Large cortical lesions produce enduring forelimb placing deficits in un-treated rats and treatment with NMDA antagonists or anti-oxidant drugs induces behavioral recovery

Vitamins and nutrients as primary treatments in experimental brain injury: Clinical implications for nutraceutical therapies

With the numerous failures of pharmaceuticals to treat traumatic brain injury in humans, more researchers have become interested in combination therapies. This is largely due to the multimodal nature of damage from injury, which causes excitotoxicity, oxidative stress, edema, neuroinflammation and cell death. Polydrug treatments have the potential to target multiple aspects of the secondary injury cascade, while many previous therapies focused on one particular aspect. Of specific note are vitamins, minerals and nutrients that can be utilized to supplement other therapies. Many of these have low toxicity, are already FDA approved and have minimal interactions with other drugs, making them attractive targets for therapeutics. Over the past 20 years, interest in supplementation and supraphysiologic dosing of nutrients for brain injury has increased and indeed many vitamins and nutrients now have a considerable body of the literature backing their use. Here, we review several of the prominent therapies in the category of nutraceutical treatment for brain injury in experimental models, including vitamins (B2, B3, B6, B9, C, D, E), herbs and traditional medicines (ginseng, Gingko biloba), flavonoids, and other nutrients (magnesium, zinc, carnitine, omega-3 fatty acids). While there is still much work to be done, several of these have strong potential for clinical therapies, particularly with regard to polydrug regimens. This article is part of a Special Issue entitled SI:Brain injury and recovery.

Magnesium sulfate for acute traumatic brain injury

BACKGROUND

The purpose of this systematic review was to evaluate the effect of magnesium sulfate in the treatment of acute traumatic brain injury.

MATERIALS AND METHODS

A systematic search of ClinicalTrials.gov, the Cochrane Library database, EMBASE, MEDLINE, Web of Science, and the World Health Organization trial registry, plus manual searches of gray literature, was undertaken in April 2013. Two reviewers independently extracted the data with a predefined data extraction form. RevMan 5 software was used to synthesize data and calculate the risk ratio for mortality with the 95% confidence interval. For the Glasgow Outcome Scale and posttreatment Glasgow Coma Scale data, the weighted mean difference was calculated with the 95% confidence interval.

RESULTS

A total of 8 randomized controlled trials with a total of 786 patients were included. Meta-analysis showed that there was no significant difference between the groups for mortality. The Glasgow Outcome Scale of the treatment group was higher than that of the control group, although the significance was borderline. The Glasgow Coma Scale score change posttreatment was significantly higher than that of the control.

CONCLUSIONS

The present meta-analysis of existing randomized controlled trials does not identify a significant beneficial effect in the mortality of traumatic brain injury patients; however, it suggests that magnesium sulfate shows a tendency to improve the Glasgow Outcome Scale and Glasgow Coma Scale scores, which is a promising result for traumatic brain injury therapy. Further effort is necessary to explore which subgroup of traumatic brain injury patients could benefit from magnesium sulfate.

D-cycloserine improves functional outcome after traumatic brain injury with wide therapeutic window

It has been long thought that hyperactivation of N-methyl-D-aspartate (NMDA) receptors underlies neurological decline after traumatic brain injury. However, all clinical trials with NMDA receptor antagonists failed. Since NMDA receptors are down-regulated from 4h to 2weeks after brain injury, activation at 24h, rather than inhibition, of these receptors, was previously shown to be beneficial in mice. Here, we tested the therapeutic window, dose regimen and mechanism of action of the NMDA receptor partial agonist D-cycloserine (DCS) in traumatic brain injury. Male mice were subjected to trauma using a weight-drop model, and administered 10mg/kg (i.p.) DCS or vehicle once (8, 16, 24, or 72h) twice (24 and 48h) or three times (24, 48 and 72h). Functional recovery was assessed for up to 60days, using a Neurological Severity Score that measures neurobehavioral parameters. In all groups in which treatment was begun at 24 or 72h neurobehavioral function was significantly better than in the vehicle-treated groups. Additional doses, on days 2 and 3 did not further improve recovery. Mice treated at 8h or 16h post injury did not differ from the vehicle-treated controls. Co-administration of the NMDA receptor antagonist MK-801 completely blocked the protective effect of DCS given at 24h. Infarct volume measured by 2,3,5-triphenyltetrazolium chloride staining at 48h or by cresyl violet at 28days was not affected by DCS treatment. Since DCS is used clinically for other indications, the present study offers a novel approach for treating human traumatic brain injury with a therapeutic window of at least 24h.

