Weightlessness in the space environment affects astronauts' learning memory and cognitive function. Repetitive transcranial magnetic stimulation has been shown to be effective in improving cognitive dysfunction. In this study, we investigated the effects of repetitive transcranial magnetic stimulation on neural excitability and ion channels in simulated weightlessness mice from a neurophysiological perspective. Young C57 mice were divided into control, hindlimb unloading and magnetic stimulation groups. The mice in the hindlimb unloading and magnetic stimulation groups were treated with hindlimb unloading for 14 days to establish a simulated weightlessness model, while the mice in the magnetic stimulation group were subjected to 14 days of repetitive transcranial magnetic stimulation. Using isolated brain slice patch clamp experiments, the relevant indexes of action potential and the kinetic property changes of voltage-gated sodium and potassium channels were detected to analyze the excitability of neurons and their ion channel mechanisms. The results showed that the behavioral cognitive ability and neuronal excitability of the mice decreased significantly with hindlimb unloading. Repetitive transcranial magnetic stimulation could significantly improve the cognitive impairment and neuroelectrophysiological indexes of the hindlimb unloading mice. Repetitive transcranial magnetic stimulation may change the activation, inactivation and reactivation process of sodium and potassium ion channels by promoting sodium ion outflow and inhibiting potassium ion, and affect the dynamic characteristics of ion channels, so as to enhance the excitability of single neurons and improve the cognitive damage and spatial memory ability of hindlimb unloading mice.
Animals ; Mice ; Transcranial Magnetic Stimulation ; Hindlimb Suspension ; Neurons ; Cognitive Dysfunction ; Brain

OBJECTIVE: To introduce a modified protocol for generating the simulated weightlessness rat model by hindlimb unloading. METHODS: Ninety male adult SD rats were randomly divided into three groups: the control group, classical suspension group and modified suspension group (n=30/group). In the classical suspension group, a strip of medical adhesive tape was attached to the tail, with horizontal filament tape wrapping. A piece of gauze was wrapped around the tail at the outermost layer and the tail was suspended for hindlimb unloading. In the modified suspension group, a layer of plastic net was added between the horizontal filament tape and the gauze to reduce the squeeze on the tail as a buffer zone and ensure proper circulation of the tail. After 4 weeks of suspension, damage to the tail and sheath detachment were observed. Meanwhile the body weight and right soleus wet weight of rats were measured. RESULTS: The ratio of right soleus wet weight to body weight was decreased significantly in both the classical suspension group and the modified suspension group compared with the control group, while there was no difference in body weight among the three different groups. Importantly, the incidence of tail ischemia and necrosis (13.3% vs 40.0% in the classical suspension group) and the incidence of sheath detachment from tail (3.3% vs 26.7% in the classical suspension group) were significantly lower whereas the success rates of model (33.3% vs 83.3% in classical suspension group) was significantly higher in the modified suspension group. CONCLUSION The modified protocol decreases the incidence of tail necrosis and sheath detachment in the rat tail suspension and increases the success rate of the hindlimb unloading rat model, with improved simplicity and practicability.
Animals ; Hindlimb Suspension ; Male ; Muscle, Skeletal ; Random Allocation ; Rats ; Rats, Sprague-Dawley ; Weightlessness Simulation ; methods

OBJECTIVE: Sequelae of behavioral impairments associated with human traumatic brain injury (TBI) include neurobehavioral problems. We compared exploratory, cognitive, and depressive-like behaviors in pediatric and adult male mice exposed to controlled cortical impact (CCI).METHODS: Pediatric (21 to 25 days old) and adult (8 to 12 weeks old) male C57Bl/6 mice underwent CCI at a 2-mm depth of deflection. Hematoxylin and eosin staining was performed 3 to 7 days after recovery from CCI, and injury volume was analyzed using ImageJ. Neurobehavioral characterization after CCI was performed using the Barnes maze test (BMT), passive avoidance test, open-field test, light/dark test, tail suspension test, and rotarod test. Acutely and subacutely (3 and 7 days after CCI, respectively), CCI mice showed graded injury compared to sham mice for all analyzed deflection depths.RESULTS: Time-dependent differences in injury volume were noted between 3 and 7 days following 2-mm TBI in adult mice. In the BMT, 2-mm TBI adults showed spatial memory deficits compared to sham adults (P < 0.05). However, no difference in spatial learning and memory was found between sham and 2-mm CCI groups among pediatric mice. The open-field test, light/dark test, and tail suspension test did not reveal differences in anxiety-like behaviors in both age groups.CONCLUSION: Our findings revealed a graded injury response in both age groups. The BMT was an efficient cognitive test for assessing spatial/non-spatial learning following CCI in adult mice; however, spatial learning impairments in pediatric mice could not be assessed.
Adult ; Animals ; Brain Injuries ; Eosine Yellowish-(YS) ; Hematoxylin ; Hindlimb Suspension ; Humans ; Learning ; Male ; Memory ; Mice ; Rotarod Performance Test ; Spatial Learning ; Spatial Memory

