Presentation Authors: Amanda Wolf-Johnston*, Steven Truschel, Bronagh McDonnell, Aura Kullmann, Anthony Kanai, Gerard Apodaca, Lori Birder, Pittsburgh, PA
Introduction: Spinal cord injury (SCI) is associated with significant changes in bladder function. We have previously shown that early after SCI there are morphological changes to the rat bladder urothelium (UT), which plays a prominent role in bladder function. Studies have shown that SCI can lead to increased oxidative stress at both cellular and mitochondrial (MITO) levels resulting in tissue damage and functional decline. The objective of this study was designed to provide a comprehensive assessment of MITO alterations including reactive free oxygen (ROS) levels within the bladder UT following acute SCI in mice and whether MITO targeted anti-oxidant treatment could mitigate these effects.
Methods: We used female C57 mice (C57Bl/6; 20 gm; 4-5 wks) with complete SCI transection at T9-T10 vertebrae level and collected bladders at 3 days post transection for cell culture, electron microscopy and western immunoblotting. Some animals were treated with the MITO ROS scavenger MitoTempo (mTEM; 1 mg/kg/day delivered by subcutaneous osmotic pump implanted at the time of SCI).
Results: Following acute SCI, we find an increase in MITO morphology with increase in electron dense &[prime]mitobodies&[prime] (indicative of cellular damage) which is also supported by an increase (1.25-fold) in the MITO mass marker TOM20. We also find increased (1.3-fold) levels of the autophagy marker light chain 3 (LC3) in SCI. Increased oxidative stress markers nitrotyrosine (2-fold) and ROS (1.6-fold) were also evident as well as increased cleaved caspase 3 (1.5-fold) in SCI versus sham control. These changes were restored with mTEM treatment to that of control or sham levels.
Conclusions: There are a number of factors that play a role in impaired bladder and UT function after traumatic SCI. Recent evidence has revealed that altered cellular metabolism (i.e., MITO functions) plays an important role. Our study demonstrates that acute traumatic SCI elicits significant changes within UT that involve increased oxidative stress and ROS, and activation of caspases (which play a role in apoptosis). Increased LC3 may be associated with reduction in turnover of autophagosomes- the key structure and system for the degradation of intracellular debris. Strikingly, the dysregulation of this quality control system in SCI is restored by mTEM treatment. Taken together, early treatment with MITO-targeted antioxidant therapy may optimize the management of SCI-bladder dysfunction.
Source of Funding: PO1 DK093424