FIGURE 6.

Postinfection administration of vinpocetine inhibits MUC5AC expression in a mouse model of S. pneumoniae–induced OM. (A–D) Mice were inoculated transtympanically with S. pneumoniae (1 × 10⁷ CFU per mouse) for 9 h, and pretreated or posttreated ototopically with vinpocetine (0.5 mg/kg) 3 h before or 3 h after S. pneumoniae inoculation. (A) MUC5AC mRNA expression in the middle ear of mice was measured with real-time qPCR assay. (B) Tympanic cavity of the mouse ear was observed and recorded with the video-otoscope. (C) H&E staining of the middle ear tissues from mice was performed (original magnification ×400; scale bar, 20 μm) for histologic analysis, and (D) the thickness of middle ear mucosa was measured from 15 middle ear sections per experimental group. (E) Hearing thresholds on each ear of the mice were measured with ABR tests across a frequency range of 4–32 kHz for 1–3 d after S. pneumoniae inoculation (2 × 10⁶ CFU per mouse). Mice were posttreated with vinpocetine (10 mg/kg) i.p. 3 h after S. pneumoniae inoculation; this was repeated at a dose of 5 mg/kg/day during the experiment. Pictures of the video otoscopy and H&E-stained middle ear tissues from one representative experiment are shown in (B) and (C) (B, n = 6; C, n = 15). Data in (A), (D), and (E) are mean ± SD (A, n = 3; D, n = 15; E, n = 6). Statistical analysis was performed using Student t test. Data are representative of three independent experiments. *p < 0.05, **p < 0.01. CON, control; PRE, preinoculation; POST, postinoculation; Sp, S. pneumoniae; Vinp, vinpocetine.