Application of liver X receptor agonist in improving and / or treating depression-like behavior

Abstract

The invention relates to the technical field of biological medicines, and discloses an application of a liver X receptor stimulant in improving and / or treating depression-like behaviors and a medicine for improving and / or treating depression-like behaviors, and the active component of the medicine comprises GW3965. According to the application disclosed by the invention, the condition that the expression of microglial cells in mPFC can be reduced and the phagocytic effect of the microglial cells on myelin sheath can be reduced by using an LXR agonist GW3965 for treatment is determined, and the condition that the depression-like behavior is regulated by influencing the myelin sheath phagocytic capacity of the activated microglial cells is determined. Therefore, the function of regulating the myelin sheath phagocytosis of the microglial cells through medicines is expected to become a potential treatment way for treating mental diseases.

Description

Technical Field

[0001] The present invention relates to the field of biomedicine technology, and in particular to the use of a liver X receptor agonist in improving and / or treating depressive-like behavior. Background Art

[0002] Depression is one of the most common mental illnesses today, characterized by long-term and profound low moods. Clinical manifestations include lack of pleasure, inferiority, loss of interest, and even pessimism and world-weariness, and there may also be suicidal attempts or behaviors. It is difficult for patients with depression to be completely cured, and most of them need to rely on long-term medication. Therefore, finding the pathogenesis of depression is the top priority in the current clinical treatment of depression. Exploring new targets for the treatment of depression can provide new directions for clinical drug treatment.

[0003] Microglia are intrinsic immune cells of the central nervous system and the first major line of defense of the central nervous system, accounting for about 5-20% of all glial cells. In patients with depression and suicide, microglia in the brain proliferate significantly, and psychological stress can promote microglial proliferation by increasing glucocorticoid levels. In addition, various antidepressants can significantly inhibit the enhanced activity of microglia induced by various stimuli. Studies have shown that microglia help maintain healthy myelin, which is essential for the optimal function of brain and spinal cord nerve cells. Activated microglia can engulf damaged myelin fragments after demyelination; in addition, myelin lesions and demyelination occur in the brains of patients with depression. So far, it is unclear whether the phagocytosis of myelin by microglia in the brains of patients with depression is abnormal.

[0004] Liver X receptors (LXRs) are a subfamily of the nuclear receptor superfamily of transcription factors. LXRα (nuclear receptor 1H3, NR1H3) and LXRβ (nuclear receptor 1H2, NR1H2) are classified according to their encoding genes. LXRs are involved in a variety of physiological functions, including promoting neurogenesis and synaptic plasticity, preventing neurodegeneration, inhibiting inflammation, and regulating cholesterol metabolism. These functions are consistent with the pathogenesis of depression and the antidepressant drugs used for treatment.

[0005] Previous studies have found that rats exposed to chronic unpredictable stress (CUS) showed reduced hippocampal LXRβ expression, which was negatively correlated with the severity of CUS-induced depressive-like behavior; in addition, after shRNA-mediated LXRβ knockout, rats showed depressive-like behavior and impaired hippocampal neurogenesis, which was similar to what was observed after CUS intervention; in contrast, the LXR agonist GW3965 (GW) improved depressive-like behavior and reversed impaired hippocampal neurogenesis, both of which indicated that LXRβ isozymes mediated the antidepressant effects and hippocampal neurogenesis-promoting effects of LXR agonists.

[0006] Adult microglia show baseline diversity in cell number, cellular and subcellular structure, molecular characteristics and related functions. Microglia differ regionally under peripheral inflammatory conditions associated with depressive-like behavior. Studies have shown that microglia selectively phagocytose myelin to promote myelination. However, it is not clear whether LXRs agonists in the medial prefrontal cortex can improve depressive-like behavior by affecting the ability of activated microglia to phagocytose myelin. Summary of the invention

[0007] The object of the present invention is to provide a use of a liver X receptor agonist in improving and / or treating depressive-like behavior in view of the above problems.

[0008] In order to achieve its purpose, the present invention adopts the following technical solution:

[0009] The first aspect of the present invention provides use of a liver X receptor agonist in the preparation of a medicament for improving and / or treating depressive-like behavior.

[0010] In the application technology scheme, the liver X receptor agonist is GW3965.

[0011] In the application technology scheme, the GW3965 reduces the expression of microglia in mPFC.

