Review of the Role of Environmental Cues in Various Aspects of Nicotine Addiction

Nicotine in cigarettes is a highly addictive substance but can also alter the incentive value of cues associated with smoking as well as other natural reinforcers, such as food. While previous work has shown nicotine to enhance the saliency of and reactivity to sucrose-paired cues by serving as an occasion-setting stimulus while also enhancing reward-learning, much of this work has been done in male rats. In the present study, we explore whether nicotine can enhance sucrose self-administration and sucrose-seeking in female rats. For ten days female Sprague-Dawley rats were either given subcutaneous saline (ST, saline trained) or nicotine (NT, nicotine trained, 0.4 mg/kg) prior to sucrose self-administration. Then, rats were given two separate tests for sucrose-seeking in which they received either a saline or nicotine challenge. We show that ST and NT animals have mostly comparable acquisition of sucrose self-administration, with the exception of NT animals lever pressing at a higher rate when the sucrose-paired audiovisual cue was on. We also show that NT trained animals elevate responding during sucrose-seeking tests when given a nicotine challenge compared to a saline challenge while ST animals have comparable responding. Thus, we show that nicotine is an occasion-setting stimulus for sucrose-seeking in female rats, as is in male rats, but unlike in male rats where the effects of nicotine on reward-learning are profound, we observed subtler effects on acquisition of sucrose-self administration. Consideration of nicotine and cue-saliency leads to implications for treatment in those with a nicotine addiction, targeting various aspects of the addiction cycle. Menthol has been shown to effect various aspects of nicotine’s mechanism of action and would be worth further investigation into its effect nicotine’s relationship with cue-seeking

Exploring the Effects of Nicotine on Reward Learning in Female Sprague-Dawley Rats

Nicotine addiction harms millions of individuals worldwide: financially, socially, and psychologically. Successful smoking cessation could dramatically improve the quality of life for these people. A key driver of smoking relapse centers around associated environmental cues, which induces craving and drives a smoker to re-initiate smoking. Previous work has shown that nicotine can enhance the reinforcing properties of reward-associated cues in male rats. This research aims to evaluate nicotine’s effect on female rats using a behavioral assay called “cue-induced reward-seeking.” In this behavioral assay, rats are trained to press a lever that produces liquid sucrose along with an audiovisual cue. After the training period, the liquid sucrose reward is omitted. Surprisingly, animals will keep pressing the lever, as the cue has become synonymous with the reward. Here, we describe various approaches (water deprivation, food restriction, and shaping) that could potentially be helpful in establishing sucrose self-administration with the goal of examining how nicotine influences cue-induced sucrose-seeking. Shaping was found to be the most influential approach in promoting sucrose self-administration. In future experiments, nicotine (0.4 mg/kg, s.c.) will be administered in these rats in a comparison with controls (saline, s.c.) prior to training to assess the effects of nicotine on cue-induced sucrose-seeking