Hippocampal Morphology Research Articles

Neuroprotective potential of Cordia dichotoma in Parkinson's syndrome induced by haloperidol: An animal study

BackgroundParkinson’s disease (PD) is one of the major neurodegenerative disorders and the prevalence is expected to increaseduring the next couple of decades. There is a need for safe and effective therapeutic regimen that can effectively manage this neurotoxicity. The leaves and several other parts ofCordia dichotomaare known to possess number of medicinal properties. The purpose of this study was to examine the neuroprotective role ofCordia dichotomain an experimental model of haloperidol-induced P.D. Materials and methodsFive groups of rats were randomly assigned into different groups. Intraperitoneal haloperidol 1 mg/kg was given to the inducer group and 0.5% CMC to the normal control. The reference standard was syndopa 10 mg/kg, p.o., and the test group animals receivedC. dichotoma'sethanolic extract at 200 and 400 mg/kg orally for one week. Rats exposed to haloperidol were assessed for behavioral, neurochemical, and histopathological parameters. ResultsC. dichotoma leaves extract dose-dependently increased behavioral activity and muscle coordination. The extract at 400 mg/kg was found to increase significantly (P < 0.001) the central square activity in open-field test, compared to haloperidol treated rats. In stepping test, both tested doses ofC. dichotoma(200 mg and 400 mg/kg) were found to significantly (P < 0.001) reduce akinesia, besides these doses also decreased the catatonic responses induced by haloperidol. Further, the extraction treatment (200 mg and 400 mg/kg) significantly (P < 0.001) decreased malonaldehyde and increased antioxidant enzymes like catalase compared to the control group. Histopathological changes in the test group showed a significant reduction in haloperidol damage to normal morphology in cortical, hippocampus, substantia nigra, and pyramidal. ConclusionThe observations of the study suggest thatCordia dichotomaattenuated the haloperidol-induced neurological changes, indicating that the plant might benefit in the treatment of Parkinson’s disease. The activity ofCordia dichotomacould be linked to its antioxidant property. Since, the drug is traditionally used in different parts of world; it could be a promising agent if more research establishes its safety and efficacy in other experimental models of Parkinson’s Disease.

Electromagnetic Fields: Insight into Sources, and Their Effects on Vital Organs and the Risk of Cancer

Background: Electromagnetic radiation has become an extensive new pollution source in modern civilization. Therefore, the biological effects of electromagnetic radiation have attracted considerable attention worldwide. Objectives: The current review was aimed to highlight on sources of electromagnetic fields and their effects on vital organs and the risk of cancer. Electromagnetic sources can be classified into natural electromagnetic sources (sun, some distant stars, atmospheric discharges like thunder, or human body) and unnatural or human made sources (printers, vacuum cleaners, cellular phones, hair dryers, refrigerators, washing machines, kettles microwaves, cables that carry electrical currents, television and computers, electrical home gadgets, radio and television base stations, mobile phone base stations and phone equipment), home wiring airport, and transformers. Electromagnetic fields (EMFs) are electromagnetic waves less than 300 GHz, that are divided into extremely low frequencies (ELFs; 3–3,000 Hz), involving high-voltage transmission lines and in-house wiring; and radiofrequencies (RFs; 30 kHz to 300 GHz), involving mobile phones, smart devices, base stations, WiFi, and 5G technologies. Cell phone technology is an integral part of everyday life and its use is not only restricted to voice conversations but also conveying news, high-resolution pictures, and the internet. Exposure to electromagnetic fields might produce oxidative stress, sperm damage, DNA damage, changes in the chromatin conformation, formation of micronucleus in different cell types, gene expression, enzyme activity, and changes in the structure and function of cell membrane, stimulated an increase in apoptosis and biosynthesis of plasma metallothionein and corticosterone. It causes headaches, chronic fatigue, heart problems, stress, nausea, chest pain, gastrointestinal issues, pain in the muscles and joints, sweating, neurocognitive disturbances, eye burning, nose, ear, and throat issues, bad effects on reproductive, central nervous, endocrine, cardiovascular, and immune systems. Also, it increases anxiety-related behavior; spatial memory, and learning deficits in male mice offspring, decreased thermal pain perception, induced a sleep disturbance, latency, and day dysfunction especially in females, a change in memory performance, damage to the lens epithelial cells of rabbits after 8 hours of exposure to microwave radiation, produced lens opacity in rats, which is linked to the production of cataracts, and derangement of chicken embryo retinal differentiation. There are a relationship between exposure to electromagnetic fields and the increased incidence of the occurrence of some tumors types, particularly brain cancer and leukemia. EMFs induce damage of tissues by increasing free radicals and changing the antioxidant defense systems of tissues, eventually leading to oxidative stress which leads to behavioral, histopathological and biochemical alterations. Exposure to radar, which uses RF fields above 6 GHz similar to 5 G causes effects on production of cancer at different sites, and other diseases. The possible mechanism proposed of how EMFs lead to cancer is the impact of EMFs on free radical combination rates in certain enzymes, such as coenzyme B12-dependent ethanolamine ammonia lyase. The enzyme reaction rate may be amplified by a factor of up to 100. A case-control studies found an increased risk of gliomas, acoustic neuromas, and temporal lobe tumours in users with highest self-reported cell phone use. Exposure of experimental animals to microwave radiation caused a decrease in learning and memory ability, abnormal hippocampal morphology and abnormal Electroencephalogram. Also, it could lead to a decrease in norepinephrine and epinephrine contents in the brain, leading to neurotransmitter production disorders. Conclusion: It can be concluded that electromagnetic sources classified into natural electromagnetic and human made sources. EMFs) are electromagnetic waves less than 300 GHz are divided into extremely low frequencies and radiofrequencies. Exposure to electromagnetic fields might produce oxidative stress, which leads to histopathological and biochemical alterations in different body organs and increased risk of gliomas, acoustic neuromas, and temporal lobe tumours in users with highest self-reported cell phone use. Further studies are needed to confirm these effects in human and experimental animals.

