Hi all
I am having trouble getting LTP in hippocampal slices (CA3-CA1) from 9-16-week-old WT mice.
I can get LTP fine in aCSF containing 1uM gabazine (I cut CA3 to prevent epileptic activity) but in plain aCSF I don't see any LTP. When I record using Gabazine I often see spiking after LTP induction and I'm worried these are skewing my data. So it would be good if i could record LTP without using Gabazine to prevent this.
In both conditions I get stable baselines and the slices look healthy. For the baseline I use 40% of the max response. I extract in choline chloride aCSF (i have also tried slicing in aCSF containing sucrose). After slicing, the slices are maintained in standard aCSF and left to rest for 1 hour before being transferred to the rig at 30 degrees. I induce LTP using a theta burst stimulus.
Please can anyone help explain why I cannot get LTP without Gabazine? And please let me know if you have any suggestions of what I could try to get LTP.
Thanks in advance
I remember that one of my lab collegues had similar problems, she induced the CA3-CA1 LTP in rats just by increasing Ca2+ concentration to 2.5 mM in the aCSF. I attached two of her papers, hope this helps you.
Hi Lauren, for me, for some reason, LTP is inducible only in like 20% of slices at 50% of amplitude at first PS response. But if instead, I take ~60-70% of this amplitude, the success rate increases to 75% (with no PS at during LTP recording).
And also I think it is better to deepen the stim much deeper (like penetrate it >half of a slice), so more fibers would be stimulated. But I didn't try it yet.
And for some reason, bad slices (FV/fEPSP ratio 2-2.5) also have a higher frequency of LTP induction, than healthy ones. I guess because of inhibitory neurons dying out. So it works like picrotoxin.
By the way, since I'm answering pretty late and have similar problems (wish to have 100% success rate at 50% stim of max), could you please tell, did you solve the issue? If so, how?
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