Traumatic brain injury models in rats

Studies have confirmed the salutary effects of progesterone (P4) on traumatic brain injury (TBI). This study investigated the beneficial effects of P4 via its receptors on TBI, and also whether progesterone receptors (PRs) can modulate TBI through PI3K/Akt pathway. Marmarou method was utilized to induce diffuse TBI in ovariectomized rats. P4 (1.7mg/kg) or the vehicle (oil) was administered 30min after TBI induction. Moreover, RU486 (PR antagonist) and its vehicle (DMSO) were injected before TBI induction and P4 injection. Brain Evans blue content, brain water content (WC), various oxidative stress parameters, IL-1β levels, tumor necrosis factor-α (TNF-α), histopathological alterations, and also phosphorylated Akt (p-Akt) and PI3K expressions in the brain were assessed 24h after TBI. The veterinary comma scale (VCS) was measured before and after TBI at different times. The findings revealed that P4 caused an increase in VCS and a decrease in brain WC, oxidative stress, TNF-α and IL-1β levels. RU486 inhibited the beneficial effects of P4 on these indices. Moreover, RU486 prevented the reduction of brain edema, inflammation, and apoptosis caused by P4. Moreover, P4 following TBI increased the expression of PI3K/p-Akt protein in the brain. RU486 eliminated the effects of P4 on PI3K/p-Akt expression. According to these findings, PRs are acting as critical mediators for the neuroprotective properties of P4 on oxidative stress, pro-inflammatory cytokine levels, and neurological outcomes. PRs also play an important role in regulating the PI3K/p-Akt expression and nongenomic function of P4.

Objectives This study evaluated the effects of dexmedetomidine, ketamine, and midazolam on oxidative stress, neuronal injury, and inflammation in a rat traumatic brain injury (TBI) model by measuring malondialdehyde (MDA), S100B, total antioxidant status (TAS), and tumor necrosis factor-alpha (TNF-α) in brain tissue homogenates and serum. Methods Forty adult male rats were randomized into five groups (n = 8): Sham (S), TBI (T), TBI + Dexmedetomidine (D), TBI + Ketamine (K), and TBI + Midazolam (M). TBI was induced using the controlled cortical impact method. Study drugs were administered intraperitoneally 30 minutes after trauma. At 24 hours, blood and brain samples were collected, and homogenates were prepared. MDA, S100B, TAS, and TNF-α were quantified using validated biochemical assays. Results Relative to Sham, the TBI group showed significantly higher MDA, S100B, and TNF-α and lower TAS in both tissue and serum (p < 0.05). Dexmedetomidine significantly increased TAS and reduced MDA, S100B, and TNF-α in both compartments (p < 0.01). Ketamine produced a pronounced reduction in MDA (p < 0.01), with limited effects on S100B, TAS, and TNF-α. Midazolam yielded partial improvement, mainly lowering TNF-α, without significant changes in the other markers. Conclusion Among the tested agents, dexmedetomidine provided the most robust protection against oxidative stress, neuronal injury, and inflammation after TBI. Ketamine and midazolam conferred moderate benefits. These data suggest dexmedetomidine may be a more effective option for mitigating secondary brain injury following traumatic insult and support further translational studies to clarify optimal dosing, timing, and mechanisms. Findings align with neuroprotective profiles previously reported for dexmedetomidine in TBI.

Traumatic brain injury (TBI) represents one of the most common social problems worldwide. This neurologic pathology often affects several body systemic organs, including the cardiovascular autonomic system. Changes in cardiac autonomic nervous system (ANS) regulation through the heart rate variability (HRV) analysis have been observed in all degrees of TBI in patients. On the other hand, little research has been addressed in TBI models using rats as a potential target for better explore therapeutic approaches in this pathology. In this sense, we investigate the relationship before and after an induced moderate fluid percussion injury (FPI) model in rats on the HRV features. The findings found in our work showed clearly a decreasing the sympathetic (LF), parasympathetic (HF), and overall HRV (p < 0.01 for mean NN) activities post-TBI when compared to baseline animals. In concomitant to this, the heart rate increased, such as showed by decreasing the mean NN. Therefore, this study indicates that the impacted severity moderate TBI in rats impairs some cardiac autonomic function parameters. However, further research is needed to better understand this pathophysiology.KeywordsTraumatic brain injuryFluid percussion injuryAutonomic nervous systemHeart rate variabilityRat