A recent study reveals that missense mutations of EWSR1 are associated with neurodegenerative disorders such as amyotrophic lateral sclerosis, but the function of wild-type (WT) EWSR1 in the central nervous system (CNS) is not known yet. Herein, we investigated the neuroanatomical and motor function changes in Ewsr1 knock out (KO) mice. First, we quantified neuronal nucleus size in the motor cortex, dorsal striatum and hippocampus of three different groups: WT, heterozygous Ewsr1 KO (+/−), and homozygous Ewsr1 KO (−/−) mice. The neuronal nucleus size was significantly smaller in the motor cortex and striatum of homozygous Ewsr1 KO (−/−) mice than that of WT. In addition, in the hippocampus, the neuronal nucleus size was significantly smaller in both heterozygous Ewsr1 KO (+/−) and homozygous Ewsr1 KO (−/−) mice. We then assessed motor function of Ewsr1 KO (−/−) and WT mice by a tail suspension test. Both forelimb and hindlimb movements were significantly increased in Ewsr1 KO (−/−) mice. Lastly, we performed immunohistochemistry to examine the expression of TH, DARPP-32, and phosphorylated (p)-DARPP-32 (Thr75) in the striatum and substantia nigra, which are associated with dopaminergic signaling. The immunoreactivity of TH and DARPP-32 was decreased in Ewsr1 KO (−/−) mice. Together, our results suggest that EWSR1 plays a significant role in neuronal morphology, dopaminergic signaling pathways, and motor function in the CNS of mice.
Amyotrophic Lateral Sclerosis ; Animals ; Central Nervous System ; Dopamine ; Forelimb ; Hindlimb ; Hindlimb Suspension ; Hippocampus ; Immunohistochemistry ; Mice* ; Motor Cortex ; Mutation, Missense ; Neurodegenerative Diseases ; Neurons ; RNA* ; RNA-Binding Proteins* ; Substantia Nigra

Depression causes mental and physical changes which affect quality of life. It is estimated to become the second most prevalent disease, but despite its commonness, the pathophysiology of depression remains unclear and medicine is not sufficiently protective. p-Coumaric acid (p-CA) is a dietary phenolic acid which has been proven to have antifungal, anti-HIV, anti-melanogenic, antioxidant and anti-inflammatory effects. Considering these effects, we investigated whether p-CA can prevent depressive symptoms by reducing inflammatory cytokines in animals injected with lipopolysaccharide (LPS). Changes in despair-related behaviors, inflammatory cytokines, neurotrophic factors and synaptic activity were measured. In these animals, p-CA improved despair-related behavioral symptoms induced by LPS in the forced swim test (FST), tail suspension test (TST) and sucrose splash test (SST). p-CA also prevented the increase of inflammatory cytokines in the hippocampus such as cycloxigenase-2 and tumor necrosis factor-α due to LPS. Similarly, it prevented the reduction of brain-derived neurotrophic factor (BDNF) by LPS. Electrophysiologically, p-CA blocked the reduction of long-term depression in LPS-treated organotypic tissue slices. In conclusion, p-CA prevented LPS-induced depressive symptoms in animals, as determined by behavioral, biochemical and electrophysiological measures. These findings suggest the potential use of p-CA as a preventive and therapeutic medicine for depression.
Animals ; Behavioral Symptoms ; Brain-Derived Neurotrophic Factor ; Cytokines ; Depression ; Hindlimb Suspension ; Hippocampus ; Necrosis ; Nerve Growth Factors ; Phenol ; Quality of Life ; Rats* ; Sucrose