The novel apolipoprotein E-based peptide COG1410 improves sensorimotor performance and reduces injury magnitude following cortical contusion injury

It has previously been shown that small peptide molecules derived from the apolipoprotein E (ApoE) receptor binding region are anti-inflammatory in nature and can improve outcome following head injury. The present study evaluated the preclinical efficacy of COG1410, a small molecule ApoE-mimetic peptide (1410 daltons), following cortical contusion injury (CCI). Animals were prepared with a unilateral CCI of the sensorimotor cortex (SMC) or sham procedure. Thirty mins post-CCI the animals received i.v. infusions of 0.8 mg/kg COG1410, 0.4 mg/kg COG1410, or vehicle. Starting on day 2, the animals were tested on a battery of behavioral measures to assess sensorimotor (vibrissae-forelimb placing and forelimb use-asymmetry), and motor (tapered balance beam) performance. Administration of the 0.8 mg/kg dose of COG1410 significantly improved recovery on the vibrissae-forelimb and limb asymmetry tests. However, no facilitation was observed on the tapered beam. The low dose (0.4 mg/kg) of COG1410 did not show any significant differences compared to vehicle. Lesion analysis revealed that the 0.8 mg/kg dose of COG1410 significantly reduced the size of the injury cavity compared to the 0.4 mg/kg dose and vehicle. The 0.8 mg/kg dose also reduced the number of glial fibrillary acid protein (GFAP+) reactive cells in the injured cortex. These results suggest that a single dose of COG1410 facilitates behavioral recovery and provides neuroprotection in a dose and task-dependent manner. Thus, the continued clinical development of ApoE based therapeutics is warranted and could represent a novel strategy for the treatment of traumatic brain injuries.

Transplantation of GABAergic neurons but not astrocytes induces recovery of sensorimotor function in the traumatically injured brain

Embryonic stem (ES) cells have been investigated in many animal models of injury and disease. However, few studies have examined the ability of pre-differentiated ES cells to improve functional outcome following traumatic brain injury (TBI). The purpose of the present study was to compare the effect of murine ES cells that were pre-differentiated into GABAergic neurons or astrocytes on functional recovery following TBI. Neural and astrocyte induction was achieved by co-culturing ES cells on a bone marrow stromal fibroblast (M2-10B4) feeder layer and incubating them with various mitogenic factors. Rats were initially prepared with a unilateral controlled cortical contusion injury of the sensorimotor cortex or sham procedure. Rats were transplanted 7 days following injury with approximately 100K GABAergic neurons, astrocytes, fibroblasts, or media. Animals were assessed on a battery of sensorimotor tasks following transplantation. The stromal fibroblast cells (M2-10B4), as a control cell line, did not differ significantly from media infusions. Transplantation of GABAergic neurons facilitated complete and total recovery on the vibrissae-forelimb placing test as opposed to all other groups, which failed to show any recovery. It was also found that GABAergic neurons reduced the magnitude of the initial impairment on the limb use test. Histological analysis revealed infiltration of host brain with transplanted neurons and astrocytes. The results of the present study suggest that transplantation of pre-differentiated GABAergic neurons significantly induces recovery of sensorimotor function; whereas, astrocytes do not.

