Recombinant human erythropoietin prevents motor neuron apoptosis in a rat model of cervical sub-acute spinal cord compression

The objective of the study was to investigate the effects of recombinant human erythropoietin (rhEPO) in a rat model of cervical sub-acute spinal cord compression. 80 Wistar rats were randomly divided into 4 groups. Rats in the sham group (Group A, n = 5) underwent surgical procedures without cervical spinal cord compression; while rats in other groups were subjected to the spinal compression process. In the control group (Group B, n = 25), rats received an i.v. injection of 1 mL saline at day 7 post-surgery. Rats in the low-dose group (Group C, n = 25) and the high-dose group (Group D, n = 25) were treated with rhEPO at 500 units/kg body-weight and 5000 units/kg, respectively, via intravenous injection at day 7 post surgery. Limb motor function was scored by Basso–Beattie–Bresnahan (BBB) standards at 3, 7, 14, 21 and 28 days post-surgery. The distribution and quantities of EPO and its receptor (EPO-R) in the compressed segment of the spinal cord were detected by immunohistochemistry. Motor neuron apoptosis in the spinal cord was evaluated using TUNEL staining and flow cytometry at the indicated time points. Finally, IL-8, TNF-α, IL-6, and IL-1β levels in the compressed cervical spinal cord were determined by ELISA within the lesion epicenter at each time point post-surgery. The data suggest that expression of EPO-R was significantly increased following sub-acute cervical spinal cord compression; Groups C and D exhibited better BBB scores at all observed time points compared with the control group (p < 0.01). Using TUNEL staining and FCM, we observed that rhEPO profoundly inhibited motor neuron apoptosis in the spinal cord at day 21 (p < 0.01). Additionally, treatment with rhEPO halted the elevation of inflammatory cytokines. rhEPO administration decreased motor neuron apoptosis in the cervical spinal cord, improved motor functions and reduced the inflammatory response in a sub-acute cervical spinal cord compression model. Moreover, sustained treatment with low doses of rhEPO revealed a positive therapeutic effect.     

Differential time-course of the increase of antioxidant thiol-defenses in the acute phase after spinal cord injury in rats

Spinal cord injury (SCI) is a world-wide health problem. After traumatic injury, spinal cord tissue starts a series of self-destructive mechanisms, known as the secondary lesion. The leading mechanisms of damage after SCI are excitotoxicity, free radicals’ overproduction, inflammation and apoptosis. Metallothionein (MT) and reduced glutathione (GSH) are low-molecular-weight, cysteine-rich peptides able to scavenge free radicals. MT and GSH participation as neuroprotective molecules after SCI is unknown. The aim of the present study is to describe the changes of MT and GSH contents and GSH peroxidase (GPx) activity in the acute phase after SCI in rats. Female Wistar rats weighing 200–250 g were submitted to spinal cord contusion model, by means of a computer-controlled device (NYU impactor). Rats receiving laminectomy were used as a control group. Animals were killed 2, 4, 12 and 24 h after surgery. MT was quantified by the silver-saturation method, using atomic absorption spectrophotometry. GSH and GPx were assayed by spectrophotometry. Results indicate an increased MT content by effect of SCI, only at 4 and 24 h, as compared to sham group values. Meanwhile, GSH was found decreased at 4, 12 and 24 h after SCI. Interestingly, GPx activity was raised at all time points, indicating that this enzymatic defense is activated soon after SCI. Results suggest that thiol-based defenses, MT and GSH, are differentially expressed by spinal cord tissue to cope with the various processes of damage after lesion.     

电针刺激对脊髓挫伤模型大鼠神经细胞凋亡的影响

BACKGROUND: Electroacupuncture has promoting effects on the functional recovery of the injured spinal cord, can decrease pain, and elevate postoperative effect after acute spinal cord contusion.  OBJECTIVE: To observe the effect of electroacupuncture on apoptosis in the injured site after spinal cord contusion, and analyze its neuroprotective effects on neurological function in rats with spinal cord contusion. METHODS: A total of 66 adult female Sprague-Dawley rats were randomly divided into: sham surgery group (n=20), spinal cord contusion group (n=20), electroacupuncture stimulation group (n=20) because six rats were excluded due to modeling failure and death. Before model establishment, at 1, 3 days, 1, 2, 3 and 4 weeks after model establishment, motor functions were evaluated by BBB score and the inclined plate test. At 3 days after model establishment, apoptosis of nerve cells could be detected in the site of injury in each experimental group using TUNEL assay. mRNA and protein expression of bax, bcl-2 and caspase-3 was detected surrounding the injury site using RT-PCR and western blot assay. Morphological changes in the site of injury could be observed using hematoxylin-eosin staining. The regeneration of nerve fibers was observed using HRP tracing.  RESULTS AND CONCLUSION: (1) Motor function score was significantly increased at various time points in the 2nd week of treatment in the electroacupuncture stimulation group than in the spinal cord contusion group (P < 0.05). (2) Apoptotic index was significantly lower in the electroacupuncture stimulation group than in the spinal cord contusion group at 3 days after model establishment (P < 0.05). (3) mRNA and protein expression of bax and caspase-3 was significantly lower in the electroacupuncture stimulation group than in the spinal cord contusion group at 72 hours (P < 0.05); bcl-2 gene and protein expression was significantly higher (P < 0.05). (4) The number of HRP-positive nerve fibers was highest in the sham surgery group, followed by electroacupuncture stimulation group, and lowest in the spinal cord contusion group at 4 weeks (P < 0.05). Results indicated that electroacupuncture plays a protective role on the spinal cord contusion by reducing apoptosis of nerve cells at the site of injury.      

