Effects of dopamine D1 and dopamine D2 antagonists on the free feeding and drinking patterns of rats

In male rats with food and water freely available, the specific dopamine D 2 antagonist YM-09151-2 had little effect on total food or water intake across a 24-hr period. However, it produced a substantial dose-related decrease in feeding rate during meals and an enhancement of both meal size and duration. The equivalent parameters for water intake were affected to a much lesser extent. A second dopamine D 2 antagonist, remoxipride, had similar effects on feeding patterns and, in addition, raised food intake during the 2 hr after drug administration. A third dopamine D 2 antagonist, raclopride, produced a short-lived rise in food intake and a slowing of feeding rate with a nonsignificant increase in meal size at intermediate doses