Aberrant Amygdala-dependent Fear Memory in Corticosterone-treated Mice

Area of Science:

• Neuroscience
• Psychiatry
• Molecular Biology

Background:

• Anxiety disorders involve fear and worry, but underlying molecular mechanisms of neural plasticity are unclear.
• Chronic stress is a known contributor to anxiety disorders.
• Understanding these mechanisms is crucial for developing effective treatments.

Purpose of the Study:

• To investigate the molecular mechanisms of neural plasticity in anxiety disorders.
• To examine the role of the amygdala and hippocampus in stress-induced anxiety-like behaviors.
• To identify specific molecular changes in fear circuits following chronic stress.

Main Methods:

• Utilized a mouse model with chronic corticosterone (CORT) administration to induce anxiety-like behaviors.
• Assessed anxiety behaviors using elevated plus maze, light-dark, open-field, and marble-burying tasks.
• Analyzed amygdala and hippocampus function, c-Fos expression, long-term potentiation (LTP), and molecular signaling pathways (CaMKII, CREB, BDNF) in the basolateral amygdala (BLA).

Main Results:

• Chronic CORT treatment significantly increased anxiety-related behaviors and enhanced amygdala-dependent fear memory, while hippocampus-dependent memory remained normal.
• Increased c-Fos expression and enhanced LTP were observed in the BLA of CORT-treated mice.
• Autophosphorylation of CaMKIIα and phosphorylation of CREB, along with increased BDNF levels, were elevated in the BLA.

Conclusions:

• Increased CaMKII activity and synaptic plasticity in the BLA contribute to aberrant amygdala-dependent fear memory in chronic stress models.
• These findings highlight the BLA's critical role in the neural circuitry of anxiety disorders.
• The study identifies specific molecular targets for potential therapeutic interventions.