Neural Function In Rats Research Articles

Fingolimod improves diffuse brain injury by promoting AQP4 polarization and functional recovery of the glymphatic system.

Diffuse brain injury (DBI) models are characterized by intense global brain inflammation and edema, which characterize the most severe form of TBI. In a previous experiment, we found that fingolimod promoted recovery after controlled cortical impact injury (CCI) by modulating inflammation around brain lesions. However, it remains unclear whether fingolimod can also attenuate DBI because of its different injury mechanisms. Furthermore, whether fingolimod has additional underlying effects on repairing DBI is unknown. The impact acceleration model of DBI was established in adult Sprague-Dawley rats. Fingolimod (0.5 mg/kg) was administered 0.5, 24, and 48 h after injury for 3 consecutive days. Immunohistochemistry, immunofluorescence analysis, cytokine array, and western blotting were used to evaluate inflammatory cells, inflammatory factors, AQP4 polarization, apoptosis in brain cells, and the accumulation of APP after DBI in rats. To evaluate the function of the glymphatic system (GS), a fluorescent tracer was injected into the cistern. The neural function of rats with DBI was evaluated using various tests, including the modified neurological severity score (mNSS), horizontal ladder-crossing test, beam walking test, and tape sensing and removal test. Brain water content was also measured. Fingolimod administration for 3 consecutive days could reduce the levels of inflammatory cytokines, neutrophil recruitment, microglia, and astrocyte activation in the brain following DBI. Moreover, fingolimod reduced apoptotic protein expression, brain cell apoptosis, brain edema, and APP accumulation. Additionally, fingolimod inhibited the loss of AQP4 polarization, improved lymphatic system function, and reduced damage to nervous system function. Notably, inhibiting the GS weakened the therapeutic effect of fingolimod on the neurological function of rats with DBI and increased the accumulation of APP in the brain. In brief, these findings suggest that fingolimod alleviates whole-brain inflammation and GS system damage after DBI and that inhibiting the GS could weaken the positive effect of fingolimod on nerve function in rats with DBI. Thus, inhibiting inflammation and regulating the GS may be critical for the therapeutic effect of fingolimod on DBI.

Constraint-Induced Movement Therapy Promotes Myelin Remodeling and Motor Function by Mediating Sox2/Fyn Signals in Rats With Hemiplegic Cerebral Palsy.

Hypoxic-ischemic brain injury in infants often leads to hemiplegic motor dysfunction. The mechanism of their motor dysfunction has been attributed to deficiencies of the transcription factor sex-determining region (SRY) box 2 (Sox2) or the non-receptor-type tyrosine kinase Fyn (involved in neuronal signal transduction), which causes a defect in myelin formation. Constraint-induced movement therapy (CIMT) following cerebral hypoxia-ischemia may stimulate myelin growth by regulating Sox2/Fyn, Ras homolog protein family A (RhoA), and rho-associated kinase 2 (ROCK2) expression levels. This study investigated how Sox2/Fyn regulates myelin remodeling following CIMT to improve motor function in rats with hemiplegic cerebral palsy (HCP). To investigate the mechanism of Sox2 involvement in myelin growth and neural function in rats with HCP, Lentivirus (Lenti)-Sox2 adeno-associated virus and negative control-Lenti-Sox2 (LS) adeno-associated virus were injected into the lateral ventricle. The rats were divided into a control group and an HCP group with different interventions (CIMT, LS, or negative control-LS [NS] treatment), yielding the HCP, HCP plus CIMT (HCP + CIMT), HCP + LS, HCP + LS + CIMT, HCP + NS, and HCP + NS + CIMT groups. Front-limb suspension and RotaRod tests, Golgi-Cox staining, transmission electron microscopy, immunofluorescence staining, western blotting, and quantitative polymerase chain reaction experiments were used to analyze the motor function, dendrite/axon area, myelin ultrastructure, and levels of expression of oligodendrocytes and Sox2/Fyn/RhoA/ROCK2 in the motor cortex. The rats in the HCP + LS + CIMT group had better values for motor function, dendrite/axon area, myelin ultrastructure, oligodendrocytes, and Sox2/Fyn/RhoA/ROCK2 expression in the motor cortex than rats in the HCP and HCP + NS groups. The improvement of motor function and myelin remodeling, the expression of oligodendrocytes, and the expression of Sox2/Fyn/RhoA/ROCK2 in the HCP + LS group were similar to those in the HCP + CIMT group. CIMT might overcome RhoA/ROCK2 signaling by upregulating the transcription of Sox2 to Fyn in the brain to induce the maturation and differentiation of oligodendrocytes, thereby promoting myelin remodeling and improving motor function in rats with HCP. The pathway mediated by Sox2/Fyn could be a promising therapeutic target for HCP.

