Emodin Prevented Depression in Chronic Unpredicted Mild Stress-Exposed Rats by Targeting miR-139-5p/5-Lipoxygenase.

BACKGROUND: The use of medicinal plant ingredients is one of the goals of developing potential drugs for treating depression. Compelling evidence suggests that anti-inflammatory medicines may block the occurrence of depression. We studied the effect of a natural compound, emodin, on the development of psychosocial stress-induced depression and the underlying mechanisms. METHODS: Chronic unpredicted mild stress (CUMS) for 7 weeks was performed to replicate psychosocial stress in rats. The sucrose preference test, force swimming test, and open field test were used to evaluate their behaviors. The differentially expressed proteins in the hippocampus were analyzed using proteomics. Nissl staining and Golgi staining were used to detect the loss of neurons and synapses, immunohistochemical staining was used to detect the activation of microglia, and the enzyme-linked immunosorbent assay was used to detect the levels of pro-inflammatory cytokines. Western blotting, immunofluorescence, and quantitative polymerase chain reaction were also performed. RESULTS: Hippocampal inflammation with up-regulated 5-lipoxygenase (5-LO) was observed in the depressed rats after CUMS exposure. The upregulation of 5-LO was caused by decreased miR-139-5p. To observe the effect of emodin, we screened out depression-susceptible (DeS) rats during CUMS and treated them with emodin (80 mg/kg/day). Two weeks later, emodin prevented the depression behaviors in DeS rats along with a series of pathological changes in their hippocampi, such as loss of neurons and spines, microglial activation, increased interleukin-1ß and tumor necrosis factor-α, and the activation of 5-LO. Furthermore, we demonstrated that emodin inhibited its excess inflammatory response, possibly by targeting miR-139-5p/5-LO and modulating glycogen synthase kinase 3ß and nuclear factor erythroid 2-related factor 2. CONCLUSION: These results provide important evidence that emodin may be a candidate agent for the treatment of depression and established a key role of miR-139-5p/5-LO in the inflammation of depression.

Protective effects of Da-cheng-qi decoction in rats with intracerebral hemorrhage.

BACKGROUND: Intracerebral hemorrhage (ICH), the most fatal subtype of stroke, has no disease-modifying treatment. Da-cheng-qi decoction (DCQ), composed of rhubarb, is one of the most commonly used Chinese traditional decoctions in ICH treatment. But the mechanism is not clear. Emodin is an active compound found in rhubarb. PURPOSE: To study the protective effects of DCQ on ICH and its possible mechanisms of action. METHODS: The ICH model was reproduced by injecting collagenase-VII into the left caudate putamen (CPu) of rats. DCQ and emodin were used to treat the ICH rats for 7 days. Behavior tests, proteomic analysis, morphological studies, and western blotting were performed. RESULTS: The neurological deficits in the ICH rats recovered with DCQ and emodin on the 14th day after ICH. The proteomics data revealed that DCQ significantly corrected the pathological signals in the CPu and hippocampus after ICH. The numbers of amoebic microglia in the CPu and M2 microglia in both CPu and hippocampus were significantly increased after DCQ and emodin treatment. The increase in GluN2B-containing NMDA receptor (NR2B) and postsynaptic density protein-95, activation of mitogen-activated protein kinase (MAPK) signals in the CPu, and secondary neurodegeneration (SND) in the hippocampus were significantly recovered in DCQ-treated rats. Inhibition of MAPK p38 (p38) in the hippocampus was observed after DCQ and emodin treatment. CONCLUSION: The protective effects of DCQ on ICH were confirmed in this study, and its mechanism may be related to the inhibition of MAPK and activation of M2 microglia. These results are beneficial to the development of ICH therapeutic targets.

Estrogen Receptor α Agonist is Beneficial for Young Female Rats Against Chronic Unpredicted Mild Stress-Induced Depressive Behavior and Cognitive Deficits.

