbridge, 4401 University Drive, Lethbridge, AB T1K 4N8, Canada.
authors.forename: R J
authors.initials: RJ
authors.lastname: McDonald
mesh_terms: D000375:Aging; D000818:Animals; D001007:Anxiety / Q000503:physiopathology; D001921:Brain / Q000033:anatomy & histology / Q000187:drug effects* / Q000254:growth & development / Q000502:physiology; D013759:Dronabinol / Q000494:pharmacology*; D005260:Female; D007858:Learning / Q000187:drug effects / Q000502:physiology; D008297:Male; D008568:Memory / Q000187:drug effects / Q000502:physiology; D009048:Motor Skills / Q000187:drug effects / Q000502:physiology; D009929:Organ Size; D011581:Psychological Tests; D011619:Psychotropic Drugs / Q000494:pharmacology*; D020318:Rats, Long-Evans / Q000033:anatomy & histology / Q000502:physiology* / Q000523:psychology; D017208:Rats, Wistar / Q000033:anatomy & histology / Q000502:physiology* / Q000523:psychology; D012727:Sex Characteristics; D013045:Species Specificity
chemical_list: D011619:Psychotropic Drugs; D013759:Dronabinol
keywords: Behavior; Brain volumetrics; Rat; Sex; Strain; THC