[0012] In the application technology scheme, the GW3965 reduces the density of microglia in the mPFC and increases the density of myelin proteins.

[0013] In the application technology scheme, the GW3965 improves depressive-like behavior by reducing the phagocytic effect of microglia on myelin.

[0014] The second aspect of the present invention provides a drug for improving and / or treating depressive-like behavior, wherein the active ingredient of the drug comprises GW3965.

[0015] Preferably, the medicament is a pharmaceutical composition.

[0016] Preferably, the pharmaceutical composition further comprises a pharmaceutically acceptable carrier.

[0017] The beneficial effects of the present invention are:

[0018] The present study confirmed that the liver X receptor agonist W3965 can reverse the behavioral test results of CUS mice, and W3965 reduces the number of microglia in the mPFC, reduces the density of microglia and increases the density of MBP, and confirms that GW3965 treatment can reduce the phagocytosis of myelin by microglia in the mPFC, thus establishing that the use of LXR agonist treatment can regulate depressive-like behavior by affecting the ability of activated microglia to phagocytose myelin. Drug regulation of the function of microglia to phagocytose myelin is expected to become a potential therapeutic approach for the treatment of mental illness. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is a schematic diagram of the mouse modeling time in the embodiment of the present application;

[0020] Figure 2 The statistical results of the weight changes of mice in the first six weeks of modeling and the results of the sugar water preference experiment in the present application example are as follows: Figure 2 (a) is a statistical chart of weight changes of mice in the control+NS group and the CUS+NS group. Figure 2 (b) is a statistical chart of the sugar water preference results of the two groups of mice before modeling. Figure 2 (c) is a statistical chart of the sugar water preference results of the two groups of mice 6 weeks after modeling;

[0021] Figure 3 It is a statistical graph of the immobility time of the control+NS group, the CUS+NS group and the CUS+GW group in the tail suspension test in the embodiment of the present application;

[0022] Figure 4 The results of the weight change of mice after 4 weeks of treatment with GW3965 and the sugar water preference experiment in the examples of this application are as follows: Figure 4 (a) is the weight change diagram of mice in control+NS, CUS+NS and CUS+GW groups. Figure 4 (b) is the sugar water preference result diagram of the three groups of mice;

[0023] Figure 5 : is the result of histochemical staining of Iba1+ microglia in the medial prefrontal cortex (mPFC) of each group of mice in the examples of the present application, wherein Figure 5 (a) Anti-Iba1 + Representative images of immunohistochemical staining of the medial prefrontal cortex of mice in the control+NS group, CUS+NS group, and CUS+GW group. Arrows point to microglia. Figure 5 (b) is a statistical diagram of the total number of Iba1+ cells in the mPFC of the three groups of mice;

[0024] Figure 6is the immunofluorescence staining result of each group of mice in the examples of this application, wherein Figure 6 (a) Iba1 in mPFC of three groups of mice + and MBP immunofluorescence staining images, Figure 6 (b) Iba1 in mPFC of three groups of mice + Statistical graph of staining intensity, Figure 6 (c) is a statistical graph of the MBP staining intensity in the mPFC of the three groups of mice;

[0025] Figure 7 is the co-immunostaining result of each group of mice in the examples of this application, wherein, Figure 7 (a) is a schematic diagram of fluorescent double labeling of mice in the control+NS group, where green is Iba1 + , red indicates MBP, and the yellow arrow indicates MBP / Iba1 + cell, Figure 7 (b) is the 3D reconstruction image after immunofluorescence layer scanning. The length and width of the layer scanning image are both 212.13 μm, and the thickness of the longer scanning image is 28.47 μm. Figure 7 (c) Iba1 in the mPFC of three groups of mice + / MBP staining intensity comparison statistical graph. DETAILED DESCRIPTION

[0026] The present invention will be further described below in conjunction with embodiments, but the present invention is not limited thereto.

[0027] The experimental methods in the following examples are conventional methods unless otherwise specified.

[0028] Example 1

[0029] The research method of the present invention is as follows: 4-6 week-old male C57BL / 6J mice were selected, and after adaptive feeding for 1 week, the sugar water baseline was adjusted, and then they were randomly divided into a control group (control), a depression model group (CUS), and a depression model + GW3965 group (CUS+GW). The mice in the CUS group and the CUS+GW group were subjected to CUS intervention for 10 consecutive weeks; the CUS+GW group mice were given GW3965 for 4 weeks starting from the 7th week of intervention; behavioral tests were performed at the end of the 10th week, and then immunohistochemistry and modern stereology techniques were used to accurately quantify the changes in the density and total number of microglia in the MPFC of mice, and the density of microglia and myelin in the MPFC of mice was evaluated by immunofluorescence.