BACKGROUND: Women are reported more likely to develop depression and dementia. However, the involved mechanism is poorly understood. OBJECTIVE: Here, we clarified the role of estrogen receptor α (ERα) in depression and cognitive deficit in young female rats. METHODS: After being exposed to 7-weeks' chronic unpredicted mild stress (CUMS), the depression resilient rats (Res rats) and depressed rats (Dep rats) were selected according to their records in sucrose preference test, forced swimming test, and open field test. Their cognition abilities were tested by Morris water maze. Proteomic assay, immunoprecipitation, western blotting, immunohistochemical, and Nissl staining were also used to understand the involved mechanism. RESULTS: Compared with control rats and Res rats, Dep rats showed cognitive deficits and hippocampal impairments revealed by proteomic data, neuron losses, increased cleaved caspase-3, ß-catenin phosphorylation, and glycogen synthase kinase3ß (GSK3ß) activation. As ERα, but not ERß, was found declined in hippocampi of Dep rats, 4,4k,4a-(4-propyl-[1H]-pyrazole-1,3,5-triyl) trisphenol (PPT, an ERα agonist, 1 mg/kg/day), was used to treat Dep rats (Dep + PPT). Twenty days later, the depressive behaviors, cognition deficits, and hippocampal neuron loss were rescued in Dep + PPT rats. Furthermore, Res and Dep + PPT rats had higher levels of ß-catenin combined with ERα and lower levels of ß-catenin combined with GSK3ß than Dep rats in hippocampi. CONCLUSION: These results demonstrated hippocampal ERα is an important pro-resilient factor in CUMS-induced depressive behaviors and cognitive deficits. It was also given that the neuroprotection afforded by hippocampal ERα/Wnt interactions have significant implications for cognition and emotion in young females.

Evidence of altered depression and dementia-related proteins in the brains of young rats after ovariectomy.

Menopause, a risk factor for brain dysfunction in women, is characterized by neuropsychological symptoms including depression and dementia, which are closely related to alterations in different brain regions after menopause. However, little is known about the variability in pathophysiologic changes associated with menopause in the brain. Here, we observed that menopause in rats induced by bilateral ovariectomy (OVX) showed depressive and dementia-related behaviors along with neuronal loss in the prefrontal cortex (PFC), hippocampus (HIP), hypothalamus (HYP), and amygdala (AMY) by Nissl staining. Meanwhile, by immunohistochemical staining, increased microglia in the HIP and AMY and increased astrocytes in the PFC, HYP, and AMY were shown. Using quantitative proteomics, we identified 146 differentially expressed proteins in the brains of OVX rats, for example, 20 in the PFC, 41 in the HIP, 17 in the HYP, and 79 in the AMY, and performed further detection by western blotting. A link between neuronal loss and apoptosis was suggested, as evidenced by increases in adenylate kinase 2 (AK2), B-cell lymphoma 2 associated X (Bax), cleaved caspase 3, and phosphorylated p53 and decreases in Huntingtin-interacting protein K, hexokinase, and phosphorylated B-cell lymphoma 2 (Bcl-2), and apoptosis might be triggered by endoplasmic reticulum stress (probed by increased glucose-regulated protein 78 (GRP78), cleaved caspase 12, phosphorylated protein kinase R (PKR)-like endoplasmic reticulum kinase, inositol-requiring enzyme-1 and activating transcription factor 6), and mitochondrial dysfunction (probed by increased cytochrome c and cleaved caspase 3 and decreased sideroflexin-1 (SFXN1) and NADH dehydrogenase (ubiquinone) 1 α subcomplex 11 (NDUFA11)). Activation of autophagy was also indicated by increased autophagy-related 7, γ-aminobutyric acid (GABA) receptor-associated protein-like 2, and oxysterol-binding protein-related protein 1 and confirmed by increased microtubule-associated protein light chain 3 (LC3II/I), autophagy-related 5, and Beclin1 in the HIP and AMY. In the AMY, which is important in emotion, higher GABA transporter 3 and lower vesicular glutamate transporter 1 levels indicated an imbalance between excitatory and inhibitory neurotransmission, and the increased calretinin and decreased calbindin levels suggested an adjustment of GABAergic transmission after OVX. In addition, cytoskeletal abnormalities including tau hyperphosphorylation, dysregulated Ca²+ signals, and glutamic synaptic impairments were observed in the brains of OVX rats. Collectively, our study showed the changes in different brain regions related to depression and dementia during menopause.

