Depression mouse model as well as construction method and application thereof

Abstract

The invention relates to the technical field of biological medicines, and particularly discloses a depression mouse model as well as a construction method and application thereof. The construction method of the depression mouse model comprises the step of carrying out microglial cell specific Csf1r heterozygous knockout on a mouse. The depression mouse model is obtained by inducing the depression-like behavior of the mouse through microglial specific Csf1r heterozygous knockout, and compared with an existing method for causing the depression-like behavior of the animal through chronic unpredictable mild pressure stimulation, the depression phenotype is stable, the depression phenotype appears quickly, and the depression-like behavior of the animal is not influenced by the depression-like behavior. Repeated experiments of depression related researches are facilitated, and experimental results with high repeatability can be obtained.

Description

Technical Field

[0001] The present application relates to the field of biomedicine technology, and in particular to a depression mouse model and a construction method and application thereof. Background Art

[0002] Depression is a common mental disorder and a disabling disease. According to the World Health Organization (WHO), approximately 3.8% of the population, including 2.6% of children and young people, and 5.0% of adults are affected by depression. The prevalence of depression in China continues to rise, and the incidence rate in women is generally higher than that in men. Social pressure, psychological pressure and biological factors can all trigger the occurrence of depression. At present, the study of the causes of depression and the evaluation of therapeutic drugs generally use chronic unpredictable mild stress to cause a depressive phenotype in mice, but this animal model is unstable and has large individual differences, which brings uncertainty to the experiment.

[0003] Therefore, the prior art needs to be improved. Summary of the invention

[0004] In view of the above-mentioned deficiencies in the prior art, the purpose of the present application is to provide a depression mouse model and a construction method and application thereof, aiming to solve the problem that the existing depression animal model is not stable, has large individual differences, and brings uncertainty to the experiment.

[0005] The technical solution of this application is as follows:

[0006] In a first aspect of the present application, a method for constructing a depression mouse model is provided, wherein the method for constructing a depression mouse model comprises: performing microglia-specific Csf1r heterozygous knockout on mice.

[0007] Optionally, the mouse is a Cre mouse.

[0008] Optionally, the step of performing microglia-specific Csf1r heterozygous knockout on mice includes: mating wild-type Cre mice, a first Cre mouse and a second Cre mouse to obtain a depression mouse model; inserting LoxP sites on both sides of the exon of the Csf1r gene of the first Cre mouse; and inserting a creERT2-WPRE-polyA sequence at the start codon of the Cx3cr1 gene of the second Cre mouse.

[0009] Optionally, the method for constructing the depression mouse model further includes genotyping the depression mouse model.

[0010] Optionally, the genes identified in the genotyping identification include Cx3cr1-Cre gene and Csf1r-flox gene.

[0011] Optionally, the method for constructing the depression mouse model also includes evaluating the depressive-like behavior of the depression mouse model.

[0012] Optionally, the method for evaluating the depressive-like behavior includes at least one of an elevated plus maze test, an open field test, a sugar water preference test, and a forced swimming test.

[0013] In a second aspect of the present application, a depression mouse model constructed by the method for constructing a depression mouse model provided in the present application is provided.

[0014] The third aspect of the present application provides an application of the depression mouse model provided in the present application in theoretical research on depression.

[0015] The fourth aspect of the present application provides an application of the depression mouse model provided by the present application in screening depression drugs.

[0016] Compared with the prior art, this application has the following advantages:

[0017] The present application induces depressive-like behavior in mice by microglia-specific Csf1r heterozygous knockout to obtain a depression mouse model. Compared with the existing method of causing depressive-like behavior in animals by chronic unpredictable mild stress CUMS stimulation, the depressive phenotype is stable and the depressive phenotype appears quickly, which is convenient for repeated experiments in depression-related research and can obtain highly reproducible experimental results. In addition, the depression mouse model prepared by the method of the present application can simulate microglia-related depression and neuroinflammation-related depression, providing a basis for the mechanism research and drug screening of microglia-related or neuroinflammation-related depression. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for describing the embodiments are briefly introduced below.

