ADMINISTRATION OF LHRH ANALOG CAN IMPROVE WORKING-MEMORY IN AGED FEMALE RATS

We had previously found that an age-related deficit in working memory appeared in middle-aged females, possibly related to their ageing repr oductive system. This experiment investigates the effect of administer ing an analog of luteinizing hormone-releasing hormone (LHRH), D-Trp6- LHRH, to 22-mo-old female rats submitted to successive trainings in a water-reinforced matching to sample task since the age of three months . Animals were injected SC with a long-lasting microcapsule formulatio n (800 mug/kg continuously releasing 5 mug D-Trp6-LHRH per day for at least 28 days). The action of the analog on ovary weight and estradiol and progesterone levels was also studied. Administration of D-Trp6-LH RH counteracted the deleterious effect of age on performance and inhib ited ovary function. However, hormone plasma levels were not modified. These results suggest that the hypothalamo-ovarian axis might be impl icated in memory deficits of middle-aged females.