Objective To explore the protective effect of focal cerebral hypothermia on traumatic brain injury (TBI) model in SD rats and the underlying mechanisms. Methods Fifteen male SD rats were randomly divided into a sham group, a non-cooling group, and a cooling group, with 5 in each group. The TBI model was made by non-cooling group and cooling group. Three groups of experiments were performed simultaneously. After trauma, the mice were treated with hypothermia for 3 h and rewarmed for 3 h. Rat blood gas and cortical brain electricity were detected during the experiment. Rats were sacrificed at the end of rewarming, and brain tissue was stained with TTC or HE to evaluate brain death. The cerebral edema was evaluated and the expression of related proteins was detected by Western blot. Results Sham group and non-cooling group were increased in metabolism by externally stimulated brain tissue, and metabolism of cooling group is low (P<0.05). TTC and HE staining showed that the area of brain death and cell death in the cooling group were less than those in the non-cooling group (P<0.05). Focal hypothermia after TBI significantly reduces epileptic spikes in the cerebral cortex (P<0.05). This incomplete inhibition persists during rewarming, and hypothermia treatment reduces the expression of GABAB1R (P<0.05). Brain edema in the cooling group was significantly improved compared with the non-cooling group (P<0.05) and expression of AQP4 protein in the cooling group was significantly lower (P<0.05). Conclusion Focal hypothermia has a protective effect on TBI rats, which significantly reduce brain edema caused by TBI and inhibit epileptic spikes in the cerebral cortex. The underlying mechanism may be related to GABAB1R and AQP4, respectively. It provides a safer, simpler and more effective method for clinical treatment of TBI. Key words: Traumatic brain injury; Focal cerebral hypothermia; Epileptic spike; Edema

Neuroinflammation plays an important role in secondary injury after traumatic brain injury (TBI). Andrographolide (Andro), a diterpenoid lactone isolated from Andrographis paniculata, has been demonstrated to exhibit anti-inflammatory activity in neurodegenerative disorders. This study therefore aimed to investigate the potential neuroprotective effects of Andro after TBI and explore the underlying mechanisms. In our study, we used a weight-dropped model to induce TBI in Sprague–Dawley rats, the neurological deficits were assessed using modified neurological severity scores, Fluoro-Jade B (FJB) and terminal deoxynucleotidyl transferase (TdT) dUTP Nick-End Labeling (TUNEL) staining were employed to examine neuronal degeneration and apoptosis after TBI, immunofluorescence was designed to investigate microglial activation. Quantitative Real-time PCR and ELISA were conducted to detect the expression levels of pro-inflammatory cytokines, Western blot was used to examine the expression level of proteins of relative signaling pathway. Our results showed that after Andro administration, the neurological deficit was attenuated, and the cerebral edema and apoptosis in brain tissues were also decreased following TBI. Both microglial activation and the expression of pro-inflammatory cytokines were significantly inhibited by Andro after TBI. Moreover, Andro inhibited NF-κB p65 subunit translocation and decreased the expression levels of phosphorylated extracellular signal regulated kinase (ERK) and p38 MAPK after TBI. Altogether, this study suggests that Andro could improve neurobehavioral function by inhibiting NF-κB and MAPK signaling pathway in TBI, which might provide a new approach for treating brain injury.

Treadmill exercise inhibits traumatic brain injury-induced hippocampal apoptosis

Pyrroloquinoline quinone is an anionic, water-soluble compound with antioxidant characteristic. The role of pyrroloquinoline quinone in pharmacology and nutrition has attracted wide attention of researchers. Although a few experiments have confirmed that pyrroloquinoline quinone plays an obvious effective role in neuroprotection. There are few reports about the effect of pyrroloquinoline quinone on traumatic brain injury. Traumatic brain injury is one of the leading causes for adult disability and death. So far, there are no effective treatment methods for the injury because of its complex pathophysiology. In the present study, a model of traumatic brain injury in rat was established to study the role of pyrroloquinoline quinone in central nervous system injury. The results showed that the protein expression of cleaved-Caspase 3/Caspase 3 increased after traumatic brain injury and the expression decreased by treatment with 2mM pyrroloquinoline quinone. Terminal-deoxynucleoitidyl transferase mediated nick end labeling (TUNEL) staining displayed that the TUNEL positive signals were up-regulated after traumatic brain injury and were down-regulated after treatment with 2mM pyrroloquinoline quinone. The protein expression of LC3II/LC3I or lysosome-associated membrane protein 2(LAMP2) was elevated after traumatic brain injury and reduced after administration with 2mM pyrroloquinoline quinone. Transmission electron microscopy showed that the number of autophagosomes increased markedly after traumatic brain injury and decreased on administration of 2mM pyrroloquinoline quinone. Electroencephalogram indicated that pyrroloquinoline quinone improved brain electrophysiological function after traumatic brain injury. The results of CCK-8 test showed that pyrroloquinoline quinone could increase the viability of primary astrocyte treated with Glutamate. Lactate dehydrogenase (LDH) assay demonstrated that pyrroloquinoline quinone decreased LDH content in primary astrocyte exposed to Glutamate. Pyrroloquinoline quinone could play a neuroprotective role after traumatic brain injury in rat, which might be associated with inhibiting apoptosis and autophagy caused by traumatic brain injury.