Chemotherapeutic agents induce long-term side effects, including cognitive impairment and mood disorders, particularly in breast cancer survivors who have undergone chemotherapy. However, the precise mechanisms underpinning chemotherapy-induced hippocampal dysfunction remain unknown. In this study, we investigated the detrimental effects of chronic treatment with a combination of adriamycin and cyclophosphamide (AC) on the neuronal architecture and functions of the hippocampi of female C57BL/6 mice. After chronic AC administration, mice showed memory impairment (measured using a novel object recognition memory task) and depression-like behavior (measured using the tail suspension test and forced swim test). According to Golgi staining, chronic AC treatment significantly reduced the total dendritic length, ramification, and complexity as well as spine density and maturation in hippocampal neurons in a sub-region-specific manner. Additionally, the AC combination significantly reduced adult neurogenesis, the extent of the vascular network, and the levels of hippocampal angiogenesis-related factors. However, chronic AC treatment did not increase the levels of inflammation-related signals (microglial or astrocytic distribution, or the levels of pro-inflammatory cytokines or M1/M2 macrophage markers). Thus, chronic AC treatment changed the neuronal architecture of the adult hippocampus, possibly by reducing neurogenesis and the extent of the vasculature, independently of neuroinflammation. Such detrimental changes in micromorphometric parameters may explain the hippocampal dysfunction observed after cancer chemotherapy.
Adult ; Animals ; Breast Neoplasms ; Cognition Disorders ; Cyclophosphamide ; Cytokines ; Doxorubicin ; Drug Therapy ; Female ; Hindlimb Suspension ; Hippocampus ; Humans ; Macrophages ; Memory ; Mice* ; Mood Disorders ; Neurogenesis ; Neurons ; Spine ; Survivors

PURPOSE: Sleep deprivation induces depressive symptoms. Dexmedetomidine is a α2-adrenoreceptor agonist and this drug possesses sedative, anxiolytic, analgesic, and anesthetic-sparing effect. In this study, the action of dexmedetomidine on sleep deprivation-induced depressive behaviors was investigated using mice. METHODS: For the inducing of sleep deprivation, the mice were placed inside a water cage containing 15 platforms and filled with water up to 1 cm below the platform surface for 7 days. One day after sleep deprivation, dexmedetomidine at the respective dosage (0.5, 1, and 2 μg/kg) was intraperitoneally treated into the mice, one time per a day during 6 days. Then, forced swimming test and tail suspension test were conducted. Immunohistochemistry for tyrosine hydroxylase (TH), 5-hydroxytryptamine (5-HT; serotonin), tryptophan hydroxylase (TPH) and western blot for D1 dopamine receptor were also performed. RESULTS: Sleep deprivation increased the immobility latency in the forced swimming test and tail suspension test. The expressions of TPH, 5-HT, and D1 dopamine receptor were decreased, whereas, TH expression was increased by sleep deprivation. Dexmedetomidine decreased the immobility latency and increased the expressions of TPH, 5-HT, and D1 dopamine receptor, whereas, HT expression was decreased by dexmedetomidine treatment. CONCLUSIONS: In our results, dexmedetomidine alleviated sleep deprivation-induced depressive behaviors by increasing 5-HT synthesis and by decreasing dopamine production with up-regulation of D1 dopamine receptor.
Animals ; Blotting, Western ; Depression ; Dexmedetomidine* ; Dopamine ; Hindlimb Suspension ; Immunohistochemistry ; Mice* ; Physical Exertion ; Receptors, Dopamine ; Serotonin ; Sleep Deprivation ; Tryptophan Hydroxylase ; Tyrosine 3-Monooxygenase ; Up-Regulation ; Water

