Longitudinal evaluation of female and male Wistar rats performance in some memory tasks

NATALIA CLAUDIA COLETTIS; MARTIN HABIF; M. V. OBERHOLZER; DIANA ALICIA JERUSALINSKY

Buenos Aires

Simposio; Simposio de Neurociencias "100 años del IBCN"; 2022

Instituto de Biologia Celular y Neurociencias Prof. Dr. Eduardo de Robertis

Learning and memory studies in animal models often rely on an overrepresentation of males or do not discriminate by sex. We present a comparative longitudinal study (4 and 12 month old rats) that reveals sexual dimorphism in some cognitive functions. In the open field task 4 and 12 month‐old female and male Wistar rats showed similar performances, except for a higher vertical activity/exploration (rearings) by females. All groups remembered, recognized, and discriminated the novel item in the Novel Object Recognition task. While in the Novel Object Location task young rats of both sexes and middle‐aged females though not males, spent significantly more time exploring the novel location than the familiar one. Furthermore, in the inhibitory avoidance step‐through task 24 hours-LTM consolidation and expression was preserved. Memory persistence (14 days later) was observed for middle‐aged females and for both sexes at 4 months of age, but there was a tendency towards an amnesic effect in middle‐aged males. Thus, a sexual dimorphism appears to emerge, since middle‐aged males evidenced cognitive impairments: for NOL, lacking spatial reference LTM, compared to both females and 4‐month‐old males, since acquisition and STM of objects were preserved, and for IA, tending to be amnesic for memory persistence compared to females. This dimorphism emphasizes the necessity of considering sex when assessing spatial reference LTM and persistence of associative memories from middle‐age on.