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Margolis LM, Wilson M, Drummer DJ, Carrigan CT, Murphy NE, Allen JT, Dawson MA, Mantzoros CS, Young AJ, Pasiakos SM. Pioglitazone does not enhance exogenous glucose oxidation or metabolic clearance rate during aerobic exercise in men under acute high altitude exposure. Am J Physiol Regul Integr Comp Physiol 2024. [PMID: 38682243 DOI: 10.1152/ajpregu.00064.2024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2024] [Accepted: 04/23/2024] [Indexed: 05/01/2024]
Abstract
Insulin insensitivity decreases exogenous glucose oxidation and metabolic clearance rate (MCR) during aerobic exercise in unacclimatized lowlanders at high altitude (HA). Whether use of an oral insulin sensitizer prior to acute HA exposure enhances exogenous glucose oxidation is unclear. This study investigated the impact of Pioglitazone (PIO) on exogenous glucose oxidation and glucose turnover compared to placebo (PLA) during aerobic exercise at HA. Using a randomized, crossover design, native lowlanders (n=7 males, mean±SD, age: 23±6 yr, body mass: 84±11 kg) consumed 145 g (1.8 g/min) glucose while performing 80-min of steady-state (1.43±0.16 V̇O2 L/min) treadmill exercise at HA (460 mmHg) following short-term (5 days) use of PIO (15 mg oral dose per day) or PLA (microcrystalline cellulose pill). Substrate oxidation and glucose turnover were determined using indirect calorimetry and stable isotopes (13C-glucose and [6,6-2H2]-glucose). Exogenous glucose oxidation was not different between PIO (0.31±0.03 g/min) and PLA (0.32±0.09 g/min). Total carbohydrate oxidation (PIO: 1.65±0.22 g/min, PLA: 1.68±0.32 g/min) or fat oxidation (PIO: 0.10±0.0.08 g/min, PLA: 0.09±0.07 g/min) were not different between treatments. There was no treatment effect on glucose rate of appearance (PIO: 2.46±0.27, PLA: 2.43±0.27 mg/kg/min), disappearance (PIO: 2.19±0.17, PLA: 2.20 ± 0.22 mg/kg/min), or MCR (PIO: 1.63±0.37, PLA: 1.73±0.40 mL/kg/min). Results from this study indicate that PIO is not an effective intervention to enhance exogenous glucose oxidation or MCR during acute HA exposure. Lack of effect with PIO suggests the etiology of glucose metabolism dysregulation during acute HA exposure may not result from insulin resistance in peripheral tissues.
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Affiliation(s)
| | - Marques Wilson
- Military Nutrition Division, US Army Research Institute of Environmental Medicine, Natick, MA, United States
| | - Devin J Drummer
- Military Nutrition Division, US Army Research Institute of Environmental Medicine, Natick, MA, United States
| | | | - Nancy E Murphy
- Military Nutrition Division, US Army Research Institute of Environmental Medicine, United States
| | - Jillian T Allen
- Military Nutrition Division, US Army Research Institute of Environmental Medicine, United States
| | - M Alan Dawson
- Military Nutrition Division, US Army Research Institute of Environmental Medicine, Natick, MA, United States
| | - Christos S Mantzoros
- Division of Endocrinology, Diabetes and Metabolism, Harvard Medical School / Beth Israel Deaconess Medical Center, Boston, United States
| | - Andrew J Young
- US Army Research Institute of Environmental Medicine, United States
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Kalyani P, Lippa SM, Werner JK, Amyot F, Moore CB, Kenney K, Diaz-Arrastia R. Phosphodiesterase-5 (PDE-5) Inhibitors as Therapy for Cerebrovascular Dysfunction in Chronic Traumatic Brain Injury. Neurotherapeutics 2023; 20:1629-1640. [PMID: 37697134 PMCID: PMC10684467 DOI: 10.1007/s13311-023-01430-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/22/2023] [Indexed: 09/13/2023] Open
Abstract
Multiple phase III randomized controlled trials (RCTs) for pharmacologic interventions in traumatic brain injury (TBI) have failed despite promising results in experimental models. The heterogeneity of TBI, in terms of pathomechanisms and impacted brain structures, likely contributes to these failures. Biomarkers have been recommended to identify patients with relevant pathology (predictive biomarkers) and confirm target engagement and monitor therapy response (pharmacodynamic biomarkers). Our group focuses on traumatic cerebrovascular injury as an understudied endophenotype of TBI and is validating a predictive and pharmacodynamic imaging biomarker (cerebrovascular reactivity; CVR) in moderate-severe TBI. We aim to extend these studies to milder forms of TBI to determine the optimal dose of sildenafil for maximal improvement in CVR. We will conduct a phase II dose-finding study involving 160 chronic TBI patients (mostly mild) using three doses of sildenafil, a phosphodiesterase-5 (PDE-5) inhibitor. The study measures baseline CVR and evaluates the effect of escalating sildenafil doses on CVR improvement. A 4-week trial of thrice daily sildenafil will assess safety, tolerability, and clinical efficacy. This dual-site 4-year study, funded by the Department of Defense and registered in ClinicalTrials.gov (NCT05782244), plans to launch in June 2023. Biomarker-informed RCTs are essential for developing effective TBI interventions, relying on an understanding of underlying pathomechanisms. Traumatic microvascular injury (TMVI) is an attractive mechanism which can be targeted by vaso-active drugs such as PDE-5 inhibitors. CVR is a potential predictive and pharmacodynamic biomarker for targeted interventions aimed at TMVI. (Trial registration: NCT05782244, ClinicalTrials.gov ).
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Affiliation(s)
- Priyanka Kalyani
- Department of Neurology, University of Pennsylvania, 3400 Spruce St, Philadelphia, PA, 19104, USA.
| | - Sara M Lippa
- Walter Reed National Military Medical Center, The National Intrepid Center of Excellence, Palmer Rd S, Bethesda, MD, 20814, USA
- Department of Neuroscience, Uniformed Services University Health Sciences, 4301, Jones Bridge Rd, Bethesda, MD, 20814, USA
| | - J Kent Werner
- Walter Reed National Military Medical Center, The National Intrepid Center of Excellence, Palmer Rd S, Bethesda, MD, 20814, USA
- Department of Neuroscience, Uniformed Services University Health Sciences, 4301, Jones Bridge Rd, Bethesda, MD, 20814, USA
| | - Franck Amyot
- Walter Reed National Military Medical Center, The National Intrepid Center of Excellence, Palmer Rd S, Bethesda, MD, 20814, USA
| | - Carol B Moore
- Department of Neuroscience, Uniformed Services University Health Sciences, 4301, Jones Bridge Rd, Bethesda, MD, 20814, USA
| | - Kimbra Kenney
- Department of Neuroscience, Uniformed Services University Health Sciences, 4301, Jones Bridge Rd, Bethesda, MD, 20814, USA
| | - Ramon Diaz-Arrastia
- Department of Neurology, University of Pennsylvania, 3400 Spruce St, Philadelphia, PA, 19104, USA
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