Effect of Jieyuwan on depression-like behaviors and expression of BDNF in hippocampus and prefrontal cortex of WKY rats

AIM:To investigate the mechanism of depression and its development, and to study the expression of brain-derived neurotrophic factor (BDNF) in the hippocampus and prefrontal cortex of Wistar-Kyoto (WKY) rats treated with Jieyuwan. METHODS:Adult male WKY rats were used as an animal model of endogenous depression. Wistar rats of the same strain were selected as control group. WKY rats were randomly divided into model group, citalopram group and Jieyuwan group. After intragastric administration for 21 d, the changes of depression-like behaviors were observed by sucrose preference test and forced swimming test. Immunofluorescence and Western blot were used to detect the expression of BDNF in the hippocampus and prefrontal cortex. RESULTS:WKY rats showed significant depression-like behaviors, and the expression of BDNF was significantly decreased in the hippocampus and prefrontal cortex (P<0.01). The reduction of neuronal axons in hippocampus was also observed. After drug treatment, the depression-like behaviors of WKY rats were significantly attenuated, and the expression of BDNF and the number of axons were increased (P<0.01). CONCLUSION:Jieyuwan effectively attenuates the depression-like behaviors of WKY rats, and BDNF is a key factor in its antidepressant effect. Our findings further confirm the involvement of BDNF in the development of depression.     

Phosphodiesterase 4 inhibitor rolipram prevents chronic alcoholism and withdrawal-induced depression-like behaviors in mice

AIM: To investigate the effect of phosphodiesterase 4 (PDE4) inhibitor rolipram on the levels of cyclic adenosine monophosphate (cAMP), protein kinase A (PKA), cAMP response element-binding protein (CREB), phosphorylated CREB (p-CREB) and brain-derived neurotrophic factor (BDNF) in the hippocampus and the prefrontal cortex (PFC) of alcoholism model mice.METHODS: The mice (n=60) were randomly divided into control group, control+rolipram group, alcoholism model group, and alcohol+rolipram (0.1, 0.5 and 1 mg/kg) groups. The mice were given alcohol preference test on days 6, 13, 20 and 27. After the test, the mice received withdrawal of alcohol for 1 d. On day 28, the mice were given behavior test of depression, and after the test, the mice were sacrificed. The cAMP levels in the hippocampus and PFC were detected by ELISA, and the protein levels of PKA, CREB, p-CREB and BDNF were detected by Western blot.RESULTS: The mice showed an obvious drinking phenomenon (P<0.01), and the immobility time of forced swimming test and tail suspension test was significantly increased (P<0.01), with increasing drinking days and withdrawal times. However, chronic treatment with rolipram for 28 d reversed this phenomenon. Moreover, the cAMP levels in the hippocampus and PFC were significantly decreased after 28 d alcohol treatment (P<0.01), and pretreatment with rolipram (1 mg/kg) obviously reversed this decrease (P<0.01). Parallel to these changes of cAMP, the protein levels of PKA, p-CREB and BDNF were also decreased in the hippocampus and PFC (P<0.01), and 28 d rolipram administration inhibited the decreased cAMP, PKA, p-CREB and BDNF levels in the hippocampus. Moreover, 28 d rolipram administration also reversed decreased cAMP, PKA and p-CREB in the PFC.CONCLUSION: Rolipram treatment protects against alcohol-induced depression-like behaviors, and also reduces alcohol drinking. These effects may be related to PDE4-cAMP-PKA-CREB-BDNF pathway.     

Relationship between hippocampal structure and high incidence of depression after spinal cord injury in mice

AIM: To explore whether the high risk of depression caused by spinal cord injury is related to structural changes of hippocampus. METHODS: Mouse spinal cord injury model was established. The Basso Mouse Scale (BMS) was used to evaluate the postoperative motor function of mice at different periods after injury. The depression of mice was evaluated by behavior experiment. The morphological changes of cells in hippocampal tissue were observed by HE staining. The structural changes of hippocampal subcellular synapses were observed by electron microscopy. RT-qPCR was used to detect the changes of synaptic protein markers synaptophysin (SYP) and postsynaptic density protein 95 (PSD-95) at the mRNA level. RESULTS: The mice had significant depressive behaviors in model group, and the depression degree was the most serious on the 7th day (P<0.01). Compared with control group, the arrangement of hippocampal cells was disordered, the cell number was decreased, and the shape was irregular in model group. Compared with control group, the observation results of electron microscopy showed that the number of synapses in the hippocampal ultrastructure was decreased, the length of synaptic activity zone was shortened, the thickness of postsynaptic density was thinned, the width of synaptic gap was increased, and the curvature of synaptic interface was decreased in the model group (P<0.05). The mRNA expression levels of SYP and PSD-95 in model group were lower than those in control group (P<0.05). CONCLUSION: The change of hippocampal structure is one of the important reasons leading to high risk of depression caused by spinal cord injury.     

