The effect of topical intranasal H89 and dimethylsulfoxide on AQP5 levels and histopathological findings in an experimental allergic rhinitis rat model

Aim: To investigate the protective effects of protein kinase A inhibitor H89 and its solvent, DMSO (dimethylsulfoxide), on the nasal mucosa of rats in an allergic rhinitis model. Method: In total, 32 adult male Wistar albino rats were divided into four groups, with eight rats in each group. Ovalbumin (OVA) sensitization was used to induce allergic rhinitis. DMSO, a solvent of H89, was administered through a topical intranasal spray to the sham group. No treatment was involved in the allergic rhinitis group. H89 was administered through a topical intranasal spray to the H89 group. After the experiment, rat nasal tissues were stained with hematoxylin-eosin and AQP5 (Aquaporin 5) antibodies. Histopathological and immunohistochemical evaluations were performed under a light microscope. Results: Vascular congestion, eosinophil infiltration, cilia loss, goblet cell proliferation, and degeneration in the mucosal glands were statistically significantly lower in the H89 group compared to the allergic rhinitis group. There was no statistical difference in the increase of connective tissue, vascular proliferation, or inflammatory cell infiltration. We posit that the histological improvements in the H89 group are due to the DMSO distribution of AQP5 was statistically significantly reduced in the H89 group compared to the allergic rhinitis group. Conclusion: H89 reduces the level of AQP5 but does not lessen allergic manifestations in the mucosa. DMSO, which we used as a solvent, did not affect the AQP5 level but reduced nasal inflammation.