Mitochondrial uncoupling prodrug improves tissue sparing, cognitive outcome, and mitochondrial bioenergetics after traumatic brain injury in male mice

Abstract

Traumatic brain injury (TBI) results in cognitive impairment, which can be long-lasting after moderate to severe TBI. Currently, there are no FDA-approved therapeutics to treat the devastating consequences of TBI and improve recovery. This study utilizes a prodrug of 2,4-dinitrophenol, MP201, a mitochondrial uncoupler with extended elimination time, that was administered after TBI to target mitochondrial dysfunction, a hallmark of TBI. Using a model of cortical impact in male C57/BL6 mice, MP201 (80 mg/kg) was provided via oral gavage 2-hr post-injury and daily afterwards. At 25-hr post-injury, mice were euthanized and the acute rescue of mitochondrial bioenergetics was assessed demonstrating a significant improvement in both the ipsilateral cortex and ipsilateral hippocampus after treatment with MP201. Additionally, oxidative markers, 4-hydroxyneneal and protein carbonyls, were reduced compared to vehicle animals after MP201 administration. At 2-weeks post-injury, mice treated with MP201 post-injury (80 mg/kg; q.d.) displayed significantly increased cortical sparing (p = .0059; 38% lesion spared) and improved cognitive outcome (p = .0133) compared to vehicle-treated mice. Additionally, vehicle-treated mice had significantly lower (p = .0019) CA3 neuron count compared to sham while MP201-treated mice were not significantly different from sham levels. These results suggest that acute mitochondrial dysfunction can be targeted to impart neuroprotection from reactive oxygen species, but chronic administration may have an added benefit in recovery. This study highlights the potential for safe, effective therapy by MP201 to alleviate negative outcomes of TBI.

Acute Mitochondrial Impairment Underlies Prolonged Cellular Dysfunction after Repeated Mild Traumatic Brain Injuries

“…8). 16,17,21 While mitochondrial dysfunction is observed typically in the contusion and its penumbra in the more severe controlled cortical impact (CCI) model, 32,33,46,49 we observe bioenergetic impairment in regions remote from the impact location validating the diffuse, bilateral profile of this injury paradigm. Diffuse alterations in mitochondrial respiration are also observed after rapid non-impact rotational brain injury in a pediatric swine model, highlighting that this bioenergetic profile can be replicated in larger animal species.…”

“…Statistical outliers, after averaging technical triplicates, were identified by internally studentized residuals as published previously. 49 For the single CHI experiments, one statistical outlier was removed for all measures from the 48 h survival group. In the repeated CHI experiments, one statistical outlier was removed for all measures from each of two groups: the single CHI group and the group with repeated CHI at a 96 h interval euthanized at 96 h after the final CHI.…”

Novel imaging biomarkers for mapping the impact of mild mitochondrial uncoupling in the outer retina in vivo

“…In summary, the present results support continued investigation of ELM-RPE OCT thickness and R1 MRI measurements as useful approaches for monitoring the impact of mitochondrial protonophores for evaluating in vivo the rod photoreceptor mitochondrial energy ecosystem [9,46,47,52,61]. The development of new approaches for in vivo imaging of mitochondrial uncoupling response maps raises the possibility for promising future applications for evaluating mitochondrial protonophore treatment in neurodegenerative disease [46,47,52,61].…”

“…Our observations that the ELM-RPE region gets smaller than normal with DNP in dark-and light-adapted B6 and S6 mice are in-line with a greater removal of acidified water linked with increased metabolism [4,53]. In addition, an DNP-evoked increase in oxygen consumption will reduce levels of paramagnetic oxygen and free radical production that together provide a reasonable explanation for the observed reduction in R1 in S6 mice (Figs 1 and 2) [5,8,19,21,52,54].…”

“…Future studies will investigate the usefulness of using other anesthetics that do not interact with DNP for the MRI experiments, as well as controlled-release oral formulations of DNP [52]. Alternatively, MP201 (a prodrug to DNP) also has a high safety index and no reported negative consequences in B6 mice at 80 mg/kg [52].…”