PURPOSE: Although aging causes functional declines in cognition, the molecular mechanism underlying these declines remains largely unknown. Recently, the spindle checkpoint kinase budding uninhibited by benzimidazole-related 1 (BubR1) has emerged as a key determinant for age-related pathology in various tissues including brain. However, the neurobehavioral impact of BubR1 has not been explored. In this study, we investigated the role of BubR1 in behavioral function. METHODS: To investigate the neurobiological functions of BubR1 in vivo, we utilized transgenic mice harboring BubR1 hypomorphic alleles (BubR1 H/H mice), which produce low amounts of BubR1 protein, as well as mice that have specific knockdown of BubR1 in the adult dentate gyrus. To assess anxiety-like behavior, the above groups were subjected to the elevated plus maze and the light-dark test, in addition to utilizing the tail-suspension and forced-swim test to determine depression-like behavior. We used novel object recognition to test for memory-related function. RESULTS: We found that BubR1 H/H mice display several behavioral deficits when compared to wild-type littermates, including increased anxiety in the elevated-plus maze test, depression-like behavior in the tail suspension test, as well as impaired memory function in the novel object recognition test. Similar to BubR1 H/H mice, knockdown of BubR1 within the adult dentate gyrus led to increased anxiety-like behavior as well as depression-like behavior, and impaired memory function. CONCLUSIONS: Our study demonstrates a requirement of BubR1 in maintaining proper affective and memory-related behavioral function. These results suggest that a decline in BubR1 levels with advanced age may be a crucial contributor to age-related hippocampal dysfunction.
Adult ; Aging ; Alleles ; Animals ; Anxiety ; Brain ; Cognition ; Dentate Gyrus ; Hindlimb Suspension ; Hippocampus ; Humans ; Memory* ; Mice* ; Mice, Transgenic ; Pathology ; Phosphotransferases

OBJECTIVE: To better understand the pathological causes of bone loss in a space environment, including microgravity, ionizing radiation, and ultradian rhythms. METHODS: Sprague Dawley (SD) rats were randomly divided into a baseline group, a control group, a hindlimb suspension group, a radiation group, a ultradian rhythms group and a combined-three-factor group. After four weeks of hindlimb suspension followed by X-ray exposure and/or ultradian rhythms, biomechanical properties, bone mineral density, histological analysis, microstructure parameters, and bone turnover markers were detected to evaluate bone loss in hindlimbs of rats. RESULTS: Simulated microgravity or combined-three factors treatment led to a significant decrease in the biomechanical properties of bones, reduction in bone mineral density, and deterioration of trabecular parameters. Ionizing radiation exposure also showed adverse impact while ultradian rhythms had no significant effect on these outcomes. Decrease in the concentration of the turnover markers bone alkaline phosphatase (bALP), osteocalcin (OCN), and tartrate-resistant acid phosphatase-5b (TRAP-5b) in serum was in line with the changes in trabecular parameters. CONCLUSION Simulated microgravity is the main contributor of bone loss. Radiation also results in deleterious effects but ultradian rhythms has no significant effect. Combined-three factors treatment do not exacerbate bone loss when compared to simulated microgravity treatment alone.
Animals ; Biomechanical Phenomena ; Bone Density ; physiology ; Bone Resorption ; etiology ; metabolism ; Femur ; metabolism ; Hindlimb Suspension ; Rats, Sprague-Dawley ; Tibia ; metabolism ; Ultradian Rhythm ; Weightlessness Simulation ; adverse effects ; X-Rays ; adverse effects

To investigate the behavioral and biomolecular similarity between neuralgia and depression, a trigeminal neuralgia (TN) mouse model was established by constriction of the infraorbital nerve (CION) to mimic clinical trigeminal neuropathic pain. A mouse learned helplessness (LH) model was developed to investigate inescapable foot-shock-induced psychiatric disorders like depression in humans. Mass spectrometry was used to assess changes in the biomolecules and signaling pathways in the hippocampus from TN or LH mice. TN mice developed not only significant mechanical allodynia but also depressive-like behaviors (mainly behavioral despair) at 2 weeks after CION, similar to LH mice. MS analysis demonstrated common and distinctive protein changes in the hippocampus between groups. Many protein function families (such as cell-to-cell signaling and interaction, and cell assembly and organization,) and signaling pathways (e.g., the Huntington's disease pathway) were involved in chronic neuralgia and depression. Together, these results demonstrated that the LH and TN models both develop depressive-like behaviors, and revealed the involvement of many psychiatric disorder-related biomolecules/pathways in the pathogenesis of TN and LH.
Animals ; Avoidance Learning ; physiology ; Brain-Derived Neurotrophic Factor ; metabolism ; Depression ; etiology ; pathology ; Disease Models, Animal ; Electroshock ; adverse effects ; Functional Laterality ; Helplessness, Learned ; Hindlimb Suspension ; psychology ; Hippocampus ; metabolism ; Male ; Mass Spectrometry ; Mice ; Mice, Inbred C57BL ; Orbit ; innervation ; Pain Measurement ; Proteomics ; methods ; Reaction Time ; physiology ; Signal Transduction ; physiology ; Trigeminal Neuralgia ; etiology ; pathology