Electrophysiological Research On Insular Pyramidal Cells Of αCaMKII-F89G Mice

Insula is one of the most important regions in the brain. It belongs to the limbic system. Numerous studies show that Insula is the integration of a variety of brain neural networks. It plays an important role in visceral sensory, visceral movement, attention, pain, emotion, language and other aspects. CaMKII plays an important role in learning and memory and synaptic plasticity. CaMKII is a multifunctional serine/ threonine protein kinase. it was distributed inside the cells in peripheral and central neurons. There are four subtypes:a,β,γandδCaMKII. The main subtype in forebrain is aCaMKII and it is the main ingredients of PSD. aCaMKII changes their amount in postsynaptic membrane and regulate synaptic transmission by changing the postsynaptic NMDA and AMPA receptor phosphorylation. aCaMKII plays an important role in synaptic plasticity in different brain regions.While there is alse a large number of expression of aCaMKII in the insular cortex.But there has not been any research report in the insular cortex in the role of synaptic transmission. Whether aCaMKII increases would affect the basic electrophysiological characteristics of insular cortex and the synaptic transmission? In order to explore these issues, we use aCaMKII-F89G transgenic mice-forebrain overexpression of aCaMKII, resreach the electrophysiological properties and synaptic transmission in insular cortex of aCaMKII-F89G transgenic mice, and analyzed the possible mechanism.Basal Electrophysiological analysis of insular cortex pyramidal cells in aCaMKII-F89G miceTo study the expression of aCaMKII pyramidal cells of the insular cortex of the basal electrophysiological properties.We use the brain slice patch clamp technique, survey and evaluate the resting membrane potential (Vm), membrane time constant (τm),Action Potentials (APs) and current-voltage curve (I-V Curve) of insular cortex pyramidal cells of aCaMKII-F89G transgenic mice and wild-type mice. The results showed that there were no significant differences between wt and tg mice in all respects. High expression of aCaMKII did not change the basal electrophysiological properties of insular cortex pyramidal cells. Basic synaptic transmission analysis of insular cortex pyramidal cells in aCaMKII-F89G miceTo study the influence of aCaMKII overexpression on insular cortex on the basic synaptic transmission, We use brain slice patch clamp method to record and compare the spontaneously excitatory postsynaptic currents (sEPSCs), miniature excitatory postsynaptic currents (mEPSCs) and paired-pulse facilitation curve (Paired Pulse Facilitation, PPF) of insular pyramidal cells of wild type and a CaMKII-F89G transgenic mice. We also use field potential recording method to record and compare Input-Output Curve(I/O Curve) in insular cortex of wild type and aCaMKII-F89G transgenic mice. The results showed that the amplitude of sEPSCs and mEPSCs of aCaMKII-F89G transgenic mice is significant larger than wild-type mice, while the frequency did not change. There was also no difference in PPF curve, but significant differece in the I/O curve. The I/O curve of transgenic mice turn higher than the I/O curve of wild type. These results showed that high expression of aCaMKII in insular cortex increased the activity of AMPA and (or) NMDA receptor in postsynaptic membrane and enhanced synaptic transmission.Synaptic plasticity analysis of insular cortex in aCaMKII-F89G miceMake use of brain slice patch clamp method to record and compare the evoked excitatory postsynaptic currents(eEPSCs)mediated long-term potentiation (LTP) induced by tetanic stimulation of insular cortex pyramidal cells of wild-type and aCaMKII-F89G transgenic mice. There was no difference between the wt and tg mice. Brain slices field potential recording was used to test compared the field excitatory postsynaptic potential (fEPSP) mediated long term depression(LTD) induced by low frequency stimulation of wild-type and aCaMKII-F89G transgenic mice.The amplitude of LTD of transgenic mice is lower than the amplitude of wild type mice's. These results showed that high expression of aCaMKII in the insular cortex may not involved in the regulation of LTP formation, but blocked the formation of LTD in insular cortex.