Mice lacking dopamine D1 receptors express normal lithium chloride-induced conditioned taste aversion for salt but not sucrose.

Conditioned taste aversion (CTA), is a form of Pavlovian learning wherein a novel flavour is powerfully associated with subsequent feelings of illness, and is afterwards avoided. In rats, pharmacological blockade of dopamine D1 receptors has been reported to prevent the expression of a CTA to the sweet taste of sucrose or saccharine. We used genetically modified mice to determine whether dopamine D1 receptors are necessary for the expression of a CTA.

Dysregulation of striatal dopamine signaling by amphetamine inhibits feeding by hungry mice.

Amphetamine (AMPH) releases monoamines, transiently stimulates locomotion, and inhibits feeding. Using a genetic approach, we show that mice lacking dopamine (DA-deficient, or DD, mice) are resistant to the hypophagic effects of a moderate dose of AMPH (2 microg/g) but manifest normal AMPH-induced hypophagia after restoration of DA signaling in the caudate putamen by viral gene therapy. By contrast, AMPH-induced hypophagia in response to the same dose of AMPH is not blunted in mice lacking the ability to make norepinephrine and epinephrine (Dbh(-/-)), dopamine D(2) receptors (D2r(-/-)), dopamine D(1) receptors (D1r(-/-)), serotonin 2C receptors (Htr2c(-/Y)), neuropeptide Y (Npy(-/-)), and in mice with compromised melanocortin signaling (A(y)).

Is dopamine required for natural reward?

Reward is fundamental to the organization of behavior, and the neurotransmitter dopamine (DA) is widely recognized to be critical to the neurobiology of reward, learning and addiction. Virtually all drugs of abuse, including heroin and other opiates, alcohol, cocaine, amphetamine and nicotine activate dopaminergic systems. So called "natural" rewards such as food, positive social interactions and even humor, likewise activate DA neurons and are powerful aids to attention and learning.

Reward without dopamine.

Dopamine (DA) is believed to play a fundamental role in reward processes. Virtually all drugs of abuse activate dopaminergic systems, as do "natural" rewards such as sexual interaction and food. Sweet-tasting solutions, for example, are a well characterized natural reward.