Fig. 5.

Rate-decreasing effects of raclopride, haloperidol, ketamine (left panel), quinpirole, amphetamine, cocaine and GHB (right panel) before (open symbols) and after (closed symbols) streptozotocin treatment on lever pressing maintained under the fixed-ratio schedule of food presentation. Data above “S” represent the rate of responding after vehicle (saline) injections, given at the beginning of the first cycle of a cumulative dose-effect curve. Rate is plotted as a percentage of the average rate in the three control (saline) sessions immediately preceding the test. Each symbol represents mean ± S.E.M. for 7 rats. *P<0.05 compared with corresponding data obtained before streptozotocin treatment.