Research reportThe metabotropic glutamate receptor 5 is necessary for late-phase long-term potentiation in the hippocampal CA1 region
Section snippets
Electrophysiological techniques
Hippocampal slices were prepared as previously described [26], [27]. Briefly, Wistar rats (28–35 days of age) were decapitated under halothane anesthesia. Brains were rapidly transferred into ice-cold artificial cerebrospinal fluid (ACSF) (130 mM NaCl; 3.5 mM KCl; 24 mM NaHCO3; 1.25 mM NaH2PO4; 2.2 mM CaCl2; 10 mM glucose; 2 mM MgSO4, oxygenated with a mixture of 95% O2/5% CO2, pH 7.4) and transverse hippocampal slices (400 μm) were obtained with a Leica (Wetzlar, Germany) VT1000E automatic
Results
The role of group I metabotropic glutamate receptors on the induction of L-LTP [11] of fEPSP at Schaffer collateral/commissural fiber-CA1 synapses was investigated in rat hippocampal slices with selective pharmacological inhibitors. A transient application (10 min) of the mGluR5-selective inhibitor MPEP (10 μM) during the L-LTP induction paradigm resulted in a much reduced level of potentiation (Fig. 1A). In fact, the fEPSP slopes following application of MPEP during tetanization were 136.7%
Discussion
We have shown here that mGluR5, but not mGluR1, is required for the induction of L-LTP. We have also observed that both mGluR1 and mGluR5 are required for protein synthesis-independent LTP obtained with a single train of tetanization at 100 Hz. The latter is in good agreement with some previous mouse mutant studies in the literature [1], [15] (but see Ref. [10]). The present findings are also in agreement with the work of Rodriguez et al. [23], who showed that MPEP impairs NMDAR-dependent
Acknowledgments
Supported by NIMH. We are grateful to Dr. Paul Kenny of TSRI for critical review of the manuscript. We are also grateful to Alvin King of TSRI for technical help and to Tom Deerinck and Mark Ellisman of the National Center for Microscopy and Imaging Research at the University of California, San Diego, for their expert assistance with confocal microscopy.
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2016, Neurobiology of Learning and MemoryCitation Excerpt :The protein p70 is a kinase which regulates replication of genes related to learning and memory (Antion et al., 2008; Bekinschtein et al., 2007; Slipczuk et al., 2009). Increased phosphorylation of this protein has been shown in inhibitory avoidance and fear conditioning tasks (Bekinschtein et al., 2007; Gafford, Parsons, & Helmstetter, 2011); and it has also been implicated as an important regulator in the occurrence of late LTP in the hippocampus (Francesconi, Cammalleri, & Sanna, 2004; Hoeffer et al., 2008). In order to further investigate involvement of NI in PAL we aimed to measure the ratio of hippocampal phosphorylated p70 to p70 (p-p70/p70).
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