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Yauch LM, Ennis-Czerniak K, Frey WH, Tkac I, Rao RB. Intranasal Insulin Attenuates the Long-Term Adverse Effects of Neonatal Hyperglycemia on the Hippocampus in Rats. Dev Neurosci 2022; 44:590-602. [PMID: 36041414 PMCID: PMC9928603 DOI: 10.1159/000526627] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2022] [Accepted: 08/16/2022] [Indexed: 11/19/2022] Open
Abstract
Hyperglycemia due to relative hypoinsulinism is common in extremely preterm infants and is associated with hippocampus-mediated long-term cognitive impairment. In neonatal rats, hypoinsulinemic hyperglycemia leads to oxidative stress, altered neurochemistry, microgliosis, and abnormal synaptogenesis in the hippocampus. Intranasal insulin (INS) bypasses the blood-brain barrier, targets the brain, and improves synaptogenesis in rodent models, and memory in adult humans with Alzheimer's disease or type 2 diabetes, without altering the blood levels of insulin or glucose. To test whether INS improves hippocampal development in neonatal hyperglycemia, rat pups were subjected to hypoinsulinemic hyperglycemia by injecting streptozotocin (STZ) at a dose of 80 mg/kg i.p. on postnatal day (P) 2 and randomized to INS, 0.3U twice daily from P3-P6 (STZ + INS group), or no treatment (STZ group). The acute effects on hippocampal neurochemical profile and transcript mRNA expression of insulin receptor (Insr), glucose transporters (Glut1, Glut4, and Glut8), and poly(ADP-ribose) polymerase-1 (Parp1, a marker of oxidative stress) were determined on P7 using in vivo 1H MR spectroscopy (MRS) and qPCR. The long-term effects on the neurochemical profile, microgliosis, and synaptogenesis were determined at adulthood using 1H MRS and histochemical analysis. Relative to the control (CONT) group, mean blood glucose concentration was higher from P3 to P6 in the STZ and STZ + INS groups. On P7, MRS showed 10% higher taurine concentration in both STZ groups. qPCR showed 3-folds higher Insr and 5-folds higher Glut8 expression in the two STZ groups. Parp1 expression was 18% higher in the STZ group and normal in the STZ + INS group. At adulthood, blood glucose concentration in the fed state was higher in the STZ and STZ + INS groups. MRS showed 59% higher brain glucose concentration and histochemistry showed microgliosis in the hippocampal subareas in the STZ group. Brain glucose was normal in the STZ + INS group. Compared with the STZ group, phosphocreatine and phosphocreatine/creatine ratio were higher, and microglia in the hippocampal subareas fewer in the STZ + INS group (p < 0.05 for all). Neonatal hyperglycemia was associated with abnormal glucose metabolism and microgliosis in the adult hippocampus. INS administration during hyperglycemia attenuated these adverse effects and improved energy metabolism in the hippocampus.
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Affiliation(s)
- Lauren McClure Yauch
- Division of Endocrinology, Department of Pediatrics, University of Minnesota, Minneapolis, MN, USA
| | - Kathleen Ennis-Czerniak
- Division of Neonatology, Department of Pediatrics, University of Minnesota, Minneapolis, MN 55455, USA
| | - William H. Frey
- HealthPartners Center for Memory and Aging, HealthPartners Neurosciences, St. Paul, MN, 55130, USA
- Graduate Program in Neuroscience, University of Minnesota, Minneapolis, MN, 55455, USA
| | - Ivan Tkac
- Center for Magnetic Resonance Research, University of Minnesota, Minneapolis, MN, 55455, USA
| | - Raghavendra B. Rao
- Division of Neonatology, Department of Pediatrics, University of Minnesota, Minneapolis, MN 55455, USA
- Graduate Program in Neuroscience, University of Minnesota, Minneapolis, MN, 55455, USA
- Masonic Institute for the Developing Brain, University of Minnesota, Minneapolis, MN, 55414, USA
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Metoprolol prevents neuronal dendrite remodeling in a canine model of chronic obstructive sleep apnea. Acta Pharmacol Sin 2020; 41:620-628. [PMID: 31863057 PMCID: PMC7470867 DOI: 10.1038/s41401-019-0323-8] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2019] [Accepted: 10/26/2019] [Indexed: 12/30/2022] Open
Abstract
