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Brandauer J, Receno CN, Anyaoku C, Cooke LE, Schwarzer HM, DeRuisseau KC, Cunningham CM, DeRuisseau LR. Senescent hearts from male Ts65Dn mice exhibit preserved function but altered size and nicotinamide adenine dinucleotide pathway signaling. Am J Physiol Regul Integr Comp Physiol 2024; 326:R176-R183. [PMID: 38047317 PMCID: PMC11283890 DOI: 10.1152/ajpregu.00164.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2023] [Revised: 10/30/2023] [Accepted: 11/29/2023] [Indexed: 12/05/2023]
Abstract
Down syndrome (DS) is associated with congenital heart defects at birth, but cardiac function has not been assessed at older ages. We used the Ts65Dn mouse, a model of DS, to quantify heart structure and function with echocardiography in 18-mo male Ts65Dn and wild-type (WT) mice. Heart weight, nicotinamide adenine dinucleotide (NAD) signaling, and mitochondrial (citrate synthase) activity were investigated, as these pathways may be implicated in the cardiac pathology of DS. The left ventricle was smaller in Ts65Dn versus WT, as well as the anterior wall thickness of the left ventricle during both diastole (LVAW_d; mm) and systole (LVAW_s; mm) as assessed by echocardiography. Other functional metrics were similar between groups including left ventricular area end systole (mm2), left ventricular area end diastole (mm2), left ventricular diameter end systole (mm), left ventricular diameter end diastole (mm), isovolumetric relaxation time (ms), mitral valve atrial peak velocity (mm/s), mitral valve early peak velocity (mm/s), ratio of atrial and early peak velocities (E/A), heart rate (beats/min), ejection fraction (%), and fractional shortening (%). Nicotinamide phosphoribosyltransferase (NAMPT) protein expression, NAD concentration, and tissue weight were lower in the left ventricle of Ts65Dn versus WT mice. Sirtuin 3 (SIRT3) protein expression and citrate synthase activity were not different between groups. Although cardiac function was generally preserved in male Ts65Dn, the altered heart size and bioenergetic disturbances may contribute to differences in aging for DS.
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Affiliation(s)
- Josef Brandauer
- Health Sciences Department, Gettysburg College, Gettysburg, Pennsylvania, United States
| | - Candace N Receno
- Department of Exercise Science and Athletic Training, Ithaca College, Ithaca, New York, United States
| | - Cynthia Anyaoku
- Health Sciences Department, Gettysburg College, Gettysburg, Pennsylvania, United States
| | - Lauren E Cooke
- Health Sciences Department, Gettysburg College, Gettysburg, Pennsylvania, United States
| | - Hannalyn M Schwarzer
- Health Sciences Department, Gettysburg College, Gettysburg, Pennsylvania, United States
| | - Keith C DeRuisseau
- Department of Basic Sciences, University of Health Sciences and Pharmacy, St. Louis, Missouri, United States
| | - Caitlin M Cunningham
- Department of Computer Science, Mathematics, and Statistics, Le Moyne College, Syracuse, New York, United States
| | - Lara R DeRuisseau
- Department of Basic Sciences, University of Health Sciences and Pharmacy, St. Louis, Missouri, United States
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DeRuisseau LR, Receno CN, Cunningham C, Bates ML, Goodell M, Liang C, Eassa B, Pascolla J, DeRuisseau KC. Breathing and Oxygen Carrying Capacity in Ts65Dn and Down Syndrome. FUNCTION 2023; 4:zqad058. [PMID: 37954975 PMCID: PMC10634617 DOI: 10.1093/function/zqad058] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2023] [Revised: 09/29/2023] [Accepted: 10/03/2023] [Indexed: 11/14/2023] Open
Abstract
Individuals with Down syndrome (Ds) are at increased risk of respiratory infection, aspiration pneumonia, and apnea. The Ts65Dn mouse is a commonly used model of Ds, but there have been no formal investigations of awake breathing and respiratory muscle function in these mice. We hypothesized that breathing would be impaired in Ts65Dn vs. wild-type (WT), and would be mediated by both neural and muscular inputs. Baseline minute ventilation was not different at 3, 6, or 12 mo of age. However, VT/Ti, a marker of the neural drive to breathe, was lower in Ts65Dn vs. WT and central apneas were more prevalent. The response to breathing hypoxia was not different, but the response to hypercapnia was attenuated, revealing a difference