BACKGROUND: Ultra-high field magnetic resonance imaging (MRI) has obvious advantages in acquiring high-resolution images. 7 T MRI has been clinically approved and 21.1 T MRI has also been tested on rodents. PURPOSE: To examine the effects of ultra-high field on mice behavior and neuron activity. STUDY TYPE: Prospective, animal model. ANIMAL MODEL: Ninety-eight healthy C57BL/6 mice and 18 depression model mice. FIELD STRENGTH: 11.1-33.0 T SMF (static magnetic field) for 1 hour and 7 T for 8 hours. Gradients were not on and no imaging sequence was used. ASSESSMENT: Open field test, elevated plus maze, three-chambered social test, Morris water maze, tail suspension test, sucrose preference test, blood routine, biochemistry examinations, enzyme-linked immunosorbent assay, immunofluorescent assay. STATISTICAL TESTS: The normality of the data was assessed by Shapiro-Wilk test, followed by Student's t test or the Mann-Whitney U test for statistical significance. The statistical cut-off line is P < 0.05. RESULTS: Compared to the sham group, healthy C57/6 mice spent more time in the center area (35.12 ± 4.034, increased by 47.19%) in open field test and improved novel index (0.6201 ± 0.02522, increased by 16.76%) in three-chambered social test a few weeks after 1 hour 11.1-33.0 T SMF exposure. 7 T SMF exposure for 8 hours alleviated the depression state of depression mice, including less immobile time in tail suspension test (58.32% reduction) and higher sucrose preference (increased by 8.80%). Brain tissue analysis shows that 11.1-33.0 T and 7 T SMFs can increase oxytocin by 164.65% and 36.03%, respectively. Moreover, the c-Fos level in hippocampus region was increased by 14.79%. DATA CONCLUSION: 11.1-33.0 T SMFs exposure for 1 hour or 7 T SMF exposure for 8 hours did not have detrimental effects on healthy or depressed mice. Instead, these ultra-high field SMFs have anti-depressive potentials. EVIDENCE LEVEL: 1 TECHNICAL EFFICACY: Stage 1.
