Dear all,
i am using LTP protocol on mice hippocampus and i am facing recently a new issue: the amplitude of fEPSP is decreasing with time while recording (the recording of 1st slice has no issue, this problem starts with the recording of the 2nd slice and the slices after).
This decrease is probably due to neuronal cell death, i did not have this problem before, i am using the same parameters from start to finish as before, does anybody know this problem?
Thank you
Best,
Oussama
Are you oxygenating the slices properly? Or has any other parameter changed, like flow rate, temperature, age of animals, etc? All things being equal, you should be able to get several consecutive (and stable) long recordings per day from one mouse. I would first check for possible changes in and around the rig before searching for complicated solutions.
If neuron death occurs during LTP, there are several potential strategies that can be employed to mitigate this effect:
It's important to note that these strategies may not be effective in all cases, and that more research is needed to fully understand the underlying mechanisms of neuron death during LTP and to develop effective treatments. Additionally, it's also important to consider the context and the conditions in which LTP is being induced as it can be associated with different types of neuron death.
To answer your Q? properly, we need more details about your Solutions especially Cutting Sol. and Maintenance Sol. I am assuming that aCSF is what you use for internal and external recording solutions. I am also assuming that you cut your brain in cold cutting solution and that you maintain it at 34 degrees Celsius afterwards for at least 1 to 2h before you start recording. And Paulo is absolutely right when he said that perfusion flow rate of the external media can affect the size of the evoked EPSPs. if your tubes are somehow clogging during the experiment, you would see what you described. Severe neuronal death can only occur if you are not properly oxygenating all through (From cutting, maintaining and recording) or your brain is from older animals (See Paulo's answer above). If you use old animals, there are protocols available e.g. Ting et al., 2018 (doi:10.3791/53825). I use juvenile mice so I don't have that problem and I am happy using a simple protocol from Thomas Papouin and Philip G. Haydon (2018). All the best!
Hi Oussama,
even if this is quite unlikely, check your stimulation apparatus, especially if you use batteries to power your stimulator. When these batteries start to decay, it can affect the maintenance of the stimulation intensity (it happened to me during long in vivo LTP recording).
All Best.
Bruno
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