Neuroprotective mechanism of autophagy in bradykinin postconditioning after cardiac arrest in rats

To explore the protective effects of bradykinin postconditioning on cardiopulmonary resuscitation (CPR) rats, and to assess the underlying mechanisms. Forty-eight adult male Sprague-Dawley (SD) rats were randomly divided into four groups according to random number table: Sham operation group, cardiac arrest (CA) group, bradykinin treatment (BK) group, and AMP-activated protein kinase (AMPK) inhibitor Compound C+ bradykinin treatment (CP+BK) group, finally, 8 rats in each group were taken for follow-up experiment. CA was induced by asphyxia. Rats in the Sham group received arteriovenous catheterization, endotracheal intubation, and mechanical ventilation, without CA. Compound C (250 μg/kg) was intraperitoneally injected in CP+BK group 30 minutes before CA, and the same volume of dimethyl sulfoxide (DMSO) was given in the remaining groups. Bradykinin (150 μg/kg) was intraperitoneally injected in BK group and CP+BK group 48 hours after restoration of spontaneous circulation (ROSC), and same volume of saline was given in the remaining groups. The neural function of rats in each group was evaluated with neurological deficit score (NDS) 72 hours after ROSC. Microtubule-associated protein light chain 3 (LC3) and p62 expressions were detected by immunohistochemistry, autophagosomes were observed by transmission electron microscopy, and terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling method (TUNEL) assay was used to assess apoptosis. Compared with the Sham group, the NDS was decreased (60.75±5.80 vs. 80.00±0.00, P < 0.01), the expression levels of LC3 and p62 elevated [LC3 (A value): 1.04±0.64 vs. 0.40±0.14, p62 (A value): 2.75±0.57 vs. 0.36±0.12, both P < 0.05], the number of autophagosomes and apoptotic cells increased in the CA group [(39.00±8.00)% vs. (3.87±1.90)%, P < 0.05]. Compared with the CA group, the NDS (67.75±6.32 vs. 60.75±5.80, P < 0.05), the expression of LC3 (A value: 1.60±0.34 vs. 1.04±0.64, P < 0.05), and the number of autophagosomes increased in the BK group, while the expression of p62 and the rate of apoptotic cells reduced [p62 (A value): 1.51±0.32 vs. 2.75±0.57, apoptotic cells rate: (23.03±1.91)% vs. (39.00±8.00)%, both P < 0.05]. Compared with the BK group, the NDS (59.00±8.19 vs. 67.75±6.32, P < 0.05), the expression of LC3 (A value: 0.62±0.41 vs. 1.60±0.34, P < 0.05) and the number of autophagosomes declined in the CP+BK group, while the expression of p62 and the rate of apoptotic cells elevated [p62 (A value): 3.50±0.47 vs. 1.51±0.32, apoptotic cells rate: (44.53±10.15)% vs. (23.03±1.91)%, both P < 0.05]. Bradykinin postconditioning played a neuroprotective role in CPR rats by activating autophagy and reducing apoptosis.

