Neuroprotection by glucagon: role of gluconeogenesis

Laboratory investigation

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Object

The severity of neurological impairment following traumatic brain injury (TBI) is exacerbated by several endogenous processes, including hyperglycemia, hypotension, and the generation of glutamate. However, in addition to controlling hyperglycemia, insulin has pleiotropic effects on tissue metabolism, which include reducing the concentration of the neurotoxic amino acid glutamate, making it unclear whether insulin's beneficial effects are attributable to the establishment of euglycemia per se. In the present study, the authors asked if reducing glutamate via approaches that do not lower glucose levels would improve neurological outcome following TBI.

Methods

Glucagon activates gluconeogenesis by increasing the hepatic uptake of amino acids such as glutamate and facilitating their conversion to glucose. Glucagon was administered as a single intraperitoneal injection before or after closed head injury (CHI). Neurological function, brain histological features, blood glutamate and glucose levels, and CSF glutamate concentrations were measured.

Results

A single intraperitoneal injection of glucagon (25 μg) into mice 10 minutes before or after CHI reduced lesion size by about 60% (p < 0.0001) and accelerated neurological recovery. The neuroprotective effect of glucagon was related to gluconeogenesis by decreasing the concentration of the neuroexcitatory amino acid glutamate in the circulation from 207 ± 32.1 μmol/L in untreated mice to 101.11 ± 21.6 μmol/L in treated mice (p < 0.001); a similar effect occurred in the CSF. The neuroprotective effect of glucagon was seen notwithstanding the attendant increase in blood glucose, the final substrate of gluconeogenesis.

Conclusions

Glucagon exerts a marked neuroprotective effect post-TBI by decreasing CNS glutamate. Glucagon was beneficial despite increasing blood glucose. Favorable effects also occurred when glucagon was given prior to TBI, suggesting its involvement in the preconditioning process. Thus, glucagon may be of value in providing neuroprotection when administered after TBI or prior to certain neurosurgical or cardiac interventions in which the incidence of perioperative ischemia is high.

Abbreviations used in this paper: ADC = apparent diffusion coefficient; CHI = closed head injury; NSS = neurological severity score; TBI = traumatic brain injury.

Article Information

* Drs. Fanne and Nassar contributed equally to this work.

Current address for Dr. Fanne: Tel Aviv Sourasky Medical Center, Tel Aviv, Israel.

Address correspondence to: Abd Al-Roof Higazi, M.D., Department of Pathology and Laboratory Medicine, University of Pennsylvania, 513A Stellar-Chance, 422 Curie Boulevard, Philadelphia, Pennsylvania 19104. email: higazi@mail.med.upenn.edu.

Please include this information when citing this paper: published online May 28, 2010; DOI: 10.31712010.4.JNS10263.

© AANS, except where prohibited by US copyright law.

Headings

Figures

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    Effect of glucagon on post-CHI neurobehavioral function. Ten minutes post-CHI, mice were intraperitoneally injected with 25 μg of glucagon in normal saline (black squares, Glucagon) or with saline alone (white squares, CTR [untreated controls]), and the NSS was measured. Graph showing the results in 24 animals in each of these 2 cohorts for a total of 48 mice. The mean ± SD is shown. p < 0.0001.

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    Time-dependent effect of CHI on the ADC. A: Representative images obtained from animals given saline (untreated) or glucagon (treated), showing brain tissues 24 hours after CHI. Areas with low ADC values are shown in color overlaid on grayscale T2-weighted MR images. B: Representative images showing brain tissues 28 days (1M [1 month]) after CHI. Areas with high ADC values are shown in color overlaid on grayscale T2-weighted MR images. C: Graph of a comparison of calculated volumes with low ADC values in uninjured controls (naïve) and mice given glucagon (treated) or saline (untreated) at 24 hours post-CHI. One day post-CHI both injured groups had significantly larger volumes with low ADCs compared with uninjured mice (naïve). #p < 0.033, treated versus naïve; *p < 0.039, untreated versus naïve. D: Graph of comparison of the calculated volumes with high ADC values among the same groups at 28 days post-CHI. Significant differences between mice given glucagon (treated) or saline (untreated) were observed on Day 28 post-CHI. *p = 0.004, treated versus untreated; #p = 0.002, untreated versus naïve. Ten mice in each group.

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    Appearance of brain lesions post-CHI. A: Photograph of representative brains from mice given saline (control) at 28 days post-CHI. B: Photograph of representative brains from mice given glucagon (treated) at 28 days post-CHI. C: Representative brain tissue sections from mice given glucagon (right) or saline (left) showing areas of damage (missing portions) 28 days post-CHI. D: Graph showing volume of damaged area after glucagon versus saline injection. The mean ± SD of the lesion size from 12 animals/group, treated with glucagon (treated) versus saline (control) is shown. *p = 0.0003, glucagon versus saline.

