Dynamic contrast-enhanced MRI reveals glymphatic dysfunction in mice with depressive-like behavior
Cui Lyu, Yong Xia, Li Yang, Jun Que, Feifan Han, Qin Guan, Yiming Wang, Bo Gao
Abstract
This study aimed to investigate glymphatic system dysfunction in chronic unpredictable mild stress (CUMS)-induced depressive-like mice and its association with aquaporin-4 (AQP4) and astrocyte alterations using dynamic contrast-enhanced MRI (DCE-MRI). Thirty-eight C57BL/6 mice were randomized into CUMS (28-day stress protocol) and control groups. Behavioral tests (sucrose preference, forced swim, tail suspension) assessed depressive phenotypes. DCE-MRI with Gd-DTPA cisterna magna injection was performed to evaluate glymphatic dynamics via hierarchical and k-means clustering of time-signal curves. Ex vivo Texas Red-dextran-3 tracer imaging quantified cerebrospinal fluid (CSF) influx. Immunofluorescence measured AQP4 polarization and GFAP expression in the hippocampus, prefrontal cortex, and hypothalamic regions. Statistical analyses included independent t -tests. CUMS mice exhibited reduced sucrose preference (0.71 vs. 0.81, t = 2.113, P = 0.0418) and prolonged immobility in forced swim tests (176.6 vs. 156.4 s, t = 2.200, P = 0.0343). DCE-MRI revealed a statistically significant intergroup difference in contrast agent signal intensity distribution within the Right Cortical Amygdala(Cortical amygdalar-R), ( t = 2.641, P = 0.0247, P < 0.05). Simultaneously, CUMS mice exhibited significant contrast agent accumulation in the thalamus. Hierarchical clustering identified enhanced Gd-DTPA influx but delayed peak timing in CUMS clusters, while k-means analysis showed reduced efflux in CSF-dense regions ( P < 0.01). Ex vivo tracer influx was reduced in CUMS (24.64 %vs.39.09 %, t = 5.440, P = 0.0003). Immunofluorescence revealed reduced AQP4 expression in CUMS hippocampus ( t = 2.697, P = 0.027) and prefrontal cortex ( t = 4.543, P = 0.0007), decreased polarization ( t = 2.308, P = 0.0396), and diminished GFAP expression ( t = 10.08, P < 0.0001). CUMS-induced depressive-like behavior is linked to glymphatic dysfunction, characterized by impaired CSF influx/efflux and AQP4/astrocyte downregulation. DCE-MRI clustering analysis provides novel insights into spatiotemporal glymphatic abnormalities, highlighting potential therapeutic targets for depression. • Key spatial anomaly linked to emotional processing regions : Right cortical amygdala exhibits distinct Gd-DTPA distribution in CUMS mice. • Novel spatiotemporal mapping of impaired waste clearance : Hierarchical/k-means clustering reveals delayed glymphatic efflux in CSF-rich areas. • Quantified functional impairment of glymphatic inflow : CUMS reduces CSF influx by 37 % (Texas Red-dextran) vs. controls. • Glymphatic kinetics align with depressive-like symptom severity : Delayed contrast peak timing correlates with behavioral despair phenotypes.