Effects of dexmedetomidine on behaviors and expression of BDNF and mTOR in hippocampus of depressive rats

AIM: To investigate the effects of dexmedetomidine (DEX) on the behaviors and the expression of brain-derived neurotrophic factor (BDNF) and mammalian target of rapamycin (mTOR) in the hippocampus of depressive rats. METHODS: Sprague-Dawley (SD) rats were randomly divided into 5 groups: sham operation group, model group, and DEX (2.5, 5 and 10 μg/kg) groups. The rats were randomly selected in each group (n=12). The rat depression model was established by chronic unpredictable mild stress and ovariectomy. The rats in DEX groups received daily DEX treatment via intraperitoneal injection for 21 d. The forced swimming immobility time (FSIT) and open-field test were used to evaluate the antidepressant effect of DEX. Escape latency and times of crossing the flat were evaluated by Morris water maze. The histological changes of hippocampal neurons were determined by Nissl staining. The mRNA levels of interleukin-1β (IL-1β), IL-6 and tumor necrosis factor-α (TNF-α) were detected by RT-qPCR. The protein expression of IL-1β, IL-6, TNF-α and BDNF, and the phosphorylation levels of protein kinase A (PKA), cAMP response element-binding protein (CREB), tropomyosin-related kinase B (TrkB), phosphatidylinositol 3-kinase (PI3K), protein kinase B (Akt) and mTOR in hippocampus were evaluated by Western blot. RESULTS: Compared with model group, the FSIT was significantly reduced and the spontaneous activity was markedly increased in DEX groups. The damage of the hippocampal neurons was obviously attenuated, the escape latency was obviously decreased, and times of crossing the flat were markedly increased (P<0.05 or P<0.01). The levels of IL-1β, IL-6 and TNF-α were obviously decreased, and the protein levels of p-PKA, p-CREB, BDNF, p-TrkB and p-PI3K, p-Akt, p-mTOR in hippocampal tissues were obviously increased (P<0.05 or P<0.01). CONCLUSION: Dexmedetomidine improves the behaviors and the spatial learning and memory ability of depressive model rats, which may be related to its anti-inflammatory effects, as well as up-regulating the protein levels of BDNF and p-TrkB, and activating PI3K/Akt/mTOR signaling pathway in the hippocampus.     

广叶绣球菌多糖对免疫低下小鼠海马组织cAMP-PKA-CREB-BDNF信号通路的影响

分别灌胃环磷酰胺所致免疫低下小鼠广叶绣球菌(Sparassis latifolia)多糖(SCPs,低、中、高剂量分别为100、200、400 mg·kg;),观察小鼠海马组织形态变化,检测5-羟色胺(5-hydroxytryptamine, 5-HT)、色氨酸羟化酶(tryptophan hydroxylase 2,TPH2)和环磷酸腺苷(cyclic adenosine monophosphate, cAMP)含量,测定细胞因子和cAMP-PKA-CREB-BDNF信号通路基因mRNA表达量、cAMP反应元件结合蛋白(cAMP response element binding protein, CREB)和磷酸化CREB(phosphorylated CREB, p-CREB)蛋白表达量,探讨SCPs对海马组织损伤的干预作用。结果表明:SCPs使免疫低下小鼠海马组织神经细胞数量增多,细胞间隙缩小,结构更为完整。与模型组相比,SCPs各剂量组5-HT和TPH2含量、中和高剂量组cAMP含量极显著增加;SCPs各剂量组TNF-α、中和高剂量组IL-1β mRNA表达量显著降低,SCPs中和高剂量组5-HT;受体、高剂量组蛋白激酶A和脑源性神经营养因子基因mRNA表达量显著增加;SCPs高剂量组CREB蛋白、各剂量组p-CREB蛋白表达量显著提高。研究结果为揭示广叶绣球菌多糖对海马组织保护作用的机制提供参考。     

Effects of voluntary wheel running exercise on depressive-like behavior and circadian rhythmic alterations of neuroendocrine induced by chronic unpredictable mild stress in rats