in carbon dioxide sensing, and/or motor output in Ts65Dn. Oxygen desaturations were present in room air, demonstrating that ventilation may not be sufficient to maintain adequate oxygen saturation in Ts65Dn. We observed no differences in arterial PO2 or PCO2, but Ts65Dn had lower hemoglobin and hematocrit. A retrospective medical record review of 52,346 Ds and 52,346 controls confirmed an elevated relative risk of anemia in Ds. We also performed eupneic in-vivo electromyography and in-vitro muscle function and histological fiber typing of the diaphragm, and found no difference between strains. Overall, conscious respiration is impaired in Ts65Dn, is mediated by neural mechanisms, and results in reduced hemoglobin saturation. Oxygen carrying capacity is reduced in Ts65Dn vs. WT, and we demonstrate that individuals with Ds are also at increased risk of anemia.
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Affiliation(s)
- Lara R DeRuisseau
- Department of Basic Sciences, University of Health Sciences and Pharmacy, St. Louis, MO 63110, USA
| | - Candace N Receno
- Department of Exercise Science and Athletic Training, Ithaca College, Ithaca, NY 14850, USA
| | - Caitlin Cunningham
- Department of Statistics, Mathematics and Computer Science, Le Moyne College, Syracuse, NY 13214, USA
| | - Melissa L Bates
- Departments of Health and Human Physiology, Internal Medicine, and the Stead Family Department of Pediatrics, University of Iowa, Iowa City, IA 52242, USA
| | - Morgan Goodell
- Lake Erie College of Osteopathic Medicine, Elmira, NY 14901, USA
| | - Chen Liang
- Department of Pharmacology and Physiology, University of Rochester Medical Center, Rochester, NY 14642,USA
| | - Brianna Eassa
- Department of Biological Sciences, Le Moyne College, Syracuse, NY 13214, USA
| | - Jessica Pascolla
- Department of Basic Sciences, University of Health Sciences and Pharmacy, St. Louis, MO 63110, USA
| | - Keith C DeRuisseau
- Department of Basic Sciences, University of Health Sciences and Pharmacy, St. Louis, MO 63110, USA
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Ageta K, Hirayama T, Aokage T, Seya M, Meng Y, Nojima T, Yamamoto H, Obara T, Nakao A, Yumoto T, Tsukahara K, Naito H. Hydrogen inhalation attenuates lung contusion after blunt chest trauma in mice. Surgery 2023; 174:343-349. [PMID: 37210236 PMCID: PMC10193194 DOI: 10.1016/j.surg.2023.04.029] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2023] [Revised: 03/01/2023] [Accepted: 04/09/2023] [Indexed: 05/22/2023]
Abstract
BACKGROUND Lung contusion caused by blunt chest trauma evokes a severe inflammatory reaction in the pulmonary parenchyma that may be associated with acute respiratory distress syndrome. Although hydrogen gas has antioxidant and anti-inflammatory effects and is protective against multiple types of lung injury at safe concentrations, the effects of inhaled hydrogen gas on blunt lung injury have not been previously investigated. Therefore, using a mouse model, we tested the hypothesis that hydrogen inhalation after chest trauma would reduce pulmonary inflammation and acute lung injury associated with lung contusion. METHODS Inbred male C57BL/6 mice were randomly divided into 3 groups: sham with air inhalation, lung contusion with air inhalation, and lung contusion with 1.3% hydrogen inhalation. Experimental lung contusion was induced using a highly reproducible and standardized apparatus. Immediately after induction of lung contusion, mice were placed in a chamber exposed to 1.3% hydrogen gas in the air. Histopathological analysis and real-time polymerase chain reaction in lung tissue and blood gas analysis were performed 6 hours after contusion. RESULTS Histopathological examination of the lung tissue after contusion revealed perivascular/intra-alveolar hemorrhage, perivascular/interstitial leukocyte infiltration, and interstitial/intra-alveolar edema. These histological changes and the extent of lung contusion, as determined by computed tomography, were significantly mitigated by hydrogen inhalation. Hydrogen inhalation also significantly reduced inflammatory cytokine and chemokine mRNA levels and improved oxygenation. CONCLUSION Hydrogen inhalation therapy significantly mitigated inflammatory responses associated with lung contusion in mice. Hydrogen inhalation therapy may be a supplemental therapeutic strategy for treating lung contusion.