Effect of acupuncture on NLRP3 inflammatory corpuscle in rats with intracerebral hemorrhage

To observe the effect of acupuncture at "Baihui" (GV 20) through "Qubin" (GB 7) on NLRP3 inflammatory corpuscle in rats with intracerebral hemorrhage (ICH), and to explore the action mechanism of acupuncture on promoting the recovery of neural function in rats with ICH. Forty SPF six-week-old male SD rats were randomly divided into a sham operation group, a model group, a non-acupoint group and an acupuncture group, 10 rats in each group. The rats in the model group, non-acupoint group and acupuncture group were intervened with autologous blood injection to prepare ICH model, while the rats in the sham operation group were only intervened with operation but not injection with autologous blood. About 3 hours after the establishment of the model, the rats in the acupuncture group were intervened with acupuncture at "Baihui" (GV 20) through "Qubin" (GB 7), once every 12 hours, for 7 days; the rats in the non-acupoint group were intervened with acupuncture at the non-acupoint [parallel to the "Baihui" (GV 20), 1 cm next to the midline] on the affected side, and other treatment was the same as the acupuncture group. At the end of the intervention, the composite nerve function score of each group was evaluated; the histomorphology of the hemorrhage penumbra was observed by HE staining; the expression of NLRP3 inflammatory corpuscle in the brain was detected by immunohistochemistry; the relative protein expression levels of NLRP3, interleukin-1β (IL-1β) and interleukin-18 (IL-18) in brain were detected by the method of Western blot. Seven days into intervention, compared with the sham operation group, each item score and total score of composite nerve function in the model group were significantly reduced (P<0.01, P<0.05). There was edema and karyopyknosis in brain neuron as well as necrocytosis and inflammatory cell infiltration in the model group. Compared with the model group and the non-acupoint group, the total score of composite nerve function and the scores of symmetrical movement of limbs (LS) and proprioception of tentacles (VP) in the acupuncture group were increased (P<0.01, P<0.05), and the cell necrosis and inflammatory cell infiltration were relieved. Compared with the sham operation group, NLRP3 inflammatory corpuscle expression and the relative protein expression levels of NLRP3, IL-1β and IL-18 in brain tissue in the model group were increased (P<0.01); compared with the model group and the non-acupoint group, NLRP3 inflammatory corpuscle expression and the relative protein expression levels of NLRP3, IL-1β and IL-18 in brain tissue in the acupuncture group were reduced (P<0.01). Acupuncture at "Baihui" (GV 20) through "Qubin" (GB 7) could downregulate the expression of NLRP3, IL-1β and IL-18 in the brain tissue of ICH rats, inhibit the inflammatory response, and promote the recovery of neural function.

Continuous exposure to α-glycosyl isoquercitrin from developmental stage facilitates fear extinction learning in rats

Abstract This study investigated the effect of exogenously administered polyphenolic antioxidant, α-glycosyl isoquercitrin (AGIQ), on neural function in rats following dietary exposure at 0.5% from gestational day 6 to postnatal day 77, in comparison with nonpolyphenolic α-lipoic acid (ALA) at 0.2%. AGIQ-exposed offspring revealed enhanced fear extinction learning at the 3rd trial and transcript upregulation of Fos and Kif21b in the hippocampal dentate gyrus and Grin2d in the amygdala. AGIQ also increased the number of FOS-immunoreactive (+) hippocampal granule cells. While ALA showed fear extinction learning-related transcript expression changes, it changed neither fear extinction learning nor FOS+ cell numbers. The increases of FOS+ cells and Grin2d transcripts by AGIQ suggested an association with increase of synaptic plasticity, leading to enhancement of fear extinction learning. AGIQ may also upregulate KIF21B, a recently identified memory-rewriting molecule. The present study findings suggest a possible therapeutic use of AGIQ in mitigating some stress disorders.

Enantioselectivity in the tissue distribution of perhexiline contributes to different effects on hepatic histology and peripheral neural function in rats.

Perhexiline, a chiral drug, is a potent antiischemic agent whose clinical utility is limited by hepatic and neural toxicities. It inhibits mitochondrial carnitine palmitoyltransferase‐1, however, excessive inhibition predisposes toward tissue steatosis. This pilot study investigated the distribution of the two enantiomers and their toxicological potential. Dark Agouti rats (n = 4 per group) were administered vehicle or 200 mg/kg daily of racemic, (+)− or (−)‐perhexiline maleate orally for 8 weeks. Plasma biochemical liver function tests and Von Frey assessments of peripheral neural function were performed. Hepatic and neuronal histology, including lipid and glycogen content, was assessed using electron microscopy. Concentrations of the perhexiline enantiomers and metabolites were quantified in plasma, liver and heart. Plasma perhexiline concentrations following administration of racemate, (+)− or (‐)‐enantiomer were within the mid‐upper clinical therapeutic range. There was extensive uptake of both enantiomers into liver and heart, with 2.5‐ to 4.5‐fold greater net uptake of (+)‐ compared to (−)‐perhexiline (P < .05) when administered as pure enantiomers, but not when administered as racemate. There was no biochemical or gross histological evidence of hepatotoxicity. However, livers of animals administered (+)‐perhexiline had higher lipid (P < .01) and lower glycogen (P < .05) content, compared to those administered (−)‐perhexiline. Animals administered racemic perhexiline had reduced peripheral neural function (P < .05) compared to controls or animals administered (−)‐perhexiline. For the same plasma concentrations, differences in tissue distribution may contribute to disparities in the effects of (+)‐ and (−)‐perhexiline on hepatic histology and neural function.

