Progestins influence performance on cognitive tasks independent of changesin affective behavior

In this study, the effects of progestins on various cognitive and affective tasks were investigated. Ovariectomized rats (N = 72) received subcutaneou sly 0.0, 4.0, or 8.0 mg/kg of progesterone (P), dihy-droprogesterone (DHP), or 5 alpha -pregnan-3 alpha -ol-20-one (3 alpha ,5 alpha -THP) suspended i n 10% ethanol/sesame oil v/v. For the cognitive tasks (Y-maze, inhibitory a voidance, and object recognition), the subjects were injected after habitua tion and training trials and were tested 24 h later. For the nociception an d affective tasks (open field, elevated plus-maze, and tailflick), the subj ects were injected 1 or 24 h before testing. P reduced latencies to the goa l arm in the Y-maze, enhanced latencies to the shock-associated side of the inhibitory avoidance chamber, and increased the percentage of time with a novel object. DHP reduced latencies to the goal arm, increased the percenta ge of correct choices in the Y-maze, and increased crossover latencies in t he inhibitory avoidance task. 3 alpha ,5 alpha -THP administration enhanced performance in the inhibitory avoidance task. P, DHP, and 3 alpha ,5 alpha -THP increased the number of entries into the central squares of a brightl y lit open field, open arm time in the elevated plus-maze, and tailflick la tencies, when administered 1 h, but not 24 h, prior to testing. These data suggest that some progestins, when administered following habituation and t raining and 24h prior to testing, produce changes in cognitive performance that do not coincide with overt, changes in the affective behaviors examine d.