Anatomical and ventilatory disturbances in PD mice model. A, B, Photomicrographs showing a reduction in catecholaminergic neurons in the SNpc. Rostro-caudal distribution (C) and mean (D) of TH⁺ neurons after bilateral injection of 6-OHDA or vehicle into the CPu (n = 59–60/group). Changes in (E) ventilation (VE_E), (F) respiratory frequency (f_R), (G) tidal volume (V_T), (H) inspiratory time (T_I), and (I) expiratory time (T_E) in unanesthetized mice at room air 10 d after bilateral injection of 6-OHDA or vehicle into the CPu. Event distribution of (J) respiratory frequency (f_R), (K) tidal volume (V_T), and (L) expiratory time (T_E) in unanesthetized mice at room air 10 d after bilateral injection of 6-OHDA or vehicle into the CPu. Irregularity score in (M) ventilation (VE_E), (N) respiratory frequency (f_R), (O) tidal volume (V_T), (P) inspiratory time (T_I), and Q) expiratory time (T_E) in unanesthetized mice at room air 10 d after bilateral injection of 6-OHDA or vehicle into the CPu; t test followed by Mann–Whitney sum-rank test, p < 0.05. R, Representative recordings of O₂ and CO₂ expired fraction from two mice (vehicle-injected and PD-induced mice). Changes in (S) V̇O₂ and (T) V̇CO₂ in unanesthetized mice at room pre and 10 d postbilateral injection of 6-OHDA or vehicle into the CPu. (n = 8/group). Two-way ANOVA, followed by Newman–Keuls test, p < 0.05. SNR, substantia nigra pars reticulata; SNpc, substantia nigra pars compacta; ml, medial lemniscus; VTA, ventral tegmental área; IP, interpeduncular nucleus. Scale bars: 500 µm (A, B).