Wheel running exercise attenuates vulnerability to self-administer nicotine in rats - PubMed (original) (raw)

Wheel running exercise attenuates vulnerability to self-administer nicotine in rats

Victoria Sanchez et al. Drug Alcohol Depend. 2015.

Abstract

Background: Preventing or postponing tobacco use initiation could greatly reduce the number of tobacco-related deaths. While evidence suggests that exercise is a promising treatment for tobacco addiction, it is not clear whether exercise could prevent initial vulnerability to tobacco use. Thus, using an animal model, we examined whether exercise attenuates vulnerability to the use and reinforcing effects of nicotine, the primary addictive chemical in tobacco.

Methods: Initial vulnerability was assessed using an acquisition procedure wherein exercising (unlocked running wheel, n=10) and sedentary (locked or no wheel, n=12) male adolescent rats had access to nicotine infusions (0.01-mg/kg) during daily 21.5-h sessions beginning on postnatal day 30. Exercise/sedentary sessions (2-h/day) were conducted prior to each of the acquisition sessions. The effects of exercise on nicotine's reinforcing effects were further assessed in separate groups of exercising (unlocked wheel, n=7) and sedentary (no wheel, n=5) rats responding for nicotine under a progressive-ratio schedule with exercise/sedentary sessions (2-h/day) conducted before the daily progressive-ratio sessions.

Results: While high rates of acquisition of nicotine self-administration were observed among both groups of sedentary controls, acquisition was robustly attenuated in the exercise group with only 20% of exercising rats meeting the acquisition criterion within the 16-day testing period as compared to 67% of the sedentary controls. Exercise also decreased progressive-ratio responding for nicotine as compared to baseline and to sedentary controls.

Conclusions: Exercise may effectively prevent the initiation of nicotine use in adolescents by reducing the reinforcing effects of nicotine.

Keywords: Acquisition; Adolescent; Exercise; Motivation; Nicotine; Self-administration.

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Figures

Figure 1

Experimental timeline used to examine the effect of exercise on the acquisition of nicotine self-administration in adolescent rats. Rats were given 2-hour access to their exercise or sedentary condition each day prior to nicotine self-administration beginning on postnatal day 30.

Figure 2

Timeline for Experiment 2 in which the effect of exercise on nicotine self-administration under a progressive ratio schedule in adolescent rats was examined. Following self-administration acquisition and stable baseline PR responding, adolescent rats were given 2-hour access to their exercise or sedentary condition each day prior to the PR session for 5 days. The persistent effect of exercise was determined in 3 post-exercise sessions, in which the rats did not have access to sedentary or exercise conditions prior to PR sessions.

Figure 3

Acquisition of nicotine self-administration in male adolescent rats with exposure to a locked wheel (squares) or no wheel (triangles) conditions for 2 hours prior to each self-administration session.

Figure 4

Percent group reaching nicotine self-administration acquisition criteria in male adolescent rats with exposure to sedentary (locked or no wheel condition; open circles) or exercise (unlocked wheel; black circles) groups for 2-hours prior to each 21.5-hour self-administration session. Asterisk indicates a significant difference between the exercise and control groups.

Figure 5

Number of infusions during daily PR nicotine self-administration sessions in male adolescent rats are shown at baseline (B1-B3), following 2-hours of wheel running exercise (E1-E5), and after removal of the exercise session (P1-P3) for sedentary (no wheel; open circles) and exercise (unlocked wheel; black circles) groups. Asterisk indicates a significant difference between the exercise and control groups (p < 0.05).

Figure 6

Scatter plot and Pearson product moment correlation of average daily distance run in wheel and percent change from baseline PR breakpoint during exercise sessions. A strong negative correlation between these two variables was observed (p < 0.01).

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Wheel running exercise attenuates vulnerability to self-administer nicotine in rats - PubMed (original) (raw)