To observe the effect of electroacupuncture (EA) on behavior, pathomorphology and brain cell apoptosis in traumatic brain injury (TBI) rats, so as to explore its mechanisms underlying treatment of TBI. Male SD rats were randomly divided into control (n=10), sham (n=30), model (n=30) and EA (n=30) groups, the latter three groups were further divided into 3, 7, 14 d subgroups （n=10）. TBI model was established by using a free fall brain injury striking device after exposing the local cranial bone (to induce the left parietal cerebral contusion). Twenty-four hours after modeling, EA (2 Hz, 1 mA) was applied at "Quchi"(LI11), "Neiguan"(PC6), "Zusanli"(ST36) and "Yongquan" (KI1) combined with acupuncture at "Shuigou"(GV26) and "Baihui"(GV20) for 15 min, once a day for 14 consecutive days. After 3, 7, and 14 days treatment, the behavioral function (balance, walking, nerve, and limb retraction) of the rats was evaluated. The histopathological changes of the injured brain tissue were observed by HE staining. TUNEL method was used to detect the apoptosis of cells in the brain injury area. After modeling, the scores of balance and walking in the model group were higher than those in the sham group (P<0.01, P<0.05), the neurological function score and the right limb retraction force were lower than those in the sham group(P<0.01). After 3 days treatment, the neurological function score and the right limb retraction force in the EA group were higher than those in the model group (P<0.05). After 7 and 14 days treatment, the scores of balance and walking function in the EA group were lower than those in the model group (P<0.05, P<0.01), while the scores of nerve function and right limb retraction force were higher (P<0.05, P<0.01). HE staining showed that modeling induced pathological changes such as the inflammatory cell infiltration, interstitial edema, necrosis, nuclear pyknosis and nuclear lysis were relatively milder in the EA group on the 7th and 14th day. Compared with the sham group, the cell apoptosis of brain injury area was higher in the model group (P<0.01); while it was lower on day 7 and 14 in the EA group in comparison with the model group (P<0.01, P<0.05). EA can improve the behavioral function, reduce the apoptosis of brain cells in the injured area, and promote the rehabilitation of craniocerebral injury.

Lateral fluid percussion injury: A rat model of experimental traumatic brain injury.

Objective To study the mechanism of interaction between neuronal nitric oxide syn-thase (nNOS) and inducible nitric oxide synthase (iNOS) following traumatic brain injury (TBI) in rats. Methods A total of 250 male Wistar rats were randomly divided into five groups, ie, sham oper-ation group, trauma group, 7-nitroindazole (7-NI) treatment group, aminoguanidine (AG) treatment group and combined AG and 7-NI treatment group. Severe closed TBI was made by using Marmarou meth-od. Protein expressions of nNOS and iNOS in hippocampus CAI were detected by means of immunohisto-chemical staining at 1,3, 6, 12 hours and at days 1,3, 7 and 14 after TBI. Results The expression of nNOS reached a peak at 6 hour after injury in all groups, with no statistical difference between groups (P > 0. 05), when there was no statistical difference between 7-NI treatment group and trauma group (P > 0. 05) but statistical difference in AG treatment group and combined AG and 7-NI treatment group compared with trauma group at 12 hours after TBI (P <0.05). The expression of iNOS reached maximal level at day 3 after TBI, with lower level in 7-NI group, AG treatment group and combined AG and 7-NI treatment group compared with trauma group (P < 0.05). Conclusions After TBI, nNOS interacts with iNOS by means of the feedback of nitric oxide. The enhanced expression of nNOS is initial factor for increase of iNOS expression, which can down regulate the expression of iNOS. Key words: Brain injuries; Nitric oxide synthase; Rats

