Objective: We aimed to determine: 1) the feasibility of obtaining and characterising skeletal muscle; and 2) if muscle mitochondrial respiratory chain (MRC) function and content are preserved in older adults with PD.

Background: There has been a paucity of work on the relationship between sarcopenia, a progressive skeletal muscle disorder, and age-related neurological diseases such as Parkinson’s disease (PD).

Method: Sarcopenia was defined using grip strength, chair rise and bioimpedance analysis. MRC function was assessed using phosphorous magnetic resonance spectroscopy (MRS) by estimating tau 0.5 PCr (s) (phosphocreatine half-time recovery) in the calf muscles following a bout of aerobic exercise. Biopsy of the vastus lateralis muscle was performed, and MRC content assessed by fluorescent immunohistochemistry for porin and components of MRC complexes I and IV.

Results: Nine participants (78% male; mean age 79.9; PD duration 3.3 years) were recruited. Four had evidence of cognitive impairment. Six participants had probable sarcopenia. Eight participants completed MRS and had mean (SD) tau_1/2 PCr  of 37.8 (7.6) seconds, suggesting preserved mitochondrial function. Muscle biopsies were obtained in all and the procedure was well tolerated. Porin Z-score, a proxy for mitochondrial mass, was lower than expected compared to controls (0-89% of fibres with low porin). There was also a small amount of complex I (0.16-4.59%) and complex IV (0-3.79%) deficiency.

Conclusion: Detailed phenotyping, muscle biopsy and imaging was feasible and acceptable across a range of cognitive function in PD. Sarcopenia was relatively common and may be associated with lower mitochondrial mass and low levels of respiratory chain deficiency.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/the-feasibility-of-detailed-phenotyping-of-muscle-mitochondrial-respiratory-chain-function-and-content-in-parkinsons-disease/