Effects of environmental enrichment on d-amphetamine self-administration following nicotine exposure.

Abstract

Adolescent nicotine exposure has been shown to lead to further psychostimulant use in adulthood. Previous preclinical research in rats has shown that environmental enrichment may protect against drug abuse vulnerability. The current study was designed to examine whether environmental enrichment can block the ability of adolescent nicotine exposure to increase d-amphetamine self-administration in adulthood. Male Sprague Dawley rats were raised in either enriched conditions (EC) or isolated conditions (IC) and then injected with saline or nicotine (0.4 mg/kg, s.c.) for seven days during adolescence. In adulthood rats were allowed to self-administer d-amphetamine under fixed ratio (0, 0.006, 0.01, 0.02, 0.06, and 0.1 mg/kg/infusion) and progressive ratio (0, 0.006, 0.06, and 0.1 mg/kg/infusion) schedule of reinforcement. Nicotine-treated IC rats self-administered more d-amphetamine at 0.006, 0.01 and 0.02 mg/kg/infusion doses compared to their saline-treated IC counterparts regardless of the schedule maintaining behavior. This effect of nicotine was reversed in EC rats on a fixed ratio schedule. These findings indicate that environmental enrichment can limit the ability of adolescent nicotine exposure to increase vulnerability to other psychostimulant drugs, such as d-amphetamine.

The co-use of nicotine and prescription psychostimulants: A comprehensive review of their behavioral and neuropharmacological interactions

“…Interestingly, another study found that home cage nicotine exposure during the rat adolescent period enhanced d-amphetamine selfadministration during adulthood. This study by Stairs and colleagues (2017), however, only found enhanced d-amphetamine self-administration as a function of nicotine exposure in rats that were housed in isolation, but not in socially-housed rats (Stairs et al, 2017). Notably, Cortright and colleagues utilized individually housed rats, akin to the isolation group of Stairs and colleagues.…”

“…We could not find self-administration studies that examined the impact of amphetamine pre-exposure on later nicotine intake. Rather, the limited extant preclinical literature has only examined the impact of nicotine exposure on later d-amphetamine selfadministration (Cortright et al, 2012;Stairs et al, 2017). Cortright and colleagues found that nicotine exposure in adult rats enhanced d-amphetamine self-administration and amphetamine-primed reinstatement only when prior nicotine exposure occurred in the selfadministration chamber.…”

“…Adolescent nicotine exposure only increased amphetamine IVSA in rats that were reared in socially isolated conditions. Stairs et al, 2017…”