AIM: To investigate the effect of 8-week middle intensity voluntary wheeling exercise on the depressive-like behavior and the circadian rhythmic alterations of plasma hormone and peptide induced by chronic unpredictable mild stress (CUMS) in rats. METHODS: Male Sprague-Dawley rats (n=90) were randomly divided into model group, model+exercise group and control group. Rats in model+exercise group received 8-week voluntary wheel running exercise plus CUMS procedure during the last 3 weeks at the same time. Exploratory locomotor activity was assessed by open field test, the anxiety-like behavior was measured by elevated plus-maze test, and lack of pleasure was detected by sucrose preference test. Blood samples were collected at each of 6 time points (ZT1, 5, 9, 13, 17 and 21 on the 2nd day after behavior testing). Plasma concentrations of corticosterone (CORT), melatonin (MT) and vasoactive intestinal peptide (VIP) were detected by ELISA. The plasma concentration of adrenocorticotropic hormone (ACTH) was measured by radioimmunoassay. The circadian rhythm changes of serum CORT, MT, VIP and ACTH concentrations in each group were compared by cosinor analysis. RESULTS: Compared with control group, locomotor activity, weight gain and sucrose consumption in model group were significantly reduced (P<0.01). The values of the percentage of open-arm time (OT%) and open arm entries (OE%) were obviously lower in model group than those in control group (P<0.01). Eight-week voluntary wheel running exercise may improve the above depression behavior caused by CUMS. The rats in model group showed an obvious disorder in circadian rhythm of plasma ACTH and CORT, including phase advance and decrease in amplitude. There also showed a markedly blunted circadian rhythm and decreased level of plasma MT in model rats compared to control rats. VIP expression was significantly higher than that in control group with 24 h rhythm, but the amplitude was significantly lower than that in control group, peak phase also delayed for 6 h. Eight-week exercise significantly ameliorated the abnormal expression and the disturbance secretion rhythm of ACTH, CORT, MT and VIP in plasma. CONCLUSION: Eight-week voluntary wheeling exercise ameliorates CUMS-induced depressive-like behaviors probably by rescuing the disturbed circadian rhythms and abnormal secretion of these neuroendocrine factors.     

Effect of Jieyuwan on dendritic spines in prefrontal cortex and hippocampus in WKY depression-like rats

AIM To observe the changes of dendritic spines in prefrontal cortex and hippocampus of Wistar-Kyoto (WKY) depression-like rats, and to explore the effects of Jieyuwan (JYW) on them. METHODS The male WKY rats were selected as the experimental group, and the same strain of Wistar rats were selected as the control group. Firstly, sucrose preference test, open-field experiment and forced swimming test were used to detect the behavior changes in the rats as their baseline. Then, all WKY rats were randomly divided into model (WKY+NaCl) group, WKY+JYW group and WKY+citalopram group. All WKY rats and Wistar rats (Wistar+NaCl group) were administered intragastrically for 21 d, and the changes of behavior after administration were detected by the same behavioral methods. Golgi staining was used to observe the pathological characteristics of dendritic spines in the prefrontal cortex and hippocampus, and Western blot was used to detect the protein expression level of postsynaptic density protein-95 (PSD-95) in the prefrontal cortex and hippocampus. RESULTS Before administration, WKY rats clearly showed depression-like behavior, the density of dendritic spines in the prefrontal cortex and hippocampus decreased significantly (P<0.01), and the protein expression level of PSD-95 was significantly reduced (P<0.01). After treatment with the drugs, the depression-like behavior of WKY rats was significantly attenuated, the density of dendritic spines in the prefrontal cortex and hippocampus increased (P<0.01), and the protein expression level of PSD-95 also increased (P<0.01). CONCLUSION Jieyuwan significantly attenuates the depression-like behavior of WKY rats, and affects the structural changes of dendritic spines and the expression of PSD-95 protein, which further proves that dendritic spines may be one of the importantearly structural changes in depression.     

Change of depression-like behavior in chronic alcoholism and withdrawal model,and co-mechanism of depression and chronic alcoholism in mice

AIM: To investigate the behavior of depression in chronic alcoholism and withdrawal model of mice, and to explore the co-mechanism of alcoholism and depression. METHODS: A novel model of chronic alcoholism was constructed in this study. The animals were divided into normal control group, and alcohol 7 d, 14 d, 21 d and 28 d groups. The mice were given alcohol preference test on the 6th, 13th, 20th and 27th days. After the test, alcohol were withdrawn for 1 d, then the next day the mice were given behavior test of depression. After the test, the mice were sacrificed. The contents of 5-hydroxytryptamine (5-HT) and norepinephrine (NE) were detected by HPLC. The expression of cAMP response element-binding protein (CREB) and brain-derived neurotrophic factor (BDNF) was detected by Western blot. RESULTS: The mice showed an obvious drinking phenomenon, and the immobility time of forced swimming test and tail suspension test was significantly increased, with increasing drinking days and withdrawal times. 5-HT level in 7 d group mice only increased in frontal cortex (P < 0.05). However, compared with control group, 5-HT levels in hippocampus and cortex were decreased on the 21th and 28th days (P < 0.01). NE levels in 21 d and 28 d groups were decreased in hippocampus and frontal cortex (P < 0.05), and no significant change was observed in 7 d and 14 d groups. The protein levels of p-CREB and BDNF were significantly decreased in hippocampus and frontal cortex of 12 d and 28 d groups (P < 0.05), and no significant change was observed in 7 d group and 14 d group. CONCLUSION: The co-mechanism of alcoholism, withdrawal and depression is related to 5-HT. 5-HT-cAMP-CREB-BDNF signaling pathway may be a common mechanism for alcoholism and depression.     

