The hippocampus participates in the control of locomotion speed

Walk Locomotion Kinematic Changes in a Model of Penetrating Hippocampal Injury in Male/Female Mice and Rats

Traumatic brain injury has been the leading cause of mortality and morbidity in human beings. One of the most susceptible structures to this damage is the hippocampus due to cellular and synaptic loss and impaired hippocampal connectivity to the brain, brain stem, and spinal cord. Thus, hippocampal damage in rodents using a stereotaxic device could be an adequate method to study a precise lesion from CA1 to the dentate gyrus structures. We studied male and female rats and mice, analyzing hindlimb locomotion kinematics changes to compare the locomotion kinematics using the same methodology in rodents. We measure (1) the vertical hindlimb metatarsus, ankle, and knee joint vertical displacements (VD) and (2) the factor of dissimilarity (DF). The VD in intact rats in metatarsus, ankle, and knee joints differs from that in intact mice in similar joints. In rats, the vertical displacement through the step cycle changed in the left and right metatarsus, ankle, and knee joints compared to the intact group versus the lesioned group. More subtle changes were also observed in mice. DF demonstrates contrasting results when studying locomotion kinematics of mice or rats and sex-dependent differences. Thus, a precise lesion in a rodent's hippocampal structure discloses some hindlimb locomotion changes related to species and sex. Thus, we only have a qualitative comparison between murine species. In order to make a comparison with other species, we should standardize the model.

Neuroprotective effects of pre-ischemic exercise are linked to expression of NT-3/NT-4 and TrkB/TrkC in rats

INTRODUCTION AND OBJECTIVE

Stroke causes irreversible damage, particularly to the hippocampus. Evidence suggests that exercise training may mitigate adverse structural and functional consequences of an ischemic lesion in the brain. The purpose of this study was to investigate the effects of preconditioning exercise on expression of neurotrophic factor genes and proteins in hippocampalCA1 region and their relationship with sensorimotor recovery following global ischemia/reperfusion (Is/Re) injury in a rat model of stroke.

METHODS

Male Wistar rats were randomly assigned to Exercise+Ischemia/Reperfusion (Ex+Is/Re),Control+Ischemia/Reperfusion (Co+Is/Re), and Sham treatments. Rats in the exercise groups ran on a treadmill for 45 min/d for five days/week for 8 consecutive weeks prior to Is/Re lesion.Ischemia was induced by common carotid artery occlusion (CCAO). The ladder rung walking task was used to assess functional impairments and recovery following ischemic lesion.Tissue from hippocampal area CA1 was inspected for ischemia-induced cell loss and gene and protein expression linked to neurotrophins NT-3, NT-4, and their receptorsTrkB and TrkC.

RESULTS

CCAO caused hippocampal cell death in CA1 and resulted in significant sensori motor impairments in the ladder rung walking task. In contrast, pre-ischemic exercise considerably reduced cell death and supported sensorimotor recovery following CCAO.In addition, NT-3, NT-4,TrkB and TrkC gene expression and their protein levels were significantly increased inthe Ex+Is/Re group compared to Co+Is/Re (p < 0.05).

CONCLUSION

The findings showed that pre-ischemic exercise can exert neuroprotective effects via NT-3 and NT-4 pathways against ischemia in hippocampal CA1 neurons and promote post-injury sensorimotor recovery.

Toxicity of internalized polyalanine to cells depends on aggregation

In polyalanine (PA) diseases, the disease-causing transcription factors contain an expansion of alanine repeats. While aggregated proteins that are responsible for the pathogenesis of neurodegenerative disorders show cell-to-cell propagation and thereby exert toxic effects on the recipient cells, whether this is also the case with expanded PA has not been studied. It is also not known whether the internalized PA is toxic to recipient cells based on the degree of aggregation. In this study, we therefore prepared different degrees of aggregation of a peptide having 13 alanine repeats without flanking sequences of PA disease-causative proteins (13A). The aggregated 13A was spontaneously taken up by neuron-like cultured cells. Functionally, strong aggregates but not weak aggregates displayed a deficit in neuron-like differentiation in vitro. Moreover, the injection of strong but not weak 13A aggregates into the ventricle of mice during the neonatal stage led to enhanced spontaneous motor activity later in life. Thus, PA in the extracellular space has the potential to enter adjacent cells, and may exert toxicity depending on the degree of aggregation.