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    Effect of pretreatment with glucagon. Left: Mice were injected with saline containing 25 μg of glucagon (pretreated) or with saline alone (control) 10 minutes prior to CHI, and the NSS was evaluated periodically. The mean NSS (± SD) from 10 mice/group on Day 28 is shown. *p = 0.001, 1-way ANOVA, glucagon versus saline. Right: Volume of damaged area after glucagon or saline injection. The mean (± SD) lesion size from 10 mice/group pretreated with glucagon (pretreated) or saline (control) is shown. *p = 0.0007, 1-way ANOVA, glucagon versus saline.

References

  • 1

    Alsop DCMurai HDetre JAMcIntosh TKSmith DH: Detection of acute pathologic changes following experimental traumatic brain injury using diffusion-weighted magnetic resonance imaging. J Neurotrauma 13:5155211996

    • Search Google Scholar
    • Export Citation
  • 2

    Bendotti CTortarolo MSuchak SKCalvaresi NCarvelli LBastone A: Transgenic SOD1 G93A mice develop reduced GLT-1 in spinal cord without alterations in cerebrospinal fluid glutamate levels. J Neurochem 79:7377462001

    • Search Google Scholar
    • Export Citation
  • 3

    Beni-Adani LGozes ICohen YAssaf YSteingart RABrenneman DE: A peptide derived from activity-dependent neuroprotective protein (ADNP) ameliorates injury response in closed head injury in mice. J Pharmacol Exp Ther 296:57632001

    • Search Google Scholar
    • Export Citation
  • 4

    Bilotta FCaramia RCernak IPaoloni FPDoronzio ACuzzone V: Intensive insulin therapy after severe traumatic brain injury: a randomized clinical trial. Neurocrit Care 9:1591662008

    • Search Google Scholar
    • Export Citation
  • 5

    Brockman RPBergman ENJoo PKManns JG: Effects of glucagon and insulin on net hepatic metabolism of glucose precursors in sheep. Am J Physiol 229:134413491975

    • Search Google Scholar
    • Export Citation
  • 6

    Chen YConstantini STrembovler VWeinstock MShohami E: An experimental model of closed head injury in mice: pathophysiology, histopathology, and cognitive deficits. J Neurotrauma 13:5575681996

    • Search Google Scholar
    • Export Citation
  • 7

    Dahl NABalfour WM: Prolonged anoxic survival due to anoxia pre-exposure: brain ATP, lactate, and pyruvate. Am J Physiol 207:4524561964

    • Search Google Scholar
    • Export Citation
  • 8

    Davis LMPauly JRReadnower RDRho JMSullivan PG: Fasting is neuroprotective following traumatic brain injury. J Neurosci Res 86:181218222008

    • Search Google Scholar
    • Export Citation
  • 9

    Faden AIDemediuk PPanter SSVink R: The role of excitatory amino acids and NMDA receptors in traumatic brain injury. Science 244:7988001989

    • Search Google Scholar
    • Export Citation
  • 10

    Fujiwara TCherrington ADNeal DNMcGuinness OP: Role of cortisol in the metabolic response to stress hormone infusion in the conscious dog. Metabolism 45:5715781996

    • Search Google Scholar
    • Export Citation
  • 11

    Gottlieb MWang YTeichberg VI: Blood-mediated scavenging of cerebrospinal fluid glutamate. J Neurochem 87:1191262003

  • 12

    Griesdale DETremblay MHMcEwen JChittock DR: Glucose control and mortality in patients with severe traumatic brain injury. Neurocrit Care [epub ahead of print]2009

    • Search Google Scholar
    • Export Citation
  • 13

    Hu ZGWang HDQiao LYan WTan QFYin HX: The protective effect of the ketogenic diet on traumatic brain injury-induced cell death in juvenile rats. Brain Inj 23:4594652009

    • Search Google Scholar
    • Export Citation
  • 14

    Ito JMarmarou ABarzó PFatouros PCorwin F: Characterization of edema by diffusion-weighted imaging in experimental traumatic brain injury. J Neurosurg 84:971031996

    • Search Google Scholar
    • Export Citation
  • 15

    Lipton SA: Paradigm shift in neuroprotection by NMDA receptor blockade: memantine and beyond. Nat Rev Drug Discov 5:1601702006

  • 16

    Liu-DeRyke XCollingridge DSOrme JRoller DZurasky JRhoney DH: Clinical impact of early hyperglycemia during acute phase of traumatic brain injury. Neurocrit Care 11:1511572009

