Side effects of drugs stimulating prolactin secretion on the behavior of male rats.

The behavioral effects of drugs stimulating prolactin (PRL) secretion have been studied in male rats. Acquisition of active avoidance behavior was facilitated by short- (SHPRL) and long-term hyperprolactinaemia (LHPRL) induced by pituitary homografts under the kidney capsule. Dopamine antagonists, such as haloperidol and bromperidol, though causing hyperprolactinaemia, suppressed the acquisition of active avoidance behavior. Sulpiride was not effective in this respect. SHPRL facilitated and LHPRL inhibited sexual behavior of male rats. Haloperidol, but not sulpiride, suppressed sexual capacity of these animals. Sulpiride and domperidone, but not haloperidol, increased locomotor activity of male rats. These data suggest that differences in the behavioral effects of dopamine antagonists may depend on their capacity to compete with PRL at the central level.