Objective To investigate the protective effect of hypoxia-inducible factor-1α(HIF-1α) on the neurovascular unit in rats with traumatic brain injury (TBI). Methods The fluid percussion model was applied to induce TBI in rats. A total of 600 rats were divided into sham operation group, TBI group, TBI+ HIF-1α silence group and TBI+ control virus group according to the random number table, with 150 rats in each. Virus-mediated HIF-1α silence gene and control virus were delivered 24 h before the fluid percussion injury. After 3, 7 and 14 d, brain injury area and morphological changes in injured region were detected by HE staining, expressions of vascular endothelial cell markers (vWF) and HIF-1α were detected by Western blot method, and expressions of vascular endothelial growth factor (VEGF), matrix metalloproteinase-9 (MMP-9), tumor necrosis factor-α (TNF-α), interleukin 6 (IL-6) and nuclear factor-κB (NF -κB) in peripheral blood and brain tissue were detected by ELISA method. Rat neural function was dynamically assessed using the modified neurological severity score (mNSS). Results (1) Brain injury area and edema area in TBI+ HIF-1α silence group were higher than those in TBI group at all time points (P<0. 05). (2) Compared with sham operation group and TBI+ control virus group, expression of HIF-1α in TBI group gradually increased and remained high at 7 and 14 d postinjury (P<0. 05). Compared with TBI group, expression of vWF in TBI+ HIF-1αsilence group decreased at all time points (P<0. 05) and inhibited angiogenesis. (3) TBI+ HIF-1α silence group versus TBI group showed remarkably decreased VEGF at all time points, increased expressions of TNF-α, IL-6 and NF -κB at all time point, and increased expression of MMP-9 at 7 and 14 d postinjury ( all P<0. 05). (4) TBI+ HIF-1α silence group versus TBI group showed significant difference in mNSS at 7 and 14 d postinjury ( all P<0. 05). Conclusions After TBI, high expression of HIF-1αcan facilitate vascular formation and inhibit inflammatory reaction related factor expression, inducing the mitigation of brain edema and brain injury. Therefore, promoting HIF-1α expression may become a new means to improvement of neurovascular function after TBI. Key words: Brain injuries; Hypoxia-inducible factor 1, alpha subunit; Inflammation; Angiogenesis

<title/>Objectives: This work was designed to compare levels of endothelin-1 following brain injury in both rat and porcine models of head injury. In a broader sense, this work also determines the feasibility of testing traumatic brain injury-related phenomenology across species and models.Methods: Male Sprague-Dawley rats (400-450 g) were subjected to traumatic brain injury using a weight acceleration impact injury device (n = 5 per group). Following impact, cerebrospinal fluid was collected for enzyme-linked immunosorbent assay analysis of endothelin-1 concentration using a standard endothelin-1 detection kit at 4 hours, 24 hours, 48 hours, and 7 days post-traumatic brain injury. Sham operated animals (n = 5) were used as controls. In another set of experiments, traumatic brain injury was induced in newborn and juvenile pigs (n = 6 per group) using a lateral fluid percussion model of brain injury. Cerebrospinal fluid was collected at 4 hours, 8 hours, 72 hours, and 7 days post-injury and endothelin-1 levels were measured using a radiolabeled kit.Results: Endothelin-1 levels rapidly increased from ∼35 in sham operated animals to over 200 pg/g tissue 4 hours post-impact in both rat cortex and hippocampus. This elevation was sustained through 48 hours post-impact. By 7 days post-injury, endothelin-1 levels returned to normal, control concentrations. This trend was consistent with the porcine model, being more pronounced in newborn versus juvenile pigs.Conclusion: These results show that endothelin-1 peptide concentration elevation is a consistent finding between rat and pig and between weight acceleration and fluid percussion models of traumatic brain injury. This suggests that endothelin-1 elevation is not only a conserved phenomenon in different models of traumatic brain injury, but that it is a likely target for understanding the observed enhanced vascular response to traumatic brain injury and ultimately developing strategies to improve outcome following traumatic brain injury.

