Effects of statins on regeneration of olfactory epithelium

Background: This study was performed to investigate whether statins can enhance the recovery of the olfactory epithelium (OE) damaged by 3-methylindole (3MI), an olfactotoxicant, and to compare the effects with those of steroids. Methods: Randomized placebo-controlled trial was performed. Fifty-four healthy female Sprague-Dawley rats (aged 9-10 weeks and weighing 160-180 g each) were randomly allocated to the statin-treated, steroid-treated, or control groups. Olfactory loss was induced using i.p. injection of 3MI in adult rats. Atorvastatin (10 mg/kg for 4 weeks), prednisolone (1 mg/kg for 2 weeks), or normal saline (1 cc for 4 weeks) was then administered per os with a gastric tube. Hematoxylin and eosin (H&E) staining and immunohistochemical staining were performed to evaluate the change of thickness and the arrangement of the OE, and immunoreactivity to protein gene product (PGP) 9.5 and proliferating cell nuclear antigen (PCNA). Results: The statin-treated group showed the earliest increase of the thickness of the OE (p = 0.002 at 7 days after 3MI injection) and the immunoreactivity to PCNA (p = 0.032 at 7 days after 3MI injection) among the three groups. The immunoreactivity to PGP 9.5 showed significantly better improvement at the 7th and 28th days after 3MI injection compared with the steroid-treated or control groups (p = 0.002 and p < 0.001, respectively). Conclusion: Statins might enhance the proliferation and neuroregenesis of the OE after 3MI injection.