Structural abnormality of the hippocampus associated with depressive symptoms in heart failure rats
Hideaki Suzuki1, Akira Sumiyoshi2, Yasuharu Matsumoto1
1Department of Cardiovascular Medicine, Tohoku University Graduate School of Medicine, Sendai, Japan.
Insights
Heart failure (HF) is linked to brain changes, specifically in the ventral hippocampus. This study found structural abnormalities in the rat HF model
Area of Science:
- Neuroscience
- Cardiology
- Psychiatry
Background:
- Heart failure (HF) affects the brain and is linked to depression, but the underlying mechanisms are unclear.
- Structural abnormalities in the ventral hippocampus are known in depression but not reported in HF.
- Investigating the brain's structural changes in HF is crucial for understanding comorbid depression.
Purpose of the Study:
- To investigate structural brain abnormalities in a rat model of heart failure (HF).
- To explore the relationship between HF, ventral hippocampus structure, and depressive behaviors.
Main Methods:
- Utilized voxel-based morphometry (VBM) and histological analysis in a rat model of HF.
- Assessed gray matter concentration (GMC) via T2-weighted imaging and VBM.
- Measured neurogenesis, astrocyte numbers, and neurite outgrowth in the ventral hippocampus; monitored locomotor activity for depressive behavior.
Main Results:
- VBM revealed a significant decrease in gray matter concentration (GMC) in the ventral hippocampus of HF rats.
- HF rats exhibited decreased neurogenesis and neurite outgrowth, with increased astrocyte numbers in the ventral hippocampus.
- Ventral hippocampal GMC negatively correlated with locomotor activity, indicating a link to depressive symptoms.
Conclusions:
- Structural abnormalities in the ventral hippocampus are associated with depressive symptoms in heart failure.
- This study provides the first evidence of ventral hippocampal structural changes in HF rats.
- Findings highlight the ventral hippocampus as a potential target for understanding and treating HF-related depression.
Abstract:
Heart failure (HF) is characterized by a blood supply which is insufficient to meet the body's demand. HF can potentially affect the brain and is associated with a high prevalence of depression. However, the mechanisms by which the two are related remain largely unclear. Structural abnormalities of the ventral hippocampus have been observed in depression but have never been reported in HF. In this study, we thus investigated structural brain abnormality in HF using voxel-based morphometry (VBM) and histological analysis in a rat model of HF. T2-weighted images were obtained in rats with HF (n = 20) and sham rats (n = 17) and VBM was used to produce gray matter concentration (GMC) maps. Twenty-four hour locomotor activity was used as a sign of depressive behavior. Brains of HF and sham rats (n = 8, each) were fixed and histologically analyzed for the measurement of neurogenesis, the number of astrocytes and neurite outgrowth in the ventral hippocampus. VBM demonstrated significant GMC decrease in the hippocampus, which was restricted to the ventral segment. Similarly, neurogenesis and neurite outgrowth were significantly decreased and the number of astrocytes was significantly increased in HF rats as compared with sham rats in the ventral hippocampus. GMC values in the ventral hippocampus were significantly and negatively correlated with 24 hour locomotor activity in HF rats. In conclusion, the present study has demonstrated for the first time that the structural abnormality of the ventral hippocampus is associated with depressive symptoms in HF rats.
