Gadd45b mediates depressive-like role through DNA demethylation

Area of Science:

• Neuroscience
• Molecular Psychiatry
• Behavioral Neuroscience

Background:

• Brain-derived neurotrophic factor (BDNF) signaling in the mesolimbic dopamine (DA) circuit is crucial for social aversion development following chronic social defeat stress (CSDS).
• The specific downstream molecular targets of BDNF released from ventral tegmental area (VTA) DA terminals remain largely unknown.

Purpose of the Study:

• To identify downstream molecular targets of BDNF signaling in the nucleus accumbens (NAc) following CSDS.
• To investigate the role of Gadd45b in mediating depressive-like behaviors and social aversion induced by CSDS.
• To explore the function of Gadd45b in DNA methylation changes associated with social stress.

Main Methods:

• Utilized a chronic social defeat stress (CSDS) mouse model.
• Measured Gadd45b mRNA levels in susceptible and resilient mice.
• Administered intra-nucleus accumbens (NAc) BDNF infusions and used optical stimulation of VTA DA terminals.
• Assessed the impact of Gadd45b downregulation on social avoidance behaviors.
• Investigated Gadd45b's role in demethylating CpG islands of specific gene targets.

Main Results:

• Gadd45b mRNA levels were elevated in susceptible but not resilient mice following CSDS.
• BDNF infusion or VTA DA terminal stimulation increased Gadd45b expression in the NAc.
• Reducing Gadd45b levels effectively reversed social avoidance in susceptible mice.
• Gadd45b downregulation altered DNA methylation patterns in a specific, gene-dependent manner.

Conclusions:

• Gadd45b in the NAc is a key mediator of susceptibility to social stress and depressive-like behaviors.
• Gadd45b contributes to social avoidance by influencing DNA methylation within the mesolimbic DA circuit.
• These findings identify Gadd45b as a potential therapeutic target for stress-induced psychiatric disorders.