OPRM1 and depressive symptom measurement: We targeted the excitatory vglut2-expressing neurons in the ventrolateral medulla because they contain the populations of inspiratory rhythm-generating preBötC neurons (Wallén-Mackenzie et al., 2006; Gray et al., 2010; Cui et al., 2016) and inspiratory premotor rVRG neurons, and MOR deletion from vglut2 neurons prevents opioid-induced respiratory depression in medullary slices (Sun et al., 2019; Bachmutsky et al., 2020).