Rats subjected to chronic-intermittent hypoxia have increased density of noradrenergic terminals in the trigeminal sensory and motor nuclei

► Chronic intermittent hypoxia (CIH) is a pathogenic factor in sleep apnea syndrome. ► We quantified noradrenergic (NE) terminals in trigeminal motor and sensory nuclei. ► Rats subjected to CIH had increased NE innervation. ► NE terminal sprouting occurred in motor and sensory regions, in pons and medulla. ► This may enhance orofacial muscle activity and cardiorespiratory reflexes.