Unilateral nasal obstruction affects development of cortical orofacial motor representation in the cortical masticatory area of growing rats

Abstract

The cortical masticatory area (CMA) regulates masticatory movements. However, there is limited information regarding the effect of respiratory disturbances on the functional development of the CMA. This study aimed to examine the effect of chronic unilateral nasal obstruction (UNO) on the CMA during the growth period. Forty-eight 8-day-old male Wistar albino rats were randomized into control (CONT, n = 24) and UNO (n = 24) groups. Arterial oxygen saturation (SpO₂) and the number of positive intracortical microstimulation (ICMS) sites in the anterior digastric (AD) muscle were recorded at 5, 7, and 9 weeks of age. ICMS was performed under anesthesia. The CONT group exhibited significantly higher SpO₂ values than the UNO group at each age. Furthermore, the number of positive ICMS sites in the AD muscle was significantly higher in the UNO group than in the CONT group at each age. The right AD was more strongly affected by UNO than the left AD. In addition, it was found that the P-area was more strongly affected by UNO than the A-area. These findings suggest that UNO during development induces changes in the motor representation in the CMA, which may affect respiratory and orofacial functions in rats. Therefore, we suggest that the development of respiratory dysfunction needs to be monitored and corrected promptly to avoid complications in physiological function.

Keywords: Cortical masticatory area; Development; Intracortical microstimulation; Masticatory movement; Nasal obstruction.