Traumatic brain injury (TBI) afflicts 70 million people worldwide annually and is the 3rd overall risk factor for developing Alzheimer's disease (AD), behind genetics and aging. In patients with AD, a history of TBI is associated with a 3-4 year earlier onset of cognitive impairment. TBI and AD share many pathologies, including blood brain barrier dysfunction, neuroinflammation, and protein aggregation. Yet, the underlying mechanism of this relationship is not understood, and there are no treatments that protect patients from accelerated AD after TBI. We recently reported that tau, a microtubule binding protein essential for neuronal health, is acetylated after TBI. Acetylation impairs tau binding to microtubules, leading to its mis-localization into the cell soma and pathological aggregation. Acetylated tau is also elevated early in AD, and acetylated tau was significantly more elevated in the brains of human AD subjects with a history of TBI, compared to AD alone and healthy controls. Therefore, we hypothesize that TBI-induced tau acetylation drives the acceleration of AD. To study this phenomenon, we developed a mouse model of TBI that accelerates AD-like pathology and cognitive impairment in 5xFAD mice, and amyloid-driven AD model. Our unique model of multimodal TBI produces a complex and reproducible brain injury with neurodegeneration and neurobehavioral impairment, beginning with acute axonal degeneration and persisting chronically with blood-brain barrier degradation and nerve cell death. This model of TBI also produces the same systemic metabolic alterations that are reported in TBI patients. TBI causes learning deficits in young 5xFAD mice that are not seen in either sham-injured 5xFAD mice or in wild type littermates subjected to TBI. TBI also accelerates amyloid deposition in 5xFAD mice. We hypothesize that TBI will also worsen blood brain barrier function in 5xFAD mice. Importantly, 5xFAD mice show greater elevation of acetylated tau after TBI, compared to WT mice. Preliminary data suggests that treatment with the FDA-approved non-steroidal inflammatory drug diflunisal, which inhibits the enzyme that acetylates tau, reduces acetylated tau and rescues behavior deficits after TBI in 5xFAD mice.

Objective To investigate the neuroprotective effect of cattle encephalon glycoside and ignotin injection on the rat model of traumatic brain injury (TBI). Methods Three hundred and six SD rats were randomly divided into sham group, TBI group, high dose group, middle dose group and low dose group according to the random number table. Rats received 1.8, 0.6 and 0.2 ml/kg of cattle encephalon glycoside and ignotin injection for 28 days in high, middle and low dose groups, respectively. TBI was induced by the modified Feeney's weight-drop method. Rat mortality, neurological function score and learning and memory ability were recorded. Brain morphological changes were evaluated with 7.0 T small animal nuclear magnetic resonance and HE staining. Evans blue was applied to assess blood brain barrier (BBB) permeability and hydrocephalus was evaluated by the brain water content. Results Mortality in high dose group decreased significantly compared to that in TBI group (22.40% vs. 28.14%, P<0.05). Defects in neurological function and learning and memory induced by TBI were significantly mitigated in middle and high dose groups (P<0.05). Pathological damage and contralateral hippocampal atrophy in middle and high dose groups were reduced significantly compared to TBI group (P<0.05). Hippocampus neuroapoptosis in middle and high dose groups was significantly improved compared to TBI group (P<0.05). BBB damage was less severe in middle and high dose groups than in TBI group (P<0.05). The treatment was preventive against secondary hydrocephalus. Conclusion Middle or high dose cattle encephalon glycoside and ignotin injection over a 28-day period has significant neuroprotective effect on the TBI rats. Key words: Neuroprotective agents; Brain injuries; Cattle Encephalon Glycoside and Ignotin

The Centers for Disease Control and Injury Prevention estimate that almost 2 million people sustain a traumatic brain injury (TBI) every year in the United States. In fact, TBI is a contributing factor to over a third of all injury-related mortality. Nonetheless, the cellular and molecular mechanisms underlying the pathophysiology of TBI are poorly understood. Thus, preclinical models of TBI capable of replicating the injury mechanisms pertinent to TBI in human patients are a critical research need. The controlled cortical impact (CCI) model of TBI utilizes a mechanical device to directly impact the exposed cortex. While no model can full recapitulate the disparate injury patterns and heterogeneous nature of TBI in human patients, CCI is capable of inducing a wide range of clinically applicable TBI. Furthermore, CCI is easily standardized allowing investigators to compare results across experiments as well as across investigative groups. The following protocol is a detailed description of applying a severe CCI with a commercially available impacting device in a murine model of TBI.