Nicotinamide treatment reduces behavioral impairments and provides cortical protection after fluid percussion injury in the rat

This study examined the ability of nicotinamide (vitamin B3) to improve functional outcome in a dose-dependent manner following fluid percussion injury (FPI). Injured (duration of unconsciousness mean = 85.8 sec; apnea = 9.9 sec), rats were administered nicotinamide (500 or 50 mg/kg; ip) or saline at 15 min and 24 h. Serum analysis of nicotinamide concentrations were conducted 1 h following the last injection. Sensorimotor and cognitive tests were conducted for 35 days following FPI. Both the 500 and 50 mg/kg doses of nicotinamide significantly facilitated recovery on the vibrissae-forelimb placing test compared to saline treatment, which showed chronic impairments. Both treatments also significantly improved performance on the bilateral tactile adhesive removal test. On the cognitive tests, the 500 mg/kg dose, but not the 50 mg/kg dose, improved performance on a working memory task in the Morris water maze (MWM). However, acquisition of a reference memory task in the MWM was not improved. Serum analysis showed that the 500 mg/kg dose significantly raised nicotinamide concentrations by 30-fold and the 50 mg/kg dose by 3-fold compared to the saline administration. This study demonstrated that raising nicotinamide concentrations resulted in the reduction of the behavioral impairments following FPI. In fact, the 500 mg/kg dose prevented the occurrence of the behavioral deficits on the bilateral tactile removal and working memory tests. Both doses significantly reduced tissue loss and glial fibrillary acid protein (GFAP) expression in the cortex. The 500 mg/kg dose reduced GFAP expression in the hippocampus. This data suggests that nicotinamide has substantial preclinical efficacy for TBI, and there appears to be some differences in the ability of the doses to improve performance in the MWM.

An animal model of capsular infarct: Endothelin-1 injections in the rat

In this study stereotaxic injections of the vasoconstrictive peptide endothelin-1 (ET-1) were used to create infarcts in the white matter of the internal capsule underlying sensorimotor cortex in rats. Resulting deficits were assessed using established sensorimotor tests conducted on each rat before and after the ET-1-induced infarct. After a 14-day survival period, histological examination revealed tissue necrosis and demyelination in the infarcted white matter of ET-1-injected rats, but not saline-injected control rats. Infarcts resulted in measurable sensorimotor deficits in rats that received ET-1 injections. The same sensorimotor tests showed no deficits in surgical-control rats. The present model of white matter infarct should be valuable in examining the underlying mechanisms of subcortical ischemic stroke and to evaluate potential therapeutic interventions.

Administration of raloxifene reduces sensorimotor and working memory deficits following traumatic brain injury

Hormonal differences between males and females have surfaced as a crucial component in the search for effective treatments after experimental models of traumatic brain injury (TBI). Recent findings have shown that selective estrogen receptor modulators (SERMs) may have therapeutic benefit. The present study examined the effects of raloxifene, a SERM, on functional recovery after bilateral cortical contusion injury (bCCI) or sham procedure. Male rats received injections of raloxifene (3.0mg/kg, i.p.) or vehicle (1.0 ml/kg, i.p.) 15 min, 24, 48, 72, and 96 h after bCCI or sham procedure. Rats were tested on both sensorimotor (bilateral tactile removal and locomotor placing tests) and cognitive tests (reference and working memory in the Morris water maze). Raloxifene-treated animals showed a significant reduction in the initial magnitude of the deficit and facilitated the rate of recovery for the bilateral tactile removal test, compared to vehicle-treated animals. The raloxifene-treated animals also showed a significant improvement in the acquisition of working memory compared to vehicle-treated animals. However, raloxifene did not significantly improve the acquisition of reference memory or locomotor placing ability. Raloxifene treatment also did not result in a significant reduction in the size of the lesion cavity. Thus, the task-dependent improvements seen following raloxifene treatment do not appear to be the result of cortical neuroprotection. However, these results suggest that raloxifene improves functional outcome following bCCI and may present an interesting avenue for future research.

