Environmental enrichment attenuates nicotine behavioral sensitization in male and female rats.

Environmental enrichment decreases nicotine reactivity in male rats, but these effects have not been examined in females. This research was conducted to examine the effects of enrichment on nicotine behavioral sensitization (i.e., nicotine reactivity) in male and female rats. One hundred forty-four Sprague-Dawley rats (72 male, 72 female) were raised in isolation, social enrichment (groups of three rats [SE]), or combined physical enrichment and social enrichment (groups of three rats with novel toys [PESE]) housing conditions. As adults, they received daily subcutaneous injections of saline or nicotine (0.1, 0.5, or 1.0 mg/kg) for 12 days; locomotor activity was measured on drug days 1, 5, 9, and 12. Before drug administration, PESE and SE decreased activity in males; only PESE decreased activity in females, F(2, 120) = 6.51, p < .01. In the drug phase, nicotine behavioral sensitization occurred, F(8.46, 341.04) = 20.71, p < .001, and was greater in females than males, F(8.340, 319.715) = 2.072, p < .05. Enrichment decreased nicotine behavioral sensitization in both sexes, F(16.91, 341.04) = 2.48, p < .01. In conclusion, nicotine behavioral sensitization occurred in male and female rats and was attenuated by environmental enrichment. This research has implications for treatment and prevention strategies in humans. Programs that incorporate aspects of social and environmental stimulation may have enhanced effectiveness in preventing and reducing cigarette smoking and may have implications for relapse prevention.