The mechanism of mesenchymal stem cells on neural function in rats with traumatic brain injury

Objective To investigate the effect of mesenchymal stem cells (MSCs) on the neurological function of rats with traumatic brain injury, and to investigate the mechanism of the effect of MSCs. Methods 60 SD rats models with brain injury established by the modified Feeney method were divided into model group, MSCs group and phosphate buffer (PBS) group by. Another 20 healthy SD rats were chosen as the control group. Rats of MSCs group were transplantated with Umbilical cord mesenchymal stem cells isolated and cultured in vitro. Neurological function of rats in each group were evaluated by improved neurological function score (mNSS) standard at 1, 3, 7, 14, 21, 28 d after transplantation. Neuronal nuclear antigen (NeuN) expression level in the brain tissue of rats was detected with immunohistochemical method. Brain-derived neurotrophic factor (BDNF) mRNA level of in the brain tissue of rats was detected with reverse transcriptase-polymerase chain reaction (RT-PCR) method. The apoptosis level of cerebral tissue cells in rats was detected by TdT-mediated dUTP nick end labeling (TUNEL) method. Results Compared with the control group, mNSS score of rats in model group, MSCs group and PBS group increased, NeuN expression decreased increased (P=0.000). Compared with the model group and PBS group, mNSS score of rats in MSCs group significantly decreased, NeuN expression significantly decreased(P=0.000). Compared with the control group BDNF mRNA level (0.31±0.12), BDNF mRNA level in model group, PBS group and MSCs Group (1.32±0.34, 1.23±0.30, 0.81±0.21) significantly increased (P=0.000). Compared with model group and PBS group, the levels of BDNF mRNA in MSCs group significantly reduced (P=0.014, P=0.019). Compared with the apoptosis level of brain tissue in control group (3.14±1.12), apoptosis level in model group, PBS group and MSCs group (27.84±4.32, 25.35±4.89, 10.33±3.32) significantly increased (P=0.000). Compared with model group and PBS group, the level of apoptosis in brain tissue of MSCs group significantly decreased (P=0.000). Conclusion Mesenchymal stem cells can decreased the apoptosis level of brain injury in rats through the mechanism of repairing damaged neurons and promoting the BDNF secretion. It can promote the repair effect on neural function of rats with traumatic brain injury. Key words: Brain injury; Mesenchymal stem cells; Nerve function

Effect of exercise preconditioning on nerve growth factor and learning-and-memory abilities in rats suffered from focal cerebral ischemia

Objective To investigate the effect of exercise preconditioning on the expression of nerve growth factor(NGF) and its receptor TrkA as well as learning-and-memory abilities in rats suffered from focal cerebral ischemia. Methods Thirty-six male SD rats were randomly divided into sham operation group (Sham-MCAO, n=12), focal cerebral ischemia-reperfusion group (MCAO, n=12) and exercise preconditioning + cerebral ischemia-reperfusion group (EX+ MCAO, n=12). Rats in EX+ MCAO group were placed in the treadmill device and accepted 4 weeks exercise training. Then method of middle cerebral artery occlusion was applied to prepare transient focal cerebral ischemia reperfusion model. Garcia’s method was used to assess the neural function in rats. Western blotting was applied to test the expression of NGF and TrkA protein in the successfully established experimental MCAO rats. Morris water maze experiment was utilized to test the learning-and-memory abilities of the rats. Results (1)Compared with Sham-MCAO group, the expression of NGF in rats’ brain tissue was lower in MCAO group (cerebral ischemia 1h reperfusion 24h) (P 0.05). Conclusion Exercise preconditioning can up-regulate the expressions of NGF and TrkA protein, which can also improve the learning-and-memory abilities in rats suffered from focal cerebral ischemia reperfusion injury. Key words: Exercise preconditioning; NFG; TrkA; Focal cerebral ischemia reperfusion; Learning and memory

