Prestin as an Otologic Biomarker of Cisplatin Ototoxicity in a Guinea Pig Model

Objective To evaluate (1) whether changes in serum prestin aid in early detection of cisplatin ototoxicity, (2) the role of diltiazem as an otoprotectant, and (3) whether prestin levels are sensitive to effects of diltiazem. Study Design Experimental animal study. Setting Translational research laboratory. Subjects Twenty female guinea pigs. Methods Two groups of 10 guinea pigs were used. The relationship between serum prestin levels and auditory brainstem response (ABR) thresholds was compared between the groups. All animals had baseline blood draws and ABR thresholds recorded prior to cisplatin administration. Intraperitoneal cisplatin bolus (8 mg/kg) was administered followed by 5 consecutive days of intratympanic (IT) diltiazem (2 mg/kg) or sham IT-saline injection. Serum prestin levels and ABR thresholds were measured at days 1, 2, 3, 7, and 14 postcisplatin. Results In sham, IT-saline-treated animals, mean prestin levels were elevated above baseline on days 1 to 7. The prestin levels were significantly elevated from baseline on day 1 ( P < .001), while significant ABR threshold elevations did not occur until day 2 ( P = .028) for click-evoked ABRs and day 3 ( P = .041) for tones. In diltiazem-treated animals, prestin levels were not elevated above baseline but ABR thresholds were elevated on days 1 to 3. However, the thresholds returned toward baseline on days 7 and 14. Conclusion Changes in serum prestin levels were detectable prior to shifts in ABR thresholds in a guinea pig cisplatin ototoxicity model. These changes did not occur in diltiazem-treated animals. Prestin may serve as a biomarker of cochlear injury that is sensitive to therapeutic interventions in cisplatin ototoxicity.