The Research Of Ion Channel And Signal Pathway Involved In Long-term Synaptic Plasticity And Behavior

Background:Synapses are important links between neurons, which also play a key part in nerve impulse transmission. The synaptic plasticity is thought to be a foundation of memory and learning. The morphology of neurons and synaptic structure change will affect the synaptic plasticity as well as learning and memory.Transient Receptor Potential Canonical (TRPC) channel is a kind of nonselective cation channel on the cell membrane. These channels exist in various cells of mammals, and play an important role in a lot of physiological functions. TRPC3and TRPC6are important in neuronal survival. Research has proved that calcium ion flow through TRPC5can inhibits hippocampal neuron dendritic growth via activing calmodulin kinase II (CaKII). While the Ca2+flow through TRPC6channel can promote hippocampal neuron dendritic growth via CaMKIV to activate the downstream cAMP response element binding protein (cAMP response element binding protein, after CREB) and the expression of related target genes.Many researches have shown that Notch signaling pathway play an important role in the development process of the nervous system, it can influence the morphology of neurons, including the spike density and length of the neurons dendrite. And this may be a result of that the Notch pathway can affected the actin cytoskeleton.Objective:1. To investigate the expression of TRPC3, TRPC5, TRPC6ion channel in a depression rat model and its influence on spatial cognitive ability and long-term potentiation.2. To investigate the influence of the Notchl signaling pathway on the behavior and long-term potentiation in mice.Methods and material:1.24male Wistar rats were randomly divided into three groups:control group, stress, hyperforin treatment group. Chronic unpredictability stimulation method is adopted to establish the model of depression. The rats in the hyperforin treatment group were received hyperforin lavage treatment1week later and the treatment lasted for3consecutive weeks.1. Record the weitht of rats every other day, and perform the sugar water experiment every week.ii. Using Morris water maze experiment to test the spatial learning and memory ability of model animals. By open field experiments to detect the spontaneous activity and the degree of anxiety of the animals.iii. The change of the synaptie plasticity:Recording the LTP of PP-DG pathways s to evaluate the change of the synaptie plasticity under depressive symptoms.iv. Using elisa kit to test monoamines neurotransmitter concentrations change (5-HT&DA) in cerebrospinal fluid as well as hippocampus.v. Using western blot method to detect the expression of TRPC3, TRPC5, TRPC6in hippocampal tissues Use Dil and golgi staining method to detect morphological changes of hippocampal neurons.2.12Wild type C57mice and12Notchl knock down C57mice, first performed the Morris water maze, elevated cross maze and open field experiment, then recording the LTP and LTD in hippocampus, finally detect neuron morphology and self-renewal status with immunofluorescence method and histological staining.Result:1. The spatial cognitive ability, spontaneous locomotor activity as well as synaptie plasticity were impaired in CUS animal model, and hyperforin treatment for3weeks can achieve partial remission.2. The staining showed that the neuron dendrite morphology was changed after CUS modeling.3. The expression levels of TRPC3&TRPC6were reduced while the expression of TRPC5was unchanged.4. The spatial cognitive ability, spontaneous locomotor activity as well as synaptie plasticity were impaired in Notch1knocked down mice the histological staining showed lower hippocampal neuron dendritic lengthand density in Notch1knocked down mice than that of the wild type.Conclusion:1. Chronic unpredictable stimulation can impair the rat spatial learning and cognitive, at the same time reduce the spontaneous activity, increase anxiety degree, the synaptic plasticity of PP-DG pathways in hippocampal is damaged. The possible mechanism underlying may be the morphological changes of hippocampus neurons and the change of concentration of monoamine neurotransmitter in the brain, and all the changes above may be a result of diffenrent expression of TRPC ion channels in the neuron.2. Notchl signal pathway has a profound influence on the morphology and synaptic plasticity, and which may be accounted for the behavior changes in the animals.