Fine scale hippocampus morphology variation cross 552 healthy subjects from age 20 to 80.

The cerebral cortex varies over the course of a person's life span: at birth, the surface is smooth, before becoming more bumpy (deeper sulci and thicker gyri) in middle age, and thinner in senior years. In this work, a similar phenomenon was observed on the hippocampus. It was previously believed the fine-scale morphology of the hippocampus could only be extracted only with high field scanners (7T, 9.4T); however, recent studies show that regular 3T MR scanners can be sufficient for this purpose. This finding opens the door for the study of fine hippocampal morphometry for a large amount of clinical data. In particular, a characteristic bumpy and subtle feature on the inferior aspect of the hippocampus, which we refer to as hippocampal dentation, presents a dramatic degree of variability between individuals from very smooth to highly dentated. In this report, we propose a combined method joining deep learning and sub-pixel level set evolution to efficiently obtain fine-scale hippocampal segmentation on 552 healthy subjects. Through non-linear dentation extraction and fitting, we reveal that the bumpiness of the inferior surface of the human hippocampus has a clear temporal trend. It is bumpiest between 40 and 50 years old. This observation should be aligned with neurodevelopmental and aging stages.

MR-based spatiotemporal anisotropic atrophy evaluation of hippocampus in Alzheimer's disease progression by multiscale skeletal representation.

Increasing evidence has shown a higher sensitivity of Alzheimer's disease (AD) progression by local hippocampal atrophy rather than the whole volume. However, existing morphological methods based on subfield-volume or surface in imaging studies are not capable to describe the comprehensive process of hippocampal atrophy as sensitive as histological findings. To map histological distinctive measurements onto medical magnetic resonance (MR) images, we propose a multiscale skeletal representation (m-s-rep) to quantify focal hippocampal atrophy during AD progression in longitudinal cohorts from the Alzheimer's Disease Neuroimaging Initiative (ADNI). The m-s-rep captures large-to-small-scale hippocampal morphology by spoke interpolation over label projection on skeletal models. To enhance morphological correspondence within subjects, we align the longitudinal m-s-reps by surface-based transformations from baseline to subsequent timepoints. Cross-sectional and longitudinal measurements derived from m-s-rep are statistically analyzed to comprehensively evaluate the bilateral hippocampal atrophy. Our findings reveal that during the early AD progression, atrophy primarily affects the lateral-medial extent of the hippocampus, with a difference of 1.8 mm in lateral-medial width in 2 years preceding conversion (p < .001), and the medial head exhibits a maximum difference of 3.05%/year in local atrophy rate (p = .011) compared to controls. Moreover, progressive mild cognitive impairment (pMCI) exhibits more severe and widespread atrophy in the head and body compared to stable mild cognitive impairment (sMCI), with a maximum difference of 1.21 mm in thickness in the medial head 1 year preceding conversion (p = .012). In summary, our proposed method can quantitatively measure the hippocampal morphological changes on 3T MR images, potentially assisting the pre-diagnosis and prognosis of AD.

Effects of thymoquinone and memantine alone and in combination on memory and hippocampal morphology in rats with streptozotocin-induced Alzheimer's disease.