Obstructive sleep apnea (OSA) is closely associated with central nervous system diseases and could lead to autonomic nerve dysfunction, which is often seen in neurodegenerative diseases. Previous studies have shown that metoprolol prevents several chronic OSA-induced cardiovascular diseases through inhibiting autonomic nerve hyperactivity. It remains unclear whether chronic OSA can lead to dendritic remodeling in the brain, and whether metoprolol affects the dendritic remodeling. In this study we investigated the effect of metoprolol on dendrite morphology in a canine model of chronic OSA, which was established in beagles through clamping and reopening the endotracheal tube for 4 h every other day for 12 weeks. OSA beagles were administered metoprolol (5 mg· kg−1· d−1). The dendritic number, length, crossings and spine density of neurons in hippocampi and prefrontal cortices were assessed by Golgi staining. And the protein levels of hypoxia-inducible factor-1α (HIF-1α) and brain-derived neurotrophic factor (BDNF) were measured by Western blotting. We showed that chronic OSA successfully induced significant brain hypoxia evidenced by increased HIF-1α levels in CA1 region and dentate gyrus of hippocampi, as well as in prefrontal cortex. Furthermore, OSA led to markedly decreased dendrite number, length and intersections, spine loss as well as reduced BDNF levels. Administration of metoprolol effectively prevented the dendritic remodeling and spine loss induced by chronic OSA. In addition, administration of metoprolol reversed the decreased BDNF, which might be associated with the metoprolol-induced neuronal protection. In conclusion, metoprolol protects against neuronal dendritic remodeling in hippocampi and prefrontal cortices induced by chronic OSA in canine.
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Rao R, Nashawaty M, Fatima S, Ennis K, Tkac I. Neonatal hyperglycemia alters the neurochemical profile, dendritic arborization and gene expression in the developing rat hippocampus. NMR IN BIOMEDICINE 2018; 31. [PMID: 29532970 PMCID: PMC6489495 DOI: 10.1002/nbm.3910] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
Hyperglycemia (blood glucose concentration >150 mg/dL) is common in extremely low gestational age newborns (ELGANs; birth at <28 week gestation). Hyperglycemia increases the risk of brain injury in the neonatal period. The long-term effects are not well understood. In adult rats, hyperglycemia alters hippocampal energy metabolism. The effects of hyperglycemia on the developing hippocampus were studied in rat pups. In Experiment 1, recurrent hyperglycemia of graded severity (moderate hyperglycemia (moderate-HG), mean blood glucose 214.6 ± 11.6 mg/dL; severe hyperglycemia (severe-HG), 338.9 ± 21.7 mg/dL; control, 137.7 ± 2.6 mg/dL) was induced from postnatal day (P) 3 to P12. On P30, the hippocampal neurochemical profile was determined using in vivo 1 H MR spectroscopy. Dendritic arborization in the hippocampal CA1 region was determined using microtubule-associated protein (MAP)-2 immunohistochemistry. In Experiment 2, continuous hyperglycemia (mean blood glucose 275.3 ± 25.8 mg/dL; control, 142.3 ± 2.6 mg/dL) was induced from P2 to P6 by injecting streptozotocin (STZ) on P2. The mRNA expression of glycogen synthase 1 (Gys1), lactate dehydrogenase (Ldh), glucose transporters 1 (Glut1) and 3 (Glut3) and monocarboxylate transporters 1 (Mct1), 2 (Mct2) and 4 (Mct4) in the hippocampus was determined on P6. In Experiment 1, MRS demonstrated lower lactate concentration and glutamate/glutamine (Glu/Gln) ratio in the severe-HG group, compared with the control group (p < 0.05). Phosphocreatine/creatine ratio was higher in both hyperglycemia groups (p < 0.05). MAP-2 histochemistry demonstrated longer apical segment length, indicating abnormal synaptic efficacy in both hyperglycemia groups (p < 0.05). Experiment 2 showed lower Glut1, Gys1 and Mct4 expression and higher Mct1 expression in the hyperglycemia group, relative to the control group (p < 0.05). These results suggest that hyperglycemia alters substrate transport, lactate homeostasis, dendritogenesis and Glu-Gln cycling in the developing hippocampus. Abnormal neurochemical profile and dendritic structure due to hyperglycemia may partially explain the long-term hippocampus-mediated cognitive deficits in human ELGANs.