Magnesium and riboflavin combination therapy following cortical contusion injury in the rat

Previous research has shown that magnesium chloride (MgCl(2)) and riboflavin (B(2)) both significantly improve functional recovery when administered shortly after frontal cortical contusion injury (CCI). The purpose of the present study was to examine the ability of combination treatments of MgCl(2) and B(2) to improve functional outcome following unilateral CCI. One hour post-injury, rats were administered MgCl(2) (1.0 mmol/kg), B(2) (7.5mg/kg), MgCl(2)+B(2) (1 mmol/kg+7.5mg/kg), 1/2 MgCl(2)+1/2 B(2) (0.5 mmol/kg and 3.75 mg/kg), or saline. Two days following CCI rats were tested on a battery of sensorimotor (vibrissae-->forelimb placing and tactile removal test) and motor (staircase test). A regimen of MgCl(2)+B(2) significantly reduced the initial impairment and facilitated the rate of recovery on the tactile removal test and facilitated the rate of recovery on the forelimb placing test. The half-dose combination did not significantly improve functional recovery on the tactile removal test compared to the individual treatments; however, it did improve performance on the forelimb placing test compared to saline treatment. Administration of MgCl(2) improved performance on the placing and tactile removal tests on 2 post-operative days, as did treatment with B(2) on the tactile removal test. The results indicate that the full combination of MgCl(2)+B(2) significantly improved functional recovery to a greater extent than the individual treatments or the low dose combination group on forelimb placing but not on tactile removal. These findings suggest that administration of MgCl(2)+B(2) may provide better therapeutic action than individual treatments.

Middle age increases tissue vulnerability and impairs sensorimotor and cognitive recovery following traumatic brain injury in the rat

With increasing age comes an increased risk for sustaining traumatic brain injuries (TBI). However, the effect of age is rarely studied in animal models of TBI. The present study evaluated the effect of increased age on recovery of function following bilateral medial frontal cortex injury. Groups of young (3 months) and middle-aged (14 months) rats received bilateral frontal cortex contusions or sham injuries. The rats were tested on a variety of tests to measure sensorimotor performance (bilateral tactile adhesive removal test), skilled forelimb use (staircase test), and the acquisition of reference and working memory in the Morris water maze. Results indicated that injury produced significant impairments on all behavioral tests compared to sham controls. Middle-aged rats that received cortical contusions were significantly impaired on the bilateral tactile adhesive removal test, acquisition of a reference memory task, and working memory compared to young-injured rats. Histological analysis showed that middle-aged rats developed significantly larger lesion cavities but did not show an increase in the number of glial fibrillary acidic protein (GFAP+) cells compared to young-injured rats. Age alone also significantly impaired function on the bilateral adhesive tactile removal test, skilled forelimb use, the acquisition of a reference memory task, and also increased the number of GFAP+ cells compared to young rats. These results indicate that middle-aged rats respond to brain injury differently than young rats and that age is an important factor to consider in pre-clinical efficacy studies.

Transplantation of Neuronal and Glial Precursors Dramatically Improves Sensorimotor Function but Not Cognitive Function in the Traumatically Injured Brain

Embryonic stem (ES) cells have been investigated in various animal models of neurodegenerative disease; however, few studies have examined the ability of ES cells to improve functional outcome following traumatic brain injury (TBI). The purpose of the present study was to examine the ability of pre-differentiated murine ES cells (neuronal and glial precursors) to improve functional outcome. Rats were prepared with a unilateral controlled cortical impact injury or sham and then transplanted 7 days later with 100K ES cells (WW6G) (~30% neurons) or media. Two days following transplantation rats were tested on a battery of behavioral tests. It was found that transplantation of ES cells improved behavioral outcome by reducing the initial magnitude of the deficit on the bilateral tactile removal and locomotor placing tests. ES cells also induced almost complete recovery on the vibrissae --> forelimb placing test, whereas, media-transplanted rats failed to show recovery. Acquisition of a reference memory task in the Morris water maze was not improved by transplantation of ES cells. Histological analysis revealed a large number of surviving ES cells in the lesion cavity and showed migration of ES cells into subcortical structures. It was found that transplantation of ES cells prevented the occurrence of multiple small necrotic cavities that were seen in the cortex adjacent to the lesion cavity in media transplanted rats. Additionally, ES cells transplants also significantly reduced lesion size. Results of this study suggest that ES cells that have been pre-differentiated into neuronal precursors prior to transplantation have therapeutic potential.