[0030] Results: After 10 weeks of stress intervention, the body weight and sugar water preference percentage of mice in the CUS group decreased significantly, and the immobility time of mice in the tail suspension test increased significantly. Stereological results showed that CUS intervention significantly increased the density of Iba1+ microglia in the medial prefrontal cortex (MPFC) of mice, and immunofluorescence results showed that the density of Iba1+ microglia in the MPFC increased and the level of phagocytic MBP increased significantly, while GW3965 treatment could reverse the above changes.

[0031] The specific experimental process is as follows:

[0032] 1. Materials

[0033] 1.1 Experimental animals

[0034] Animal source: Adult male C57BL / 6J mice aged 4-6 weeks were provided by the Experimental Animal Center of Chongqing Medical University.

[0035] Experimental feeding: A total of 43 male C57 mice (6-8 weeks old) were used in the experiment, 3-4 mice per cage; during the first two weeks of adaptation, all mice will receive sufficient and equal amounts of food and water. Animal use and procedures were in accordance with the guidelines of the National Institutes of Health and approved by the Animal Care and Use Committee of Chongqing Medical University, in accordance with the ethical standards of animal experiments.

[0036] 1.2 Main experimental reagents and instruments

[0037]

[0038]

[0039] For other specific conditions not specified, the experiments were carried out according to conventional conditions or those recommended by the manufacturer. Reagents or instruments used without indicating the manufacturer were conventional products that can be purchased commercially.

[0040] 2. Methods

[0041] 2.1 Construction of animal model

[0042] Forty-three male C57BL / 6J mice aged 6-8 weeks were selected and adaptively fed for two weeks. After two weeks of glucose-water baseline testing, the mice were randomly divided into a control group and a CUS group. After grouping, the CUS group will receive depressive stimulation and start drug intervention after behavioral testing; the control group was given normal saline and renamed the control + NS group (control + NS, n = 14), and the CUS group was randomly divided into a CUS + NS group (CUS + NS, n = 15) and a CUS + GW3965 treatment group (CUS + GW, n = 14).

[0043] The CUS model was established according to references (see reference 1). Specific stress intervention measures included fasting / drinking (≤20h), circadian rhythm reversal (24-48h), noise (3-5h), night strobe (8-12h), empty bottle stimulation (2h), tilting (≥20h), behavioral restriction (≥2h), hot water bath (42℃, 5 minutes), ice water bath (4℃, 5 minutes), wet / empty bedding (≥20 hours) and a combination of the above two treatments. Rats in the CUS+NS group were fed in a cage and received two types of stress every day; except for the reversal of day and night, each type of stress was not repeated within 5 days, and the entire modeling process lasted for 6 weeks; treatment began after the 6th week of CUS modeling. During the 4-week treatment, mice in the CUS+GW group were injected with GW3965 (10 mg / kg) every day, while mice in the control+NS group and the CUS+NS group were injected with the same dose of normal saline every day.

[0044] Mouse modeling schedule Figure 1 As indicated, all experimental interventions and drug treatments lasted for a total of 10 weeks.

[0045] 2.2 Drug injection

[0046] According to the drug instructions, 10 mg of GW3965 was dissolved in 1 mL of solvent, and the drug concentration was diluted to 10 mg / mL before injection. Six weeks after CUS modeling, mice in the CUS+GW group began to receive intraperitoneal injections of GW3965 (10 mg / kg-D), while mice in the control+NS group and CUS+NS group were injected with the same dose of normal saline.

[0047] 2.3 Weight assessment

[0048] The changes in the weight of mice during the experiment can intuitively reflect the growth rate and health status of the mice over a period of time. At the end of each week, the researchers measured and recorded the weight of each group of mice until the modeling was completed.

[0049] 2.4 Animal behavior testing

[0050] 2.4.1 Sucrose Preference Test (SPT)

[0051] The sugar water preference experiment is a standard for evaluating the core symptom of depression model animals - anhedonia. At the end of each week, the researchers measured and recorded the sugar water preference of each group of mice until the modeling was completed.

