Cineradiographic analysis of respiratory movements in a mouse model for early Parkinson's disease

Parkinson's disease (PD) is a progressive degenerative disorder of the central nervous system known to cause a typical pattern of motor symptoms. In its later stages, PD is known to cause respiratory alterations including shortening of operational volumes and reduced velocity of respiratory-muscle contraction. It has been proposed that such changes are secondary to changes in posture and osteoarticular degeneration, leading to an alteration in the spinal axis that in turn could affect breathing mechanics. In this study, we examined respiratory movements by using cineradiography on a murine (C57BL/6J) model of mild hemi-PD. Under surgical anesthesia, PD mice received an injection of 6-OHDA solution to the right striatum, and were compared to control mice, which received an injection of saline solution. Two weeks after surgery, all mice had their respiratory movements recorded by video X-ray without any restraint. Behavioral tests were performed to assess the severity of the 6-OHDA lesion. As a result, behavioral tests confirmed mild motor impairments in PD mice as compared to controls. Parameters of respiratory function showed mild alterations in the PD group, suggestive of a restrictive-type respiratory disorder. These results suggest that respiratory alterations in PD may emerge simultaneously to other motor symptoms, and not as a consequence of the latter.