Treatment with vitamin B3 improves functional recovery and reduces GFAP expression following traumatic brain injury in rats

Previous studies have shown that administration of vitamin B(3) (B(3)) in animal models of ischemia significantly reduced the size of infarction and improved functional recovery. The present study evaluated the effect of administration of B(3) on recovery of function following traumatic brain injury (TBI), incorporating the bilateral medial frontal cortex contusion injury model. Groups of rats were assigned to B(3) (500 mg/kg) or saline (1.0 ml/kg) treatment conditions and received contusion injuries or sham surgeries. Drug treatment was administered 15 min and 24 h following injury. Rats were examined on a variety of tests to measure sensorimotor performance (bilateral tactile adhesive removal), skilled forelimb use (staircase test), and cognitive ability (reference and working memory) in the Morris Water Maze. Administration of B(3) following injury significantly reduced the behavioral impairments observed on the bilateral tactile removal test, but not on skilled forelimb use. The acquisition of reference and working memory tests were also significantly improved compared to saline-treated rats. Examination of the brains revealed that administration of B(3) significantly reduced the size of the lesion compared to treatment with saline. In addition, examination of glial fibrillary acidic protein (GFAP) expression around the lesion revealed that B(3) significantly reduced the number of GFAP(+) astrocytes. These results indicate that B(3) administration significantly improved behavioral outcome following injury, reduced the size of the lesion, and reduced the expression of GFAP. The current findings suggest that B(3) may have therapeutic potential for the treatment of TBI.

Acute treatment with MgSO4 attenuates long-term hippocampal tissue loss after brain trauma in the rat

Previous studies have shown that magnesium salts and the noncompetitive N-methyl-D-aspartate (NMDA) receptor antagonist, NPS 1506, attenuated short-term cognitive deficits and histopathological changes associated with traumatic brain injury (TBI). We evaluated the long-term effects of both therapies after brain trauma. Young adult rats were subjected to parasagittal fluid-percussion brain injury and received either MgSO(4) (125 micromol/400 g rat; n = 12) 15 min post-injury, NPS 1506 (1.15 mg/kg; n = 12) 15 min and 4 hr post-injury, or vehicle (n = 9) 15 min post-injury. Uninjured animals (sham) received vehicle (n = 10). Learning function in these animals was evaluated using a water maze paradigm 8 months after injury or sham treatment, and the brains were examined for cortical and hippocampal tissue loss. Compared to sham animals, injured vehicle-treated animals displayed a substantial learning dysfunction, indicated by an increased latency to find a hidden platform in the water maze (P < 0.001). No improvements in learning, however, were found for injured animals treated with NPS 1506 or MgSO(4). Injury induced >30% loss of tissue in the ipsilateral cortex in vehicle-treated animals that was not reduced in animals treated with either NPS 1506 or MgSO(4). Treatment with MgSO(4) significantly reduced progressive tissue loss in the hippocampus (P < 0.001). These findings are the first to demonstrate long-term neuroprotection of hippocampal tissue by an acute treatment in a TBI model. These data also show that the previously reported broad efficacy of MgSO(4) or NPS 1506 observed shortly after brain trauma could not be detected 8 months post-injury.

Behavioral and neuroplastic effects of focal endothelin-1 induced sensorimotor cortex lesions

Previous studies have established the usefulness of endothelin-1 (ET-1) for the production of focal cerebral ischemia. The present study assessed the behavioral effects of focal ET-1-induced lesions of the sensorimotor cortex (SMC) in adult rats as well as cellular and structural changes in the contralateral homotopic motor cortex at early (2 days) and later (14 days) post-lesion time points. ET-1 lesions resulted in somatosensory and postural-motor impairments in the contralateral (to the lesion) forelimb as assessed on a battery of sensitive measures of sensorimotor function. The lesions also resulted in the development of a hyper-reliance on the ipsilateral forelimb for postural-support behaviors. In comparison to sham-operated rats, in layer V of the motor cortex opposite the lesions, there were time- and laminar-dependent increases in the surface density of dendritic processes immunoreactive for microtubule-associated protein 2, in the optical density of N-methyl-D-asparate receptor (NMDA) subunit 1 immunoreactivity, and in the numerical density of cells immunolabeled for Fos, the protein product of the immediate early gene c-fos. These findings corroborate and extend previous findings of the effects of electrolytic lesions of the SMC. It is likely that compensatory forelimb behavioral changes and transcallosal degeneration play important roles in these changes in the cortex opposite the lesion, similar to previously reported effects of electrolytic SMC lesions.