[0052] Before the experiment began, the mice were fed with adaptive feeding for two weeks, and their preference for sugar water gradually stabilized. Then, the mice were tested for their preference for sugar water. The specific steps are briefly described as follows: First, they were fasted and deprived of water for 24 hours, and then each rat was given a bottle of 1% sugar water and a bottle of plain water. The positions of the two bottles were swapped at 12 hours. After 24 hours, the weight of the remaining sugar water and plain water bottles were weighed, and the corresponding consumption was calculated. Finally, the sugar water preference of the rats was calculated according to the following formula: Sugar water preference percentage = sugar water consumption / (sugar water consumption + plain water consumption) × 100%.

[0053] 2.4.2 Tail Suspension Test (TST)

[0054] The tail suspension test is a behavioral method for evaluating antidepressant effects. The degree of despair of experimental animals is determined by measuring the animals' immobility time. Each group of mice was tested with the tail suspension test at the end of the sixth and tenth weeks.

[0055] During the test, the mice were suspended on a stand with the posterior 1 / 3 of their tails fixed with tape and their heads 15 cm away from the table. The entire experiment was recorded using video equipment. Each mouse was suspended for the same amount of time (6 minutes), and the activity status of the mice was mainly recorded after 2 minutes.

[0056] 2.4.3 Open Field Test (OFT)

[0057] The open field test is an experimental method used to test the spontaneous exploration, activity level and depressive behavior of experimental animals. The shorter the activity time of mice in the central area, the higher the anxiety level. The open field test was performed on each group of mice at the end of the sixth and tenth weeks.

[0058] During the test, the mice were gently placed in the center of an open field box of size 50cm×50cm×50cm, and allowed to move freely for 6 minutes. An automatic tracking system was used to record the mouse's activity time and distance in the central area of ​​the open field within the next 5 minutes.

[0059] 2.5 Immunohistochemistry

[0060] After perfusion, the anesthetized mice were removed and the brain tissue was fixed and preserved with paraformaldehyde, dehydrated, transparent, wax-impregnated and sectioned according to conventional methods, and then immunohistochemical experiments were performed.

[0061] One group of brain slices was randomly selected from each animal and rinsed with 0.01 mol / L PBS solution containing 0.3% Triton X-100 + 0.1% Tween-20, then incubated in 3% hydrogen peroxide solution in the dark, placed in a citrate solution for boiling water bath repair, and finally placed in a solution-prepared blocking solution (10% goat serum SP-9002, 1% fetal bovine serum, 2 μl fish gelatin, 0.3 ml The sections were incubated in 0.3% Triton + 0.1% Tween) in a 37°C water bath for 2 h; then incubated with mouse anti-APC (CCI) IgG (1:1000) in a 4°C refrigerator for 48 h, and then incubated with SP-9002 biotin-labeled goat anti-mouse IgG secondary antibody (1:10) and SP-9002C horseradish enzyme-labeled streptavidin in a 37°C water bath, DAB color development, and then DAB color development in the dark for 1 min, deionized water and PBS rinsed for 10 min each, finally patch fixed, hematoxylin counterstained, gradient ethanol dehydrated, xylene transparent, neutral resin sealing, and photographed.

[0062] 2.6 Stereological analysis

[0063] The mouse medial prefrontal cortex (mPFC) includes the prelimbic cortex (PrL), infralimbic cortex (IL), and cingulate cortex (Cg). In the coronal plane, PrL appears first, followed by Cg1, and then IL; when PrL and IL disappear, Cg2 appears, and in subsequent brain slices, only Cg1 and Cg2 exist, and when the posterior cortex appears, Cg1 and Cg2 disappear. However, due to differences between animals, the boundaries need to be subdivided by cell structure; the layer 4 cells of the mPFC are naturally defective, so the differences between these areas are mainly the differences between layers I, II, III, V, and VI.