[0019] Figure 1 Depression-like behavior test diagram of each group of mice (WT, Cre-, Cre+) provided in the examples of this application:

[0020] A is the drug administration and behavioral test schedule for the mouse depression model; B is the behavioral results of the mouse elevated plus maze test; C is the behavioral results of the mouse open field test; D is the behavioral results of the mouse sugar water preference test; E is the behavioral results of the mouse forced swimming test;

[0021] Figure 2 Immunofluorescence staining images of the mPFC brain region of each group of mice (WT, Cre-, Cre+) provided in the examples of this application:

[0022] A is the result of immunofluorescence staining of Iba1 in each group of mice; B is the statistics of microglial coverage area in the mPFC brain region of each group of mice; C is the statistics of the total length of microglial branches in the mPFC brain region of each group of mice; D is the statistics of the total number of microglial branches in the mPFC brain region of each group of mice; E is the representative picture of Golgi staining in the mPFC brain region of each group of mice; F is the statistics of the number of dendritic spines in the mPFC brain region of each group of mice; G is the representative picture of co-localization of Iba1 and PSD95 immunofluorescence in the mPFC brain region of each group of mice; H is the statistics of the volume of PSD95 in Iba1 in the mPFC brain region of each group of mice;

[0023] Figure 3 Depression-like behavior test diagram of each group of mice (Cre-, Cre+, Cre+_PLX) provided in the examples of this application:

[0024] A is the schedule of drug administration and behavioral testing of the mouse depression model; B is the behavioral results of the mouse elevated plus maze test; C is the behavioral results of the mouse open field test; D is the behavioral results of the mouse sugar water preference test; E is the behavioral results of the mouse forced swimming test;

[0025] Figure 4 Immunofluorescence staining images of the mPFC brain region of each group of mice (Cre-, Cre+, Cre+_PLX) provided in the examples of this application:

[0026] A is the result of immunofluorescence staining of Iba1 in each group of mice; B is the statistics of microglial coverage area in the mPFC brain region of each group of mice; C is the statistics of the total length of microglial branches in the mPFC brain region of each group of mice; D is the statistics of the total number of microglial branches in the mPFC brain region of each group of mice; E is the representative picture of Golgi staining in the mPFC brain region of each group of mice; F is the statistics of the number of dendritic spines in the mPFC brain region of each group of mice; G is the representative picture of co-localization of Iba1 and PSD95 immunofluorescence in the mPFC brain region of each group of mice; H is the statistics of the volume of PSD95 in Iba1 in the mPFC brain region of each group of mice;

[0027] Figure 5 The signal pathway analysis diagram in the mPFC brain region of the mouse depression model provided in the embodiment of the present application is as follows:

[0028] A is the KEGG enrichment analysis of differentially expressed genes between Cre- mice and Cre+ mice; B is the heat map of NOD family gene enrichment; C is the difference in the expression of each molecule protein of the NLRP6 / caspase-1 / IL-1β / IL-18 pathway in the mPFC brain region of Cre- mice and Cre+ mice; D is the immunofluorescence co-localization of Iba1 and Caspase-1 in the mPFC brain region of Cre- mice and Cre+ mice; E is the linear statistics of the co-localization of Iba1 and Caspase-1; F is the immunofluorescence co-localization of NeuN and Caspase-1 in the mPFC brain region of Cre- mice and Cre+ mice; G is the linear statistics of the co-localization of NeuN and Caspase-1; H is the immunofluorescence co-localization of GFAP and Caspase-1 in the mPFC brain region of Cre- mice and Cre+ mice; I is the linear statistics of the co-localization of GFAP and Caspase-1;

[0029] Figure 6 Depression-like behavior test diagram of each group of mice (Cre-, Cre+, Cre+_VX765) provided in the examples of this application:

[0030] A is the drug administration and behavioral test schedule for the mouse depression model; B is the behavioral results of the mouse elevated plus maze test; C is the behavioral results of the mouse open field test; D is the behavioral results of the mouse sugar water preference test; E is the behavioral results of the mouse forced swimming test;

[0031] Figure 7 Immunofluorescence staining images of the mPFC brain region of each group of mice (Cre-, Cre+, Cre+_VX765) provided in the examples of this application:

