Format

Send to:

Choose Destination
See comment in PubMed Commons below
Eur J Pharmacol. 2010 Jun 10;635(1-3):72-8. doi: 10.1016/j.ejphar.2010.03.004. Epub 2010 Mar 19.

Presynaptic kainate receptors increase GABAergic neurotransmission in rat periaqueductal gray neurons.

Author information

  • 1Department of Pharmacology, School of Dentistry, Kyungpook National University, Daegu, Republic of Korea.

Abstract

Neurons within the periaqueductal gray (PAG) have been implicated in the central regulation of pain signals by affecting the descending inhibitory pathway. Here we report on the functional role of presynaptic kainate receptors within the PAG. Using a conventional whole-cell patch clamp technique, we recorded GABAergic spontaneous miniature inhibitory postsynaptic currents (mIPSCs) from mechanically isolated rat PAG neurons in the presence of 300nM tetrodotoxin and 20microM DL-2-amino-5-phosphonovaleric acid under voltage-clamp conditions. Kainic acid at a 10microM concentration significantly increased the frequency of GABAergic mIPSCs without affecting their amplitude, suggesting that kainic acid acts presynaptically to enhance spontaneous GABA release. The kainic acid-induced increase in mIPSC frequency was completely blocked by CNQX, a selective AMPA/kainate receptor antagonist. While neither AMPA nor NMDA affected GABAergic mIPSC frequency, ATPA, a selective agonist of GluR5-containing kainate receptors, increased GABAergic mIPSC frequency in a concentration-dependent manner. The kainic acid-induced increase in mIPSC frequency was completely suppressed either in the presence of 100microM Cd(2+), a general voltage-dependent Ca(2+) channel (VDCC) blocker, or in the Na(+)-free external solution. These results suggest that presynaptic kainate receptors have a low permeability to Ca(2+), and that their activation elicits a presynaptic depolarization large enough to activate presynaptic VDCCs. Presynaptic kainate receptors on GABAergic nerve terminals appear to modulate GABAergic transmission, and in doing so may play an important role in the regulation of PAG neuron excitability.

PMID:
20303934
[PubMed - indexed for MEDLINE]
PubMed Commons home

PubMed Commons

0 comments
How to join PubMed Commons

    Supplemental Content

    Full text links

    Icon for Elsevier Science
    Loading ...
    Write to the Help Desk