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Sex-Specific Outcomes in a Rat Model of Early-Life Stress Due to Adverse Caregiving
Jazmín Grillo Balboa1,2,3, Ailén A Colapietro3, Verónica I Cantarelli4
1Laboratorio de Neuroepigenética y Adversidades Tempranas, Departamento de Química Biológica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires, Argentina.
Insights
Early life adversity, modeled by the Scarcity-Adversity Model (SAM), disrupts maternal care and causes long-term behavioral changes in offspring. This highlights the critical role of nurturing in preventing mood disorders and promoting well-being.
Area of Science:
- Neuroscience
- Developmental Psychology
- Animal Behavior
Background:
- Early parental care shapes cortico-limbic circuits crucial for stress response and emotional health.
- Infant maltreatment elevates the risk for mood disorders like anxiety and depression, impairing stress coping.
Purpose of the Study:
- To investigate the effects of the Scarcity-Adversity Model (SAM) on maternal behavior and adult offspring emotionality and stress reactivity in rats.
- To determine if early life adversity induces sex-specific behavioral changes.
Main Methods:
- The Scarcity-Adversity Model (SAM) was used, restricting nesting resources in rats from postnatal days 8-12.
- Maternal stress (fecal corticosterone metabolites) and behavior were assessed.
- Offspring underwent behavioral tests in adulthood, including the Elevated Plus Maze (EPM), Light-Dark Box, Open Field, Forced Swim, and Sucrose Splash tests.
- Acute stress exposure and subsequent fecal corticosterone metabolite levels were measured in adult offspring.
Main Results:
- SAM-exposed mothers displayed fragmented care, increased aggression, and elevated stress hormones.
- Adult SAM offspring exhibited altered anxiety-like behaviors, with sex-specific differences observed across various tests.
- Male SAM rats showed passive stress reactivity, indicated by lower corticosterone levels under acute stress.
Conclusions:
- The Scarcity-Adversity Model (SAM) induces enduring, sex-specific alterations in risk-taking, novelty response, and stress reactions.
- Early life adversity significantly impacts emotional well-being and psychopathological risk.
- Nurturing environments are vital for healthy development and stress resilience.
Abstract:
Early parental care is critical for the development of cortico-limbic circuits regulating stress responses and emotional well-being. Conversely, infant maltreatment can increase susceptibility to mood disorders-such as anxiety and depression-and impair stress-coping abilities. Here, we employed the Scarcity-Adversity Model (SAM) in rats, limiting nesting resources from postnatal days 8-12, to examine its effects on maternal and adult offspring behavior. SAM-exposed mothers exhibited fragmented care and increased violence towards pups. By postpartum day (PPD) 13, maternal fecal corticosterone metabolites (FCM) were elevated, indicating heightened stress. At weaning, SAM dams also showed increased anxiety-like behavior in the Elevated Plus Maze (EPM), suggesting significant emotional alterations. In adulthood, SAM-exposed offspring underwent anxiogenic tests. Both male and female SAM offspring showed increased latency to enter open arms and reduced risk-assessment in the EPM, though females displayed anxiolytic-like behavior in the Light-Dark Box. Male SAM rats had reduced locomotion in the Open Field, earlier onset and increased immobility in the Forced Swim, and increased latency to groom in the Sucrose Splash. When exposed to acute stress, male SAM rats had lower FCM levels, consistent with their passive stress reactivity. These findings confirm SAM induces long-lasting, sex-specific changes in risk-taking, novelty responsiveness, and stress reactions, underscoring the importance of early nurturing in promoting well-being and reducing psychopathological risk.