Female dominance of both spatial cognitive dysfunction and neuropsychiatric symptoms in a mouse model of Alzheimer's disease

Alzheimer’s disease (AD) is a prevalent neurological disorder affecting memory function in elderly persons. Indeed, AD exhibits abnormality in cognitive behaviors and higher susceptibility to neuropsychiatric symptoms (NPS). Various factors including aging, sex difference and NPS severity, are implicated during in development of AD. In this study, we evaluated behavioral abnormalities of AD model, PDAPP transgenic mice at young age using the Morris Water Maze test, which was established to assess hippocampal-dependent learning and memory. We found that female AD model mice exhibited spatial learning dysfunction and highly susceptible to NPS such as anxiety and depression, whereas spatial reference memory function was comparable in female PDAPP Tg mice to female wild type (WT) mice. Spatial learning function was comparable in male AD model mice to male WT mice. Multiple regression analysis showed that spatial learning dysfunction was associated with NPS severity such as anxiety and depression. Furthermore, the analysis showed that spatial reference memory function was associated with status of depression, but not anxiety. Thus, these results suggest female dominance of spatial learning dysfunction in the AD model mice accompanying increased NPS severity. The understandings of AD model may be useful for the development of therapeutic agents and methods in human AD.

Dementia model mice exhibited improvements of neuropsychiatric symptoms as well as cognitive dysfunction with neural cell transplantation

Elderly patients with dementia suffer from cognitive dysfunctions and neuropsychiatric symptoms (NPS) such as anxiety and depression. Alzheimer’s disease (AD) is a form of age-related dementia, and loss of cholinergic neurons is intimately associated with development of AD symptoms. We and others have reported that neural cell transplantation ameliorated cognitive dysfunction in AD model mice. It remains largely unclear whether neural cell transplantation ameliorates the NPS of AD. It would be interesting to determine whether NPS correlates with cognitive dysfunctions before and after neural cell transplantation in AD model mice. Based on the revalidation of our previous data from a Morris water maze test, we found that neural cell transplantation improved anxiety and depression significantly and marginally affected locomotion activity in AD mice. A correlation analysis revealed that the spatial learning function of AD mice was correlated with their NPS scores both before and after cell transplantation in a similar manner. In contrast, in the mice subjected to cell transplantation, spatial reference memory function was not correlated with NPS scores. These results suggested the neural cell transplantation in the AD model mice significantly improved NPS to the same degree as cognitive dysfunctions, possibly via distinct mechanisms, such as the cholinergic and GABAergic systems.

Structural and functional brain signatures of endurance runners

Although endurance running (ER) seems to be a simple repetitive exercise, good ER performance also requires and relies on multiple cognitive and motor control processes. Most of previous neuroimaging studies on ER were conducted using a single MRI modality, yet no multimodal study to our knowledge has been performed in this regard. In this study, we used multimodal MRI data to investigate the brain structural and functional differences between endurance runners (n = 22; age = 26.27 ± 6.07 years; endurance training = 6.23 ± 2.41 years) and healthy controls (HCs; n = 20; age = 24.60 ± 4.14 years). Compared with the HCs, the endurance runners showed greater gray matter volume (GMV) and cortical surface area in the left precentral gyrus, which at the same time had higher functional connectivity (FC) with the right postcentral and precentral gyrus. Subcortically, the endurance runners showed greater GMV in the left hippocampus and regional inflation in the right hippocampus. Using the bilateral hippocampi as seeds, further seed-based FC analyses showed higher hippocampal FC with the supplementary motor area, middle cingulate cortex, and left posterior lobe of the cerebellum. Moreover, compared with the HCs, the endurance runners also showed higher fractional anisotropy in several white matter regions, involving the corpus callosum, left internal capsule, left corona radiata, left external capsule, left posterior lobe of cerebellum and bilateral precuneus. Taken together, our findings provide several lines of evidence for the brain structural and functional differences between endurance runners and HCs. The current data suggest that these brain characteristics may have arisen as a result of regular ER training; however, whether they represent the neural correlates underlying the good ER performances of the endurance runners requires further investigations.

