Effects of Pyruvate Administration on Mitochondrial Enzymes, Neurological Behaviors, and Neurodegeneration after Traumatic Brain Injury.

Traumatic brain injury (TBI) is known to increase the susceptibility to various age-related neurodegenerative disorders such as Alzheimer's disease (AD) and Parkinson's disease (PD). Although the role of damaged mitochondrial electron transport chain (ETC) in the progression of AD and PD has been identified, its relationship with altered expression of neurodegenerative proteins has not been examined before. This study aimed to investigate 1) how TBI could affect mitochondrial ETC and neurodegeneration in rat brain regions related to behavioral alteration, and 2) if administration of the key mitochondrial substrate pyruvate can improve the outcome of mild TBI (mTBI). In a rat lateral fluid percussion injury model of mTBI, sodium pyruvate in sterile distilled water (1 g/kg body weight) was administered orally daily for 7 days. The protein expression of mitochondrial ETC enzymes, and neurodegeneration proteins in the hippocampus and cerebral cortex and was assessed on Day 7. The hippocampal and cortical expressions of ETC complex I, III, IV, V were significantly and variably impaired following mTBI. Pyruvate treatment altered ETC complex expression, reduced the nitrosyl stress and the MBP expression in the injured brain area, but increased the expression of the glial fibrillary acidic protein (GFAP) and Tau proteins. Pyruvate after mTBI augmented the Rotarod performance but decreased the horizontal and vertical open field locomotion activities and worsened neurobehavioural severity score, indicating a debilitating therapeutic effect on the acute phase of mTBI. These results suggest bidirectional neuroprotective and neurodegenerative modulating effects of pyruvate on TBI-induced alteration in mitochondrial activity and motor behavior. Pyruvate could potentially stimulate the proliferation of astrogliosis, and lactate acidosis, and caution should be exercised when used as a therapy in the acute phase of mTBI. More effective interventions targeted at multiple mechanisms are needed for the prevention and treatment of TBI-induced long-term neurodegeneration.

Impact of repeated stress on traumatic brain injury-induced mitochondrial electron transport chain expression and behavioral responses in rats.

A significant proportion of the military personnel returning from Iraq and Afghanistan conflicts have suffered from both mild traumatic brain injury (mTBI) and post-traumatic stress disorder. The mechanisms are unknown. We used a rat model of repeated stress and mTBI to examine brain activity and behavioral function. Adult male Sprague-Dawley rats were divided into four groups: Naïve; 3 days repeated tail-shock stress; lateral fluid percussion mTBI; and repeated stress followed by mTBI (S-mTBI). Open field activity, sensorimotor responses, and acoustic startle responses (ASRs) were measured at various time points after mTBI. The protein expression of mitochondrial electron transport chain (ETC) complex subunits (CI-V) and pyruvate dehydrogenase (PDHE1α1) were determined in four brain regions at day 7-post mTBI. Compared to Naïves, repeated stress decreased horizontal activity; repeated stress and mTBI both decreased vertical activity; and the mTBI and S-mTBI groups were impaired in sensorimotor and ASRs. Repeated stress significantly increased CI, CII, and CIII protein levels in the prefrontal cortex (PFC), but decreased PDHE1α1 protein in the PFC and cerebellum, and decreased CIV protein in the hippocampus. The mTBI treatment decreased CV protein levels in the ipsilateral hippocampus. The S-mTBI treatment resulted in increased CII, CIII, CIV, and CV protein levels in the PFC, increased CI level in the cerebellum, and increased CIII and CV levels in the cerebral cortex, but decreased CI, CII, CIV, and PDHE1α1 protein levels in the hippocampus. Thus, repeated stress or mTBI alone differentially altered ETC expression in heterogeneous brain regions. Repeated stress followed by mTBI had synergistic effects on brain ETC expression, and resulted in more severe behavioral deficits. These results suggest that repeated stress could have contributed to the high incidence of long-term neurologic and neuropsychiatric morbidity in military personnel with or without mTBI.