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Affiliation(s)
- Raghavendra Rao
- Division of Neonatology, Department of Pediatrics, University of Minnesota
- Centre for Neurobehavioral Development, University of Minnesota
- Address for correspondence: Mayo Mail Code 39, 420 Delaware Street, SE, Minneapolis, MN 55455 (USA). Phone: 612-625-3260; Fax: 612-624-8176;
| | - Motaz Nashawaty
- Division of Neonatology, Department of Pediatrics, University of Minnesota
| | - Saher Fatima
- Division of Neonatology, Department of Pediatrics, University of Minnesota
| | - Kathleen Ennis
- Division of Neonatology, Department of Pediatrics, University of Minnesota
| | - Ivan Tkac
- Center for Magnetic Resonance Research, University of Minnesota
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Satrom KM, Ennis K, Sweis BM, Matveeva TM, Chen J, Hanson L, Maheshwari A, Rao R. Neonatal hyperglycemia induces CXCL10/CXCR3 signaling and microglial activation and impairs long-term synaptogenesis in the hippocampus and alters behavior in rats. J Neuroinflammation 2018; 15:82. [PMID: 29544513 PMCID: PMC5856387 DOI: 10.1186/s12974-018-1121-9] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2017] [Accepted: 03/08/2018] [Indexed: 12/18/2022] Open
Abstract
BACKGROUND Hyperglycemia is common in extremely low gestational age newborns (ELGAN) and is associated with increased mortality and morbidity, including abnormal neurodevelopment. Hippocampus-mediated cognitive deficits are common in this population, but the specific effects of hyperglycemia on the developing hippocampus are not known. METHODS The objective of this study was to determine the acute and long-term effects of hyperglycemia on the developing hippocampus in neonatal rats using a streptozotocin (STZ)-induced model of hyperglycemia. STZ was injected on postnatal day (P) 2, and littermates in the control group were injected with an equivalent volume of citrate buffer. The acute effects of hyperglycemia on markers of oxidative stress, inflammatory cytokines, microglial activation, and reactive astrocytosis in the hippocampus were determined in the brain tissue collected on P6. The long-term effects on hippocampus-mediated behavior and hippocampal dendrite structure were determined on P90. RESULTS On P6, the transcript and protein expression of markers of oxidative stress and inflammatory cytokines, including the CXCL10/CXCR3 pathway, were upregulated in the hyperglycemia group. Histological evaluation revealed microglial activation and astrocytosis. The long-term assessment on P90 demonstrated abnormal performance in Barnes maze neurobehavioral testing and altered dendrite structure in the hippocampus of formerly hyperglycemic rats. CONCLUSIONS Neonatal hyperglycemia induces CXCL10/CXCR3 signaling, microglial activation, and astrocytosis in the rat hippocampus and alters long-term synaptogenesis and behavior. These results may explain the hippocampus-specific cognitive deficits common in ELGAN who experience neonatal hyperglycemia.
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Affiliation(s)
- Katherine M Satrom
- Division of Neonatology, Department of Pediatrics, University of Minnesota, PWB 420 Delaware St SE, Minneapolis, MN, 55455, USA.
| | - Kathleen Ennis
- Division of Neonatology, Department of Pediatrics, University of Minnesota, PWB 420 Delaware St SE, Minneapolis, MN, 55455, USA
| | - Brian M Sweis
- Department of Neuroscience, University of Minnesota, Jackson Hall, 321 Church St SE, Minneapolis, MN, USA
| | - Tatyana M Matveeva
- Department of Psychology, University of Minnesota, Elliot Hall, 75 E River Rd, Minneapolis, MN, USA
| | - Jun Chen
- Division of Neonatology, Department of Pediatrics, University of Minnesota, PWB 420 Delaware St SE, Minneapolis, MN, 55455, USA
| | - Leif Hanson
- Division of Neonatology, Department of Pediatrics, University of Minnesota, PWB 420 Delaware St SE, Minneapolis, MN, 55455, USA
| | - Akhil Maheshwari
- Department of Pediatrics, Division of Neonatology, University of South Florida, Tampa General Cir, Suite HMT 450.19, Tampa, Florida, 33606, USA
| | - Raghavendra Rao
- Division of Neonatology, Department of Pediatrics, University of Minnesota, PWB 420 Delaware St SE, Minneapolis, MN, 55455, USA
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Bolaños L, Matute E, Ramírez-Dueñas MDL, Zarabozo D. Neuropsychological Impairment in School-Aged Children Born to Mothers With Gestational Diabetes. J Child Neurol 2015; 30:1616-24. [PMID: 25814475 DOI: 10.1177/0883073815575574] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/27/2014] [Accepted: 02/08/2015] [Indexed: 11/15/2022]
Abstract
The aim of this study was to determine whether school-aged children born to mothers with gestational diabetes show delays in their neuropsychological development. Several key neuropsychological characteristics of 32 children aged 7 to 9 years born to mothers with gestational diabetes were examined by comparing their performance on cognitive tasks to that of 28 children aged 8 to 10 years whose mothers had glucose levels within normal limits during pregnancy. The gestational diabetes group showed low performance on graphic, spatial, and bimanual skills and a higher presence of soft neurologic signs. Lower scores for general intellectual level and the working memory index were also evident. Our results suggest that gestational diabetes is associated with mild cognitive impairment.