[0032] A is the results of Iba1 immunofluorescence staining of mice in each group; B is the statistics of microglial coverage area in the mPFC brain region of mice in each group; C is the statistics of the total length of microglial branches in the mPFC brain region of mice in each group; D is the statistics of the total number of microglial branches in the mPFC brain region of mice in each group; E is the representative picture of Golgi staining in the mPFC brain region of mice in each group; F is the statistics of the number of dendritic spines in the mPFC brain region of mice in each group; G is the representative picture of co-localization of Iba1 and PSD95 immunofluorescence in the mPFC brain region of mice in each group; H is the statistics of the volume of PSD95 in Iba1 in the mPFC brain region of mice in each group. DETAILED DESCRIPTION

[0033] In order to make the purpose, technical solutions and advantages of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below in combination with the drawings and embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments of the present application, all other embodiments obtained by ordinary technicians in this field without making creative work belong to the protection scope of the present application. In the absence of conflict, the following embodiments and features in the embodiments can be combined with each other.

[0034] It should be noted that if there are descriptions involving "first", "second", etc. in the implementation of this application, the descriptions of "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or suggesting their relative importance and implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In addition, the technical solutions between the various embodiments can be combined with each other, but they must be based on the fact that ordinary technicians in the field can implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such combination of technical solutions does not exist and is not within the scope of protection required by this application.

[0035] Microglia play an important role in the pathogenesis of depression. One of the main functions of microglia in the brain is to respond to immune signals and participate in inflammatory responses. When the brain is damaged or infected, microglia are activated and release various inflammatory factors and cytokines (such as TNF-α, IL-1β, and IL-6), which may lead to neuroinflammation. Patients with depression often experience neuroinflammation, and activated microglia promote inflammation, thereby aggravating depressive symptoms. Microglia also play a key role in neuroplasticity. They are involved in the formation and pruning of synapses. Depression is closely related to neuroplasticity disorders. Dysfunction of microglia may lead to abnormal neural connections, which in turn affects mood. The pathological mechanisms of depression may include excessive activation of microglia and persistent neuroinflammation, which may lead to neuronal damage and death and aggravate depressive symptoms.

[0036] Csf1r (Colony Stimulating Factor 1Receptor) plays a vital role in maintaining the function and survival of microglia. Microglia are embryonic bone marrow mononuclear cell precursors. During development, Csf1r signaling is essential for the increase and differentiation of microglia. Csf1r signaling not only promotes the survival of microglia, but also participates in regulating their activation state. When responding to neural damage or disease, microglia regulate their functions through Csf1r-mediated signals, including the production and release of various inflammatory mediators, thereby affecting the process of neuroinflammation. In Alzheimer's disease and other neurodegenerative diseases, changes in Csf1r expression may directly affect the function of microglia, thereby affecting the progression of the disease, but in depression, the function of Csf1r remains to be explored.

[0037] Based on this, the present application provides a method for preparing a depression mouse model, comprising the steps of: performing microglia-specific Csf1r heterozygous knockout on mice to obtain a Cre mouse.

[0038] In some embodiments, the step of performing microglia-specific Csf1r heterozygous knockout on mice can be: mating wild-type Cre mice, first Cre mice, and second Cre mice to obtain a depression mouse model, wherein LoxP sites are inserted on both sides of the exon of the Csf1r gene of the first Cre mouse, and the creERT2-WPRE-polyA sequence is inserted at the start codon of the Cx3cr1 gene of the second Cre mouse.

[0039] The Csf1r gene in mouse microglia was heterozygous knocked out using the Cre-Lox gene recombination system. LoxP sites were inserted on both sides of the exon of the Csf1r gene of the first Cre mouse, and the creERT2-WPRE-polyA sequence was inserted at the start codon of the Cx3cr1 gene of the second Cre mouse. During the mating process of wild-type Cre mice, the first Cre mouse, and the second Cre mouse, the Cre recombinase was expressed and could cut out the DNA sequence between the two LoxP sites and recircularize the two ends, thereby achieving specific knockout of the Csf1r gene.

