Expression and localization of histamine H1, H2, and H3 receptors in rat olfactory epithelium

Objective: Histamine is an important chemical mediator in the development of allergic rhinitis and plays a key role in eliciting the nasal symptoms of the disorder. Histamine may also affect smell as a neurotransmitter. However, whether histamine receptors are present in the mammalian olfactory epithelium has not yet been examined. The aim of this study was to investigate the expression and distribution of histamine H-1, H-2, and H-3 receptors in rat olfactory epithelium. Methods: Real-time quantitative PCR and immunohistochemical staining were performed to examine the mRNA level and protein expression and localization of histamine receptors (H-1, H-2, and H-3) in rat olfactory epithelium. Results: We demonstrated that mRNAs encoding histamine H-1, H-2, and H-3 receptors were detected in rat olfactory epithelium. Immunohistochemistry also showed strong positive staining for these receptors. Co-localization of histamine H-1, H-2, and H-3 receptors with olfactory mature protein revealed that these three histamine receptors were mainly localized in olfactory receptor neurons. Conclusions: These findings indicate that histamine H-1, H-2, and H-3 receptors are present in rat olfactory epithelium and may play a physiological role in olfactory transmission. (C) 2017 Elsevier B.V. All rights reserved.