Alzheimer's disease (AD) is a progressive neurodegenerative disease. Thymoquinone (TQ) has broad biological functions, including antiinflammatory, antioxidant, neuroprotective properties. Memantine (MEM) is indicated for the symptomatic treatment of moderate to severe AD. We aimed to evaluate the effect of TQ alone or in combination with MEM on memory and hippocampal morphology in an STZ-induced rat AD model. Thirty male rats were included in this study. The AD model was created by giving ICV STZ. The rats were divided into 5 groups (n = 6 each). Group 1 (control group): The rats received only ICV-STZ 3 mg/kg for 2 weeks. Group 2 (sham group): In addition to ICV STZ, 9% NaCl, 1 mL/day i.p. for 2 weeks of injection, was applied. Group 3 (TQ group): In addition to ICV STZ, rats received TQ 10 mg/kg i.p. for 2 weeks. Group 4 (MEM group): In addition to ICV STZ, rats were given MEM at a dose of 5 mg/kg for two weeks. Group 5 (TQ+MEM group): In addition to ICV STZ, this group was given TQ (10 mg/kg/day, i.p.) and MEM (5 mg/kg/day, i.p.) for 2 weeks. On the 15th day, passive avoidance learning (PAL) was applied to all groups. Then, rats were sacrificed, neurons in the hippocampal CA1, CA2, CA3 regions were evaluated. Groups 3, 4, 5 had longer latency periods than groups 1 and 2. The neuron density in the CA1, CA2, CA3 regions had decreased in groups 1 and 2 compared to groups 3, 4, 5. There were significantly more neurons in groups 3, 4, 5 than in groups 1 and 2. We found that TQ alone and in combination with MEM showed ameliorative effects on memory and hippocampal morphology. TQ may offer a promising treatment strategy for AD.

Hippocampal morphology in Huntington's disease, implications for plasticity and pathogenesis: The IMAGE-HD study

While striatal changes in Huntington's Disease (HD) are well established, few studies have investigated changes in the hippocampus, a key neuronal hub. Using MRI scans obtained from the IMAGE-HD study, hippocampi were manually traced and then analysed with the Spherical Harmonic Point Distribution Method (SPHARM-PDM) in 36 individuals with presymptomatic-HD, 37 with early symptomatic-HD, and 36 healthy matched controls. There were no significant differences in overall hippocampal volume between groups. Interestingly we found decreased bilateral hippocampal volume in people with symptomatic-HD who took selective serotonin reuptake inhibitors compared to those who did not, despite no significant differences in anxiety, depressive symptoms, or motor incapacity between the two groups. In symptomatic-HD, there was also significant shape deflation in the right hippocampal head, showing the utility of using manual tracing and SPHARM-PDM to characterise subtle shape changes which may be missed by other methods. This study confirms previous findings of the lack of hippocampal volumetric differentiation in presymptomatic-HD and symptomatic-HD compared to controls. We also find novel shape and volume findings in those with symptomatic-HD, especially in relation to decreased hippocampal volume in those treated with SSRIs.

Effects of heterozygous deletion of autism-related gene Cullin-3 in mice.

Autism Spectrum Disorder (ASD) is a developmental disorder in which children display repetitive behavior, restricted range of interests, and atypical social interaction and communication. CUL3, coding for a Cullin family scaffold protein mediating assembly of ubiquitin ligase complexes through BTB domain substrate-recruiting adaptors, has been identified as a high-risk gene for autism. Although complete knockout of Cul3 results in embryonic lethality, Cul3 heterozygous mice have reduced CUL3 protein, demonstrate comparable body weight, and display minimal behavioral differences including decreased spatial object recognition memory. In measures of reciprocal social interaction, Cul3 heterozygous mice behaved similarly to their wild-type littermates. In area CA1 of hippocampus, reduction of Cul3 significantly increased mEPSC frequency but not amplitude nor baseline evoked synaptic transmission or paired-pulse ratio. Sholl and spine analysis data suggest there is a small yet significant difference in CA1 pyramidal neuron dendritic branching and stubby spine density. Unbiased proteomic analysis of Cul3 heterozygous brain tissue revealed dysregulation of various cytoskeletal organization proteins, among others. Overall, our results suggest that Cul3 heterozygous deletion impairs spatial object recognition memory, alters cytoskeletal organization proteins, but does not cause major hippocampal neuronal morphology, functional, or behavioral abnormalities in adult global Cul3 heterozygous mice.