Effects of three Chinese formulas on BDNF,TrkB in rat contex and hippocampus with chronic immobilization stress

AIM: To investigate the changes of brain-derived neruotrophic factor (BDNF), tyrosine kinase B (TrkB) in rat cortex and hippocampus with chronic immobilization stress and the influence of three Chinese formulas (Xiaoyaosan, Sijunzitang, Jinkuishenqiwan) on them. METHODS: Chronic immobilization stress method (180 min daily, repeated 7 days or 21 days) was taken, and the changes of BDNF, TrkB in rat forehead cortex and hippocampus CA1 were measured by immunohistochemistry integrated image analysis. RESULTS: The contents of BDNF in rat forehead cortex and hippocampus CA1 were obviously lower in the model group of 7 days and 21 days than those in the normal control group (P<0.05, P<0.01), especially the lowest in the model group of 21 days. The contents of TrkB in rat forehead cortex and hippocampus CA1 were higher in the model group of 7 days and 21 days than those in the normal control group (P<0.05, P<0.01). All three Chinese formulas increased the intergral absorbance of BDNF in rat cortex and particle number of BDNF in rat hippocampus CA1. The particle number of TrkB in rat hippocampus CA1 and cortex, and intergral absorbance of TrkB in rat hippocampus CA1 were reduced by Xiaoyaosan. The intergral absorbance of TrkB in rat forehead cortex was reduced by Sijunzitang and Jinkuishenqiwan. The particle number of TrkB in rat forehead cortex was decreased by Jinkuishenqiwan. Compared with the influence of BDNF in response to three Chinese formulas, effect of Xiaoyaosan was more remarkable.CONCLUSION: Decreased BDNF in rat forehead cortex and hippocampus CA1 may participate in changes of chronic immobilization stress, and it can be reversed by the Chinese herbs of soothing liver, strengthening spleen, nourishing kidney, but the effect of Xiaoyaosan is better than that of Sijunzitang and Jinkuishenqiwan.     

Inhibitory effect of ground dragon on the expression of α-SMA and FN in the lung tissue of mouse with asthma

AIM: To investigate the inhibitory effect of ground dragon on the expression of α-SMA and FN in the lung tissue with asthma. METHODS: The BALB/c mice were divided into four groups: control group (group A, n=20), asthmatic model group (group B, n=20), large-dose ground dragon treatment group (group C, n=20) and low-dose ground dragon treatment group (group D, n=20). To establish a mouse model of chronic asthma, we sensitized the mouse with 0.02% ovalbumin (OVA) by intraperitoneal injection, and stimulated the mice with 1% OVA by atomization. The treatment groups were given ground dragon before stimulation every time. After the last time of stimulation, the mice were subjected to laboratory tests. Inflammatory cells in bronchoalveolar lavage fluid were counted. Total level of IgE in serum was detected by ELISA. FN mRNA and α-SMA mRNA in the lung tissue were measured by RT-PCR and AlphaImager 2200 semi-quantitation analysis system. Expressions of FN and α-SMA were measured by the method of two-step immunohistochemistry and leica QWIN V3 analysis system. RESULTS: (1) Compared with those in group A, the expressions of α-SMA and FN in group B were significantly increased (P<0.01). Compared with group B, those in group C were significantly decreased (P<0.01), while those in group D were slightly decreased (P>0.05). (2) Compared with those in group A, the expression levels of α-SMA mRNA and FN mRNA in group B had a great increase (P<0.01). There was a notably decreases of α-SMA mRNA and FN mRNA levels in group C, compared with group B (P<0.01). However, α-SMA and FN mRNA level in group D was just a slightly decreased, compared with group B (P>0.05). CONCLUSION: The ground dragon inhibits α-SMA and FN expression in the lung tissue of mice with chronic asthma, indicating that ground dragon may inhibit airway remodeling in asthma through the inhibition of α-SMA and FN expressions.     

