Feltenstein MW, Ghee SM, See RE. Nicotine self-administration and reinstatement of nicotine-seeking in male and female rats. (2011) Drug Alcohol Depend, 121(3):240-246. PMCID: PMC327450 

ABSTRACT
Background: Tobacco addiction is a relapsing disorder that constitutes a substantial worldwide health problem, with evidence suggesting that nicotine and nicotine-associated stimuli play divergent roles in maintaining smoking behavior in men and women. While animal models of tobacco addiction that utilize nicotine self-administration have become more widely established, systematic examination of the multiple factors that instigate relapse to nicotine-seeking have been limited. Here, we examined nicotine self-administration and subsequent nicotine-seeking in male and female Sprague-Dawley rats using an animal model of self-administration and relapse.
Methods:  Rats lever pressed for nicotine (0.03 and 0.05mg/kg/infusion, IV) during 15 daily 2-h sessions, followed by extinction of lever responding. Once responding was extinguished, we examined the ability of previously nicotine-paired cues (tone+light), the anxiogenic drug yohimbine (2.5mg/kg, IP), a priming injection of nicotine (0.3mg/kg, SC), or combinations of drug+cues to reinstate nicotine-seeking.
Results:  Both males and females readily acquired nicotine self-administration and displayed comparable levels of responding and intake at both nicotine doses. Following extinction, exposure to the previously nicotine-paired cues or yohimbine, but not the nicotine-prime alone, reinstated nicotine-seeking in males and females. Moreover, when combined with nicotine-paired cues, both yohimbine and nicotine enhanced reinstatement. No significant sex differences or estrous cycle dependent changes were noted across reinstatement tests.

Hartwell KJ, Johnson KA , Li X, Myrick H, LeMatty T, George MS, Brady KT. Neural Correlates of craving and resisting craving for tobacco in nicotine dependent smokers. (2011) Addiction Biology, 16(4):654-666. PMCID: PMC3182826

ABSTRACT
Craving is a significant factor which can lead to relapse during smoking quit attempts. Attempts to resist urges to smoke during cue-elicited craving have been shown to activate regions in the brain associated with decision-making, anxiety regulation and visual processing. In this study, 32 treatment-seeking, nicotine-dependent smokers viewed blocks of smoking and neutral cues alternating with rest periods during magnetic resonance imaging scanning in a 3T Siemens scanner (Siemens AG, Erlangen, Bavaria, Germany). While viewing cues or control images, participants were instructed either to 'allow yourself to crave' or 'resist craving.' Data were analyzed with FSL 4.1.5, focused on the smoking cues versus neutral cues contrast, using cluster thresholding (Z > 2.3 and corrected cluster threshold of P = 0.05) at the individual and group levels. During the Crave condition, activation was seen on the left anterior cingulated cortex (LACC), medial prefrontal cortex, left middle cingulate gyrus, bilateral posterior cingulated gyrus and bilateral precuneus, areas associated with attention, decision-making and episodic memory. The LACC and areas of the prefrontal cortex associated with higher executive functioning were activated during the Resist condition. No clear distinctions between group crave and resist analyses as a whole were seen without taking into account specific strategies used to resist the urge to smoke, supporting the idea that craving is associated with some degree of resisting the urge to smoke, and trying to resist is almost always accompanied by some degree of craving. Different strategies for resisting, such as distraction, activated different regions. Understanding the underlying neurobiology of resisting craving to smoke may identify new foci for treatments.

Reichel CM, See RE. Chronic modafinil effects on drug-seeking following methamphetamine self-administration in rats. (2011) Int J Neuropsychopharmacology: DOI: 10.1017/S1461145711000988. PMCID: PMC3258466

Updated 10.2012