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Affiliation(s)
- Lourdes Bolaños
- Instituto de Neurociencias, Universidad de Guadalajara, Guadalajara, Mexico
| | - Esmeralda Matute
- Instituto de Neurociencias, Universidad de Guadalajara, Guadalajara, Mexico
| | | | - Daniel Zarabozo
- Instituto de Neurociencias, Universidad de Guadalajara, Guadalajara, Mexico
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Raman L, Kong X, Gilley JA, Kernie SG. Chronic hypoxia impairs murine hippocampal development and depletes the postnatal progenitor pool by attenuating mammalian target of rapamycin signaling. Pediatr Res 2011; 70:159-65. [PMID: 21532529 PMCID: PMC3148804 DOI: 10.1203/pdr.0b013e3182218622] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Chronic hypoxia (CH) is a major risk factor for impaired cognitive function in various disease states, particularly in the context of cyanotic congenital heart disease. Although most brain development occurs prenatally, the dentate gyrus (DG) of the hippocampus harbors progenitor stem cells that contribute to its ongoing development postnatally. It is unclear how exposure to CH might affect postnatal hippocampal development, so we used a transgenic mouse that expresses enhanced green fluorescent protein (eGFP) within this progenitor population to determine the effect of CH on the DG. We find that exposure to 10% oxygen from postnatal d 3 to 28 results in a smaller DG with long-term impairment of hippocampal neurogenesis. Because the mammalian target of rapamycin (mTOR) pathway is a well-known regulator of cell proliferation and growth and is sensitive to hypoxia, we investigated its activation on exposure to CH and find it to be attenuated specifically in neural progenitor cells. Systemic inhibition of the mTOR pathway using rapamycin also caused impairment of hippocampal neurogenesis that mimics exposure to CH. Our findings demonstrate that CH results in long-term impairment of hippocampal neurogenesis and is mediated, in part, by attenuation of the mTOR pathway.
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Affiliation(s)
- Lakshmi Raman
- Department of Pediatrics, University of Texas Southwestern Medical Center, Dallas, Texas 75390, USA.
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Järlestedt K, Atkins AL, Hagberg H, Pekna M, Mallard C. Trace Fear Conditioning Detects Hypoxic-Ischemic Brain Injury in Neonatal Mice. Dev Neurosci 2011; 33:222-30. [DOI: 10.1159/000329710] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2010] [Accepted: 05/29/2011] [Indexed: 11/19/2022] Open
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Riggins T, Miller NC, Bauer PJ, Georgieff MK, Nelson CA. Consequences of low neonatal iron status due to maternal diabetes mellitus on explicit memory performance in childhood. Dev Neuropsychol 2010; 34:762-79. [PMID: 20183732 DOI: 10.1080/87565640903265145] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
Diabetic pregnancies are characterized by chronic metabolic insults, including iron deficiency, that place the developing brain at risk for memory impairment later in life. A behavioral recall paradigm coupled with electrophysiological measures was used to assess the longevity of these effects in 40 3(1/2)-year-old children. When memory demands were high, recall was significantly impaired in the at-risk group and correlated with perinatal measures of iron. Electrophysiological results suggested both encoding and retrieval processes were compromised. These findings support the hypothesis that prenatal iron deficiency leads to alterations in neural development that have a lasting impact on memory ability.
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Affiliation(s)
- Tracy Riggins
- Department of Psychology, University of Maryland, College Park, Maryland 20742, USA.
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