Influence of predator stress on levels of IL-1β, IL-6 in BALB/C mice with brain asymmetry

AIM: To investigate the influence of predator stress on hypothalamic-pituitary-adrenal (HPA) axis and IL-1β, IL-6 in mice with brain asymmetry. METHODS: By using paw preference test, right-pawed, left-pawed, and ambidextrous-pawed mice model were established. Mice with brain lateralization were exposed to their predator (cat). After acute and chronic predator stress by cats, EIA and ELISA were applied to detect plasma levels of corticosterone (CS), IL-1β and IL-6. RESULTS: (1) The level of plasma CS: in both acute and chronic predator stress group, right-pawed and ambidextrous mice had a higher level than that in their corresponding normal group (P<0.05). Meanwhile, the two groups also showed higher level than left-pawed in acute stress. Compared with the corresponding group under acute stress, left-pawed had much higher level of CS under chronic stress (P<0.05). (2) The level of plasma IL-1β: in normal group, left and right-pawed mice were higher than that in ambidextrous mice (P<0.01), of which left-pawed was the highest. In chronic stress group, the left-pawed exhibited higher level than that in right-pawed mice (P<0.05). (3) The level of IL-6: after chronic predator stress, ambidextrous mice had much higher level than that in other two groups (P<0.05). CONCLUSION: Under predator stress, the HPA axis and plasma proinflammatory cytokines (IL-1β, IL-6) in BALB/C mice were modulated by the brain asymmetrically, and brain lateralization may influence the function of immuno-endocrine network in psychological circumstances.     

Molecular mechanism of BMSC intracerebral transplantation in improving learning and memory abilities of AD mice

AIM: To investigate the effect of bone marrow mesenchymal stem cell (BMSC) transplantation on learning and memory abilities and pathological changes of Alzheimer disease (AD) mice and the molecular mechanisms. METHODS: C57/BL6 wild-type (WT) and transgenic (Tg) mice were randomly divided into 4 groups:WT/PBS group, WT/BMSCs group, Tg/PBS group and Tg/BMSCs group. The mice were administered with PBS or BMSCs via intracerebroventricular injection. Spatial learning and memory abilities of the mice were evaluated by Morris water maze test on the 3rd day after surgery. Real-time PCR was applied to detect the mRNA expression of CX3C chemokine ligand 1 (CX3CL1), CX3C chemokine receptor 1 (CX3CR1), IL-1β, TNF-α, Nurr1, YM1, insulin-degrading enzyme (IDE) and matrix metalloproteinase 9 (MMP9). The protein levels of CX3CL1 and Aβ42 were measured by ELISA. Western blot was used to detect the protein expression of postsynaptic density protein 95 (PSD95) and synaptophysin (SYP). RESULTS: The transplanted BMSCs were observed near the hippocampus of APP/PS1 mice on the 10th postoperative day. The escape latency of the mice in Tg/PBS group was significantly longer than that in the WT/PBS mice (P<0.05). Compared with Tg/PBS group, the escape latency of Tg/BMSCs group was significantly shorter (P<0.05), and the mRNA and protein levels of CX3CL1 in Tg/BMSCs group were significantly higher than those in Tg/PBS group (P<0.01). The results of immunohistofluorescence staining showed that BMSC transplantation promoted the activation of microglia in the brain of WT and Tg mice. The mRNA expression of YM1 was up-regulated in WT/BMSCs group and Tg/BMSCs group (P<0.05). Compared with WT/PBS mice, the mRNA expression of TNF-α in the cortex and hippocampus of Tg/PBS group was significantly increased (P<0.05), and the mRNA expression of Nurr1 in the cortex was significantly decreased (P<0.01). Meanwhile, the mRNA expression of TNF-α in the cortex of Tg/BMSCs mice was decreased (P<0.01) and the mRNA expression of CX3CR1 and Nurr1 was up-regulated compared with Tg/PBS group (P<0.05). The results of Western blot showed that the protein levels of PSD95, p85, p110 and p-Akt in Tg/BMSCs group were significantly higher than those in Tg/PBS group (P<0.05). Finally, BMSC transplantation reduced the protein level of Aβ42 in APP/PS1 mice (P<0.05), and increased the mRNA expression of IDE and MMP9 in the hippocampus (P<0.05). CONCLUSION: BMSC transplantation modulates neuroinflammatory responses and promotes neuroprotective factor and synaptic protein expression, thus improving the learning and memory abilities in the APP/PS1 mice, which may be achieved by up-regulating the expression of CX3CL1.     

