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Kim DS, Santana Maldonado CM, Giulivi C, Rumbeiha WK. Metabolomic Signatures of Brainstem in Mice following Acute and Subchronic Hydrogen Sulfide Exposure. Metabolites 2024; 14:53. [PMID: 38248856 PMCID: PMC10819975 DOI: 10.3390/metabo14010053] [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: 12/21/2023] [Revised: 01/05/2024] [Accepted: 01/11/2024] [Indexed: 01/23/2024] Open
Abstract
Hydrogen sulfide (H2S) is an environmental toxicant of significant health concern. The brain is a major target in acute H2S poisoning. This study was conducted to test the hypothesis that acute and subchronic ambient H2S exposures alter the brain metabolome. Male 7-8-week-old C57BL/6J mice were exposed by whole-body inhalation to 1000 ppm H2S for 45 min and euthanized at 5 min or 72 h for acute exposure. For subchronic study, mice were exposed to 5 ppm H2S 2 h/day, 5 days/week for 5 weeks. Control mice were exposed to room air. The brainstem was removed for metabolomic analysis. Enrichment analysis showed that the metabolomic profiles in acute and subchronic H2S exposures matched with those of cerebral spinal fluid from patients with seizures or Alzheimer's disease. Acute H2S exposure decreased excitatory neurotransmitters, aspartate, and glutamate, while the inhibitory neurotransmitter, serotonin, was increased. Branched-chain amino acids and glucose were increased by acute H2S exposure. Subchronic H2S exposure within OSHA guidelines surprisingly decreased serotonin concentration. In subchronic H2S exposure, glucose was decreased, while polyunsaturated fatty acids, inosine, and hypoxanthine were increased. Collectively, these results provide important mechanistic clues for acute and subchronic ambient H2S poisoning and show that H2S alters brainstem metabolome.
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Affiliation(s)
- Dong-Suk Kim
- Department of Molecular Biosciences, School of Veterinary Medicine, UC Davis, Davis, CA 95616, USA; (D.-S.K.); (C.M.S.M.); (C.G.)
| | - Cristina M. Santana Maldonado
- Department of Molecular Biosciences, School of Veterinary Medicine, UC Davis, Davis, CA 95616, USA; (D.-S.K.); (C.M.S.M.); (C.G.)
- MRI Global, Kansas City, MO 64110, USA
| | - Cecilia Giulivi
- Department of Molecular Biosciences, School of Veterinary Medicine, UC Davis, Davis, CA 95616, USA; (D.-S.K.); (C.M.S.M.); (C.G.)
| | - Wilson Kiiza Rumbeiha
- Department of Molecular Biosciences, School of Veterinary Medicine, UC Davis, Davis, CA 95616, USA; (D.-S.K.); (C.M.S.M.); (C.G.)
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Santana Maldonado CM, Kim DS, Purnell B, Li R, Buchanan GF, Smith J, Thedens DR, Gauger P, Rumbeiha WK. Acute hydrogen sulfide-induced neurochemical and morphological changes in the brainstem. Toxicology 2023; 485:153424. [PMID: 36610655 DOI: 10.1016/j.tox.2023.153424] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2022] [Revised: 12/31/2022] [Accepted: 01/03/2023] [Indexed: 01/06/2023]
Abstract
Hydrogen sulfide (H2S) is a toxin affecting the cardiovascular, respiratory, and central nervous systems. Acute H2S exposure is associated with a high rate of mortality and morbidity. The precise pathophysiology of H2S-induced death is a controversial topic; however, inhibition of the respiratory center in the brainstem is commonly cited as a cause of death. There is a knowledge gap on toxicity and toxic mechanisms of acute H2S poisoning on the brainstem, a brain region responsible for regulating many reflective and vital functions. Serotonin (5-HT), dopamine (DA), and γ-aminobutyric acid (GABA) play a role in maintaining a normal stable respiratory rhythmicity. We hypothesized that the inhibitory respiratory effects of H2S poisoning are mediated by 5-HT in the respiratory center of the brainstem. Male C57BL/6 mice were exposed once to an LCt50 concentration of H2S (1000 ppm). Batches of surviving mice were euthanized at 5 min, 2 h, 12 h, 24 h, 72 h, and on day 7 post-exposure. Pulmonary function, vigilance state, and mortality were monitored during exposure. The brainstem was analyzed for DA, 3,4-dehydroxyphenyl acetic acid (DOPAC), 5-HT, 5-hydroxyindoleatic acid (5-HIAA), norepinephrine (NE), GABA, glutamate, and glycine using HPLC. Enzymatic activities of monoamine oxidases (MAO) were also measured in the brainstem using commercial kits. Neurodegeneration was assessed using immunohistochemistry and magnetic resonance imaging. Results showed that DA and DOPAC were significantly increased at 5 min post H2S exposure. However, by 2 h DA returned to normal. Activities of MAO were significantly increased at 5 min and 2 h post-exposure. In contrast, NE was significantly decreased at 5 min and 2 h post-exposure. Glutamate was overly sensitive to H2S-induced toxicity manifesting a time-dependent concentration reduction throughout the 7 day duration of the study. Remarkably, there were no changes in 5-HT, 5-HIAA, glycine, or GABA concentrations. Cytochrome c oxidase activity was inhibited but recovered by 24 h. Neurodegeneration was observed starting at 72 h post H2S exposure in select brainstem regions. We conclude that acute H2S exposure causes differential effects on brainstem neurotransmitters. H2S also induces neurodegeneration and biochemical changes in the brainstem. Additional work is needed to fully understand the implications of both the short- and long-term effects of acute H2S poisoning on vital functions regulated by the brainstem.
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Affiliation(s)
- Cristina M Santana Maldonado
- Veterinary Diagnostic Production and Animal Medicine, College of Veterinary Medicine, Iowa State University, Ames, IA 50010, USA.
| | - Dong-Suk Kim
- Department of Molecular Biosciences, University of California, Davis, CA 95616, USA.
| | - Benton Purnell
- Department of Neurology, University of Iowa, Iowa City, IA 52242, USA.
| | - Rui Li
- Department of Neurology, University of Iowa, Iowa City, IA 52242, USA.
| | - Gordon F Buchanan
- Department of Neurology, University of Iowa, Iowa City, IA 52242, USA.
| | - Jodi Smith
- Veterinary Pathology, College of Veterinary Medicine, Iowa State University, Ames, IA 50010, USA.
| | - Daniel R Thedens
- Seamans Center for the Engineering Arts and Sciences, Iowa City, IA 52242, USA.
| | - Phillip Gauger
- Veterinary Diagnostic Production and Animal Medicine, College of Veterinary Medicine, Iowa State University, Ames, IA 50010, USA.
| | - Wilson K Rumbeiha
- Department of Molecular Biosciences, University of California, Davis, CA 95616, USA.
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