    • Search Google Scholar
    • Export Citation
  • 17

    Luck JMMorrison GWilbur LF: The effect of insulin on the amino acid content of blood. J Biol Chem 77:1511561928

  • 18

    Martínez MLLandry CBoehm RManning SCheek AORees BB: Effects of long-term hypoxia on enzymes of carbohydrate metabolism in the Gulf killifish, Fundulus grandis. J Exp Biol 209:385138612006

    • Search Google Scholar
    • Export Citation
  • 19

    McGuinness OPFujiwara TMurrell SBracy DNeal DO'Connor D: Impact of chronic stress hormone infusion on hepatic carbohydrate metabolism in the conscious dog. Am J Physiol 265:E314E3221993

    • Search Google Scholar
    • Export Citation
  • 20

    Nelson DCox MGluconeogenesis. Lehninger AL: Principles of Biochemistry ed 4New YorkWH Freeman2005. 543549

  • 21

    Rao VLDogan ATodd KGBowen KKDempsey RJ: Neuroprotection by memantine, a non-competitive NMDA receptor antagonist after traumatic brain injury in rats. Brain Res 911:961002001

    • Search Google Scholar
    • Export Citation
  • 22

    Salim AHadjizacharia PDubose JBrown CInaba KChan LS: Persistent hyperglycemia in severe traumatic brain injury: an independent predictor of outcome. Am Surg 75:25292009

    • Search Google Scholar
    • Export Citation
  • 23

    Schaefer PWGrant PEGonzalez RG: Diffusion-weighted MR imaging of the brain. Radiology 217:3313452000

  • 24

    Schurr AReid KHTseng MTWest CRigor BM: Adaptation of adult brain tissue to anoxia and hypoxia in vitro. Brain Res 374:2442481986

    • Search Google Scholar
    • Export Citation
  • 25

    Selim M: Perioperative stroke. N Engl J Med 356:7067132007

  • 26

    Sevick RJKanda FMintorovitch JArieff AIKucharczyk JTsuruda JS: Cytotoxic brain edema: assessment with diffusion-weighted MR imaging. Radiology 185:6876901992

    • Search Google Scholar
    • Export Citation
  • 27

    Shapira YShohami ESidi ASoffer DFreeman SCotev S: Experimental closed head injury in rats: mechanical, pathophysiologic, and neurologic properties. Crit Care Med 16:2582651988

    • Search Google Scholar
    • Export Citation
  • 28

    Steiger HJHänggi D: Ischaemic preconditioning of the brain, mechanisms and applications. Acta Neurochir (Wien) 149:1102007

  • 29

    Teichberg VICohen-Kashi-Malina KCooper IZlotnik A: Homeostasis of glutamate in brain fluids: an accelerated brain-to-blood efflux of excess glutamate is produced by blood glutamate scavenging and offers protection from neuropathologies. Neuroscience 158:3013082009

    • Search Google Scholar
    • Export Citation
  • 30

    Van Putten HPBouwhuis MGMuizelaar JPLyeth BGBerman RF: Diffusion-weighted imaging of edema following traumatic brain injury in rats: effects of secondary hypoxia. J Neurotrauma 22:8578722005

    • Search Google Scholar
    • Export Citation
  • 31

    Wasserman DHSpalding JALacy DBColburn CAGoldstein RECherrington AD: Glucagon is a primary controller of hepatic glycogenolysis and gluconeogenesis during muscular work. Am J Physiol 257:E108E1171989

    • Search Google Scholar
    • Export Citation
  • 32

    Wright PAPerry SFMoon TW: Regulation of hepatic gluconeogenesis and glycogenolysis by catecholamines in rainbow trout during environmental hypoxia. J Exp Biol 147:1691881989

    • Search Google Scholar
    • Export Citation
  • 33

    Yamamoto TRossi SStiefel MDoppenberg EZauner ABullock R: CSF and ECF glutamate concentrations in head injured patients. Acta Neurochir Suppl 75:17191999

    • Search Google Scholar
    • Export Citation
  • 34

    Yellon DMDana A: The preconditioning phenomenon: a tool for the scientist or a clinical reality?. Circ Res 87:5435502000

  • 35

    Zhang HZhang XZhang TChen L: Excitatory amino acids in cerebrospinal fluid of patients with acute head injuries. Clin Chem 47:145814622001

    • Search Google Scholar
    • Export Citation
  • 36

    Zlotnik AGurevich BTkachov SMaoz IShapira YTeichberg VI: Brain neuroprotection by scavenging blood glutamate. Exp Neurol 203:2132202007

    • Search Google Scholar
    • Export Citation

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