Effects of Unilateral Nasal Obstruction on the Development of the Cortical Masticatory Area in Growing Rats

Abstract

The cortical masticatory area (CMA) regulates masticatory movements and controls rhythmic jaw movements. However, information regarding the effect of respiratory disturbances on the functional development of the CMA remains limited. This study aimed to examine the effect of chronic unilateral nasal obstruction (UNO) on the motor representation of the anterior digastric (AD) muscle 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. Both groups underwent intracortical microstimulation (ICMS) at ages 5, 7, and 9 weeks. Arterial oxygen saturation (SpO2) and the number of positive ICMS sites for the AD muscle were measured throughout the experiment. The SpO2 values were significantly lower in the UNO group than in the CONT group at each age. Further, the number of positive ICMS sites for the AD muscle was significantly higher in the UNO group than in the CONT group at each age. Intragroup comparisons revealed that the number of positive ICMS sites increased with age. The onset latencies of the evoked AD potential significantly differed between the right and left sides. However, no differences were found between the CONT and UNO groups at any age. These findings suggest that UNO during development induces changes in the motor representation in the CMA.