The behavioral effects of magnesium therapy on recovery of function following bilateral anterior medial cortex lesions in the rat

Magnesium (Mg(++)) therapy has been shown to be neuroprotective and to facilitate recovery of motor and sensorimotor function in a variety of animal models of traumatic brain injury. However, few studies have investigated the efficacy of Mg(++) therapy on cognitive impairments following injury. The present study evaluated the ability of magnesium chloride (MgCl(2)) to facilitate recovery of function following bilateral anterior medial cortex lesions (bAMC). Rats received electrolytic bAMC lesions or sham surgery and were then treated with 1 mmol/kg, i.p. MgCl(2), 2 mmol/kg, i.p. MgCl(2), or 1.0 ml/kg, i.p. 0.9% saline. Drug treatment was administered 15 min following injury with subsequent injections administered at 24 and 72 h. Rats were tested on a battery of behavioral tests that measured both cognitive (reference and working memory in the Morris Water Maze (MWM) and spatial delayed matching-to-sample (DMTS)) and sensorimotor performance (bilateral tactile adhesive removal). The results indicated that bAMC lesions produced significant cognitive impairments in reference memory and working memory in the MWM, DMTS and sensorimotor impairments compared to shams. Mg(++) therapy exhibited a dose-dependent effect in facilitating recovery of function. Administration of 2mmol of MgCl(2) significantly improved performance on the bilateral adhesive tactile removal test, DMTS and working memory tests. The 1 mmol dose of MgCl(2) reduced the initial deficit on the tactile adhesive removal test and reduced the working memory impairment on the second day of testing. These results suggest Mg(++) therapy improves cognitive performance following injury in a dose-dependent manner.

Uranyl acetate-induced sensorimotor deficit and increased nitric oxide generation in the central nervous system in rats

We investigated the effects of uranyl acetate on sensorimotor behavior, generation of nitric oxide and the central cholinergic system of rats. Male Sprague-Dawley rats were treated with intramuscular injection of 0.1 and 1 mg/kg uranyl acetate in water, daily for 7 days. Control animals received equivalent amount of water. The treatment was stopped after the seventh injection because the animals in the 1-mg/kg group appeared lethargic. The animals were maintained for an additional observation period of 30 days. The study was initiated as a dose-finding study that covered doses of 10 and 100 mg/kg, as well. However, all the animals in the 100-mg/kg treatment group died after the third and fourth injections, and all animals given 10 mg/kg died after the fifth and sixth injections. On Day 30 following the cessation of treatment, the sensorimotor functions of the animals in the 0.1- and 1-mg/kg treatment groups were evaluated using a battery of tests that included measurements of postural reflexes, limb placing, orientation to vibrissae touch, grip time, beam walking and inclined plane performance. The animals were sacrificed the same day and the cerebral cortex, brainstem, cerebellum and midbrain were dissected. The levels of nitric oxide as marker for increased oxidative stress, and the integrity of the cholinergic system as reflected in acetylcholinesterase (AChE) activity and m2 muscarinic acetylcholine receptors ligand binding, were determined. The data from behavioral observations show that there was a dose-related deficit at the 0.1- and 1-mg/kg treatment groups for inclined plane performance. Both doses reduced grip time, but there was no significant difference between the two doses. Similarly, both beam-walk score and beam-walk time were impaired at both doses as compared with the controls. A significant increase in nitric oxide was seen at 0.1 mg/kg dose in cortex and midbrain, whereas brainstem and cerebellum showed an insignificant decrease at both the doses. Similarly, there was no significant change in nitric oxide levels in kidneys and liver of the treated animals as compared with the controls. There was a significant increase in AChE activity in the cortex of the animals treated with 1 mg/kg uranyl acetate, but not in other brain regions. Ligand binding densities for the m2 muscarinic receptor did not show any change. These results show that low-dose, multiple exposure to uranyl acetate caused prolonged neurobehavioral deficits after the initial exposure has ceased.