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Affiliation(s)
- Kohei Ageta
- Department of Emergency, Critical Care, and Disaster Medicine, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences
| | - Takahiro Hirayama
- Department of Emergency, Critical Care, and Disaster Medicine, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences
| | - Toshiyuki Aokage
- Department of Emergency, Critical Care, and Disaster Medicine, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences
| | - Mizuki Seya
- Department of Emergency, Critical Care, and Disaster Medicine, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences
| | - Ying Meng
- Department of Emergency, Critical Care, and Disaster Medicine, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences
| | - Tsuyoshi Nojima
- Department of Emergency, Critical Care, and Disaster Medicine, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences
| | - Hirotsugu Yamamoto
- Department of Emergency, Critical Care, and Disaster Medicine, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences
| | - Takafumi Obara
- Department of Emergency, Critical Care, and Disaster Medicine, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences
| | - Atsunori Nakao
- Department of Emergency, Critical Care, and Disaster Medicine, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences
| | - Tetsuya Yumoto
- Department of Emergency, Critical Care, and Disaster Medicine, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences
| | - Kohei Tsukahara
- Department of Emergency, Critical Care, and Disaster Medicine, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences
| | - Hiromichi Naito
- Department of Emergency, Critical Care, and Disaster Medicine, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences.
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Characterization of brain-wide somatosensory BOLD fMRI in mice under dexmedetomidine/isoflurane and ketamine/xylazine. Sci Rep 2021; 11:13110. [PMID: 34162952 PMCID: PMC8222234 DOI: 10.1038/s41598-021-92582-5] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2021] [Accepted: 06/10/2021] [Indexed: 02/05/2023] Open
Abstract
Mouse fMRI under anesthesia has become increasingly popular due to improvement in obtaining brain-wide BOLD response. Medetomidine with isoflurane has become well-accepted for resting-state fMRI, but whether this combination allows for stable, expected, and robust brain-wide evoked response in mice has yet to be validated. We thus utilized intravenous infusion of dexmedetomidine with inhaled isoflurane and intravenous infusion of ketamine/xylazine to elucidate whether stable mouse physiology and BOLD response are obtainable in response to simultaneous forepaw and whisker-pad stimulation throughout 8 h. We found both anesthetics result in hypercapnia with depressed heart rate and respiration due to self-breathing, but these values were stable throughout 8 h. Regardless of the mouse condition, brain-wide, robust, and stable BOLD response throughout the somatosensory axis was observed with differences in sensitivity and dynamics. Dexmedetomidine/isoflurane resulted in fast, boxcar-like, BOLD response with consistent hemodynamic shapes throughout the brain. Ketamine/xylazine response showed higher sensitivity, prolonged BOLD response, and evidence for cortical disinhibition as significant bilateral cortical response was observed. In addition, differing hemodynamic shapes were observed between cortical and subcortical areas. Overall, we found both anesthetics are applicable for evoked mouse fMRI studies.
