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Adenosine A₁ receptors control the metabolic recovery after hypoxia in rat hippocampal slices

Duarte, João M N LU ; Cunha, Rodrigo A and Carvalho, Rui A. (2016) In Journal of Neurochemistry 136(5). p.57-947
Abstract

Adenosine is a neuromodulator that protects neurons from hypoxia. This effect is attributed to the ability of adenosine A1 receptors (A1 R) to inhibit excitatory synaptic transmission. However, A1 R activation also protects non-brain tissues from hypoxic insults by controlling metabolism. Thus, we now tested the hypothesis that A1 R-mediated neuroprotection after a hypoxic insult in superfused hippocampal slices also involves the control of neuronal and astrocytic metabolism. A 90-min hypoxia insult increased lactate, alanine, and pyruvate levels and decreased energy charge (EC), phosphocreatine/creatine ratio, and glutamine content. These metabolic modifications were fully recovered after reoxygenation for 3 h. The presence of the A1... (More)

Adenosine is a neuromodulator that protects neurons from hypoxia. This effect is attributed to the ability of adenosine A1 receptors (A1 R) to inhibit excitatory synaptic transmission. However, A1 R activation also protects non-brain tissues from hypoxic insults by controlling metabolism. Thus, we now tested the hypothesis that A1 R-mediated neuroprotection after a hypoxic insult in superfused hippocampal slices also involves the control of neuronal and astrocytic metabolism. A 90-min hypoxia insult increased lactate, alanine, and pyruvate levels and decreased energy charge (EC), phosphocreatine/creatine ratio, and glutamine content. These metabolic modifications were fully recovered after reoxygenation for 3 h. The presence of the A1 R-selective antagonist 1,3-dipropyl-8-cyclopentylxanthine stimulated glycolysis, prevented the hypoxia-induced decrease of EC, and increased the levels of GABA. A1 R blockade further blunted the recovery of metabolism on reoxygenation after hypoxia, as typified by a sustained decreased EC and an increased mitochondrial metabolism, as confirmed by a greater [U-(13) C]glucose oxidation through the tricarboxylic acid cycle. These results demonstrate that A1 R blockade prevents the recovery of hypoxia-induced metabolic alterations during reoxygenation, which indicates that the ability of A1 R to control primary metabolism in the brain tissue may be a hitherto unrecognized mechanism of A1 R-mediated neuroprotection. This study demonstrates that tonic activation of adenosine A1 receptors (A1 R) plays an important role in the reoxygenation recovery of the metabolic alterations caused by transient hypoxia in rat hippocampal slices. This ability of A1 R to inhibit neuronal metabolism may be a key mechanism by which adenosine affords neuroprotection upon acute hypoxia, thus preventing the long-term impairment of neuronal circuits.

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author
publishing date
type
Contribution to journal
publication status
published
keywords
Adenosine, Animals, Excitatory Postsynaptic Potentials, Hippocampus, Hypoxia, Male, Neurons, Receptor, Adenosine A1, Synaptic Transmission, Xanthines, Journal Article, Research Support, Non-U.S. Gov't
in
Journal of Neurochemistry
volume
136
issue
5
pages
11 pages
publisher
Wiley-Blackwell
external identifiers
  • scopus:84958122057
ISSN
1471-4159
DOI
10.1111/jnc.13512
language
English
LU publication?
no
id
17b75e2d-3863-496e-ba55-70fc6d966d52
date added to LUP
2017-10-19 15:09:17
date last changed
2017-11-14 09:51:24
@article{17b75e2d-3863-496e-ba55-70fc6d966d52,
  abstract     = {<p>Adenosine is a neuromodulator that protects neurons from hypoxia. This effect is attributed to the ability of adenosine A1 receptors (A1 R) to inhibit excitatory synaptic transmission. However, A1 R activation also protects non-brain tissues from hypoxic insults by controlling metabolism. Thus, we now tested the hypothesis that A1 R-mediated neuroprotection after a hypoxic insult in superfused hippocampal slices also involves the control of neuronal and astrocytic metabolism. A 90-min hypoxia insult increased lactate, alanine, and pyruvate levels and decreased energy charge (EC), phosphocreatine/creatine ratio, and glutamine content. These metabolic modifications were fully recovered after reoxygenation for 3 h. The presence of the A1 R-selective antagonist 1,3-dipropyl-8-cyclopentylxanthine stimulated glycolysis, prevented the hypoxia-induced decrease of EC, and increased the levels of GABA. A1 R blockade further blunted the recovery of metabolism on reoxygenation after hypoxia, as typified by a sustained decreased EC and an increased mitochondrial metabolism, as confirmed by a greater [U-(13) C]glucose oxidation through the tricarboxylic acid cycle. These results demonstrate that A1 R blockade prevents the recovery of hypoxia-induced metabolic alterations during reoxygenation, which indicates that the ability of A1 R to control primary metabolism in the brain tissue may be a hitherto unrecognized mechanism of A1 R-mediated neuroprotection. This study demonstrates that tonic activation of adenosine A1 receptors (A1 R) plays an important role in the reoxygenation recovery of the metabolic alterations caused by transient hypoxia in rat hippocampal slices. This ability of A1 R to inhibit neuronal metabolism may be a key mechanism by which adenosine affords neuroprotection upon acute hypoxia, thus preventing the long-term impairment of neuronal circuits.</p>},
  author       = {Duarte, João M N and Cunha, Rodrigo A and Carvalho, Rui A.},
  issn         = {1471-4159},
  keyword      = {Adenosine,Animals,Excitatory Postsynaptic Potentials,Hippocampus,Hypoxia,Male,Neurons,Receptor, Adenosine A1,Synaptic Transmission,Xanthines,Journal Article,Research Support, Non-U.S. Gov't},
  language     = {eng},
  number       = {5},
  pages        = {57--947},
  publisher    = {Wiley-Blackwell},
  series       = {Journal of Neurochemistry},
  title        = {Adenosine A₁ receptors control the metabolic recovery after hypoxia in rat hippocampal slices},
  url          = {http://dx.doi.org/10.1111/jnc.13512},
  volume       = {136},
  year         = {2016},
}