Development of a Standard Reference Material for metabolomics research.

The National Institute of Standards and Technology (NIST), in collaboration with the National Institutes of Health (NIH), has developed a Standard Reference Material (SRM) to support technology development in metabolomics research. SRM 1950 Metabolites in Human Plasma is intended to have metabolite concentrations that are representative of those found in adult human plasma. The plasma used in the preparation of SRM 1950 was collected from both male and female donors, and donor ethnicity targets were selected based upon the ethnic makeup of the U.S. population. Metabolomics research is diverse in terms of both instrumentation and scientific goals. This SRM was designed to apply broadly to the field, not toward specific applications. Therefore, concentrations of approximately 100 analytes, including amino acids, fatty acids, trace elements, vitamins, hormones, selenoproteins, clinical markers, and perfluorinated compounds (PFCs), were determined. Value assignment measurements were performed by NIST and the Centers for Disease Control and Prevention (CDC). SRM 1950 is the first reference material developed specifically for metabolomics research.

Effects of volume and composition of the resuscitative fluids in the treatment of hemorrhagic shock.

OBJECTIVES: To evaluate the effectiveness of normal saline, hypertonic saline, and Ringer's lactate solution followed by blood infusion in ameliorating the physiological, biochemical, and organ functions following hemorrhagic shock (HS) in rats. MATERIALS AND METHODS: Anesthetized, male Sprague-Dawley rats underwent computer-controlled HS, and were randomly divided into five groups consisting of (1) sham, (2) HS without resuscitation, (3) resuscitation with normal saline, (4) resuscitation with hypertonic saline, and (5) resuscitation with Ringer's lactate solution. All resuscitated animals were infused with subsequent infusion of shed blood. Animals were continuously monitored for physiological, hemodynamic, biochemical parameters, and organ dysfunctions. RESULTS: Non-resuscitated animals were unable to survive due to hypotension, poor oxygen metabolism, and lactic acidosis. Although these HS related parameters were corrected by all the fluids used in this study, additional blood infusion was more effective than fluid resuscitation alone. Also, hypertonic saline was more effective than Ringer's lactate solution, and normal saline was the least effective in preserving the liver and kidney functions and muscle damage. CONCLUSIONS: All crystalloid fluids were significantly more effective in reversing the HS outcome when used with blood infusion, but hypertonic salinewith blood was more effective in preventing the organ damage than Lactated Ringers solutions or normal saline in the treatment of HS.

Role of pyruvate dehydrogenase complex in traumatic brain injury and Measurement of pyruvate dehydrogenase enzyme by dipstick test.

OBJECTIVES: The present study was designed to investigate the role of a mitochondrial enzyme pyruvate dehydrogenase (PDH) on the severity of brain injury, and the effects of pyruvate treatment in rats with traumatic brain injury (TBI). METHODS: We examined rats subjected to closed head injury using a fluid percussion device, and treated with sodium pyruvate (antioxidant and substrate for PDH enzyme). At 72 h post injury, blood was analyzed for blood gases, acid-base status, total PDH enzyme using a dipstick test and malondialdehyde (MDA) levels as a marker of oxidative stress. Brain homogenates from right hippocampus (injured area) were analyzed for PDH content, and immunostained hippocampus sections were used to determine the severity of gliosis and PDH E1-infinity subunit. RESULTS: Our data demonstrate that TBI causes a significant reduction in PDH enzyme, disrupt-acid-base balance and increase oxidative stress in blood. Also, lower PDH enzyme in blood is related to the increased gliosis and loss of its PDH E1-infinity subunit PDH in brain tissue, and these effects of TBI were prevented by pyruvate treatment. CONCLUSION: Lower PDH enzyme levels in blood are related to the global oxidative stress, increased gliosis in brain, and severity of brain injury following TBI. These effects can be prevented by pyruvate through the protection of PDH enzyme and its subunit E-1.