[0064] Iba1 was analyzed by optical separation in stereology system + The specific steps are as follows: first, the boundaries of the medial prefrontal cortex are divided under a 2.5x objective lens according to the rules of the mouse anatomical atlas, and then the parameters are uniformly set under a 100x oil lens: the height of the stereoscopic frame is 15 μm, the upper surface protection height is 3 μm, and the area sampling fraction is 6%; then, according to the forbidden line rule of the optical stereoscopic frame, the number of microglia with clearly focused cell bodies at the test height of each field of view is counted, and the thickness of the slice (the distance between the upper and lower surfaces of the slice) is measured every 2 fields of view; finally, the optical segmentation method is used to calculate the Iba1 in the medial prefrontal cortex according to the following formula + Total number of microglia:

[0065] N=∑Q-×(1 / ssf)×(1 / asf)×(1 / hsf)

[0066] Among them, ΣQ- is the number of Iba1+ cells actually counted in the brain slices observed in the specimen, ssf is the set slice sampling fraction, asf is the area of ​​the sampling fraction, and hsf is the thickness of the sampling fraction.

[0067] When counting begins, the computer will start sampling from any starting point within the field of view of the brain slice, and six slices will be sampled as an analysis unit, so the SSF value is 1 / 6; the area of ​​each frame is the same, and the ratio of the product of the length and width of each frame to the area of ​​the unbiased counting frame is the ASF value. The ASF value of the medial prefrontal cortex area is 6%.

[0068] The average thickness (t) of all brain slices used in this experiment was about 30 μm; during the measurement, each slice had a "non-measurement zone" of about 3 μm on the upper surface and 15 μm of Iba1 below the "non-measurement zone". + The cells are included in the numerical range; therefore, the calculation formula of hsf is h / t=15 / 30; during the counting process, a red and green frame range will appear on the screen, the solid line and its extension line represent the exclusion line, and the dotted line in the frame represents the inclusion line; Iba1 within the green solid line + The cells participate in the counting, and the cells in the red frame do not participate in the counting.

[0069] 2.7 Immunofluorescence staining and cell counting

[0070] One-half of the brain tissue sections were randomly selected from each mouse; the sections were rinsed with PBS solution (concentration of 0.01 mol / L) for 3 times with an interval of 10 min, and then rinsed with PBS+T solution (prepared with 0.3% TritonX-100, 0.1% Tween-20 and PBS solution) for 6 times with an interval of 10 min; then the sections were repaired in a boiling water bath with citrate solution for 30 min, and rinsed with PBS+T solution for 3 times with an interval of 10 min; the sections were placed in blocking solution (prepared with 0.1% goat serum SP-9001, 1% fetal bovine serum and PBS+T solution) and blocked at 37°C for 2 h; then Iba1 antibody and MBP antibody were incubated at 4°C for 48 h, and PBS+T solution was continued for 3 times with an interval of 10 min; DyLight549-labeled goat anti-rabbit IgG fluorescent secondary antibody (red) and DyLight488-labeled goat anti-mouse IgG fluorescent secondary antibody (green) were added for incubation at 37°C for 2 h, and PBS solution was rinsed for 5 min×6 times; DAPI was incubated 5min, mount and seal the slices; each fluorescence image of the medial prefrontal cortex was taken by laser confocal microscopy; Iba1 + Cells and myelin sheaths are compared.

[0071] 3. Data Analysis

[0072] SPSS was used to compare the statistical differences of all data in the experiment. When measuring the weight of mice, repeated measures variance analysis was used to analyze the effect of depressive stimulation on body weight. If the sphericity assumption was met, the Mauchly test was used; otherwise, the Greenhouse-Geisser test was used.

[0073] The data related to the number of microglia and fluorescence intensity were expressed as mean ± standard deviation (SD); the test used to measure the similarity of variance between groups was Levene's test; Student's t-test was used to compare other results between two groups (control group and CUS group); one-way analysis of variance was used to compare the results between three groups (control group + NS group, CUS + NS group, and CUS + GW group).

[0074] The fluorescence density of MBP was tested using a nonparametric test, and the MBP density data were expressed as upper and lower quartiles; in all tests, P < 0.05 was considered to indicate statistical significance.

[0075] 4. Results

[0076] 4.1 CUS mice show depressive-like behavior

[0077] During the modeling period, the weight values ​​and sugar water preference results of mice in the control + NS group and the CUS + NS group were recorded. The statistical results of the weight changes of mice and the results of the sugar water preference experiment are shown in the figure. Figure 2 As shown, Figure 2 (a) is the change of body weight in control+NS group and CUS+NS group. Figure 2 (b) and (c) show the changes in sugar water preference results of the two groups of mice after 6 weeks of intervention.

