HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Full Text (PDF) All Versions of this Article: 97/3/2301    most recent 01179.2006v1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Web of Science (8) Citing Articles via Google Scholar Google Scholar Articles by McQuiston, A. R. Search for Related Content PubMed PubMed Citation Articles by McQuiston, A. R.

Effects of µ-Opioid Receptor Modulation on GABA_B Receptor Synaptic Function in Hippocampal CA1

Department of Anatomy and Neurobiology, Virginia Commonwealth University Medical Center, Richmond, Virginia

Submitted 6 November 2006; accepted in final form 9 January 2007

Activation of µ-opioid receptors (MORs) alters information coding, synaptic plasticity, and spatial memory in hippocampal CA1. In CA1, MORs act by inhibiting GABA release onto both GABA_A and GABA_B receptors exclusively. MOR activation can facilitate excitatory inputs in CA1 dendritic layers by inhibiting synaptic activation of GABA_A receptors. In this study, we use voltage-sensitive dye imaging to show that MOR activation by the MOR agonist DAMGO suppressed GABA_B inhibitory postsynaptic potentials in all layers of CA1. When stimulating excitatory input in stratum oriens (SO), stratum radiatum (SR), or stratum lacunosum-moleculare (SLM) with five pulses at 20 Hz in the presence of bicuculline (50 µM), DAMGO (1 µM) was most effective at increasing the amplitude of the last excitatory event. This effect was reversed by the MOR antagonist CTOP (1 µM) and occluded by the GABA_B receptor agonist CGP 55845 (10 µM). DAMGO was less effective at increasing the amplitude of later excitatory events compared with the effect of CGP 55845. DAMGO was relatively ineffective at increasing the amplitude of excitatory inputs in SLM but had significantly greater effects on excitatory events as they propagated to stratum pyramidale (SP). When stimulating in SR, DAMGO was least effective at increasing excitatory amplitudes in SLM and most effective in SP and SO. Finally, DAMGO was equally effective at increasing excitatory activity amplitudes in all layers of CA1 after stimulating in SO. Therefore MOR suppresses GABA_B synaptic hyperpolarizations in all layers of CA1 and most effectively facilitates excitatory activity in CA1 output layers.

This article has been cited by other articles:

				A. J. Page, T. A. O'Donnell, and L. A. Blackshaw Opioid modulation of ferret vagal afferent mechanosensitivity Am J Physiol Gastrointest Liver Physiol, April 1, 2008; 294(4): G963 - G970. [Abstract] [Full Text] [PDF]