[0040] In some embodiments, the method for constructing a depression mouse model further includes: genotyping the depression mouse model. Specifically, genotyping the depression mouse model is achieved by identifying the Cx3cr1-Cre gene and the Csf1r-flox gene. The Cx3cr1-Cre gene and the Csf1r-flox gene can be identified by using primers for the Cx3cr1-Cre gene and the Csf1r-flox gene, and by PCR amplification combined with gel electrophoresis and sequencing.

[0041] In some embodiments, the method for constructing a depression mouse model further comprises evaluating the depression-like behavior of the depression mouse model, wherein the method for evaluating the depression-like behavior comprises at least one of an elevated plus maze test, an open field test, a sugar water preference test, and a forced swimming test.

[0042] The present application also provides a depression mouse model using the depression mouse model preparation method as described above.

[0043] The present application also provides a method for alleviating the depressive-like behavior of the depression mouse model as described above: treating the depression mouse model with a Csf1r inhibitor or a Caspase-1 inhibitor. The specific steps may be treating the depression mouse model with a Csf1r inhibitor or a Caspase-1 inhibitor by gavage. The Csf1r inhibitor may be PLX3397, and the Caspase-1 inhibitor may be VX-765.

[0044] Through experimental verification, it was found that Csf1r inhibitors or Caspase-1 inhibitors can effectively alleviate the depressive-like behavior of the depression mouse model. Csf1r inhibitors alleviate the activation of microglia in the mPFC brain region of the depression mouse model and reduce the phagocytosis of synapses, thereby alleviating the depressive-like behavior of the depression mouse model. Caspase-1 inhibitors alleviate the activation of microglia in the mPFC brain region of the depression mouse model and reduce the phagocytosis of synapses by inhibiting the activation of the NLRP6 / Caspase-1 / Il-1β / Il-18 signaling pathway, thereby alleviating the depressive-like behavior of the depression mouse model.

[0045] The present application also provides an application of the depression mouse model described above in theoretical research on depression.

[0046] The present application also provides an application of the depression mouse model as described above in screening drugs for depression.

[0047] The following is further described by means of specific examples.

[0048] Example 1

[0049] The following mouse strains were used in this example: C57BL / 6 (GemPharmatech); C57BL / 6Smoc-Cx3cr1em1(creERT2-WPRE-polyA)Smoc (Shanghai Model Organisms, NM-KI-200157) and C57BL / 6Smoc-Csf1rem1(flox)Smoc (Shanghai Model Organisms, NM-CKO-200091). By mating the above mouse strains, transgenic mice with conditional knockdown of Csf1r in microglia can be obtained, and mouse genotyping and identification are performed using primers for Cx3cr1-Cre and Csf1r-flox, and finally a mouse model of depression is obtained.

[0050] The correct mice (Cx3cr1-CreERT2; Csf1r f / + Mice) were treated with tamoxifen (75 mg / kg dissolved in corn oil) or corn oil by intraperitoneal injection for 5 days. C57BL / 6 mice of the same age without special treatment were marked as WT group, and Cx3cr1-CreERT2; Csf1r treated with corn oil were used. f / + Mice were labeled as Cre-group and Cx3cr1-CreERT2; Csf1r treated with tamoxifen. f / + The mice were marked as the Cre+ group. The mice in each group were subjected to behavioral tests at 3 months of age. The elevated plus maze, open field test, sugar water preference test, and forced swimming test were used to test the depressive-like behavior of the mice in each group. The timeline of drug administration and behavioral testing is as follows: Figure 1 As shown in A.

[0051] The results of the depressive behavior tests of each group of mice are shown in Figure 1 As shown in B, C, D, and E. Figure 1As shown in Figure B, compared with the control group and Cre- mice, Cre+ mice showed a decrease in total stroke, distance walked in the open arms, time spent in the open arms, and number of times entering the open arms in the elevated plus maze test (EPM). Similar results were obtained in the open field test (OFT), where Cre+ mice showed a decrease in the distance walked and the proportion of time spent in the center of the open field, while there was no statistical difference in total stroke and speed. In the sucrose preference test (SPT), Cre+ mice had a reduced sucrose intake compared with the control group and Cre- mice. In the forced swimming test (FST), the time that Cre+ mice stopped struggling in the water was significantly increased compared with the control group and Cre- mice. Combined with the above-mentioned depressive-like behavioral test results, it can be seen that the transgenic mice with conditional knockdown of Csf1r in microglia exhibited obvious depressive-like behavior.