Curcumin supplementation shows modulatory influence on functional and morphological features of hippocampus in mice subjected to arsenic trioxide exposure

Since, oxidative stress has been suggested as one of the mechanisms underlying arsenic-induced toxicity, the present study focused on the role of antioxidant (curcumin) supplementation on behavioral, biochemical, and morphological alterations with context to mice hippocampus (CA1) following arsenic trioxide (As₂O₃) administration. Healthy male Swiss albino mice were divided into control and experimental groups. As₂O₃ (2 mg/kg bw) alone or along with curcumin (100 mg/kg bw) was administered to experimental groups by oral route for 45 days whereas the control groups received either no treatment or vehicle for curcumin. Animals were subjected to behavioral study towards the end of the experimental period (day 33-45). On day 46, the brain samples were obtained and subjected either to immersion fixation (for morphometric observations) or used afresh for biochemical test. Behavioral tests (open field, elevated plus maze, and Morris water maze) revealed enhanced anxiety levels and impairment of cognitive functions in As₂O₃ alone treated groups whereas a trend of recovery was evident in mice simultaneously treated with As₂O₃ and curcumin. Morphological observations showed noticeable reduction in stratum pyramidale thickness (CA1), along with decrease in density and size of pyramidal neurons in As₂O₃ alone exposed group as compared to As₂O₃+Cu co-treated group. Hippocampal glutathione levels were found to be downregulated in animals receiving As₂O₃ as against the levels of controls and curcumin supplemented animals, thereby, suggestive of beneficial role of curcumin on As₂O₃ induced adverse effects.

Hippocampal subfields and decline in activities of daily living in Alzheimer's disease and dementia with Lewy bodies

Background: Hippocampal atrophy is presented in Alzheimer's disease (AD) and dementia with Lewy bodies (DLB). Cognition, dual-tasks, muscular function, goal-related behaviors and neuropsychiatric symptoms are linked to hippocampal volumes and may lead to functional decline in activities of daily living. We examined the association between baseline hippocampal subfield volumes (HSv) in mild AD and DLB, and functional decline. Materials & methods: 12 HSv were computed from structural magnetic resonance images using Freesurfer 6.0 segmentation. Functional decline was assessed using the rapid disability rating scale score. Linear regressions were conducted. Results: In AD, HSv were smaller bilaterally. However, HSv were not associated with functional decline. Conclusion: Functional decline does not depend on HSv in mild AD and DLB.

Kinematic Changes in a Mouse Model of Penetrating Hippocampal Injury and Their Recovery After Intranasal Administration of Endometrial Mesenchymal Stem Cell-Derived Extracellular Vesicles

Locomotion speed changes appear following hippocampal injury. We used a hippocampal penetrating brain injury mouse model to analyze other kinematic changes. We found a significant decrease in locomotion speed in both open-field and tunnel walk tests. We described a new quantitative method that allows us to analyze and compare the displacement curves between mice steps. In the tunnel walk, we marked mice with indelible ink on the knee, ankle, and metatarsus of the left and right hindlimbs to evaluate both in every step. Animals with hippocampal damage exhibit slower locomotion speed in both hindlimbs. In contrast, in the cortical injured group, we observed significant speed decrease only in the right hindlimb. We found changes in the displacement patterns after hippocampal injury. Mesenchymal stem cell-derived extracellular vesicles had been used for the treatment of several diseases in animal models. Here, we evaluated the effects of intranasal administration of endometrial mesenchymal stem cell-derived extracellular vesicles on the outcome after the hippocampal injury. We report the presence of vascular endothelial growth factor, granulocyte–macrophage colony-stimulating factor, and interleukin 6 in these vesicles. We observed locomotion speed and displacement pattern preservation in mice after vesicle treatment. These mice had lower pyknotic cells percentage and a smaller damaged area in comparison with the nontreated group, probably due to angiogenesis, wound repair, and inflammation decrease. Our results build up on the evidence of the hippocampal role in walk control and suggest that the extracellular vesicles could confer neuroprotection to the damaged hippocampus.

