Strain differences in anxiety-like behavior: association with corticotropin-releasing factor

Area of Science:

• Neuroscience
• Behavioral Neuroscience
• Molecular Psychiatry

Background:

• Anxiety disorders are prevalent, and understanding their neurobiological underpinnings is crucial.
• The central nucleus of the amygdala (CeA) plays a significant role in processing fear and anxiety.
• Corticotropin-releasing factor (CRF) is a key neuropeptide implicated in the stress response and anxiety.

Purpose of the Study:

• To investigate the relationship between basal corticotropin-releasing factor (CRF) mRNA levels in the central nucleus of the amygdala (CeA) and anxiety-like behavior.
• To compare these measures across three distinct rat strains (Fischer 344, Wistar, and Wistar-Kyoto) known for differential stress responses.

Main Methods:

• Anxiety-like behavior was assessed using the elevated plus-maze test.
• CRF mRNA expression in the CeA was quantified using in situ hybridization.
• Plasma corticosterone levels and hypothalamic CRF mRNA were also measured.

Main Results:

• Wistar-Kyoto rats displayed significantly higher anxiety-like behavior on the elevated plus-maze compared to Fischer 344 and Wistar rats.
• Basal CRF mRNA levels in the CeA were elevated in Wistar-Kyoto rats relative to Fischer 344 rats.
• Fischer 344 rats showed elevated corticosterone levels after repeated plus-maze exposure, suggesting hypothalamopituitary adrenal axis hyperactivity.

Conclusions:

• Heightened expression of CRF in the CeA of Wistar-Kyoto rats is associated with their increased anxiety-like behaviors.
• This study highlights strain-specific differences in anxiety-related neurobiology.
• CRF in the central amygdala is a potential key mediator of anxiety-like behaviors.