Reduction of motor behavioral deficits in senescent animals via chronic prolactin administration II. Non-stereotypic behaviors

The effects of chronic prolactin administration on three non-stereotypic psychomotor behaviors (inclined screen performance, rod walking and wire hanging) were examined in senescent (24 month) Fisher 344 rats. Prolactin (150 ng/hr) was administered for 7 days via Alzet® minipumps to rats which had been pretested on the three tasks. The animals were tested on days 4 and 7 following the implants and the pumps were removed after testing on day 7. In order to assess the persistence of any prolactin effects on psychomotor performance the animals were tested again on days 7 and 14 after pump removal. Control animals were implanted with Alzet® pumps containing only saline and tested in a similar manner. Results demonstrated that the prolactin treated animals showed improvements on both the inclined screen and rod walking tasks but not the wire hanging test. Moreover, the improved performance seen on the inclined screen test persisted for as long as 7 days after pump removal. Results are discussed in terms of the importance of techniques which increase striatal dopaminergic responsivity on enhancing psychomotor performance in senescence.