Reward and its control by dynorphin peptides.

Reward is a strong behavioral cue. It is argued that a sense of reward must be strictly controlled in time and magnitude to be functional. Central to the reward system is the mesolimbic dopamine pathway which is titillated by addictive drugs and alcohol. Rat lines or strains that voluntarily drink alcohol have lower dynorphin levels in relevant brain areas than those which avoid alcohol. Reward control may be a protective factor against addiction.