Serum metabolites from walnut-fed aged rats attenuate stress-induced neurotoxicity in BV-2 microglial cells

The shift in equilibrium towards excess reactive oxygen or nitrogen species production from innate antioxidant defenses in brain is a critical factor in the declining neural function and cognitive deficit accompanying age. Previous studies from our laboratory have reported that walnuts, rich in polyphenols, antioxidants, and omega fatty acids such as alpha-linolenic acid and linoleic acid, improve the age-associated declines in cognition and neural function in rats. Possible mechanisms of action of these effects include enhancing protective signaling, altering membrane microstructures, decreasing inflammation, and preventing accumulation of polyubiquitinated protein aggregates in critical regions of the brain. In the current study, we investigated whether the serum collected from aged animals fed with walnut diets (0, 6, and 9%, w/w) would enhance protection on stressed BV-2 microglia in vitro. In the growth medium, fetal bovine serum was substituted with the serum collected from 22-month-old rats fed per protocol for 12 weeks. Walnut diet serum (6 and 9%) significantly attenuated lipopolysaccharide-induced nitrite release compared to untreated control cells and those treated with serum from rats fed 0% walnut diets. The results also indicated a significant reduction in pro-inflammatory tumor necrosis factor-alpha, cyclooxygenase-2, and inducible nitric oxide synthase. These results suggest antioxidant and anti-inflammatory protection or enhancement of membrane-associated functions in brain cells by walnut serum metabolites.

Hydrogen sulfide improves neural function in rats following cardiopulmonary resuscitation.

The alleviation of brain injury is a key issue following cardiopulmonary resuscitation (CPR). Hydrogen sulfide (H2S) is hypothesized to be involved in the pathophysiological process of ischemia-reperfusion injury, and exerts a protective effect on neurons. The aim of the present study was to investigate the effects of H2S on neural functions following cardiac arrest (CA) in rats. A total of 60 rats were allocated at random into three groups. CA was induced to establish the model and CPR was performed after 6 min. Subsequently, sodium hydrosulfide (NaHS), hydroxylamine or saline was administered to the rats. Serum levels of H2S, neuron-specific enolase (NSE) and S100β were determined following CPR. In addition, neurological deficit scoring (NDS), the beam walking test (BWT), prehensile traction test and Morris water maze experiment were conducted. Neuronal apoptosis rates were detected in the hippocampal region following sacrifice. After CPR, as the H2S levels increased or decreased, the serum NSE and S100β concentrations decreased or increased, respectively (P<0.0w. The NDS results of the NaHS group were improved compared with those of the hydroxylamine group at 24 h after CPR (P<0.05). In the Morris water maze experiment, BWT and prehensile traction test the animals in the NaHS group performed best and rats in the hydroxylamine group performed worst. At day 7, the apoptotic index and the expression of caspase-3 were reduced in the hippocampal CA1 region, while the expression of Bcl-2 increased in the NaHS group; and results of the hydroxylamine group were in contrast. Therefore, the results of the present study indicate that H2S is able to improve neural function in rats following CPR.

Body weight supported treadmill training on nerve cells differentiation after stem cells transplantation in rats of spinal cord injury

