Maternal separation with early weaning: a novel mouse model of early life neglect

Childhood adversity is associated with increased risk for mood, anxiety, impulse control, and substance disorders. Although genetic and environmental factors contribute to the development of such disorders, the neurobiological mechanisms involved are poorly understood. A reliable mouse model of early life adversity leading to lasting behavioral changes would facilitate progress in elucidating the molecular mechanisms underlying these adverse effects. Maternal separation is a commonly used model of early life neglect, but has led to inconsistent results in the mouse.

In an effort to develop a mouse model of early life neglect with long-lasting behavioral effects in C57BL/6 mice, we designed a new maternal separation paradigm that we call Maternal Separation with Early Weaning (MSEW). We tested the effects of MSEW on C57BL/6 mice as well as the genetically distinct DBA/2 strain and found significant MSEW effects on several behavioral tasks (i.e., the open field, elevated plus maze, and forced swim test) when assessed more than two months following the MSEW procedure. Our findings are consistent with MSEW causing effects within multiple behavioral domains in both strains, and suggest increased anxiety, hyperactivity, and behavioral despair in the MSEW offspring. Analysis of pup weights and metabolic parameters showed no evidence for malnutrition in the MSEW pups. Additionally, strain differences in many of the behavioral tests suggest a role for genetic factors in the response to early life neglect.

These results suggest that MSEW may serve as a useful model to examine the complex behavioral abnormalities often apparent in individuals with histories of early life neglect, and may lead to greater understanding of these later life outcomes and offer insight into novel therapeutic strategies.