[0052] Example 2

[0053] Immunofluorescence staining was used to stain Iba1 and PSD95 in the mPFC brain region of each group of mice obtained in Example 1, and the morphology and number changes of microglia in the brain region, as well as the co-localization with PSD95 were observed. Golgi staining was used to stain the neurons in the mPFC brain region of mice, and the number and morphology of dendritic spines of neurons in the brain region were observed. The results are as follows: Figure 2 The data are shown as mean ± SEM, ***p<0.001, ****p<0.0001.

[0054] from Figure 2 In A, we can see that the number of microglial branches in the mPFC of Cre+ mice increased significantly. Figure 2 As can be seen from B, C, and D, the coverage area of ​​microglia in the mPFC brain region of Cre+ mice is significantly larger than that of Cre- mice, the total length of microglia branches in the mPFC brain region of Cre+ mice is greater than that of Cre- mice, and the total number of microglia branches in the mPFC brain region of Cre+ mice is greater than that of Cre- mice, which further indicates that compared with Cre- mice, the microglia in the mPFC brain region of Cre+ mice are in a hyper-branched state. Through three-dimensional reconstruction, it can be seen that the number of cell branches increases, becomes longer, the coverage area increases, and the number of co-localizations with PSD95 increases. Figure 2 Golgi staining results in E and Figure 2 The statistics of dendritic spines in the mPFC of mice in the middle F show that the dendritic spines on neurons in the mPFC of Cre+ mice are significantly reduced compared with Cre- mice. Figure 2As can be seen in G and H, Cre+ mice have increased phagocytosis of the postsynaptic protein PSD95 and dendritic spines compared to Cre- mice.

[0055] Example 3

[0056] One week after the mice were injected with Tamoxifen or corn oil, 40 mg / kg of Csf1r inhibitor PLX3397 was used to treat Cre+ mice by gavage, with pure water as the control solvent, and the drug was continuously administered for 3 weeks. Then, behavioral tests were performed on each group of mice (Cre-, Cre+, Cre+_PLX). The elevated plus maze, open field test, sugar water preference test and forced swimming test were used to test the depressive-like behavior of each group of mice. The drug administration and behavioral test timeline process is as follows Figure 3 As shown in A.

[0057] The results of the depressive behavior tests of each group of mice are shown in Figure 3 As shown in B, C, D, and E. Figure 3 As shown in Figure B, the Cre+ mice treated with PLX3397 showed a significant increase in total distance traveled, distance walked in the open arms, time spent in the open arms, and number of times entering the open arms in the elevated cross-legged test. Figure 3 As can be seen in middle C, the distance walked and the proportion of time spent in the center of the open field increased in Cre+ mice treated with PLX3397. Figure 3 As can be seen in Figure D, PLX3397-treated Cre+ mice had increased sucrose intake compared to Cre+ mice. Figure 3 As can be seen in Figure E, the time that Cre+ mice treated with PLX3397 stopped struggling in the water was significantly reduced compared with Cre+ mice. Combined with the above results, it can be seen that the Csf1r inhibitor PLX3397 can effectively alleviate the depressive-like behavior caused by conditional knockdown of Csf1r in microglia.

[0058] Example 4

[0059] Immunofluorescence staining was used to stain Iba1 and PSD95 in the mPFC brain region of each group of mice (Cre-, Cre+, Cre+_PLX) obtained in Example 3, and the morphology and number changes of microglia in the brain region, as well as the co-localization with PSD95 were observed. Golgi staining was used to stain the neurons in the mPFC brain region of mice to observe the number and morphology of dendritic spines in the brain region. The results are as follows: Figure 4 The data are shown as mean ± SEM, ***p<0.001, ****p<0.0001.