[0078] Depend on Figure 2 It can be seen that during the baseline adjustment stage, there was no significant difference in the body weight and sucrose preference percentage between the CUS+NS group mice and the control+NS group mice; after the subsequent CUS simulation stimulation, the body weight and sucrose preference percentage of the CUS+NS group mice showed a downward trend compared with the control+NS group mice.

[0079] Next, the TST and OFT experiments were used to evaluate the depression level of mice. The results of the TST experiment are as follows: Figure 3 The OFT test results are shown in Table 2. Figure 3 is the immobility time of the control+NS group, CUS+NS group and CUS+GW group in TST, Figure 3It can be seen that there are significant differences in the immobility time of the three groups of mice, and the immobility time of the mice in the control + NS group is significantly lower than that in the CUS + NS group; Table 2 is a statistical table of OFT results of the control + NS group, the CUS + NS group and the CUS + GW group. It can be seen from Table 2 that the range of movement of the mice in the CUS + NS group is significantly smaller than that in the control + NS group, and the activity time in the central area is significantly reduced.

[0080] Table 2 Statistics of OFT results of three groups of mice

[0081]

[0082]

[0083] Among them, a means that the CUS+NS group was compared with the control+NS group, P<0.05.

[0084] Therefore, the above behavioral tests showed that the mouse CUS model was successfully established and CUS mice showed depressive-like behaviors.

[0085] 4.2 Activation of LXRs leads to increased body weight and sugar preference in a depressive mouse model

[0086] The results of the weight change of mice after 4 weeks of treatment with GW3965 and the results of the sugar water preference test are as follows Figure 4 As shown, Figure 4 (a) is the weight change diagram of mice in control+NS, CUS+NS and CUS+GW groups. Figure 4 (b) is the sugar water preference results of the three groups of mice.

[0087] Depend on Figure 4 It can be seen that after 4 weeks of drug injection treatment, the sucrose preference percentage and body weight of the CUS+NS group were still significantly lower than those of the control+NS group, while the sucrose preference percentage and body weight of the CUS+GW group were significantly higher than those of the CUS+NS group.

[0088] Combination Figure 3 As shown in Table 2, the immobility time of mice in the CUS+GW group was significantly lower than that in the CUS+NS group. After 4 weeks of drug treatment, the range of motion of mice in the CUS+GW group did not change significantly compared with that in the CUS+NS group, and the activity time in the central area increased.

[0089] GW3965 treatment inhibits the increase in the number of Iba1+ microglia in the mPFC of the depressive mouse model

[0090] The results of histochemical staining of Iba1+ microglia in the medial prefrontal cortex (mPFC) of mice in each group are shown in the figure Figure 5 As shown, Figure 5(a) Anti-Iba1 + Representative images of immunohistochemical staining of the medial prefrontal cortex of mice in the control+NS, CUS+NS, and CUS+GW groups. Arrows point to microglia. Figure 5 (b) is a statistical chart of the total number of Iba1+ cells in the mPFC of the three groups of mice.

[0091] Depend on Figure 5 It can be seen that Iba1 in the mPFC of mice in the CUS+NS group + The number of microglia was significantly higher than that in the control+NS group; after 4 weeks of GW3965 treatment, the number of Iba1+ microglia in the CUS+GW group was higher than that in the control+NS group, but significantly lower than that in the CUS+NS group.

[0092] GW3965 treatment reduces Iba1 in mPFC of depressed mice + The density of cells and increased the density of myelin basic protein (MBP)

[0093] Immunofluorescence staining results Figure 6 As shown, Figure 6 (a) Iba1 in mPFC of three groups of mice + and MBP immunofluorescence staining images, Figure 6 (b) Iba1 in mPFC of three groups of mice + Statistical graph of staining intensity, Figure 6 (c) is a statistical graph of the MBP staining intensity in the mPFC of the three groups of mice.

[0094] Depend on Figure 6 It can be seen that compared with the control+NS group, the Iba1 in the mPFC of the CUS+NS group mice + The density of cells increased significantly, while the density of MBP decreased. After 4 weeks of GW3965 treatment, Iba1 in mPFC of CUS+GW group was significantly higher than that of CUS+NS group. + The density of cells decreased and the density of MBP increased.

