TCDD (2,3,7,8-tetrachlorodibenzo-p-dioxin) induces depression-like phenotype.

Area of Science:

• Neuroscience
• Environmental Health
• Toxicology

Background:

• The causes of major depressive disorder (MDD) are not fully understood.
• Previous research indicates a potential involvement of the aryl hydrocarbon receptor (AhR) in depression.
• 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), a potent environmental contaminant, is a known high-affinity ligand for AhR.

Purpose of the Study:

• To investigate the impact of TCDD exposure on depression-like behaviors in a mouse model.
• To explore whether a high-fat diet (HFD) influences the effects of TCDD on depression-like behaviors.

Main Methods:

• Female mice were fed either standard chow or an HFD for 11 weeks.
• Following baseline behavioral tests, mice received daily oral administration of TCDD (0.1 µg/kg/day) or vehicle for 28 days.
• Depression-like behaviors were assessed using sucrose preference, splash test, forced swim test (FST), and Morris water maze (MWM).

Main Results:

• TCDD exposure significantly reduced sucrose preference and grooming behavior, and increased immobility in the FST in chow-fed mice.
• HFD alone decreased sucrose preference.
• TCDD exacerbated depression-like behaviors in HFD-fed mice, with no significant impact on body weight or spatial learning in the MWM.

Conclusions:

• TCDD exposure induces depression-like behaviors in mice, independent of gross lethal toxicity.
• These findings highlight the potential role of AhR activation by environmental pollutants in the development or exacerbation of MDD.
• Further research is warranted to explore the link between AhR, environmental contaminants, and MDD etiology.