Datura metel stramonium exacerbates behavioral deficits, medial prefrontal cortex, and hippocampal neurotoxicity in mice via redox imbalance

BackgroundDatura metel (DM) stramonium is a medicinal plant often abused by Nigerians due to its psychostimulatory properties. Hallucinations, confusion, agitation, aggressiveness, anxiety, and restlessness are reported amongst DM users. Earlier studies suggest that DM induces neurotoxicity and affect brain physiology. However, the exact neurological effects of DM extract in the medial prefrontal cortex (mPFC) and hippocampal morphology have not been elucidated. In this study, we evaluated the hypothesis that oral exposure to DM extract exerts a neurotoxic effect by increasing oxidative stress in the mPFC and the hippocampus and induces behavioral deficits in mice.ResultsDM methanolic extract exposure significantly increased MDA and NO levels and reduced SOD, GSH, GPx and CAT activities in mice brains. In addition, our results showed that DM exposure produced cognitive deficits, anxiety, and depressive-like behaviour in mice following oral exposure for 28 days. Moreover, the mPFC and hippocampus showed neurodegenerative features, loss of dendritic and axonal arborization, a dose-dependent decrease in neuronal cell bodies’ length, width, area, and perimeter, and a dose-dependent increase in the distance between neuronal cell bodies.ConclusionsOral exposure to DM in mice induces behavioural deficits, mPFC and hippocampal neuronal degenerations via redox imbalance in the brain of mice. These observations confirm the neurotoxicity of DM extracts and raises concerns on the safety and potential adverse effects of DM in humans.Graphical abstract

Effects of exercise intensity on spatial memory performance and hippocampal synaptic function in SAMP8 mice

Learning and memory impairment is commonly noted in Alzheimer's disease (AD), which is regarded as a progressive synaptic failure disease. Exercise is a nonpharmacological strategy that may help prevent cognitive decline and reduce the risk of AD, which is usually thought to be related to synaptic damage in the hippocampus. However, the effects of exercise intensity on hippocampal memory and synaptic function in AD remain unclear. In this study, senescence-accelerated mouse prone-8 (SAMP8) mice were randomly assigned to the control group (Con), low-intensity exercise group (Low), and moderate-intensity exercise group (Mid). Here, we showed that eight weeks of treadmill exercise beginning in four-month-old mice improved spatial memory and recognition memory in six-month-old SAMP8 mice, while the Con group exhibited impaired spatial memory and recognition memory. Treadmill exercise also improved hippocampal neuron morphology in SAMP8 mice. Furthermore, dendritic spine density and the levels of postsynaptic density protein-95 (PSD95) and Synaptophysin (SYN) increased significantly in the Low and Mid groups as compared with the Con group. We further showed that moderate-intensity exercise (60 % of maximum speed) was more efficacious in increasing dendritic spine density、PSD95 and SYN, than low-intensity exercise (40 % of maximum speed). In conclusion, the positive effect of treadmill exercise is closely related to exercise intensity, with moderate-intensity exercise showing the most optimal effects.

Cluster needling of scalp points improves cognitive dysfunction by regulating NF-κB activity in rats with Alzheimer's disease

To observe the effect of cluster needling of scalp points on nuclear transcription factor kappa B p65 (NF-κB p65)，NF-κB inhibitory protein α (IKBα)，β secretase 1 (BACE1)，beta-amyloid protein (Aβ) and hippocampal morphology in Alzheimer's disease (AD) rats，so as to reveal its mechanism underlying improvement of AD. Male Wistar rats were randomly divided into sham operation，model，clustering acupuncture and medication groups，with 12 trats in each group. AD model was induced by Aβ1-42 injection into bilateral hippocampus. In the clustering acupuncture group，"Baihui" (DU20) and 1 mm on left and right sides of DU20 were needled for 30 min，once daily for 14 d. Rats of the medication group were given donepezil hydrochloride (0.5 mg·kg-1·d-1) intragastric perfusion once a day for 14 d. Morris water maze test was used to evaluate the cognitive function of rats. HE staining was used to observe the structure changes of hippocampal tissue. The expressions of NF-κB p65，IKBα and BACE1 in hippocampus were detected by Western blot. ELISA was used to detect the levels of Aβ in hippocampus and serum of rats. Compared with sham operation group，the escape latency of Morris water maze test in the model group was prolonged，the number of crossing the original platform was decreased(P<0.01)，the protein expressions of NF-κB p65 and BACE1 in hippocampus，and the levels of Aβ in hippocampus and serum of AD rats were increased (P<0.01，P<0.05)，while the expression of IKBα protein was decreased (P<0.01). Compared with the model group，the escape latency of Morris water maze test was shortened and the number of crossing the original platform was increased in the clustering acupuncture and medication groups (P<0.01，P<0.05)，and the protein expressions of NF-κB p65 and BACE1 in hippocampus，the levels of Aβ in hippocampus and serum were decreased (P<0.01，P<0.05)，while the expression of IKBα protein was increased (P<0.01). In comparison of the medication group，the protein expressions of NF-κB p65 and IKBα was lower in the clustering acupuncture group (P<0.05). HE staining showed that cells in the hippocampus were arranged loosely and disordered，some cytoplasm was hyperchromatic，nucleus was pyknotic，inflammatory cells were infiltrated in the model group，which were relatively milder in the clustering acupuncture and medication groups. Cluster needling at scalp points may improve the cognitive impairment in AD rats by reducing inflammatory infiltration in hippocampus，regulating the expressions of NF-κB p65，IKBα and BACE1，and inhibiting the aggregation of Aβ.

