The Effect Of Stress On Synaptic Plasticity Of The Prefrontal Cortex And The Thalamus

Restraint water-immersion stress (RWIS) was regarded as a complex stress, it can inducevagally-mediated gastric hypercontractility, hypersecretion of gastric acid and acute gastricerosions within several hours. It is widely used to the study of the pathogenesis of stress-inducedgastric lesions and to filtrate the medicine that can cure this disease. Fos protein is the product ofthe immediate early gen（eIEG），it is often used to detect the activity status of the neurons. Nervecells and glial cells constitutite the nerve system. The neuron is the unit of the nerve systemstructure and function that can accept，integrate and transmit information. Synapses are theimportant parts of the exchange of information between two neurons，all nerve impulses inreflection activities depended on synaptic transmission，so it can be regarded as the transmissionunit of the nerve system. The integrity of the quantity and the structure function of synapse areimportant to maintain the normal function of the brain. Synaptophysin（SYN）and synapsin Iwere used to detect the synaptic plasticity of the neurons. Medial prefrontal cortex is sensitive tostress，fibrous connection between the thalamus and the medial prefrontal cortex was reported，they can regulate many physiological reactions. However，whether the thalamus is involved inRWIS，whether the synaptic plasticity of the neurons of the medial prefrontal cortex and thethalamus is changed during the RWIS reaction，these studies are not reported.To resolve these questions mentioned above，the experimental protocol were designed asfollows.Healthy male Wistar rats were randomly divided two groups：the stress group（RWIS1h）and the control group（RWIS0h）.Two groups rats were starved for24h and then give therestraint water-immersion stress to the experimental rats. After the stress，the heart perfusion，stripping out of the brain, frozen section etc were in sequence dealt with in the two groups. Inorder to estimate the prelimbic area（PL），infralimbic area（IL）of the medial prefrontal cortex（mPFC）and thalamic mediodorsal nucleus（MD），paraventricular nucleus（tPVN），centramedial nucleus（CM）whether participate in the RWIS reactions, the immunohistochemical single labelling method for neural Fos protein was used and the number of Fos positive neuronswas calculated.In order to determine whether the synaptic plasticity of the neurons in the mPFC and in thethalamus is changed during the different durations of RWIS in rats. Healthy male Wistar ratswere randomly divided four groups：three experimental groups for RWIS1h，RWIS2h，RWIS4h and one control group for RWIS0h. The four groups rats were starved for24h and then givethe restraint water-immersion stress to the experimental rats. After the end of RWIS，the heartperfusing，stripping out of the brain，freezing section etc were in sequence dealt with in the fourgroups. Then use the immunohistochemical staining technique to detect the change of SYN andsynapsin I in the PL，IL of the mPFC and MD，tPVN，CM of the thalamus. The expressionamounts of SYN and synapsin I were indicated by the Integrated Optical Density (IOD).The results were as follows：1. In the restraint water-immersion stress group（RWIS1h），the number of Fos positiveneurons within a unitary area in the MD，tPVN，CM of the thalamus significantly higher thanthat of control group，it indicated that these three nuclei of thalamus involved in restraintwater-immersion stress reaction and played a regulatory role.2. In the restraint water-immersion stress group（RWIS1h），the number of Fos positiveneurons within a unitary area in the PL and IL of the mPFC significantly higher than that ofcontrol group，it indicated that the neurons in PL and IL involved in restraint water-immersionstress reaction.3. The experimental groups（RWIS1h，2h，4h），the integrated optical density（IOD）of SYN in the MD，tPVN，CM of the thalamus significantly higher than that of control group，it indicated that the synaptic plasticity of the neurons of these three nuclei of thalamus werechanged and up regulation functionally during the RWIS reactions.4. The experimental groups（RWIS1h，2h，4h），the integrated optical density（IOD）of SYN in the PL and IL of the mPFC significantly higher than that of control group，it indicatedthat the synaptic plasticity of the neurons in PL and IL were changed and up regulationfunctionally during the RWIS reactions.5. The experimental groups（RWIS1h，2h，4h），the integrated optical density（IOD） of synapsin I in the MD，tPVN，CM of the thalamus significantly higher than that of controlgroup，it further indicated that the synaptic plasticity of the neurons of these three nuclei ofthalamus were changed and up regulation functionally during the RWIS reactions.6. The experimental groups RWIS1h，the integrated optical density（IOD）of synapsin I inthe PL and IL of the mPFC significantly higher than that of control group， it further indicatedthat the synaptic plasticity of the neurons in PL and IL were changed and up regulationfunctionally during the RWIS reactions.