The Effects Of Ketamine On Spontaneous Electrical Activity In Cortex S1Neurons Of Rat After Inhibiting Astrocytes

Background&Objective:70%neurons are glia cells in the central nervous system.It hasbeen proved that astrocyte can send messages between neurons in various ways. Astrocytesalso contribute to the coordination of neuron messages in different brain regions, thus play arole in the formation of consciousness. Based on this theory, this experiment uses thepatch-clamp system to observe the effects of ketamin on spontaneous electrical activity inpyramidal neurons of rats after inhibiting the activity of astrocytes.Methods: Preparatsion of brain slices (SD rats aged10-14days),and used whole-cell patchclamp technique to measure postsynaptic currents. The experiment was divided into twoparts: part one, observed the effects of different concentratsions ketamine(200μM、400μM、600μM、800μM、1000μM)on spontaneous postsynaptic currents (sPSCs) of S1pyramidalneurons, then calculated out the concentratsion for50%of maximal effect (EC50). PartTwo,divided SD rats into control group and experiment group,randomly. The control groupused normal artificial cerebrospinal fluid to incubate the brain slices, while the experimentgroup used the artificial cerebrospinal fluid which contains5μM fluorocitratse (FC)toincubate the brain slices.Both groups perfused the artificial cerebrospinal fluid which contai-ns ketmaine of450μM. Note down the sPSCs of pyramidal neurons under the same holdingpotential.Results:1.Ketamine of five different concentratsions all has influence on the frequency and amplitudeof sPSCs on the pyramidal neurons in cortex S1of rat(P<0.05).2.With ketamine of five different concentratsions, the inhibition ratio of sPSCs frequency onthe pyramidal neurons in cortex S1of rat:22.98%±1.70%,40.75%±0.47%,62.37%±2.10%,66.36%±0.59%,73.52±1.23%. As the ketamine concentratsion increases, the inhibition ratioof frequency increase in a dosage dependant manner, however not as evident as the inhibitionof frequency.3.With ketamine of five different concentratsions, the inhibition ratio of sPSCs amplitude on the pyramidal neurons in cortex S1of rat:22.98%±1.70%,40.75%±0.47%,34.72%±0.53%,39.86%±0.92%,45.92%±0.56%,50.94%±0.45%,56.13±0.57%.As the ketamine concentrat-ion increases, the inhibition ratio of amplitude increase in a dosage dependant manner, howe-ver not as evident as the inhibition of frequency.Drew a curve graph based on the inhibitionratio of sPSCs frequency, and calculated out EC50is452.29μM±41.73μM.At last, choose450μM as the best ketamine concentratsion.4.After inhibiting the activity of astrocyte, the inhibiton ratio of sPSCs frequency on the pyr-amidal neurons in cortex S1of rat reduced by administering450uM ketamine (P<0.05),while inhibition ratio of sPSCs amplitude is not significant (P>0.05).Conclusion:1.Ketamine inhibites sPSCs of pyramidal neurons in cortex S1in a dosage of dependantmanner.2.Astrocyte cells of S1region may be involved in the inhibition effects of ketamine on S1pyramidal neurons.