Fig. 5. Pharmacological activation of locomotor-like activities increases inspiratory-like frequencies ex vivo, which requires RTNPhox2b/Atoh1 integrity.
a Experimental strategy for recording respiratory- (C4) and locomotor-like (L2) motor activities on isolated ex vivo brainstem-spinal cord neonatal preparations. The lumbar spinal cord compartment is superfused with control or locomotor drugs enriched (NDMA and 5-HT) aCSF while the brainstem compartment remains in control aCSF. b Recordings of C4 and L2 integrated activities of one representative preparation before (CTL), during (NMDA/5-HT), and after (WO) perfusion of locomotor drugs in the lumbar spinal cord compartment. Note that C4 frequency increases when locomotor-like activities are triggered. c Quantification of the C4 frequency change (percent change to CTL) during and after drug-induced locomotor-like activity. NMDA/5-HT, p = 0,0002; WO, p = 0,0803; NMDA/5-HT vs WO, p = 0,0002; Wilcoxon matched-pairs tests. d–f Similar experiments as in (a-c) in preparations that underwent a brainstem transection to physically remove the pF respiratory area. No change of respiratory-like activity is seen during the application of locomotor drugs on the lumbar compartment. NMDA/5-HT, p = 0,8125; WO, p = 0,625; Wilcoxon matched-pairs tests. g–i Similar experiments as in a–c performed in Egr2 Cre;Phox2b 27AlaCKI neonates. These lack pF neurons that express Phox2b and are derived from rhombomere 5, a genetic intersection that recapitulates the genetically-defined RTNPhox2b/Atoh1. No change of respiratory-like activity is seen during the application of locomotor drugs on the lumbar compartment. NMDA/5-HT, p = 0,1094; WO, p = 0,1953 ; Wilcoxon matched-pairs tests. For all graphs, gray open circles are means of individual preparations, red circles are means ± SD across n preparations, *** denotes p < 0,001, and ns denotes p > 0,05. Source data are provided as a Source data file. See also Figs. S9 and S10.