Endoplasmic reticulum stress induces spatial memory deficits by activating GSK-3.

Endoplasmic reticulum (ER) stress is involved in Alzheimer's disease (AD), but the mechanism is not fully understood. Here, we injected tunicamycin (TM), a recognized ER stress inducer, into the brain ventricle of Sprague-Dawley (SD) rats to induce the unfolded protein response (UPR), demonstrated by the enhanced phosphorylation of pancreatic ER kinase (PERK), inositol-requiring enzyme-1 (IRE-1) and activating transcription factor-6 (ATF-6). We observed that UPR induced spatial memory deficits and impairments of synaptic plasticity in the rats. After TM treatment, GSK-3ß was activated and phosphorylation of cAMP response element binding protein at Ser129 (pS129-CREB) was increased with an increased nuclear co-localization of pY126-GSK-3ß and pS129-CREB. Simultaneous inhibition of GSK-3ß by hippocampal infusion of SB216763 (SB) attenuated TM-induced UPR and spatial memory impairment with restoration of pS129-CREB and synaptic plasticity. We concluded that UPR induces AD-like spatial memory deficits with mechanisms involving GSK-3ß/pS129-CREB pathway.

Gender-Related Hippocampal Proteomics Study from Young Rats After Chronic Unpredicted Mild Stress Exposure.

Clinical data have shown women are more susceptible to depression. This study was performed to identify differentially regulated proteins from hippocampus in chronic unpredicted mild stress (CUMS)-exposed male and female young rats. After 7 weeks of CUMS, depressed male (M-D) and female rats (F-D) and unstressed male (M-C) and female controls (F-C) were studied. By proteomics analysis, 74 differential proteins in F-C/M-C, 79 in F-D/M-D, 77 in F-D/F-C, and 32 in M-D/M-C were found. Further, the synapse-related proteins, cytoskeleton protein tau, and stress-related kinases in hippocampus were assayed by Western blotting. F-C rats were found to have lower levels of metabotropic glutamate receptor 1 (mGluR1) and mGluR2 and higher levels of N-methyl-D-aspartate receptor 2B (NR2B), synapsin1, total tau, and dephosphorylated tau than M-C rats. Both F-D and M-D rats had lower levels of glutamate transporter SLC1α2, mGluR1, and mGluR2, and higher levels of total tau and phosphorylated tau than their controls. Compared with their controls, M-D rats had lower NR1 and higher NR2B, and F-D rats had lower NR2A, NR2B, PSD95, and synapsin1. F-C rats had higher JNK and lower phosphorylation levels of ERK at Thr202/Thr204, JNK at Thr183/Thr185, and GSK-3ß at Ser9 than M-C ones. Both M-D and F-D rats had decreased phosphorylation of ERK at Thr202/Thr204 and GSK-3ß at Ser9, and increased JNK phosphorylation at Thr183/Thr185 compared with their controls. All these data illustrate the biochemical complexity behind the genders, and may also aid in the development of more accurate treatment strategies for depression.

High Morphologic Plasticity of Microglia/Macrophages Following Experimental Intracerebral Hemorrhage in Rats.

