Hi!

I guess that you see a difference in the frequency but not in the amplitude of IPSCs because in your test the vesicles cycling is slower, but the quantal size of spontaneous glutamate release and the number of GABA receptors didn't change. You could see a difference in the evoked IPSCs did you try it? You can try it in dual recording comparing to control, that will tell you more about the importance of your protein in the vesicle release.

Best

Salvatore

Why do you expect decreasing mIPSC amplitude? What do you mean when say fusion getting impaired? For example, decreasing fusion probability does not necessarily mean turn to "kiss-and-run" mechanism.

’Minis’ are action potential-independent synaptic currents, i.e. recorded in the presence of TTX. On the other hand, stimulation-evoked PSCs are action potential-dependent almost by definition. So another thing to consider would be the different nature and induction mechanism of the two types of postsynaptic currents. Actually, there are papers arguing that minis and evoked PSCs are elicited by different pools of presynaptic vesicles. So I don‘t thing your result is surprising at all, in fact the exact same thing happened in my lab ;)

Hello,

In your test condition, there is a presynaptic effect, that is why you see a decrement in the number of vesicle release and thus in the frequency. But the amplitude changes are related to the postsynaptic region. In your test condition, there is no significant changes in postsynaptic channel conductance and/or functional synapse. Also, evoked IPSC differents from the mIPSC, because when you evoked a neuron, it leads to synchronous release of transmitter, much more transmitters, but mIPSC is current observed in the absence of presynaptic action potential. In your test condition, already there is a decrement in release of transmitters and vesicle fusion, that is why you see also decrement in the amplitude of evoked IPSC.