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Guo J, Ran M, Gao Z, Zhang X, Wang D, Li H, Zhao S, Sun W, Dong H, Hu J. Cell-type-specific imaging of neurotransmission reveals a disrupted excitatory-inhibitory cortical network in isoflurane anaesthesia. EBioMedicine 2021; 65:103272. [PMID: 33691246 PMCID: PMC7941179 DOI: 10.1016/j.ebiom.2021.103272] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2020] [Revised: 02/06/2021] [Accepted: 02/19/2021] [Indexed: 12/21/2022] Open
Abstract
BACKGROUND Despite the fundamental clinical significance of general anaesthesia, the cortical mechanism underlying anaesthetic-induced loss of consciousness (aLOC) remains elusive. METHODS Here, we measured the dynamics of two major cortical neurotransmitters, gamma-aminobutyric acid (GABA) and glutamate, through in vivo two-photon imaging and genetically encoded neurotransmitter sensors in a cell type-specific manner in the primary visual (V1) cortex. FINDINGS We found a general decrease in cortical GABA transmission during aLOC. However, the glutamate transmission varies among different cortical cell types, where in it is almost preserved on pyramidal cells and is significantly reduced on inhibitory interneurons. Cortical interneurons expressing vasoactive intestinal peptide (VIP) and parvalbumin (PV) specialize in disinhibitory and inhibitory effects, respectively. During aLOC, VIP neuronal activity was delayed, and PV neuronal activity was dramatically inhibited and highly synchronized. INTERPRETATION These data reveal that aLOC resembles a cortical state with a disrupted excitatory-inhibitory network and suggest that a functional inhibitory network is indispensable in the maintenance of consciousness. FUNDING This work was supported by the grants of the National Natural Science Foundation of China (grant nos. 81620108012 and 82030038 to H.D. and grant nos. 31922029, 61890951, and 61890950 to J.H.).
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Affiliation(s)
- Juan Guo
- Department of Anaesthesiology and Perioperative Medicine, Xijing Hospital, The Fourth Military Medical University, Xi'an 710032, China
| | - Mingzi Ran
- Department of Anaesthesiology and Perioperative Medicine, Xijing Hospital, The Fourth Military Medical University, Xi'an 710032, China
| | - Zilong Gao
- Chinese Institute for Brain Research, Beijing 102206, China
| | - Xinxin Zhang
- Chinese Institute for Brain Research, Beijing 102206, China
| | - Dan Wang
- Department of Anaesthesiology and Perioperative Medicine, Xijing Hospital, The Fourth Military Medical University, Xi'an 710032, China
| | - Huiming Li
- Department of Anaesthesiology and Perioperative Medicine, Xijing Hospital, The Fourth Military Medical University, Xi'an 710032, China
| | - Shiyi Zhao
- Department of Anaesthesiology and Perioperative Medicine, Xijing Hospital, The Fourth Military Medical University, Xi'an 710032, China
| | - Wenzhi Sun
- Chinese Institute for Brain Research, Beijing 102206, China; School of Basic Medical Sciences, Capital Medical University, Beijing 10069, China.
| | - Hailong Dong
- Department of Anaesthesiology and Perioperative Medicine, Xijing Hospital, The Fourth Military Medical University, Xi'an 710032, China.
| | - Ji Hu
- School of Life Science and Technology, ShanghaiTech University, Shanghai 201210, China; Shanghai Key Laboratory of Psychotic Disorders, Shanghai Mental Health Center, Shanghai 200030, China; Co-Innovation Center of Neuroregeneration, Nantong University, Nantong 226000, China; CAS Center for Excellence in Brain Science and Intelligence Technology, Shanghai 200030, China.
