Rats choose high doses of nicotine in order to compensate for changes in its price and availability

摘要

Abstract Restricting when and where smoking can occur is a major focus of public health policies in Western countries. In conjunction with increased taxation, these approaches have contributed to a reduction in smoking uptake among adolescents, yet the consequences for established smokers are less clear. In order to further explore this relationship, we developed a novel animal model of restricted nicotine self‐administration. Rats were trained to choose between three doses of nicotine (15, 30 and 60 μg/kg/infusion) under conditions where nicotine was (1) freely available at a low cost (20‐second post‐infusion time‐out, fixed‐ratio 1 [FR1]), (2) available under restricted access at a low cost (300‐second post‐infusion time‐out, FR1), or (3) freely available at a high cost (20‐second post‐infusion time‐out, FR5). We demonstrate that as access to nicotine is restricted or when cost increases, rats compensate for these changes by increasing their intake of the highest dose of nicotine available. This preference was impervious to treatment with the smoking cessation medication varenicline, but was reduced when the cost of the highest dose only was increased, or when nicotine was again made freely available at a low cost. These results provide the first evidence in rats that nicotine availability and cost influence nicotine choice independently of variations in nicotine and context exposure. They imply that established smokers may compensate for changes in the availability and cost of tobacco by increasing their rate of smoking when they are free to do so.