Objective To investigate the effect of bone marrow stem cells (BMSCs) transplantation combined with body weight supported treadmill training on neural functional recovery of rats with spinal cord injury. Methods T11 complete spinal cord injury (SCI) was introduced into 40 Sprague-Dawley male rats using an improved simple device, imitating the Allen method. The rats were randomly divided into a stem cell transplantation group, a body weight support treadmill training group, a combined treatment group and a control group, each of 10 assigned according to a random number table. One week after the SCI operation, stem cell transplantation was performed on the rats in the stem cell transplantation group and the combined treatment group. One day before their transplantation, the third passage BMSCs were labeled with 5-ethynyl-2'-deoxyuridine (Edu). The rats in body weight support treadmill training group and combined treatment group were received body weight support treadmill training, while the other two groups were not given any training. At the 1st, 2nd, 3rd, 4th and 5th week after SCI modeling, Basso-Beattie-Bresnahan (BBB) movement function score was used to evaluate the motor function recovery of all rats. At the 5th week after SCI, immunohistochemical staining and immunofluorescence staining was applied to detect neural specific markers including the neuron specific enolase (NSE), microtubule associated protein (MAP-1β) and vimentin (VIM). The survival and differentiation of the transplanted cells, as well as the nerve fiber recovery in the lesion were also observed. Results The average BBB score of the combined treatment group was (6.60±0.97) at the 2nd week after SCI operation, significantly higher than the other 3 groups, while that of the stem cell transplantation group and the body weight support treadmill training group was (5.00±0.67) and (4.80±0.63) respectively, both higher than that of the control group but without significant differences (P>0.05). In the third week after modeling, however, the value of the stem cell transplantation group rose to (8.00±0.67), significantly higher than that of the body weight support treadmill training group (6.80±0.79). The immuohistochemical staining showed that a variable degree of neural specific markers (NSE, MAP-1β, VIM) positive cells were observed in the SCI tissues of all groups, with those in the combined treatment group significantly higher than the other 3 groups. The immunofluorescence also found significantly higher fluorescence expression of neural specific protein markers including NSE, MAP-1βand VIM in the combined treatment group than the rest group, with obvious proliferation and differentiation of nerve fibers. Conclusions Stem cell transplantation combined with partial body weight supported treadmill training can effectively promote the recovery of neural function of rats with spinal cord injury, and the effect is better than solely stem cell transplantation or the weight loss training. Key words: Spinal cord injuries; Stem cell transplantation; Bodyweight supported treadmill training

Protection of Ischemic Preconditioning on Renal Neural Function in Rats with Acute Renal Failure

We tested whether tolerance induced by ischemic preconditioning (IPC) in kidneys was related to renal nerves. Experimental acute renal failure (ARF) in a rat model was induced for 45 min of left renal arterial occlusion (RAO), followed by 6 or 24 h of reperfusion (ischemic reperfusion (I/R) group). The episode of IPC was four cycles of 4 min of RAO at 11 min intervals and then the I/R injury was treated as above (IPC-I/R group). After 6 h of reperfusion, polyuria was found in the I/R group associated with an enhancement of afferent renal nerve activity (ARNA) and a reflexive decrease in efferent renal nerve activity (ERNA). Changes in nerve responses were related with a reduction in neutral endopeptidase (NEP) activity and an increased release of substance P (SP). After 24 h of reperfusion, the I/R group showed oliguria which was associated with a lower ARNA, hyperactivity of ERNA and a nine-fold increase in SP release due to a further 52% loss in NEP activity. Prior IPC treatment did not affect the changed ischemia-induced excretory and nervous activity patterns during the first 6 h of reperfusion, but normalized both responses in the kidneys 24 h after ischemia. The IPC-mediated protection in oliguric ARF was related to the preservation of NEP activity to only 25% loss that caused an increase of SP amounts of only three-fold and a minor change in neurokinin 1 receptor (NK-1R) activities. Finally, both excretory and sensory responses in oliguric ARF after saline loading were significantly ameliorated by IPC. We conclude that IPC results in preservation of the renal sensory response in postischemic kidneys and has a beneficial effect on controlling efferent renal sympathetic nerve activity and excretion of solutes and water.

P-367 - Effects of chronic ACTH-treatment on the 5-HT neural function in rats (2):Functional change of 5-HT2 receptors

P-367 - Effects of chronic ACTH-treatment on the 5-HT neural function in rats (2):Functional change of 5-HT2 receptors

P-366 - Effects of chronic ACTH-treatment on the 5-HT neural function in rats (1): Functional change of pre- and post-synaptic 5-HT1A receptors

P-366 - Effects of chronic ACTH-treatment on the 5-HT neural function in rats (1): Functional change of pre- and post-synaptic 5-HT1A receptors