[0060] from Figure 4From A to D, we can see that compared with Cre+ mice, the microglia in the mPFC brain region of PLX3397-treated Cre+ mice showed normal branching and significantly reduced numbers. Through three-dimensional reconstruction, it can be seen that the cell branches are reduced, shortened, and the coverage area is significantly reduced, and the number of co-localization with PSD95 is reduced. Figure 4 Golgi staining results in Figure E Figure 4 The statistics of dendritic spines in the mPFC brain region of mice in the middle F show that compared with Cre+ mice, the dendritic spines on neurons in the mPFC brain region of Cre+ mice treated with PLX3397 increased significantly. This indicates that conditional knockdown of Csf1r in microglia activates microglia in the mPFC brain region of mice, showing a hyperbranched state. The Csf1r inhibitor PLX3397 can effectively alleviate the activation of microglia in the mPFC brain region of mice induced by conditional knockdown of Csf1r in microglia and reduce the phagocytosis of synapses.

[0061] Example 5

[0062] Primary microglia were extracted from the mPFC brain regions of Cre- and Cre+ mice for RNA high-throughput sequencing to identify differentially expressed genes between the two mice. The differentially expressed genes were screened and enriched to identify related signaling pathways. Immunofluorescence and Western blot were used for verification. The results are shown in Figure 2. Figure 5 shown.

[0063] from Figure 5 As can be seen in Figures A and B, compared with Cre- mice, inflammatory activation mainly occurred in the microglia in the mPFC brain region of Cre+ mice, and the expression of NOD-like signaling pathways was abnormal, and a series of genes in the NOD family were significantly activated, including NLRP6, NLRP1, etc. As can be seen in Figure C, the Western blot method proved that the NLRP6 / Caspase-1 / Il-1β / Il-18 signaling pathway was significantly activated in the microglia in the mPFC brain region of Cre+ mice. Figure 5 As can be seen in D, E, F, G, H and I, Caspase-1 was stained by immunofluorescence and co-localized with Iba1, NeuN and GFAP, respectively. It was found that Caspase-1 was mostly co-localized with Iba1 in the mPFC brain region of Cre+ mice, which indicates that the NLRP6 / Caspase-1 / Il-1β / Il-18 signaling pathway may be an important mechanism by which conditional knockdown of Csf1r in microglia induces depressive-like behavior in mice, and the activation of this pathway mainly occurs in the microglia of the model mice.

[0064] Example 6

[0065] One week after the mice were injected with Tamoxifen or corn oil, 40 mg / kg of Caspase-1 inhibitor VX-765 was used for Cre+ mice by gavage, with pure water as the control solvent, and the administration lasted for 3 weeks. Then, behavioral tests were performed on each group of mice (Cre-, Cre+, Cre+_VX-765). The elevated plus maze, open field test, sugar water preference test and forced swimming test were used to test the depressive-like behavior of each group of mice. The timeline of drug administration and behavioral testing is as follows: Figure 6 As shown in A.

[0066] The results of the depressive behavior tests of each group of mice are shown in Figure 6 As shown in B, C, D, and E. Figure 6 As shown in Figure B, the total distance traveled, the distance walked in the open arms, the time spent in the open arms, and the number of times entering the open arms in the elevated cross-legged test were significantly increased in the Cre+ mice treated with VX-765. Figure 6 As can be seen in middle C, the distance walked and the proportion of the time spent in the center of the open field increased in Cre+ mice treated with VX-765. Figure 6 As can be seen in Figure D, VX-765-treated Cre+ mice had increased sucrose intake compared to Cre+ mice. Figure 6 As can be seen in E, the time that Cre+ mice treated with VX-765 stopped struggling in the water was significantly reduced compared with Cre+ mice. Combined with the above results, it can be seen that the Caspase-1 inhibitor VX-765 can effectively alleviate the depressive-like behavior caused by conditional knockdown of Csf1r in microglia.

[0067] Example 7

[0068] Immunofluorescence staining was used to stain Iba1 and PSD95 in the mPFC brain region of each group of mice (Cre-, Cre+, Cre+VX-765) to observe the morphology and quantity changes of microglia in this brain region, as well as the co-localization with PSD95. Golgi staining was used to stain the neurons in the mPFC brain region of each group of mice to observe the number and morphology of dendritic spines in this brain region. The Western blot method was used to detect the molecular proteins related to the NLRP6 / Caspase-1 / Il-1β / Il-18 signaling pathway to observe the effect of VX-765 on this pathway. The results are as follows Figure 7 The data are shown as mean ± SEM, ***p<0.001, ****p<0.0001.

