This study was done to evaluate the differences in mechanisms of olfactory training and steroid therapy.

Mice were administered 3-methylindole at a dose of 300 mg/kg. Olfactory function was evaluated. The olfactory neuroepithelium was harvested for histologic examination and protein analysis. Subsequently, data analysis, gene ontology and pathway analysis, a quantitative real-time polymerase chain reaction of mRNA, and western blot analysis were conducted.

Mice were divided in 4 groups according to treatment. Control, anosmia, training, and steroid groups resumed food-finding. MMP27, CCL22, and IL18rap mRNA expressions were significantly increased in the training group compared to that in the steroid group. IL1R2 mRNA expression was significantly higher in the olfactory neuroepithelium of steroid-treated mice than in that of the training group mice.

The study concluded through its findings that the steroid therapy improved olfactory function via anti-inflammatory effects, unlike olfactory training which involved cell regeneration and tissue remodeling. Protein and gene analyses revealed that steroid therapy and olfactory training are underpinned by distinct mechanisms. The selection of the most appropriate treatment will be dependent on the cause of olfactory loss.