Chronic sub-anesthetic ketamine induces permanent hypolocomotion and impairment of hippocampus in adolescent cynomolgus monkeys

Ketamine has gained increasing popularity in adolescent drug abusers worldwide. However, relatively little is known about the long-term effects of recreational ketamine on adolescent hippocampus. The present study investigates the effects of different periods (1, 3 and 6 months) of recreational ketamine administration on locomotor activity and neuron damage in the hippocampus of adolescent cynomolgus monkeys. 32 4-year-old male cynomolgus monkeys were divided into control, 1-month, 3-month and 6-month groups. All animals in ketamine groups received daily intravenous injection with 1 mg/kg ketamine in saline for respective 1, 3 or 6 months while control group received normal saline. Automatic behaviors were recorded for 10 min before and after ketamine and saline administration. Meanwhile, the markers of apoptosis in the hippocampus were assessed using terminal deoxynucleotidyl transferase-mediated biotinylated dUTP nick end labeling (TUNEL), electron microscopy and western blotting. Results showed that ketamine significantly decreased locomotor activity, increased apoptotic neurons and pro-apoptotic proteins, cleaved Caspase-3 and Bax, while decreased the anti-apoptotic protein Bcl-2 in the hippocampus after 6-month ketamine administration. Our study suggested that chronically recreational ketamine might induce hypolocomotion and neurotoxic effect via apoptotic pathway in adolescent hippocampus of monkeys.

Kinematic Locomotion Changes in C57BL/6 Mice Infected with Toxoplasma Strain ME49

Chronic infection with the intracellular parasite Toxoplasma gondii produces an accumulation of cysts in the brain and muscle, causing tissue damage. The cysts in the brain motor regions affect some kinematic locomotion parameters in the host. To localize the brain cysts from Toxoplasma gondii and study the changes in kinematic locomotion in C57BL/6 mice. Female adult C57BL/6 mice were infected orally with 30 ME-49 Toxoplasma gondii cysts. An uninfected group (n = 7) and two infected groups, examined 15 and 40 days postinfection, were used for this study. To evaluate kinematic locomotion, the mice were marked with indelible ink on the iliac crest, hip, knee, ankle, and phalangeal metatarsus of the left and right hindlimbs. At least three recordings were carried out to obtain videos of the left and right hindlimbs. Mice were video recorded at 90 fps at a resolution of 640 × 480 pixels while walking freely in a transparent Plexiglass tunnel. We measured the hindlimb pendular movement and the hindlimb transfer [linear displacement] curves for each step and evaluated them statistically with Fréchet dissimilarity tests. Afterward, the mice were sacrificed, and the brain, heart, skeletal muscle, lung, liver, and kidney were obtained. The different tissues were stained with hematoxylin and eosin for analysis with optical microscopy. Topographic localization of the cysts was made using bregma coordinates for the mouse brain. The cysts were distributed in several brain regions. In one mouse, cyst accumulation occurred in the hippocampus, coinciding with an alteration in foot displacement. The step length was different among the different studied groups.

CAVE: An Open-Source Tool for Combined Analysis of Head-Mounted Calcium Imaging and Behavior in MATLAB

Calcium imaging in freely behaving rodents using head-mounted miniature microscopes is currently becoming an increasingly popular technique in neuroscience. Due to the large amounts of complex data that the technique produces, user friendly software is needed for quick and efficient processing. Here, we present a new tool for analyzing calcium imaging data from head-mounted microscopes together with simultaneously acquired behavioral data: CAVE (Calcium ActiVity Explorer). CAVE bundles a unique set of algorithms specifically tailored to the analysis of single-photon imaging data from awake behaving animals including efficient motion correction and automatic ROI selection with manual audit and refinement. For behavioral analysis, CAVE can automatically track animal position and orientation. Individual behavioral epochs and external events can then be analyzed in correlation to calcium imaging and tracking data. Our program is written in MATLAB, the source code is open source and particularly focuses on providing a streamlined workflow for novice users while also retaining detailed configuration options for advanced users. We evaluate the performance of CAVE by investigating neural activity in hippocampus and somatosensory cortex. The fast analysis provided by CAVE allowed us to track activity in a large set of animals over the course of several months during exploration behavior, detailing the properties of onset and offset of observable activity and the visible cells per imaging location.