[0069] from Figure 7From A to D, we can see that compared with Cre+ mice, the microglia in the mPFC brain region of Cre+ mice treated with VX-765 showed normal branching and significantly reduced number. Through three-dimensional reconstruction, it can be seen that the cell branches are reduced, shortened, and the coverage area is significantly reduced, and the number of co-localization with PSD95 is reduced. Figure 7 Golgi staining results in Figure E Figure 7 The statistics of dendritic spines in the mPFC region of mice in the middle F show that compared with Cre+ mice, the dendritic spines on neurons in the mPFC region of Cre+ mice treated with VX-765 increased significantly. This indicates that conditional knockdown of Csf1r in microglia activates microglia in the mPFC region of mice, presenting a hyperbranched state. Caspase-1 inhibitor VX-765 can effectively alleviate the activation of microglia in the mPFC region of mice induced by conditional knockdown of Csf1r in microglia and reduce the phagocytosis of synapses. It is speculated that this may be related to its ability to effectively inhibit the activation of the NLRP6 / Caspase-1 / Il-1β / Il-18 signaling pathway.

[0070] In summary, the present application obtains a depression mouse model by microglia-specific Csf1r heterozygous knockout, and verifies the depressive-like behavior of the depression mouse model through experiments. Compared with the existing method of causing animal depressive-like behavior through chronic unpredictable mild stress CUMS stimulation, the depressive phenotype is stable and the depressive phenotype appears quickly, which is convenient for repeated experiments in depression-related research, and highly reproducible experimental results can be obtained. In addition, experiments have shown that microglia-specific Csf1r heterozygous knockout can induce microglia activation in the mPFC brain region of mice and increase phagocytosis of synapses, triggering the activation of the NLRP6 / caspase-1 / IL-1β / IL-18 pathway in the mPFC brain region. And treating the depression mouse model with Caspase-1 inhibitors and Csf1r inhibitors can alleviate its depressive-like behavior, providing a basis for the mechanism study and drug screening of microglia-related or neuroinflammation-related depression.

[0071] It should be understood that the application of the present application is not limited to the above examples. For ordinary technicians in this field, improvements or changes can be made based on the above description. All these improvements and changes should fall within the scope of protection of the claims attached to this application.

Claims

1. A method for constructing a depression mouse model, characterized in that: The method for constructing the depression mouse model comprises: performing microglia-specific Csf1r heterozygous knockout on mice.

2. The method for constructing a depression mouse model according to claim 1, characterized in that: The mice are Cre mice.

3. The method for constructing a depression mouse model according to claim 2, characterized in that: The step of performing microglia-specific Csf1r heterozygous knockout on mice includes: mating wild-type Cre mice, first Cre mice, and second Cre mice to obtain a depression mouse model; LoxP sites were inserted into both sides of the exon of the Csf1r gene of the first Cre mouse; The creERT2-WPRE-polyA sequence is inserted into the start codon of the Cx3cr1 gene of the second Cre mouse.

4. The method for constructing a depression mouse model according to claim 3, characterized in that: The method for constructing the depression mouse model also includes performing genotyping identification on the depression mouse model.

5. The method for constructing a depression mouse model according to claim 4, characterized in that: The genes identified in the genotyping identification include Cx3cr1-Cre gene and Csf1r-flox gene.

6. The method for constructing a depression mouse model according to claim 1, characterized in that: The method for constructing the depression mouse model also includes evaluating the depressive-like behavior of the depression mouse model.

7. The method for constructing a depression mouse model according to claim 6, characterized in that: The evaluation method of the depressive-like behavior includes at least one of an elevated plus maze test, an open field test, a sugar water preference test, and a forced swimming test.

8. A depression mouse model constructed by using the method for constructing a depression mouse model according to any one of claims 1 to 7.

9. Use of the depression mouse model according to claim 8 in theoretical research on depression.

10. Use of the depression mouse model according to claim 8 in screening of depression drugs.

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