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Cleary CM, Moreira TS, Takakura AC, Nelson MT, Longden TA, Mulkey DK. Vascular control of the CO 2/H +-dependent drive to breathe. eLife 2020; 9:e59499. [PMID: 32924935 PMCID: PMC7521922 DOI: 10.7554/elife.59499] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2020] [Accepted: 09/14/2020] [Indexed: 12/17/2022] Open
Abstract
Respiratory chemoreceptors regulate breathing in response to changes in tissue CO2/H+. Blood flow is a fundamental determinant of tissue CO2/H+, yet little is known regarding how regulation of vascular tone in chemoreceptor regions contributes to respiratory behavior. Previously, we showed in rat that CO2/H+-vasoconstriction in the retrotrapezoid nucleus (RTN) supports chemoreception by a purinergic-dependent mechanism (Hawkins et al., 2017). Here, we show in mice that CO2/H+ dilates arterioles in other chemoreceptor regions, thus demonstrating CO2/H+ vascular reactivity in the RTN is unique. We also identify P2Y2 receptors in RTN smooth muscle cells as the substrate responsible for this response. Specifically, pharmacological blockade or genetic deletion of P2Y2 from smooth muscle cells blunted the ventilatory response to CO2, and re-expression of P2Y2 receptors only in RTN smooth muscle cells fully rescued the CO2/H+ chemoreflex. These results identify P2Y2 receptors in RTN smooth muscle cells as requisite determinants of respiratory chemoreception.
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MESH Headings
- Animals
- Carbon Dioxide/metabolism
- Chemoreceptor Cells/metabolism
- Hydrogen/metabolism
- Medulla Oblongata/physiology
- Mice
- Mice, Knockout
- Muscle, Smooth, Vascular/cytology
- Muscle, Smooth, Vascular/metabolism
- Muscle, Smooth, Vascular/physiology
- Receptors, Purinergic P2Y2/genetics
- Receptors, Purinergic P2Y2/metabolism
- Receptors, Purinergic P2Y2/physiology
- Respiration
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Affiliation(s)
- Colin M Cleary
- Department of Physiology and Neurobiology, University of ConnecticutStorrsUnited States
| | - Thiago S Moreira
- Department of Physiology and Biophysics, University of São PauloSão PauloBrazil
| | - Ana C Takakura
- Department of Pharmacology, University of São PauloSão PauloBrazil
| | - Mark T Nelson
- Department of Pharmacology, University of VermontBurlingtonUnited States
- Institute of Cardiovascular SciencesManchesterUnited Kingdom
| | - Thomas A Longden
- Department of Physiology, University of MarylandBaltimoreUnited States
| | - Daniel K Mulkey
- Department of Physiology and Neurobiology, University of ConnecticutStorrsUnited States
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Receno CN, Eassa BE, Cunningham CM, DeRuisseau LR. Young and middle-aged mouse breathing behavior during the light and dark cycles. Physiol Rep 2020; 7:e14060. [PMID: 31004390 PMCID: PMC6474843 DOI: 10.14814/phy2.14060] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2019] [Accepted: 03/13/2019] [Indexed: 12/21/2022] Open
Abstract
Unrestrained barometric plethysmography is a common method used for characterizing breathing patterns in small animals. One source of variation between unrestrained barometric plethysmography studies is the segment of baseline. Baseline may be analyzed as a predetermined time‐point, or using tailored segments when each animal is visually calm. We compared a quiet, minimally active (no sniffing/grooming) breathing segment to a predetermined time‐point at 1 h for baseline measurements in young and middle‐aged mice during the dark and light cycles. Additionally, we evaluated the magnitude of change for gas challenges based on these two baseline segments. C57BL/6JEiJ x C3Sn.BliA‐Pde6b+/DnJ male mice underwent unrestrained barometric plethysmography with the following baselines used to determine breathing frequency, tidal volume (VT) and minute ventilation (VE): (1) 30‐sec of quiet breathing and (2) a 10‐min period from 50 to 60 min. Animals were also exposed to 10 min of hypoxic (10% O2, balanced N2), hypercapnic (5% CO2, balanced air) and hypoxic hypercapnic (10% O2, 5% CO2, balanced N2) gas. Both frequency and VE were higher during the predetermined 10‐min baseline versus the 30‐sec baseline, while VT was lower (P < 0.05). However, VE/VO2 was similar between the baseline time segments (P > 0.05) in an analysis of one cohort. During baseline, dark cycle testing had increased VT values versus those in the light (P < 0.05). For gas challenges, both frequency and VE showed higher percent change from the 30‐sec baseline compared to the predetermined 10‐min baseline (P < 0.05), while VT showed a greater change from the 10‐min baseline (P < 0.05). Dark cycle hypoxic exposure resulted in larger percent change in breathing frequency versus the light cycle (P < 0.05). Overall, light and dark cycle pattern of breathing differences emerged along with differences between the 30‐sec behavior observational method versus a predetermined time segment for baseline.