[0095] GW3965 treatment reduces myelin phagocytosis by microglia in mPFC

[0096] The results of co-immunostaining were as follows Figure 7 As shown, Figure 7 (a) is a schematic diagram of fluorescent double labeling of mice in the control+NS group, where green is Iba1 + ; Red indicates MBP; Yellow arrow indicates MBP / Iba1 + cell; Figure 7(b) is a three-dimensional reconstruction image after immunofluorescence layer scanning. The length and width of the layer scanning image are both 212.13 μm, and the thickness of the longer scanning image is 28.47 μm; Figure 7 (c) Iba1 in the mPFC of three groups of mice + / MBP staining intensity comparison statistical graph.

[0097] Depend on Figure 7 It can be seen that the orange part is the myelin engulfed by microglia, which is the proof of co-labeling of microglia and myelin. + The presence of MBP in microglia indicated that functional microglia phagocytized myelin. Compared with the control+NS group, the fluorescence intensity of myelin phagocytosis by microglia in the mPFC of CUS+NS group mice was significantly increased. After GW3965 treatment, the fluorescence intensity of myelin phagocytosis by microglia in the CUS+GW group was significantly decreased compared with the CUS+NS group. Therefore, GW3965 treatment reduced the phagocytosis of myelin by microglia in the mPFC.

[0098] 5. Analysis

[0099] In the present study, it was found that compared with control mice, depressed mice had decreased body weight and reduced sugar water preference percentage, stressed mice had longer immobility time in TST and shorter stay time in the center zone in OFT, and treatment with the LXR agonist GW3965 improved these changes.

[0100] The medial prefrontal cortex (mPFC) is involved in regulating the body's behavioral and neuroendocrine responses to stress, is extremely sensitive to stress, and is one of the main areas where the brain structure and function of patients with depression change. Clinical imaging studies and autopsy studies have found that the structure and function of the mPFC in the brains of patients with depression have undergone significant changes, such as mPFC atrophy, myelin reduction, and abnormal EEG activity. Microglia are closely related to oligodendrocytes. Microglia help maintain the health of myelin, especially phagocytizing myelin, which is essential for the optimal function of nerve cells in the brain and spinal cord. The present study found that compared with the control group + NS mice, the number of Iba1+ microglia in the mPFC of CUS+NS mice increased and the number of MBP microglia decreased. It is speculated that LXRs agonists may improve depressive-like behavior by affecting the ability of activated microglia to phagocytize myelin.

[0101] Therefore, the present study adopted an unbiased modern stereotactic technology to accurately quantify the number of microglia and myelin cells in the mPFC of CUS depression model mice after LXR agonist intervention for the first time; the results showed that after 4 weeks of treatment with the LXRs agonist GW3965, the number of microglia in the mPFC of CUS model mice was significantly reduced and the myelin phagocytosis function was decreased, which is consistent with the results of some previous studies after drug intervention for depression. Based on the above results, we believe that GW3965 treatment can regulate depressive-like behavior by affecting the ability of activated microglia to phagocytose myelin.

[0102] In summary, LXRs play a crucial role in the functional balance of depressive microglia, and it is established that the use of LXR agonists can regulate depressive-like behavior by affecting the ability of activated microglia to phagocytose myelin. Therefore, drug regulation of the function of microglia to phagocytose myelin is expected to become a potential therapeutic approach for the treatment of mental illness.

[0103] Reference 1 mentioned in this application is as follows:

[0104] [1] Yohn, NL, & Blendy, JA (2017). AdolescentChronicUnpredictableSt ressExposureIsaSensitiveWindowforLong-TermChangesinAdultBehaviorinMice.Neuropsychopharmacology, 42(8),1670-1678.

Claims

1. Use of a liver X receptor agonist in the preparation of a drug for improving and / or treating depressive-like behavior.

2. The use according to claim 1, characterized in that: The liver X receptor agonist is GW3965.

3. The use according to claim 2, characterized in that: The GW3965 reduced the expression of microglia in the mPFC.

4. The use according to claim 2, characterized in that: GW3965 decreased the density of microglia and increased the density of myelin proteins in the mPFC.

5. The use according to claim 2, characterized in that: GW3965 improves depressive-like behaviors by reducing the phagocytosis of myelin by microglia.

6. A drug for improving and / or treating depressive-like behavior, characterized in that: Its active ingredients include GW3965.

7. The drug according to claim 6, characterized in that: The medicine is a pharmaceutical composition.

8. The drug according to claim 7, characterized in that: The pharmaceutical composition further comprises a pharmaceutically acceptable carrier.

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