Interaction of mechanisms involving epoxyeicosatrienoic acids, adenosine receptors, and metabotropic glutamate receptors in neurovascular coupling in rat whisker barrel cortex

Yanrong Shi, Xiaoguang Liu, Debebe Gebremedhin, John R. Falck, David R. Harder, Raymond C Koehler

Research output: Contribution to journalArticle

Abstract

Adenosine, astrocyte metabotropic glutamate receptors (mGluRs), and epoxyeicosatrienoic acids (EETs) have been implicated in neurovascular coupling. Although A2A and A2B receptors mediate cerebral vasodilation to adenosine, the role of each receptor in the cerebral blood flow (CBF) response to neural activation remains to be fully elucidated. In addition, adenosine can amplify astrocyte calcium, which may increase arachidonic acid metabolites such as EETs. The interaction of these pathways was investigated by determining if combined treatment with antagonists exerted an additive inhibitory effect on the CBF response. During whisker stimulation of anesthetized rats, the increase in cortical CBF was reduced by approximately half after individual administration of A2B, mGluR and EET antagonists and EET synthesis inhibitors. Combining treatment of either a mGluR antagonist, an EET antagonist, or an EET synthesis inhibitor with an A 2B receptor antagonist did not produce an additional decrement in the CBF response. Likewise, the CBF response also remained reduced by ∼50% when an EET antagonist was combined with an mGluR antagonist or an mGluR antagonist plus an A2B receptor antagonist. In contrast, A2A and A3 receptor antagonists had no effect on the CBF response to whisker stimulation. We conclude that (1) adenosine A2B receptors, rather than A2A or A3 receptors, play a significant role in coupling cortical CBF to neuronal activity, and (2) the adenosine A2B receptor, mGluR, and EETs signaling pathways are not functionally additive, consistent with the possibility of astrocytic mGluR and adenosine A2B receptor linkage to the synthesis and release of vasodilatory EETs.

Original languageEnglish (US)
Pages (from-to)111-125
Number of pages15
JournalJournal of Cerebral Blood Flow and Metabolism
Volume28
Issue number1
DOIs
StatePublished - Jan 2008

Fingerprint

Cerebrovascular Circulation
Vibrissae
Metabotropic Glutamate Receptors
Purinergic P1 Receptors
Adenosine A2B Receptors
Acids
Adenosine
Astrocytes
Neurovascular Coupling
Arachidonic Acid
Vasodilation
Calcium

Keywords

  • Cerebral circulation
  • Epoxygenase
  • Functional activation
  • Nitric oxide
  • Vibrissae

ASJC Scopus subject areas

  • Endocrinology
  • Neuroscience(all)
  • Endocrinology, Diabetes and Metabolism

Cite this

Interaction of mechanisms involving epoxyeicosatrienoic acids, adenosine receptors, and metabotropic glutamate receptors in neurovascular coupling in rat whisker barrel cortex. / Shi, Yanrong; Liu, Xiaoguang; Gebremedhin, Debebe; Falck, John R.; Harder, David R.; Koehler, Raymond C.

In: Journal of Cerebral Blood Flow and Metabolism, Vol. 28, No. 1, 01.2008, p. 111-125.

Research output: Contribution to journalArticle

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abstract = "Adenosine, astrocyte metabotropic glutamate receptors (mGluRs), and epoxyeicosatrienoic acids (EETs) have been implicated in neurovascular coupling. Although A2A and A2B receptors mediate cerebral vasodilation to adenosine, the role of each receptor in the cerebral blood flow (CBF) response to neural activation remains to be fully elucidated. In addition, adenosine can amplify astrocyte calcium, which may increase arachidonic acid metabolites such as EETs. The interaction of these pathways was investigated by determining if combined treatment with antagonists exerted an additive inhibitory effect on the CBF response. During whisker stimulation of anesthetized rats, the increase in cortical CBF was reduced by approximately half after individual administration of A2B, mGluR and EET antagonists and EET synthesis inhibitors. Combining treatment of either a mGluR antagonist, an EET antagonist, or an EET synthesis inhibitor with an A 2B receptor antagonist did not produce an additional decrement in the CBF response. Likewise, the CBF response also remained reduced by ∼50{\%} when an EET antagonist was combined with an mGluR antagonist or an mGluR antagonist plus an A2B receptor antagonist. In contrast, A2A and A3 receptor antagonists had no effect on the CBF response to whisker stimulation. We conclude that (1) adenosine A2B receptors, rather than A2A or A3 receptors, play a significant role in coupling cortical CBF to neuronal activity, and (2) the adenosine A2B receptor, mGluR, and EETs signaling pathways are not functionally additive, consistent with the possibility of astrocytic mGluR and adenosine A2B receptor linkage to the synthesis and release of vasodilatory EETs.",
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