As current efforts have limited effects on the clinical outcome of intracerebral hemorrhage (ICH), the mechanisms including microglia/macrophages that involved inflammation need further investigation. Here, 0.4 units of collagenase VII were injected into the left caudate putamen (CPu) to duplicate ICH rat models. In the brains of ICH rats, microglia/macrophages, the nearest cells to the hemorrhagic center, were observed as ameboid and Prussian-blue positive. Furthermore, the ameboid microglia/macrophages were differentiation (CD) 68 and interleukin-1ß (IL-1ß) positive, and neither CD206 nor chitinase3-like 3 (Ym1) positive, suggesting their strong abilities of phagocytosis and secretion of IL-1ß. According to the distance to the hemorrhagic center, we selected four areas-I, II, III, and IV-to analyze the morphology of microglia/macrophages. The processes decreased successively from region I to region IV. Microglia/macrophages in region IV had no processes. The processes in region I were radially distributed, however, they showed obvious directivity towards the hemorrhagic center in regions II and III. Region III had the largest density of compactly arrayed microglia/macrophages. All these in vivo results present the high morphologic plasticity of microglia/macrophages and their functions in the pathogenesis of ICHs.

SIL1 Rescued Bip Elevation-Related Tau Hyperphosphorylation in ER Stress.

Endoplasmic reticulum (ER) stress has been indicated in the early stage of Alzheimer's disease (AD), in which tau hyperphosphorylation is one major pathological alteration. The elevation of binding immunoglobulin protein (Bip), an important ER chaperon, was reported in AD brain. It is important to study the roles of ER-related chaperons in tau hyperphosphorylation. In this research, increased Bip was found in the brains of the AD model mice (Tg2576) compared to the age-matched control mice. Meanwhile, deficiency of SIL1, an important co-chaperon of Bip, was observed in brains of Tg2576 mice and in ER stress both in vivo and in vitro. Then, we transfected Bip-EGFP plasmid into HEK293 cells stably expressing the longest human tau (HEK293/tau) or N2a cells and found that increased Bip induced tau hyperphosphorylation via activating glycogen synthase kinase-3ß (GSK-3ß), an important tau kinase, and increased the association with tau and GSK-3ß. When we overexpressed SIL1 in Bip-transfected HEK293/tau cells and thapsigargin-treated HEK293/tau cells, significantly reduced tau hyperphosphorylation and GSK-3ß activation were observed. These results suggested the important roles of ER-related chaperons, Bip and SIL1, in AD-like tau hyperphosphorylation.

Region-specific expression of tau, amyloid-ß protein precursor, and synaptic proteins at physiological condition or under endoplasmic reticulum stress in rats.

Region-specific neurodegeneration was reported in brains of Alzheimer's disease (AD), but the mechanism is not fully understood. Here, we studied the expression of some AD-associated proteins in temporal cortex, frontal cortex, cerebellum, and hippocampus of 4-month-old male Sprague-Dawley rats. Levels of the phosphorylated tau at Thr231, Ser396, and Ser202/Thr205, phosphorylated amyloid-ß protein precursor (AßPP) and amyloid-ß, synapse-associated proteins glutamate receptors 2, N-methyl-D-aspartic receptors 1 (NR1), NR2A, NR2B, and postsynaptic density protein 95 were much lower in cerebellum, while the levels of total tau, phosphorylated tau at Thr205, Ser214, Ser262, and Ser198/199/202 epitopes, and total AßPP were similar in the four brain regions. As endoplasmic reticulum (ER) stress was reported in the early stage of AD, we injected tunicamycin, an ER stress inducer, into the lateral ventricular of rats and 48 hours later found in the other three brain regions but not cerebellum, increasing of binding immunoglobulin protein with the increased phosphorylation of pancreatic ER kinase, inositol-requiring enzyme 1, and activating transcription factor 6. Simultaneously, levels of phosphorylated tau at all of the above sites were significantly increased with the activation of glycogen synthase kinase-3ß in temporal cortex, frontal cortex, and/or hippocampus, but not cerebellum. The synapse-associated proteins, GluR2, PSD95, and synapsin1, were found decreased in the hippocampus after tunicamycin exposure. These data together may partially explain why the AD-like neuropathology, such as formation of neurofibrillary tangles, was rarely detected in cerebellum.