Differences Between Men and Women in Balance and Tremor in Relation to Plantar Fascia Laxity During the Menstrual Cycle

CONTEXT

  Although much attention has been paid to the effect of estrogen on the knee ligaments, little has been done to examine the ligaments in the foot, such as the plantar fascia, and how they may be altered during the menstrual cycle.

OBJECTIVE

  To (1) examine sex differences in plantar fascia thickness and laxity and postural sway and (2) identify any menstrual cycle effects on plantar fascia laxity, postural sway, and neuromuscular tremor between menstruation and the ovulation phase.

DESIGN

  Case-control study.

SETTING

  Research laboratory.

PATIENTS OR OTHER PARTICIPANTS

  Fifteen healthy women (age = 25.9 ± 1.8 years) and 15 healthy men (age = 27.3 ± 2.0 years) volunteered to participate in this study.

INTERVENTION(S)

  We asked participants to perform 8 balance tasks on a force platform while we assessed postural sway and tremor.

MAIN OUTCOME MEASURE(S)

  Plantar fascia length and thickness unloaded and loaded with body weight were measured via ultrasound. Postural sway and tremor were measured using a force platform.

RESULTS

  Plantar fascia length and thickness with pressure were greater in ovulating women compared with men ( P < .001), but no differences were found between women during menstruation and men. Postural sway and tremor were greater at ovulation than during menstruation ( P < .05), and men had less sway than ovulating women on the 3 most difficult balance tasks ( P < .01).

CONCLUSIONS

  Plantar fascia laxity was increased and postural sway and tremor were decreased at ovulation compared with menstruation in women. Postural sway and tremor in men were the same as in women during menstruation. These findings support the need to be aware of the effect of sex hormones on balance to prevent lower extremity injuries during sport activities.

Metastatic human breast cancer to the spine produces mechanical hyperalgesia and gait deficits in rodents

BACKGROUND CONTEXT

Metastases to the spine are a common source of severe pain in cancer patients. The secondary effects of spinal metastases include pain, bone fractures, hypercalcemia, and neurological deficits. As the disease progresses, pain severity can increase until it becomes refractory to medical treatments and leads to a decreased quality of life for patients. A key obstacle in the study of pain-induced spinal cancer is the lack of reliable and reproducible spine cancer animal models. In the present study, we developed a reproducible and reliable rat model of spinal cancer using human-derived tumor tissue to evaluate neurological decline using imaging and behavioral techniques.

PURPOSE

The present study outlines the development and characterization of an orthotopic model of human breast cancer to the spine in immunocompromised rats.

STUDY DESIGN/SETTING

This is a basic science study.

METHODS

Female immunocompromised rats were randomized into three groups: tumor (n=8), RBC3 mammary adenocarcinoma tissue engrafted in the L5 vertebra body; sham (n=6), surgery performed but not tumor engrafted; and control (n=6), naive rats, no surgery performed. To evaluate the neurological impairment due to tumor invasion, functional assessment was done in all rodents at day 40 after tumor engraftment using locomotion gait analysis and pain response to a mechanical stimulus (Randall-Selitto test). Bioluminescence (BLI) was used to evaluate tumor growth in vivo and cone beam computed tomography (CBCT) was performed to evaluate bone changes due to tumor invasion. The animals were euthanized at day 45 and their spines were harvested and processed for hematoxylin and eosin (H&E) staining.

