Circulatory disturbance of the cochlear spiral modiolar artery in a type 2 diabetic mouse model

OBJECTIVE: This study aimed to identify significant differences in cochlea microvessel size between a diabetic mouse model (db/db) and normal mice using three‐dimensional (3D) quantitative analysis. METHODS: Six control heterozygote db/+ as well as 18 male B6/BKS(D)‐Lepr(db)/J (db/db) mice aged 14 (n = 9) and 28 (n = 9) weeks were examined. After clearing the cochlea, we reconstructed the 3D volumes of the spiral modiolar artery (SMA) in the cochlea using light‐sheet microscopy and analyzed vessel wall thickness, cross‐sectional area, short and long diameter, and vessel height. RESULTS: The average SMA‐wall thickness in the db/db‐mouse group (3.418 ± 0.328 μm) was greater than that in the control group (2.388 ± 0.411 μm). The average cross‐sectional outer area, short diameter, and long diameter of the SMA in db/db mice were significantly larger than those in control mice (all p < 0.001). The cross‐sectional areas increased with age (control: 221.782 ± 121.230 μm, 14 weeks; 294.378 ± 151.008 μm, and 28 weeks; 312.925 ± 147.943 μm). CONCLUSION: The db/db mice had thicker and larger proximal‐SMA vessel walls and diameters than control mice, respectively, thus potentially inducing increased blood viscosity or vascular insufficiency and aggravating hearing loss in type 2 diabetes mellitus. LEVEL OF EVIDENCE: IIb