Background and rationale More than two decades ago, Wise proposed his “anhedonia
hypothesis” to explain the role of dopamine in motivated behaviors. The hypothesis posits …

Opioid modulation of ingestion includes general opioid antagonism of deprivation-induced
water intake and intake of sucrose and saccharin solutions. Previous studies using selective …

Opioid receptors, especially μ-opioid receptors, in the ventral tegmental area (VTA) and
nucleus accumbens (NAcc) are reported to regulate food motivation. However, the roles of μ …

The present studies tested the effect of acute and chronic administration of naloxone on food
intake of lean and genetically obese (ob/ob) mice. Acute administration of naloxone, a drug …

Complex behaviors such as those associated with reward to unconditioned positive
reinforcers are polygenic processes. In studies using genetically modified mice specific for …

Opioid antagonism and serotonergic stimulation is associated with macronutrient-specific
hypophagia in animals. In the present study we evaluated their systemic effect alone, and in …

A variety of evidence suggests that endogenous opioid peptides play a role in the short-term
control of eating. More recently, opioid receptor antagonists like naltrexone have been …

Rats maintained under restricted access to food (but at 100% free-feeding weights) received
one of two diets in their home cages: a palatable sucrose-based diet, or regular chow (grain …

Agonist stimulation of opioid receptors increases feeding in rodents, while opioid
antagonists inhibit food intake. The pan-opioid antagonist, LY255582, produces a sustained …

Mu opioid receptor (MOR) signaling in the nucleus accumbens (NAcc) elicits marked
increases in the consumption of palatable tastants. However, the mechanism and circuitry …