Synergistic Effect of Combined Walnut Peptide and Ginseng Extracts on Memory Improvement in C57BL/6 Mice and Potential Mechanism Exploration.

This work aimed to investigate whether there are synergistic effects between walnut peptide (WNP) and ginseng extracts (GSE) treatments to ameliorate the memory impairment caused by scopolamine (SCOP). The Morris water maze trial, hippocampal neuron morphology, neurotransmitters, and synaptic ultrastructure were examined, along with brain-derived neurotrophic factor (BDNF)-related signaling pathway proteins. The results of the Morris water maze trial demonstrated that the combined administration of WNP and GSE effectively alleviated memory impairment in C57BL/6 rats caused by SCOP. Improvement in the morphology of hippocampal neurons, dendritic spines, and synaptic plasticity and upregulation of neurotransmitters AChE, ACh, ChAT, Glu, DA, and 5-HT supported the memory improvement effects of WNP + GSE. In addition, compared with the model group, WNP + GSE significantly enhanced the protein levels of VAChT, Trx-1, and the CREB/BDNF/TrkB pathway in hippocampal and PC12 cells induced by SCOP (p < 0.05). Notably, WNP + GSE boosted memory via multiple pathways, not only the BDNF/TrkB/CREB target.

Hippocampal anterior- posterior shift in childhood and adolescence.

Hippocampal-cortical networks play an important role in neurocognitive development. Applying the method of Connectivity-Based Parcellation (CBP) on hippocampal-cortical structural covariance (SC) networks computed from T1-weighted magnetic resonance images, we examined how the hippocampus differentiates into subregions during childhood and adolescence (N=1105, 6-18 years). In late childhood, the hippocampus mainly differentiated along the anterior-posterior axis similar to previous reported functional differentiation patterns of the hippocampus. In contrast, in adolescence a differentiation along the medial-lateral axis was evident, reminiscent of the cytoarchitectonic division into cornu ammonis and subiculum. Further meta-analytical characterization of hippocampal subregions in terms of related structural co-maturation networks, behavioural and gene profiling suggested that the hippocampal head is related to higher order functions (e.g. language, theory of mind, autobiographical memory) in late childhood morphologically co-varying with almost the whole brain. In early adolescence but not in childhood, posterior subicular SC networks were associated with action-oriented and reward systems. The findings point to late childhood as an important developmental period for hippocampal head morphology and to early adolescence as a crucial period for hippocampal integration into action- and reward-oriented cognition. The latter may constitute a developmental feature that conveys increased propensity for addictive disorders.

A Surface-Based Federated Chow Test Model for Integrating APOE Status, Tau Deposition Measure, and Hippocampal Surface Morphometry.

Alzheimer's disease (AD) is the most common type of age-related dementia, affecting 6.2 million people aged 65 or older according to CDC data. It is commonly agreed that discovering an effective AD diagnosis biomarker could have enormous public health benefits, potentially preventing or delaying up to 40% of dementia cases. Tau neurofibrillary tangles are the primary driver of downstream neurodegeneration and subsequent cognitive impairment in AD, resulting in structural deformations such as hippocampal atrophy that can be observed in magnetic resonance imaging (MRI) scans. To build a surface-based model to 1) detect differences between APOE subgroups in patterns of tau deposition and hippocampal atrophy, and 2) use the extracted surface-based features to predict cognitive decline. Using data obtained from different institutions, we develop a surface-based federated Chow test model to study the synergistic effects of APOE, a previously reported significant risk factor of AD, and tau on hippocampal surface morphometry. We illustrate that the APOE-specific morphometry features correlate with AD progression and better predict future AD conversion than other MRI biomarkers. For example, a strong association between atrophy and abnormal tau was identified in hippocampal subregion cornu ammonis 1 (CA1 subfield) and subiculum in e4 homozygote cohort. Our model allows for identifying MRI biomarkers for AD and cognitive decline prediction and may uncover a corner of the neural mechanism of the influence of APOE and tau deposition on hippocampal morphology.

