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Abstract
Drug abuse and obesity are serious public health problems. Dopamine plays a central role in mediating the reinforcing effects of drugs and food. Prolonged use of drugs is known to alter the function and/or sensitivity of many neurotransmitter systems, including dopamine; however, the impact of consuming foods high in fat and/or sugar is less clear. These studies characterized the locomotor effects of acute and repeated cocaine in male and female C57BL/6J mice consuming 1 of 4 diets: (a) standard chow + water; (b) standard chow + 10% sucrose solution; (c) high-fat chow + water; or (d) high-fat chow + 10% sucrose solution. The acute locomotor effects of cocaine (3.2–32.0 mg/kg) were evaluated 4 weeks after initiating dietary conditions; the effects of repeated cocaine administration were evaluated after 5, 6, 7, and 12 weeks. During acute tests, mice consuming a diet high in fat and/or sucrose exhibited greater locomotor responses to cocaine than mice consuming standard chow and water, regardless of sex. Although diet-induced enhancements persisted across repeated cocaine testing, locomotor sensitization developed more rapidly in females drinking sucrose (and consuming either standard or high-fat chow) than in females consuming standard chow and water. In addition to providing evidence that consuming a diet high in fat and/or sugar enhances abuse-related effects of cocaine in ways that might increase vulnerability to abuse cocaine, these studies identified a potentially important sex-related difference in the interaction between nutrition and cocaine effects, with the impacts of sucrose consumption being greater in females than in males.
Drug abuse and obesity are serious public health problems worldwide, with recent estimates indicating that combined they cost the United States over $800 billion per year (Bouchery, Harwood, Sacks, Simon, & Brewer, 2011; Cawley & Meyerhoefer, 2010; National Drug Intelligence Center, 2011; United States Department of Health & Human Services, 2014). Dopamine systems play a crucial role in mediating the reinforcing effects of drugs of abuse and food. Prolonged use of drugs or consumption...