That is, unlike the current experimental arrangement, patterns of human tobacco use are not typically continuous but are instead intermittent throughout the waking hours. Thus, further selleck chemical Afatinib research with methods that may more closely model extended, intermittent human exposure to tobacco (e.g., O��Dell et al., 2007) may also be necessary to generalize the current time-related dissipation of the reinforcement enhancement to human behavior. Additionally, the current dose of nicotine delivered via osmotic minipump (3.16 mg/kg/day) reportedly results in plasma levels of 44 ng/ml (Kenny et al., 2003), but other reports have variable estimates of plasma levels from similar doses and route of administration (Ghosheh, Dwoskin, Miller, & Crooks, 2001; LeSage et al., 2002; Lockman et al.

, 2005; Nguyen, Rasmussen, & Perry, 2004). Given this discrepancy in the literature, the current model system may not be in complete correspondence with plasma levels observed in human research although it is problematic to equate plasma levels across species such as humans and rats. In summary, the current investigation included two experiments that both showed continuous nicotine initially enhanced nondrug reinforcement, but this effect dissipated following prolonged exposure. Furthermore, mecamylamine-precipitated withdrawal from chronic nicotine induced a decrement in reinforcement, which establishes the loss in reinforcer efficacy as an affective withdrawal symptom and a potential motivation for relapse. Funding This work was supported by the National Institutes of Health (DA10464).

Declaration of Interests None declared.
Because of the tremendous burden of disease that results from cigarette smoking, a variety of interventions have been implemented to prevent and reduce tobacco use. Increasingly, interventions have involved changing public policy related to the use, manufacture, and sale of tobacco products. Bierer and Rigotti (1992) Brefeldin_A described three categories of policy measures. The first category, efforts to inform or persuade, includes policies that require warning labels, mandatory education programs in schools and through the mass media, restrictions on tobacco advertising, and the issuance of government reports. Second, economic incentives to discourage tobacco use includes increased tobacco taxation, insurance incentives such as higher premiums for smokers and covering the cost of smoking cessation treatment, and changing the tobacco crop price support system to encourage the growing of alternative crops. The third category, direct restraints on tobacco use, includes restricting smoking in certain places, restricting sales of tobacco to minors or through certain means such as vending machines, and regulating production of tobacco products.