Effect of electroacupuncture on the expression of Iba-1 in spinal dorsal horn and hippocampus of chronic pain rats with knee osteoarthritis

To observe the effect of electroacupuncture(EA) on pain-ralated behaviors, morphology of hippocampus, concentrations of inflammatory cytokines and expression of ionized calcium binding adapter molecule 1(Iba-1) in dorsal horn of the spinal cord and the hippocampus, and brain-derived neurotrophic factor (BDNF) in hippocampus of rats with knee osteoarthritis (KOA), so as to explore the mechanism of EA in improving chronic pain of KOA. Forty SD rats were randomly divided into blank group, saline group, model group and EA group, with 10 rats in each group. Monosodium iodoacetate(MIA, 80 mg/mL, 50 μL) was injected into the left knee joint cavity of rats in the model group and EA group to establish the chronic pain model of KOA, while the same volume of normal saline was injected into the left knee joint cavity of rats in the saline group. Rats in the EA group received EA stimulation(2 Hz/100 Hz, 1-2 mA) at left "Yanglingquan"(GB34) and "Neixiyan"(EX-LE4) for 15 min, 14 d after MIA injection. The treatment was given once daily, 5 d as 1 session and 2 sessions of treatment were required. Methanical withdrawl threshold(MWT) and weight-bearing capacity tests on left hind limbs were carried out 1 d before, 7 d，14 d, 20 d and 26 d after MIA injection. At the 27th day, rats were sacrificed and HE staining was used to observe the morphology of hippocampal CA1 area. Concentrations of interleukin(IL)-1β and tumor necrosis factor(TNF)-α in the left L3-L5 spinal dorsal horn and hippocampal CA1 area were detected by ELISA, the expressions of Iba-1 in the spinal dorsal horn and hippo-campal CA1 area were detected by immunofluorescence, and the expression of BDNF in left hippocampal CA1 area was detected by Western blot. The HE staining results of the hippocampal CA1 area showed reduced number of neurons, unclear cell contour and boundary between nucleus and cytoplasm, and nuclear pyknosis in the model group, which was relatively milder in the EA group. Compared with the blank group, MWT and weight-bearing capacity of rats' left hind limbs, and expression of BDNF protein in hippocampal CA1 area were significantly decreased (P<0.01), while the contents of IL-1β and TNF-α, the expression of Iba-1 in spinal dorsal horn and hippocampal CA1 area were significantly increased (P<0.01) in the model group. In comparison with the model group, MWT and weight-bearing capacity of rats' left hind limbs, and protein expression of BDNF in hippocampal CA1 area were significantly increased (P<0.01), while the contents of IL-1β and TNF-α, and the expression of Iba-1 protein in spinal dorsal horn and hippocampal CA1 area were significantly decreased after EA intervention(P<0.01). EA at GB34 and EX-LE4 can alleviate the pain-related behaviors of KOA rats. The mechanism might be related to the inhibition of inflammatory reaction mediated by microglia in spinal dorsal horn and hippocampus, and the up-regulation of BDNF expression in hippocampus.

Pre-Adolescent Diet Normalization Restores Cognitive Function in Young Mice.

Mastication is a fundamental function critical for human health. Controlled by the central nervous system (CNS), it influences CNS development and function. A poor masticatory performance causes cognitive dysfunction in both older adults and children. Improving mastication may prevent cognitive decline. However, no study has determined the period of masticatory dysfunction that impairs children's later acquisition of cognitive function. Herein, we developed an animal model wherein a soft diet was switched to a normal diet at early and late time points in young mice. We aimed to investigate the impact of restored mastication on learning and memory function. Behavioral studies were conducted to evaluate learning and memory. Micro-CT was used to evaluate orofacial structural differences, while histological and biochemical approaches were employed to assess differences in the hippocampal morphology and function. Correction to a hard-textured diet before adolescence restored mastication and cognitive function through the stimulation of neurogenesis, extracellular signal-regulated kinases, the cyclic adenosine monophosphate-response element-binding protein pathway, and the brain-derived neurotrophic factor, tyrosine receptor B. In contrast, post-adolescent diet normalization failed to rescue full mastication and led to impaired cognitive function, neuronal loss, and decreased hippocampal neurogenesis. These findings revealed a functional linkage between the masticatory and cognitive function in mice during the juvenile to adolescent period, highlighting the need for adequate food texture and early intervention for mastication-related cognitive impairment in children.

