Sex Differences and the Effects of Stress on Subsequent Opioid Consumption in Adult Rats Following Adolescent Nicotine Exposure: A Psychopharmacologic Examination of the Gateway Hypothesis
UNIFORMED SERVICES UNIV OF THE HEALTH SCIENCES BETHESDA MD
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The present experiment examined effects of nicotine administration during adolescence on subsequent opioid consumption in male and female rats. Forty-one day old rats received saline n 40, 6 mg nicotinekgday n 40, or 12 mg nicotinekgday n 40 by osmotic minipump for 24 hoursday for 19 days. After a 7-day cessation period, consumption of fentanyl-HCl solution was evaluated for 4 weeks. Throughout the opioid consumption phase, rats received either 20 minutes of immobilization stress a 60 or no-stress a 60 prior to opioid availability. Body weight, food, and water consumption were evaluated throughout the experiment. Nicotine exposure 6 mg nicotinekgday during adolescence was related to increased, subsequent fentanyl self-administration in non-stressed male rats. Exposure to immobilization stress prior to opioid availability attenuated or reversed the effect of adolescent exposure to 6 mg nicotinekgday on fentanyl self-administration in adult male rats. These effects did not occur for female rats. Female rats consumed more fentanyl than did male rats, regardless of nicotine pre-exposure, but male and female rats did not display differences in withdrawal following naloxone challenge. Opiate self-administration decreased food consumption for all animals. Nicotine history appeared to increase plasma corticosterone levels in non-stressed, male and female rats. Nicotine decreased body weight gains and food Consumption among male and female rats and both of these effects were greater in female than in male rats. Nicotine cessation resulted in increases in body weight and food consumption and these effects were greater in females than in males. Stress increased plasma corticosterone in male and female rats and female rats had higher levels of plasma corticosterone. Stress decreased body weight and food consumption in male and female rats regardless of nicotine history.
- Anatomy and Physiology
- Medicine and Medical Research
- Stress Physiology