Effects of early maternal separation and variable chronic stress on hippocampal volume and contextual memory

ZALOSNIK, MARÍA INÉS; POLLANO, ANTONELLA; TRUJILLO, VERÓNICA; DURANDO, PATRICIA EVELINA; SUÁREZ, MARTA MAGDALENA

STRESS

TAYLOR & FRANCIS LTD

Lugar: Londres; Año: 2014 vol. 17 p. 445 - 450

1025-3890

Adverse experiences early in life may sensitize the hippocampus to subsequent stressors throughout the individual´s life. We analyzed in male rats, whether, the interaction between early maternal separation and chronic stress affects: (1) the volume of the dorsal hippocampus, (2) CA1, CA2/3 and dentate gyrus (DG) and (3) hippocampal-dependent memory in adulthood. Male Wistar rats were subjected to daily maternal separation for 4.5 h between postnatal days 1-21. From postnatal day 50, animals were exposed to a chronic unpredictable stress paradigm during 24 days. The volumes of the dorsal hippocampus, their areas or strata did not reveal significant differences between treatments. Non-maternally separated and stressed animals showed poor hippocampal performance in a contextual fear conditioning test, with a significant reduction in freezing behavior during post-conditioning compared with control and maternally separated and stressed animals. Also, memory retrieval 24 h after conditioning was significantly weaker in this group than in control animals. Memory performance in maternally separated and stressed rats was similar to control animals. Our results show an interaction between early environment experiences and chronic variable stress in young adulthood as evidence that early stressful experiences do not necessarily lead to a negative outcome but can help in maintaining brain plasticity and increase fitness when animals reach adulthood.