Figure 2
Learning-induced hyperpolarization of the fIPSP and IPSC is mediated by KCC2 upregulation. (A) Example of the effect of the KCC2 blocker, VU0463271 on the fIPSP in a neuron of a trained rat. Amplitude of the fIPSP was recorded at several holding potentials. IPSPs were measured at the first peak, as appeared in the most depolarized recording potential. Numbers on the left of the traces note the holding membrane potential. These measurements were then used to calculate the reversal potential of the responses.(B) The reversal potentials of the synaptic responses shown in A were determined by the linear regression line, describing the amplitude of the synaptic potential as a function of the membrane holding potential. Application of VU0463271 resulted in a 10 mV depolarization of the fIPSP reversal potential. Note that the slope of the curve is not modified by the KCC2 blocker application, indicating that the conductance of the chloride current via the GABAA-channel is not affected by the blocker. (C) The averaged reversal potential of the fast IPSP is reduced in neurons from trained rats only. (*P < 0.05 for trained neurons before and after VU0463271 application). Data was taken from 7 trained rats and 10 control rats. Values represent mean ± SE. (D) Example of the effect of the KCC2 blocker, VU0463271 on the spontaneous IPCSs in a neuron taken from a trained rat. Amplitude of the IPSCs was recorded at several holding potentials. Averaged amplitude of the IPSC at each membrane potential was calculated by averaging the amplitude of all recorded IPSCs, as previously described11. Numbers on the left of the traces note the holding membrane potential. These measurements were then used to calculate the reversal potential of the responses. (E) The reversal potentials of the synaptic responses shown in D were determined by the linear regression line, describing the amplitude of the synaptic current as a function of the membrane holding potential. Application of VU0463271 resulted in a 5 mV depolarization of the IPSC reversal potential. (F) The averaged reversal potential of the IPSC is reduced in neurons from trained rats only. (**P < 0.01 for trained neurons before and after VU0463271 application). Data was taken from 7 trained rats and 5 control rats. Values represent mean ± SE.