Changes of dendritic morphology and spine density in hippocampal CA1 pyramidal cells of chronic cerebral ischemic rats

AIM: To investigate the changes of dendritic morphology and spine density in hippocampal CA1 pyramidal cells of the chronic cerebral ischemic rats. METHODS: The model of chronic cerebral ischemia was established by permanent occlusion of the bilateral common carotid arteries (2VO) in rats. Two weeks, 4 weeks or 8 weeks later, the behavior of the rats in each group was evaluated through the Morris water maze to select the successful modeling, and the brains were collected for processing Golgi staining. The changes in dendritic branch and length, and spine density in hippocampal CA1 pyramidal cells were observed under optical microscope. RESULTS: Compared with sham-operated group, dendritic branch and length in model group was significantly reduced in 4-week group and 8-week group (P<0.01), and spine density in model group were significantly reduced in 2-week, 4-week and 8-week groups (P<0.01). With prolonged ischemia, dendritic branch and length, and spine density in model group were all significantly reduced (P<0.05). CONCLUSION: Chronic cerebral ischemia leads to traumatic changes in dendrites and spines in hippocampal CA1 pyramidal cells, which constitutes the pathophysiological basis in the progressive cognitive dysfunction.     

Antidepressant-like effect of N-palmitoylethanolamide by prefrontal cortex PPARα pathway in a rat model

AIM: To investigate the role of cortical peroxisome proliferator-activated receptor α (PPARα) in the regulation of depression-like behavior in the rats by N-palmitoylethanolamide (PEA). METHODS: A rat model of chronic unpredictable mild stress (CUMS) was established. The rats (n=70) were randomly divided into normal control group, CUMS model group, CUMS+ fluoxetine (10 mg/kg) group, CUMS+ PEA (2.5, 5 and 10 mg/kg) groups and CUMS+ PEA (10 mg/kg)+ MK886 (3 mg/kg) group. On the 8th day during CUMS, the drugs were continuously admi-nistered for 28 d. The body weight and the related behavioral changes in the open-field test and sucrose consumption test were monitored every week. On the 36th day, some of the brain tissues from the rats were fixed in 4% formalin solution for histomorphological and immunohistochemical observations to determine the number and morphological changes of prefrontal cortex (PFC) neurons and the protein expression of synaptophysin (SYP). Other brain tissues were quickly removed, PFC was separated and weighed, and Western blot and RT-PCR were used to detect the expression of PPARα at protein and mRNA levels in the PFC of rats. RESULTS: Compared with CUMS model group, PEA increased the body weight gain, the sucrose preference rate, and the locomotion time and distance in the open-field test, and shortened the immobility time in the open-field test. PEA increased the weight of PFC, the percentage of PFC/brain weight and the number of neurons in PFC, and improved the morphological changs of the neurons. PEA also up-regulated the protein expression of SYP in PFC, and down-regulated the expression of PPARα at mRNA and protein levels in the PFC of CUMS model rats (P<0.05). In addition, compared with PEA (10 mg/kg) group, MK886 significantly reduced the body weight gain of the rats, the percentage of sucrose preference and the locomotion distance in the open-field test, and increased the immobility time in the open-field test on the 35th day during CUMS. The number of neurons SYP expression in PFC tissues were decreased, and the expression of PPARα at protein and mRNA levels was increased in MK886 group. CONCLUSION: PEA may antagonize the depression-like behavior of rats by regulating the PPARα pathway in PFC, improving synaptic plasticity of PFC and protecting the neurons.     

Hyperbaric oxygen therapy activates CREB/BDNF signaling pathway to reduce synaptic damage in hippocampal neurons of Alzheimer disease mice

AIM To investigate the effect of hyperbaric oxygen (HBO) on synaptic damage of hippocampal neurons in APP/PS1 transgenic (TG) mice and its possible mechanism. METHODS The 6-month-old male APP/PS1 TG mice were randomly divided into TG group, HBO group and cAMP response element binding protein (CREB) inhibitor H89 group, with 10 mice in each group. Ten male wild-type (WT) C57BL/6 mice of the same age were used as negative control group (WT group). The mice in HBO and H89 groups were treated with HBO for 6 cycles, while the mice in WT group and TG group were not treated. The learning and memory abilities were observed by Morris water maze. The nesting ability of the mice was detected by nesting test. The Nissl bodies in hippocampal neurons were observed by Nissl staining. The mRNA expression of CREB and brain-derived neurotrophic factor (BDNF) in hippocampus was detected by real-time PCR. The protein levels of synapsin (SYN), postsynaptic density protein 95 (PSD95), growth-associated protein 43 (GAP43), CREB, phosphorylated CREB (p-CREB) and BDNF in the hippocampus were determined by Western blot. RESULTS Compared with WT group, the learning and memory abilities of the mice in TG group were signilficantly reduced (P<0.05). In addition, the nesting score, the number of Nissl bodies in the hippocampal neurons, the mRNA expression of CREB and BDNF, and the protein levels of SYN, PSD95, GAP43, p-CREB and BDNF were also decreased significantly (P<0.05). Compared with TG group, the learning and memory abilities of the mice in HBO group were improved (P<0.05). Meanwhile, the nesting scores of the mice were significantly increased (P<0.05), the neurons in the hippocampus were arranged neatly, and the number of Nissl bodies, the relative mRNA expression of CREB and BDNF,and the protein levels of SYN, PSD95, GAP43, p-CREB and BDNF were also increased significantly (P<0.05). Compared with HBO group, the mice in H89 group had poor learning and memory abilities, lowered nesting scores and decreased number of Nissl bodies. Futhermore, the relative mRNA expression of CREB and BDNF, and the protein levels of SYN, PSD95, GAP43, p-CREB and BDNF were also decreased significantly (P<0.05). CONCLUSION HBO improves the learning and memory abilities of APP/PS1 TG mice, and its mechanism may be related to activating the CREB/BDNF signaling pathway to reduce synaptic damage of hippocampal neurons in mice.     