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Affiliation(s)
- Candace N Receno
- Department of Biological Sciences, Le Moyne College, Syracuse, New York
| | - Brianna E Eassa
- Department of Biological Sciences, Le Moyne College, Syracuse, New York
| | - Caitlin M Cunningham
- Department of Mathematics, Statistics and Computer Science, Le Moyne College, Syracuse, New York
| | - Lara R DeRuisseau
- Department of Biological Sciences, Le Moyne College, Syracuse, New York
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Receno CN, Cunningham CM, Eassa BE, Purdy R, DeRuisseau LR. Method to Obtain Pattern of Breathing in Senescent Mice through Unrestrained Barometric Plethysmography. J Vis Exp 2020. [PMID: 32420981 DOI: 10.3791/59393] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022] Open
Abstract
Unrestrained barometric plethysmography (UBP) is a method for quantifying the pattern of breathing in mice, where breathing frequency, tidal volume, and minute ventilation are routinely reported. Moreover, information can be collected regarding the neural output of breathing, including the existence of central apneas and augmented breaths. An important consideration for UBP is obtaining a breathing segment with a minimal impact of anxious or active behaviors, to elucidate the response to breathing challenges. Here, we present a protocol that allows for short, quiet baselines to be obtained in aged mice, comparable to waiting for longer bouts of quiet breathing. The use of shorter time segments is valuable, as some strains of mice may be increasingly excitable or anxious, and longer periods of quiet breathing may not be achieved within a reasonable timeframe. We placed 22 month-old mice in a UBP chamber and compared four 15 s quiet breathing segments between minutes 60-120 to a longer 10 min quiet breathing period that took 2-3 h to acquire. We also obtained counts of central apneas and augmented breaths prior to the quiet breathing segments, following a 30 min familiarization period. We show that 10 min of quiet breathing is comparable to using a much shorter 15 s duration. Additionally, the time leading up to these 15 s quiet breathing segments can be used to gather data regarding apneas of central origin. This protocol allows investigators to collect pattern-of-breathing data in a set amount of time and makes quiet baseline measures feasible for mice that may exhibit increased amounts of excitable behavior. The UBP methodology itself provides a useful and noninvasive way to collect pattern-of-breathing data and allows for mice to be tested over several time points.