Purpurin ameliorates D-galactose-induced aging phenotypes in mouse hippocampus by reducing inflammatory responses

Purpurin, an anthraquinone, has potent anti-oxidant and anti-inflammatory effects in various types of brain damage. In a previous study, we showed that purpurin exerts neuroprotective effects against oxidative and ischemic damage by reducing pro-inflammatory cytokines. In the present study, we investigated the effects of purpurin against D-galactose-induced aging phenotypes in mice. Exposure to 100 mM D-galactose significantly decreased cell viability in HT22 cells, and purpurin treatment significantly ameliorated the reduction of cell viability, formation of reactive oxygen species, and lipid peroxidation in a concentration-dependent manner. Treatment with 6 mg/kg purpurin significantly improved D-galactose-induced memory impairment in the Morris water maze test in C57BL/6 mice and alleviated the reduction of proliferating cells and neuroblasts in the subgranular zone of the dentate gyrus. In addition, purpurin treatment significantly mitigated D-galactose-induced changes of microglial morphology in the mouse hippocampus and the release of pro-inflammatory cytokines such as interleukin-1β, interleukin-6, and tumor necrosis factor-α. In addition, purpurin treatment significantly ameliorated D-galactose-induced phosphorylation of c-Jun N-terminal kinase and cleavage of caspase-3 in HT22 cells. These results suggest that purpurin can delay aging by reducing the inflammatory cascade and phosphorylation of the c-Jun N-terminal in the hippocampus.

Levetiracetam attenuates diabetes-associated cognitive impairment and microglia polarization by suppressing neuroinflammation.

Introduction: Cognitive impairment is a common complication and comorbidity of diabetes. However, the underlying mechanisms of diabetes-associated cognitive dysfunction are currently unclear. M1 microglia secretes pro-inflammatory factors and can be marked by CD16, iNOS, Iba1 and TNF-ɑ. The decline of M2 microglia in the diabetic rats indicates that high glucose promotes the differentiation of microglia into the M1 type to trigger neuroinflammatory responses. Moreover, there is a lack of strong evidence for treatments of diabetes-associated cognitive impairment in addition to controlling blood glucose. Methods: Diabetic rats were established by intraperitoneal injection of one dose of streptozotocin (60mg/kg). Polarization transitions of microglia were induced by high glucose treatment in BV2 cells. Levetiracetam was orally administered to rats 72h after streptozotocin injection for 12weeks. Results: In STZ-induced diabetic rats, the results demonstrated that levetiracetam improved rat cognitive function (Morris water maze test) and hippocampus morphology (Hematoxylin-eosin staining), and the effect was more evident in the high-dose levetiracetam group. Microglia activation in the hippocampus was inhibited by levetiracetam treatment for 12 weeks. Serum levels of TNF-α, IL-1β, and IL-6 were reduced in the LEV-L and LEV-H groups, and IL-1β level was obviously reduced in the LEV-H group. In vitro, we found that levetiracetam 50µM attenuated high-glucose induced microglial polarization by increasing IL-10 level and decreasing IL-1β and TNF-α levels. Moreover, levetiracetam 50µM increased and decreased the proportion of CD206+/Iba1+ and iNOS+/Iba1+cells, respectively. Western blot analysis illustrated that LEV 50µM downregulated the expression of MyD88 and TRAF6, and phosphorylation of TAK1, JNK, p38, and NF-κB p65. The effect of levetiracetam on the anti-polarization and expression of p-JNK and p-NF-κB p65 were partly reversed by anisomycin (p38 and JNK activators). Discussion: Together, our data suggest that levetiracetam attenuates streptozotocin-induced cognitive impairment by suppressing microglia activation. The in vitro findings also indicate that the levetiracetam inhibited the polarization of microglia via the JNK/MAPK/NF-κB signaling pathway.

Pharmacological Modulation of Excitotoxicity through the Combined Use of NMDA Receptor Inhibition and Group III mGlu Activation Reduces TMT-Induced Neurodegeneration in the Rat Hippocampus.