Effect of chronic intermittent hypoxia on AMPK pathway in young rats

AIM: To investigate the effect of chronic intermittent hypoxia on AMP-activated protein kinase(AMPK) pathway in the brain of young rats. METHODS: Part one: SD mice(3~4 weeks old) were randomly divided into 4 groups(n=8): simulated air control group for 2 weeks(2AC), chronic intermittent hypoxia group for 2 weeks(2IH), simulated air control group for 4 weeks(4AC) and chronic intermittent hypoxia group for 4 weeks(4IH). Part two: SD mice(3~4 weeks old) were randomly divided into 2 groups(n=8): chronic intermittent hypoxia group for 4 weeks(4IH) and chronic intermittent hypoxia group treated with AMPK inhibitor for 4 weeks(4IHI). After modeling, the eight-arm maze test was performed. TUNEL method was used to detect the neuronal apoptosis in the hippocampal and prefrontal cortical tissues. The mRNA expression of adenosine A2a receptor was examined by RT-qPCR, and the protein levels of phosphorylated AMPK(p-AMPK) and mammalian target of rapamycin(p-mTOR) were determined by Western blot. RESULTS: Compared with control group, the numbers of reference memory error(RME), working memory error(WME) and total error(TE) in 2IH group and 4IH group significantly increased(P<0.01). Compared with 2IH group, the numbers of errors in 4IH group also increased significantly(P<0.01). Compared with 4IH group, the values in 4IHI group significantly decreased. Compared with control group, the neuronal apoptosis of hippocampus and prefrontal cortex in 2IH group and 4IH group increased, and that in 4IH group was more evident(P<0.05). In 4IHI group, the neuronal apoptosis decreased. The mRNA expression of adenosine A2a receptor in the hippocampal and cortical tissues in 2IH group and 4IH group was higher than that in control group. The protein level of p-AMPK was higher, and p-mTOR was lower in 2IH group and 4IH group, and those in 4IH group were more evident(P<0.05). Compared with 4IH group, the protein level of p-AMPK was lower, and p-mTOR was higher in 4IHI group. CONCLUSION: Chronic intermittent hypoxia induces neuronal apoptosis, resulting in impairment of learning and memory in a time-dependent manner by upregulating adenosine A2a receptor, activating AMPK activity, and inhibiting mTOR phosphorylation in rats.     

Effects of chronic hypobaric hypoxia exposure on dendritic spine morphological changes and filamin-A expression in neurons of mouse hippocampal CA1 region

AIM:To investigate the effects of hypobaric hypoxic exposure on the morphological changes of dendritic spines and the expression of filamin-A in the neurons of mouse hippocampal CA1 region. METHODS:C57BL/6 male mice (6~8-week-old) were divided into normoxia 7 d group, normoxia 14 d group, hypobaric hypoxia 7 d group and hypobaric hypoxia 14 d group. The mice in hypobaric hypoxia exposure groups were placed in a hypobaric chamber with hypobaric hypoxia exposure to simulate the plateau at an altitude of 6 000 m. Golgi staining assay was used to observe the branch number of dendrites, and the length and density of basal and apical dendritic spines in the hippocampal CA1 region. The protein expression of filamin-A in the hippocampus of the mice was determined by Western blot. The protein expression and distribution of filamin-A in the hippocampal CA1 region were detected by immunofluorescence staining. RESULTS:Compared with normoxia exposure group, no significant difference of the number of dendritic branches in the hippocampal CA1 region after hypobaric hypoxia exposure was observed. However, the length of basal spines and apical spines was increased significantly (P<0.05), and the density of basal spines and apical spines was significantly reduced after hypobaric hypoxia exposure (P<0.01). The results of Western blot showed that the protein expression of filamin-A in the hippocampus of the mice after hypobaric hypoxia exposure was lower than that in normoxia exposure group (P<0.01 or P<0.05). Immunofluorescence staining showed that the filamin-A protein was expressed in the mouse hippocampal CA1 region, and the expression level after hypobaric hypoxia exposure was lower than that in normoxia group. CONCLUSION:Chronic hypobaric hypoxia exposure affects the protein expression level of filamin-A in the mouse hippocampal CA1 region, thus leading to the morphological changes of dendritic spines in the hippocampal CA1 region.     

