Effects of Nicotine, Stress, and Sex on Behavioral and Biological Indices of Depression and Anxiety in Rats

The health hazards of tobacco and the addictive effects of nicotine are well established and well-known. However, these health hazards are especially pertinent upon our consideration of the military population, given the knowledge that tobacco use is more prevalent in the military as compared to civilians. Additionally, smoking status for military personnel is associated with perceived stress. These findings naturally merit questions of critical importance that affect the young Americans tasked with defending our nation it may seem that there are potential benefits of nicotine and nicotine analogues that merit consideration and experimental analysis. The present experiment used 64 male and female Sprague Dawley rats to examine the effects of nicotine with and without exposure to stressors. The dosage of nicotine was chosen to model effects of humans smoking to 1 pack of cigarettes per day. To closely model the stress experienced during a military combat deployment, the experiment utilized a stress paradigm that models threat of attack to create a substantial stress response without physical harm. The behavioral measure used was open field activity to assess general activity, depressive-like behavior, anxiety-like behavior.Overall, results differed based on sex, stress, and time. At 10 days after nicotine administration, stressed female rats receiving nicotine displayed increased horizontal activity. In contrast, male rats that received nicotine did not display increased horizontal activity until 20 days after drug administration. There were no significant effects of nicotine or stress on depressive-like or anxiety-like behaviors. The present findings suggest that nicotine increases general activity for both sexes, with females displaying more activity sooner than males, and for mainly rats that were stressed. The experiment provides important implications for military service members operating under stressful deployment conditions.