We studied the neuroprotective properties of the non-competitive NMDA receptor antagonist memantine, in combination with a positive allosteric modulator of metabotropic glutamate receptors of Group III, VU 0422288. The treatment was started 48 h after the injection of neurotoxic agent trimethyltin (TMT) at 7.5 mg/kg. Three weeks after TMT injection, functional and morphological changes in a rat hippocampus were evaluated, including the expression level of genes characterizing glutamate transmission and neuroinflammation, animal behavior, and hippocampal cell morphology. Significant neuronal cell death occurred in the CA3 and CA4 regions, and to a lesser extent, in the CA1 and CA2 regions. The death of neurons in the CA1 field was significantly reduced in animals with a combined use of memantine and VU 0422288. In the hippocampus of these animals, the level of expression of genes characterizing glutamatergic synaptic transmission (Grin2b, Gria1, EAAT2) did not differ from the level in control animals, as well as the expression of genes characterizing neuroinflammation (IL1b, TGF beta 1, Aif1, and GFAP). However, the expression of genes characterizing neuroinflammation was markedly increased in the hippocampus of animals treated with memantine or VU 0422288 alone after TMT. The results of immunohistochemical studies confirmed a significant activation of microglia in the hippocampus three weeks after TMT injection. In contrast to the hilus, microglia in the CA1 region had an increase in rod-like cells. Moreover, in the CA1 field of the hippocampus of the animals of the MEM + VU group, the amount of such microglia was close to the control. Thus, the short-term modulation of glutamatergic synaptic transmission by memantine and subsequent activation of Group III mGluR significantly affected the dynamics of neurodegeneration in the hippocampus.

Integrin β3 regulates apical dendritic morphology of pyramidal neurons throughout hippocampal CA3.

In excitatory hippocampal pyramidal neurons, integrin β3 is critical for synaptic maturation and plasticity in vitro. Itgb3 is a potential autism susceptibility gene that regulates dendritic morphology in the cerebral cortex in a cell-specific manner. However, it is unknown what role Itgb3 could have in regulating hippocampal pyramidal dendritic morphology in vivo, a key feature that is aberrant in many forms of autism and intellectual disability. We found that Itgb3 mRNA is expressed in the stratum pyramidale of CA3. We examined the apical dendritic morphology of CA3 hippocampal pyramidal neurons in conditional Itgb3 knockouts and controls, utilizing the Thy1-GFP-M line. We fully reconstructed the apical dendrite of each neuron and determined each neuron's precise location along the dorsoventral, proximodistal, and radial axes of the stratum pyramidale. We found a very strong effect for Itgb3 expression on CA3 apical dendritic morphology: neurons from conditional Itgb3 knockouts had longer and thinner apical dendrites than controls, particularly in higher branch orders. We also assessed potential relationships between pairs of topographic or morphological variables, finding that most variable pairs were free from any linear relationships to each other. We also found that some neurons from controls, but not conditional Itgb3 knockouts, had a graded pattern of overall diameter along the dorsoventral and proximodistal axes of the stratum pyramidale of CA3. Taken together, Itgb3 is essential for constructing normal dendritic morphology in pyramidal neurons throughout CA3.

The effects of kindling during pregnancy on long-term potentiation (LTP) induction and M1 muscarinic acetylcholine receptors in male rat offspring.

Neonates of pregnant women with epilepsy may compromise normal neurodevelopment and hippocampal morphology. Memory and learning disorders and a decrease in verbal IQ scores are seen in these children later in life. In the previous study, we suggested that the central muscarinic cholinergic receptors had an important role in learning and memory deficits induced by prenatal pentylenetetrazol-kindling in pups born to kindled mothers. This study aimed to investigate the effects of kindling during pregnancy on long-term potentiation (LTP) induction and the role of M1 muscarinic acetylcholine receptors in the hippocampus of male offspring. Twenty female Wistar rats were divided into two groups on the 13th day of their gestation (kindled and control; n = 10). Animals in the first group were kindled by i.p. injections of 25 mg/kg body weight pentylenetetrazol every 15 min until seizures occurred and the control group received normal saline. The effect of maternal seizures and perfusion of specific M1 muscarinic receptors antagonist (telenzepine at doses of 0.01, 0.1, and 1 nmol) on the LTP induction of 80 pups were tested at 12 weeks of age by field potential recordings. The results of the electrophysiological study revealed that recurrent seizures during pregnancy impaired field excitatory postsynaptic potentials (fEPSP)-LTP induction and normal development of M1 muscarinic receptors in the hippocampus of male offspring. Also, the results demonstrated that maternal seizure did not significantly affect the paired-pulse indexes and population spike-LTP in the hippocampus of male offspring. Our study showed that recurrent seizures during pregnancy cause impaired fEPSP-LTP induction and abnormal development of the M1 muscarinic receptor in the hippocampus.