Effect of BDNF expression in cerebral cortex and hippocampus on ability of learning and memory in APP/PS1 transgenic mice

AIM: To investigate the expression changes of brain-derived neurotrophic factor (BDNF) in the cerebral cortex and hippocampus and their effects on the ability of learning and memory in the wild-type (WT) mice and APP/PS1 transgenic mice. METHODS: WT mice and APP/PS1 transgenic mice were selected as study subjects. Aβ plaques, apoptosis rate and BDNF expression in the cerebral cortex and hippocampus of WT mice and APP/PS1 transgenic mice were detected by the methods of Congo red staining, TUNEL, immunofluorescence and Western blot. The abilities of learning and memory were determined by Morris water maze test. RESULTS: The Aβ plaques appeared in the cerebral cortex and hippocampus of APP/PS1 transgenic mice, and the number of Aβ plaques in 12-month-old mice was larger than that in 6-month-old mice (P<0.05). The number of apoptotic neurons in the cerebral cortex and hippocampus of 12-month-old APP/PS1 transgenic mice was larger than that of WT mice (P<0.01). The expression level of BDNF in the cerebral cortex and hippocampus of WT mice was higher than that of APP/PS1 transgenic mice (P<0.01). The Morris water maze test showed that the escape latency in APP/PS1 transgenic mice was longer than that in WT mice, and the times across the platform quadrant in 60 s was less than that in WT mice (P<0.01). The swim-tracking path of APP/PS1 transgenic mice was disordered and irregular. CONCLUSION: The expression of BDNF in the cerebral cortex and hippocampus of APP/PS1 transgenic mice was lower than that of WT mice, accompanied by increased neuronal apoptosis and decreased spatial learning and memory ability. The decrease in learning and memory ability may be related to decreased BDNF expression in the cerebral cortex and hippocampus of APP/PS1 transgenic mice, leading to increased neuronal apoptosis, which may be one of the pathological mechanisms of Alzheimer disease.     

Expression of p-p38 MAPK in partial cerebral tissues after hypoxic-ischemic brain damage in neonatal A2AR knockout mice

AIM： To study the expression of p-p38 MAPK in partial cerebral tissues after hypoxic-ischemic brain damage (HIBD) in the neonatal adenosine A2A receptor knockout (A2AR-/-) mice. METHODS：Base on the modified Rice method, the model of HIBD was established. The total 64 C57/BL6 neonatal mice (7 days old) of A2AR-/-(KO) and corresponding wild type (A2AR+/+, WT) were randomized into sham-operated group and model group. The mice in model group were divided into 3 subgroups： 1 d after HIBD, 3 d after HIBD and 7 d after HIBD (n=8 for each group). The cortex and hippocampal CA1 region were used as the study areas. The neuronal apoptosis was detected using TUNEL assay combined with Nissl staining. The expression of p-p38 MAPK and activated caspase-3 was determined by the method of immunohistochemistry. The KO mice and WT mice were also taken from sham-operated group (SKO and SWT, n=10) and model group (MKO and MWT, n=30) 1 d after HIBD to assess the early neurological behavior. RESULTS：The apoptotic neurons, activated caspase-3 and p-p38 MAPK increased after HIBD and peaked at 1 d after HIBD in the cortex and the hippocampal CA1 region. The apoptotic neurons and the expression of activated caspase-3 in KO mice were significantly higher than those in WT mice at the same time point after HIBD. The expression level of p-p38 MAPK in KO mice were significantly higher than that in WT mice at 1 d and 3 d after HIBD. The expression of activated caspase-3 was positively correlated with the expression of p-p38 MAPK in neonatal mice after HIBD (in the cortex：r=0.957, P<0.01; in the hippocampal CA1 region： r=0.939, P<0.01). CONCLUSION：p-p38 MAPK might be involved in the aggravated neuron apoptosis and brain damage induced by A2AR knockout after neonatal HIBO.