Dear colleagues,
I'm performing LTD experiments in the mouse hippocampus (CA1) using coronal brain slices and recording fEPSP.
Mice are 30 days old and I'm trying low frequency stimulation (900 stimuli at 1Hz) in order to induce longlasting LTD. However, after LFS the fEPSP response comes back to baseline after 10/15 minutes from the conditioning. Any suggestion from your side?
Below you can find my experimental setting:
- 400 um slice thickness;
- Ice cold cutting solution: Sucrose (195 mM), NaCl (10 mM), Glucose (10 mM), NaHCO3 (84 mM), KCl (74.55 mM), NaH2PO4 (1.25mM), Sodium Pyruvate (2mM), CaCl2 (0.5 mM), MgCl2 (7 mM);
- After cutting procedure, slices are incubated in aCSF for 40' at 35°C, then at RT
- Standard aCSF as recording solution (Cacl2 2mM and MgCl2 1mM), no blockers;
- 50% of max fEPSP response as baseline for 10 minutes (pair of stimuli every 20", ISI 50ms);
- Borosilicate capillaries (filled with aCSF) as stimulating (< 1 MOHM resistance)and recording electrodes (around 2 MOHM resistance);
- LTD protocol (900 single stimuli at 1 Hz or 900 pair of stimuli at 1 Hz, ISI 50ms).
Thanks in advance for helping me.
There are several possible reasons why you might be seeing a return to baseline after 10-15 minutes following low frequency stimulation (LFS) in your LTD experiments. Here are a few potential explanations:
It's worth noting that these are just a few potential explanations, and there may be other factors that are contributing to the lack of LTD in your experiments.
Dear Bertrand Cornu ,
thanks for your suggestions.
I would like to underline that the protocol that I used was 15' long (and it's reported to induce LTD in hippocampus).
Regarding your second suggestions: are you sure that blocking NMDAR with APV might be correct? LFS mediated LTD is a NMDAR-dependent mechanism. How can I induce LTD blocking NMDAR? Has you a reference for that?
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