Increased Orexin by High Concentration of Sevoflurane Enhances the Suprahyoid Muscle Activity Involves in Gasping‐Like Respiration of Mice

Gasping respiration enhances survival chances during cardiac arrest by activating the suprahyoid muscles (SHMs), which are crucial for airway dilation. We previously reported that the high concentration of sevoflurane (6.5%: 2.0 minimum alveolar concentration, MAC) leads to gasping-like respiration in mice. Here, to understand the molecular mechanisms of this phenomenon, we compared the hypothalamic transcriptome profiles among control, 2.3% sevoflurane (0.7 MAC; eupnea), and 2.0 MAC groups and identified the differentially expressed genes (DEGs), in which hypocretin (orexin) precursor ( Hcrt ) gene expression was significantly elevated in the 2.0 MAC group. Notably, the intracerebroventricular administration of orexin enhanced SHM activity at 0.7 MAC. Our findings suggest that the 2.0 MAC sevoflurane-induced increases in orexin enhance activation of SHMs resulting in the involvement of gasping respiration.