Adenosine modulates excitatory synaptic transmission and suppresses neuronal death induced by ischaemia in rat spinal motoneurones

Nobuyuki Miyazaki, Terumasa Nakatsuka, Daisuke Takeda, Kazuhiro Nohda, Kazuhide Inoue, Munehito Yoshida

Research output: Contribution to journalArticlepeer-review

11 Citations (Scopus)

Abstract

Although adenosine is an important neuromodulator, its role in modulating motor functions at the level of the spinal cord is poorly understood. In the present study, we investigated the effects of adenosine on excitatory synaptic transmission and neuronal death induced by experimental ischaemia by using whole-cell patch-clamp recordings from lamina IX neurones in spinal cord slices. Adenosine significantly decreased the frequency of miniature excitatory postsynaptic currents (mEPSCs) in almost all neurones examined that could be mimicked by an A1 receptor agonist, N 6- cyclopentyladenosine (CPA), and inhibited by an A1 receptor antagonist, 8-cyclopentyl-1, 3-dipropylxanthine (DPCPX). Interestingly, adenosine increased mEPSC frequency in the presence of DPCPX in a subpopulation of neurones. In these neurones, an A2A receptor agonist, 2-[4-(2-carbonylethyl)-phenethylamino]-5′-N-ethylcarboxamidoadenosine (CGS21680), increased mEPSC frequency. Adenosine also induced an outward current that was blocked by the addition of Cs+ and tetraethylammonium into the patch-pipette solution and inhibited in the presence of Ba2+. The adenosine-induced outward current was mimicked by CPA, but not CGS21680, and inhibited by DPCPX. Moreover, superfusing with ischaemia simulating medium (ISM) generated an agonal inward current in all of the neurones tested. The latencies of the inward currents induced by ISM were significantly prolonged by adenosine or CPA, but not by CGS21680. These results suggest that adenosine receptors are functionally expressed in both the pre- and postsynaptic sites of lamina IX neurones and that their activation may exert multiple effects on motor function. Moreover, this study has provided a cellular basis for an involvement of A 1 receptors in the neuroprotective actions of adenosine.

Original languageEnglish
Pages (from-to)441-451
Number of pages11
JournalPflugers Archiv European Journal of Physiology
Volume457
Issue number2
DOIs
Publication statusPublished - Nov 1 2008

All Science Journal Classification (ASJC) codes

  • Physiology
  • Clinical Biochemistry
  • Physiology (medical)

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