RESULTS

Tumor growth in the spine was confirmed by BLI imaging and corroborated by histological analysis. Cone beam computed tomography images were characterized by a decrease in the bone intensity in the lumbar spine consistent with tumor location on BLI. On H&E staining of tumor-engrafted animals, there was a near-complete ablation of the ventral and posterior elements of the L5 vertebra with severe tumor invasion in the bony components displacing the spinal cord. Locomotion gait analysis of tumor-engrafted rats showed a disruption in the normal gait pattern with asignificant reduction in length (p=.02), duration (p=.002), and velocity (p=.002) of right leg strides and only in duration (p=.0006) and velocity (p=.001) of left leg strides, as compared with control and sham rats. Tumor-engrafted animals were hypersensitive to pain stimulus shown as a significantly reduced response in time (p=.02) and pressure (p=.01) applied when compared with control groups.

CONCLUSIONS

We developed a system for the quantitative analysis of pain and locomotion in an animal model of metastatic human breast cancer of the spine. Tumor-engrafted animals showed locomotor and sensory deficits that are in accordance with clinical manifestation in patients with spine metastasis. Pain response and locomotion gait analysis were performed during follow-up. The Randall-Selitto test was a sensitive method to evaluate pain in the rat's spine. We present a model for the study of bone-associated cancer pain secondary to cancer metastasis to the spine, as well as for the study of new therapies and treatments to lessen pain from metastatic cancer to the neuroaxis.

Locomotion in intact and in brain cortex-ablated cats

The current decerebration procedures discard the role of the thalamus in the motor control and decortication only rules out the brain cortex part, leaving a gap between the brain cortex and the subthalamic motor regions. In here we define a new preparation denominated Brain Cortex-Ablated Cat (BCAC), in which the frontal and parietal brain cortices as well as the central white matter beneath them were removed, this decerebration process may be considered as suprathalamic, since the thalamus remained intact. To characterize this preparation cat hindlimb electromyograms (EMG), kinematics and cutaneous reflexes (CR) produced by electrical stimulation of sural (SU) or saphenous (SAPH) nerves were analyzed during locomotion in intact and in BCAC. In cortex-ablated cats compared to intact cats, the hindlimb EMG amplitude was increased in the flexors, whereas in most extensors the amplitude was decreased. Bifunctional muscle EMGs presented complex and speed-dependent amplitude changes. In intact cats CR produced an inhibition of extensors, as well as excitation and inhibition of flexors, and a complex pattern of withdrawal responses in bifunctional muscles. The same stimuli applied to BCAC produced no detectable responses, but in some cats cutaneous reflexes produced by electrical stimulation of saphenous nerve reappeared when the locomotion speed increased. In BCAC, EMG and kinematic changes, as well as the absence of CR, imply that for this cat preparation there is a partial compensation due to the subcortical locomotor apparatus generating close to normal locomotion.

Quantitative analysis of hindlimbs locomotion kinematics in spinalized rats treated with Tamoxifen plus treadmill exercise

Locomotion recovery after a spinal cord injury (SCI) includes axon regeneration, myelin preservation and increased plasticity in propriospinal and descending spinal circuitries. The combined effects of tamoxifen and exercise after a SCI were analyzed in this study to determine whether the combination of both treatments induces the best outcome in locomotion recovery. In this study, the penetrating injury was provoked by a sharp projectile that penetrates through right dorsal and ventral portions of the T13-L1 spinal segments, affecting propriospinal and descending/ascending tracts. Intraperitoneal application of Tamoxifen and a treadmill exercise protocol, as rehabilitation therapies, separately or combined, were used. To evaluate the functional recovery, angular patterns of the hip, knee and ankle joints as well as the leg pendulum-like movement (PLM) were measured during the unrestricted gait of treated and untreated (UT) animals, previously and after the traumatic injury (15 and 30days post-injury (dpi)). A pattern (curve) comparison analysis was made by using a locally designed Matlab script that determines the Frechet dissimilarity. The SCI magnitude was assessed by qualitative and quantitative histological analysis of the injury site 30days after SCI. Our results showed that all treated groups had an improvement in hindlimbs kinematics compared to the UT group, which showed a poor gait locomotion recovery throughout the rehabilitation period. The group with the combined treatment (tamoxifen+exercise (TE)) presented the best outcome. In conclusion, tamoxifen and treadmill exercise treatments are complementary therapies for the functional recovery of gait locomotion in hemi-spinalized rats.