Correlation between neuroanatomical and functional respiratory changes observed in an experimental model of Parkinson's disease

We showed previously that 60days after the induction of Parkinson's disease (PD) in a rat model, there are decreases in baseline breathing and in the number of phox2b-expressing neurons of the retrotrapezoid nucleus (RTN) and nucleus of the solitary tract (NTS), as well as a reduction in the density of the neurokinin-1 receptor (NK1r) in the pre-Botzinger complex (preBotC) and rostral ventrolateral respiratory group (rVRG). Here, our aim was to evaluate the correlation between neuroanatomical and functional respiratory changes in an experimental model of PD. Male Wistar rats with bilateral injections of 6-hydroxydopamine (6-OHDA, 24gl(-1)) or vehicle into the striatum had respiratory parameters assessed by whole-body plethysmography 1day before and 30, 40 or 60days after the ablation. From the 30th day after the ablation, we observed a reduction in the number of phox2b neurons in the RTN and NTS and a reduction in the density of astrocytes in the rVRG. At 40days after the ablation, we observed decreases in the density of NK1r in the preBotC and rVRG and of astrocytes in the RTN region. At 60days, we observed a reduction in the density of astrocytes in the NTS and preBotC regions. The functional data showed changes in the resting and hypercapnia-induced respiratory rates and tidal volume from days 40-60 after injury. Our data suggest that the neuroanatomical changes impair respiratory activity and are presumably a major cause of the respiratory problems observed in PD.