Microstructural meal pattern analysis reveals a paradoxical acute increase in food intake after nicotine despite its long-term anorexigenic effects

RATIONALE: Nicotine consumption in both human and animal studies has been strongly associated with changes in feeding-related behaviors and metabolism. The current dogma is that nicotine is an anorexic agent that decreases food intake and increases metabolism, leading to decreased body weight gain. However, there are conflicting reports about the acute effects of nicotine on hunger in humans. No study has reported nicotine-induced decreases in food intake within minutes of consumption, suggesting that our understanding of the pharmacological effects of nicotine on appetite and feeding may be incorrect. OBJECTIVES: The aim of this study was to elucidate effects of acute nicotine intake on feeding and drinking behavior. METHODS: Adult male Wistar rats were trained to intravenously self-administer nicotine. Microstructural and macrostructural behavioral analyses were employed to look at changes in food and water intake at different timescales. RESULTS: At the macrostructural level (hours to days), nicotine decreased body weight gain, decreased feeding, and was associated with increases in feeding and body weight gain during abstinence. At the microstructural level (seconds to minutes), nicotine increased feeding and drinking behavior during the first 5 min after nicotine self-administration. This effect was also observed in animals that passively received nicotine, but the effect was not observed in animals that self-administered saline or passively received saline. CONCLUSIONS: These results challenge the notion that the initial pharmacological effect of nicotine is anorexigenic and paradoxically suggest that an acute increase in food intake minutes after exposure to nicotine may contribute to the long-term anorexigenic effects of nicotine.