QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

HOME  |   SEARCH  |   ARCHIVE  |   SUBSCRIBE  |   CONTACT  |   HELP

The Journal of Neuroscience, April 30, 2008, 28(18):4836-4840; doi:10.1523/JNEUROSCI.3729-07.2008

This Article Full Text Full Text (PDF) Submit an eLetter Alert me when this article is cited Alert me when eLetters are posted Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Google Scholar Articles by Klausnitzer, J. Articles by Manahan-Vaughan, D. PubMed PubMed Citation Articles by Klausnitzer, J. Articles by Manahan-Vaughan, D.

 Previous Article

Brief Communications
Frequency Facilitation at Mossy Fiber–CA3 Synapses of Freely Behaving Rats Is Regulated by Adenosine A1 Receptors

Jens Klausnitzer¹ and Denise Manahan-Vaughan^1,2

¹Department of Experimental Neurophysiology, Medical Faculty, Ruhr University Bochum, 44780 Bochum, Germany, and ²International Graduate School for Neuroscience, Ruhr University Bochum, 44780 Bochum, Germany

Correspondence should be addressed to Dr. Denise Manahan-Vaughan, Department of Experimental Neurophysiology, Medical Faculty, Ruhr University Bochum, FNO 1/116, Universitaetsstrasse 150, 44780 Bochum, Germany. Email: dmv-igsn{at}rub.de

Frequency facilitation, elicited by low-frequency stimulation (LFS) is a specific property of mossy fiber–CA3 synapses. Although it has been widely described in vitro, no evidence as yet exists as to whether this phenomenon occurs in vivo. Here, we show that, in freely behaving rats, frequency facilitation at mossy fiber–CA3 synapses consistently occurs in response to LFS (1 Hz). Extracellular adenosine regulates presynaptic neurotransmitter release via action on adenosine A1 receptors and contributes to frequency facilitation in vitro. We investigated whether adenosine A1 receptors mediate frequency facilitation in freely behaving animals. The adenosine A1 receptor antagonists, DPCPX (8-cyclopentyl-1,3-dipropylxanthine) and phenylxanthine, markedly enhanced mossy fiber synaptic transmission and significantly occluded frequency facilitation. Evoked responses were suppressed by application of the group II metabotropic glutamate receptor agonist (2S,2'R,3'R)-2-(2',3'-dicarboxycyclopropyl)glycine (DCG-IV), in line with the known sensitivity of mossy fiber–CA3 synapses to this agent. By comparison, neither frequency facilitation, effects of the adenosine A1 antagonists, nor effects of DCG-IV were evident at either perforant path–dentate gyrus synapses or commissural/associational CA3 synapses in vivo. These data support that frequency facilitation is an intrinsic property of information storage processes at mossy fiber–CA3 synapses in the intact animal and that frequency facilitation in vivo may be mediated by regulation of the adenosine A1 receptor.

Key words: CA3; long-term depression; frequency facilitation; in vivo; adenosine; mossy fiber

---

Received Aug. 16, 2007; revised April 4, 2008; accepted April 4, 2008.

Correspondence should be addressed to Dr. Denise Manahan-Vaughan, Department of Experimental Neurophysiology, Medical Faculty, Ruhr University Bochum, FNO 1/116, Universitaetsstrasse 150, 44780 Bochum, Germany. Email: dmv-igsn{at}rub.de

Home  |   Search  |   Archive  |   Subscribe  |   Contact  |   Help