Electrophysiological Characterization Of CCK+Neurons In The Cultured Hippocampal

Objective: To observe the electrophysiological properties of CCK positive and negative neurons, and forobserving the effect of agonist CCK-8S on electrophysiological characteristics of CCK+neurons, then toclarify the feature of CCK positive neurons itself, and the effects of CCK-8S on local neural circuittransmission of CCK positive neurons, exploring the changing mechanism on the local neuron circuits fromthe cultured neurons.Methods: With the cell culture and whole-cell patch clamp technique, we labeled the cultured hippocampalCCK positive (CCK+) neurons using an adenovirus encoding CCK promoter and green fluorescent protein(GFP). Contrasting the differences electrophysiological properties that between normal CCK+neurons andCCK-neurons. And the more influence by chronic added CCK-8S on electrophysiological properties ofCCK+neurons.Results:(1) The length diameter and cell body of CCK+neurons are greater than CCK-neurons (P <0.05).(2) CCK-8S can affect the diameter and cell size of CCK+neurons (P <0.05).(3) The membraneelectrophysiology parameters were membrane resistance of CCK+neurons is larger, but membranecapacity and time constant of CCK+neurons is smaller than CCK-neurons (P<0.05); The action potentialof CCK+neurons is half-width longer, rise time shorter, and decay time prolongation. The firing frequencyis faster than CCK-neurons (P of all other parameters is less than0.05, except for Vm).(4) CCK-8S canchange electrophysiology properties of CCK+neurons that is CCK-8S significantly decreased themembrane capacity, membrane resistance, access resistant and time constant of CCK+neurons vs controlgroup,(P <0.05). Meanwhile, CCK-8S increased action potential firing frequency of CCK+neurons, whileit didn’t change the firing patterns (P<0.05).(5) The spontaneous excitatory postsynaptic currents (sEPSC)frequency of CCK+neurons is2.85±0.14Hz vs CCK-neurons (1.75±0.29) Hz (P<0.05). Thespontaneous inhibitory postsynaptic currents (sIPSC) frequency of CCK+neurons is5.40±0.50Hz vsCCK-neurons (1.45±0.16) Hz (P<0.05).(6)The sEPSC frequency of experiment group (4.21±0.35) Hzvs control group (2.65±0.28) Hz; the sIPSC frequency of experiments (2.59±0.42) Hz vs the controls(5.16±0.78) Hz. CCK-8S can facilitated the excitatory synaptic transmission of CCK+neurons (P<0.05),but inhibited inhibitory synaptic transmission (P<0.05).Conclusions: The membrane electrophysiological properties, action potentials and postsynaptic currents ofCCK+neurons were significantly different with CCK-neurons. It is suggest that CCK+neurons have itsown unique characteristics.CCK-8S can affect the electrophysiology parameters, action potential andpostsynaptic currents of CCK+neurons. It is explained that CCK+neurons were involvement in the localneurons regulatory processes.