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9
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DeRuisseau LR, Receno CN, Heffernan KS, Cunningham CM. Heart rate and blood pressure in male Ts65Dn mice: a model to investigate cardiovascular responses in Down syndrome. Physiol Rep 2019; 7:e14205. [PMID: 31496136 PMCID: PMC6732568 DOI: 10.14814/phy2.14205] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2019] [Accepted: 07/19/2019] [Indexed: 12/19/2022] Open
Abstract
Down syndrome (Ds) is the most common chromosomal cause of intellectual disability that results from triplication of chromosome 21 genes. Lower blood pressure (BP) and heart rate (HR) in response to exercise and other stressors are prevalent in Ds, and are mediated by autonomic dysfunction. The Ts65Dn mouse is a model of Ds that is commonly used in preclinical studies, but has not been formally investigated for cardiovascular responses in conscious mice. Based on human studies of Ds, we hypothesized Ts65Dn would have lower BP and HR, but similar arterial stiffness. BP was quantified in conscious wild-type (WT) and Ts65Dn. A main effect for strain was observed for all BP measures (systolic, diastolic, mean, pulse pressure), with WT higher than Ts65Dn. Pulse wave velocity was similar between WT and Ts65Dn. High-frequency power spectra was higher in WT suggesting autonomic differences between strains. Freely moving HR was higher in WT versus Ts65Dn in both the dark and light cycles, although a main effect of circadian cycle was also present (dark> light). Similar to what is observed in humans, Ts65Dn has a lower BP which may be attributed to autonomic differences and result in preservation of arterial function with advancing age. Ts65Dn thus appears to capture the Ds cardiovascular phenotype across the lifespan. These data support further use of Ts65Dn to investigate mechanisms that may lead to altered BP and HR responses in Ds.
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Affiliation(s)
| | | | | | - Caitlin M. Cunningham
- Department of Mathematics, Statistics, and Computer ScienceLe Moyne CollegeSyracuseNew York
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10
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Schwartz AJ, Converso-Baran K, Michele DE, Shah YM. A genetic mouse model of severe iron deficiency anemia reveals tissue-specific transcriptional stress responses and cardiac remodeling. J Biol Chem 2019; 294:14991-15002. [PMID: 31416832 DOI: 10.1074/jbc.ra119.009578] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2019] [Revised: 08/13/2019] [Indexed: 01/24/2023] Open
Abstract
Iron is a micronutrient fundamental for life. Iron homeostasis in mammals requires sustained postnatal intestinal iron absorption that maintains intracellular iron concentrations for central and systemic metabolism as well as for erythropoiesis and oxygen transport. More than 1 billion people worldwide suffer from iron deficiency anemia (IDA), a state of systemic iron insufficiency that limits the production of red blood cells and leads to tissue hypoxia and intracellular iron stress. Despite this tremendous public health concern, very few genetic models of IDA are available to study its progression. Here we developed and characterized a novel genetic mouse model of IDA. We found that tamoxifen-inducible deletion of the mammalian iron exporter ferroportin exclusively in intestinal epithelial cells leads to loss of intestinal iron absorption. Ferroportin ablation yielded a robust phenotype of progressive IDA that develops in as little as 3 months following disruption of intestinal iron absorption. We noted that, at end-stage IDA, tissue-specific transcriptional stress responses occur in which the heart shows little to no hypoxic and iron stress compared with other peripheral organs. However, morphometric and echocardiographic analysis revealed massive cardiac hypertrophy and chamber dilation, albeit with increased cardiac output at very low basal heart rates. We propose that our intestine-specific ferroportin knockout mouse model of end-stage IDA could be used in future studies to investigate IDA progression and cell-specific responses to hypoxic and iron stress.
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Affiliation(s)
- Andrew J Schwartz
- Department of Molecular & Integrative Physiology, and Internal Medicine, University of Michigan, Ann Arbor, Michigan 48109
| | - Kimber Converso-Baran
- Department of Molecular & Integrative Physiology, and Internal Medicine, University of Michigan, Ann Arbor, Michigan 48109
| | - Daniel E Michele
- Department of Molecular & Integrative Physiology, and Internal Medicine, University of Michigan, Ann Arbor, Michigan 48109.,Division of Cardiovascular Medicine, University of Michigan, Ann Arbor, Michigan 48109
| | - Yatrik M Shah
- Department of Molecular & Integrative Physiology, and Internal Medicine, University of Michigan, Ann Arbor, Michigan 48109 .,Division of Gastroenterology, University of Michigan, Ann Arbor, Michigan 48109
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