Maternal separation altered behavior and neuronal spine density without influencing amphetamine sensitization

Area of Science:

• Neuroscience
• Developmental Psychology
• Pharmacology

Background:

• Maternal separation (MS) is a significant early-life stressor.
• Understanding its long-term effects on behavior and brain plasticity is crucial.
• Sex differences in behavioral and neurobiological responses to stress are well-documented.

Purpose of the Study:

• To investigate the long-term effects of MS on periadolescent behavior in rats.
• To examine the impact of MS on adult amphetamine (AMPH) sensitization.
• To assess MS-induced structural plasticity in corticolimbic brain regions.

Main Methods:

• Daily MS (3h) was performed on male and female rat pups from postnatal day 3-21.
• Periadolescent behaviors (exploratory, emotional, cognitive, social) were assessed.
• Amphetamine sensitization was induced and tested.
• Spine density in the nucleus accumbens (NAc), medial prefrontal cortex (mPFC), and orbital frontal cortex (OFC) was analyzed.

Main Results:

• MS enhanced anxiety-like behavior in males and altered play behavior, feminizing male responses.
• MS did not affect the development or persistence of AMPH-induced behavioral sensitization.
• MS increased spine density in the NAc, mPFC, and OFC.
• MS blocked AMPH-induced changes in spine density in these regions.

Conclusions:

• Early-life maternal separation influences periadolescent behavior and causes structural reorganization in the brain.
• Despite structural changes, MS does not alter amphetamine-induced behavioral sensitization.
• These findings highlight the complex interplay between early stress, behavior, and neuroplasticity.