Fig. 1: Melatonin treatment ameliorates depression-like behavior, cognitive deficits, glymphatic dysfunction, and AQP4 dislocation in CUMS mice.

A Schematic diagram of the behavioral experimental procedure. B, C The latency to the first immobility and the duration of total immobility in the tail suspension test (TST). D The total travel distance during the open field test (OFT). E The percentage of sucrose consumption during the sucrose preference test (SPT). Control, n = 10; CUMS, n = 11; Mel, n = 14. F Tracing of locomotion for representative animals during the arena test. G The latency to finding the hidden platform in the Morris Water Maze test during the 5-days training. H, I The latency to finding the platform area and the percentage time spent in the platform quadrant in the probe test. Each group, n = 15. J–V Measurement of glymphatic function and AQP4 polarization. J Diagram of CSF tracer injection via the cisterna magna. K Representative images of CSF tracers in the whole brain and coronal slices. Scale bar, 2 mm. L, M Analysis of fluorescent area in the brains for the anesthesia and awake states. Anesthesia, each group n = 8. Awake, Control, n = 6; CUMS, n = 7; Mel, n = 8. N Diagram of stereotactic injection of exogenous mixture of human Aβ40 and Aβ42. O, P The brain concentration of exogenous human Aβ40 and Aβ42 measured by ELISA. Each group n = 7. Q Representative images of AQP4, DAPI, and GFAP immunostaining. T Representative images of AQP4 and CD31 immunostaining. Scale bars, 50 μm and 25 μm. R Quantitation of GFAP fluorescent intensity. S Quantitation of AQP4 polarization to Q. AQP4 polarization = donut-shaped area AQP4 / global AQP4. U Quantitation of AQP4 polarization to T. AQP4 polarization = vessel AQP4 (peak of the vertical line) / global AQP4. Collect 3–5 vessels from each of 6 mice (R, S and U). V Model of AQP4 fluorescence intensity plot along the yellow dotted line in (T). Signal within the vessels is the baseline intensity of AQP4. * #<0.05, ** ##<0.01, *** ###<0.001.