Unilateral nasal obstruction alters sweet taste preference and sweet taste receptors in rat circumvallate papillae

• Published in: Acta histochemica 2019-02, Vol.121 (2), p.135-142
• Main Authors: Ren, Ershu, Watari, Ippei, Jui-Chin, Hsu, Mizumachi-Kubono, Mariko, Podyma-Inoue, Katarzyna Anna, Narukawa, Masataka, Misaka, Takumi, Watabe, Tetsuro, Ono, Takashi
• Format: Article
• Language: English
• Subjects: Circumvallate papillae; Mouth breathing; Nasal obstruction; Sweet taste; Two-bottle taste preference test
• ISSN: 0065-1281; 1618-0372
• DOI: 10.1016/j.acthis.2018.10.007

•Nasal obstruction in neonatal rats induced a decreased of SpO2 regardless of weight and also affected their taste sensing.•Sweet taste preference was especially decreased among five basic tastes (sweet, salty, sour, bitter, umami).•The quantitative RT-PCR revealed that the mRNA expressions of representative sweet taste-related molecules; T1R2, T1R3, α-gustducin, and PLCβ2 in the circumvallate papillae were decreased in nasal obstruction rats. Nasal obstruction causes mouth breathing, and affects the growth and development of craniofacial structures, muscle function in the stomatognathic system, and the taste perceptive system. However, the detailed mechanism underlying the effects of nasal obstruction on taste perception has not been fully elucidated. In this study, we investigated this mechanism using the two-bottle taste preference test, immunohistological analysis, and quantification of the mRNA expression of taste-related molecules in the circumvallate papillae. Neonatal male Wistar rats were divided randomly into control and experimental groups. Rats in the experimental group underwent unilateral nasal obstruction by cauterization of the external nostril at the age of 8 days. Arterial oxygen saturation (SpO2) was recorded in awake rats using collar clip sensors. Taste preference for five basic taste solutions was evaluated. Immunohistochemical analysis and quantitative real-time polymerase chain reaction (RT-PCR) were conducted to evaluate the expressions of taste-related molecules in the taste cells of the circumvallate papillae. Body weights were similar between the two groups throughout the experimental period. The SpO2 in the 7- to 12-week-old rats in the experimental group was significantly lower than that in the age-matched rats in the control group. In the two-bottle taste preference test, the sensitivities to sweet taste decreased in the experimental group. The mRNA expression of T1R2, T1R3, α-gustducin, and PLCβ2 was significantly lower in the experimental group than in the control group as determined by quantitative RT-PCR, and the immunohistochemical staining for α-gustducin and PLCβ2 was less prominent. These findings suggest that nasal obstruction may affect sweet taste perception via the reduced expression of taste-related molecules in the taste cells in rat circumvallate papillae.