Spinal substance P and neurokinin-1 increase with high repetition reaching

Musculoskeletal injury and inflammation is associated with performance of repetitive and forceful tasks. In this study, we examined the effects of performing a voluntary, highly repetitive, negligible force (HRNF) reaching task on spinal cord neurochemicals involved in nociception. To our knowledge, no other laboratories are examining spinal cord nociceptive neurochemicals in response to repetitive motion-induced injury and inflammation. The purpose of this study was to extend our earlier findings related to central neurotransmitters from a low demand task to a higher demand task. Specifically, this study determined immunoreactivity of a peptidergic pro-nociceptive transmitter (substance P) and one of its receptors, neurokinin-1 (NK-1) receptor, in spinal cord dorsal horns in rats performing a HRNF reaching task for 6–10 weeks. The relationship of these spinal cord changes with the number of TNFα immunopositive cells in flexor forelimb muscles and with previously observed forearm grip strength changes from these same rats were examined. Performance of the HRNF task resulted in significantly increased substance P and NK-1 receptor immunoreactivity in the superficial lamina of spinal cord dorsal horns at 6 and 10 weeks compared to trained controls (p < 0.01). The increased substance P and NK-1 receptor immmunoreactivity were positively correlated with declines in forearm grip strength, an assay of movement-related hyperalgesia (r = 0.70, p < 0.01 and r = 0.64, p < 0.05, respectively). The increased substance P and NK-1 receptor immmunoreactivity were also positively correlated with increased TNF immunopositive cells in forelimb flexor muscles (r = 0.85, p < 0.001 and r = 0.88, p < 0.001, respectively). Thus, our highly repetitive task leads to increased spinal cord pro-nociceptive neurochemicals that are most likely directed by forelimb muscle inflammation and pain.     

Delayed sodium pyruvate treatment improves working memory following experimental traumatic brain injury

Prior work indicates that cerebral glycolysis is impaired following traumatic brain injury (TBI) and that pyruvate treatment acutely after TBI can improve cerebral metabolism and is neuroprotective. Since extracellular levels of glucose decrease during periods of increased cognitive demand and exogenous glucose improves cognitive performance, we hypothesized that pyruvate treatment prior to testing could ameliorate cognitive deficits in rats with TBI. Based on pre-surgical spatial alternation performance in a 4-arm plus-maze, adult male rats were randomized to receive either sham injury or unilateral (left) cortical contusion injury (CCI). On days 4, 9 and 14 after surgery animals received an intraperitoneal injection of either vehicle (Sham-Veh, n = 6; CCI-Veh, n = 7) or 1000 mg/kg of sodium pyruvate (CCI-SP, n = 7). One hour after each injection rats were retested for spatial alternation performance. Animals in the CCI-SP group showed no significant working memory deficits in the spatial alternation task compared to Sham-Veh controls. The percent four/five alternation scores for CCI-Veh rats were significantly decreased from Sham-Veh scores on days 4 and 9 (p < 0.01) and from CCI-SP scores on days 4, 9 and 14 (p < 0.05). Measures of cortical contusion volume, regional cerebral metabolic rates of glucose and regional cytochrome oxidase activity at day 15 post-injury did not differ between CCI-SP and CCI-Veh groups. These results show that spatial alternation testing can reliably detect temporal deficits and recovery of working memory after TBI and that delayed pyruvate treatment can ameliorate TBI-induced cognitive impairments.     

Matrix metalloproteinase-9 (MMP-9) expression and extracellular signal-regulated kinase 1 and 2 (ERK1/2) activation in exercise-reduced neuronal apoptosis after stroke

Exercise preconditioning has been shown to reduce neuronal damage in ischemic/reperfusion (I/R) injury. ERK1/2 signaling in injury has been thought to modulate neuroprotection. In this study, we investigated the effects of ERK1/2 activation on the expression and activity of MMP-9 and downstream neuronal apoptosis. Adult male Sprague–Dawley rats were subjected to 30 min of exercise on a treadmill for 3 weeks. Stroke was induced by a 2-h middle cerebral artery (MCA) occlusion using an intraluminal filament. Apoptotic protein caspase-3 and neuronal apoptosis in cortex and striatum was determined by Western blot at 24 h reperfusion and TUNEL staining at 48 h reperfusion in 5 I/R injury groups: no treatment, MMP-9 inhibitor (doxycycline), pre-ischemic exercise, exercised animals undergone ERK1/2 inhibition (U0126), and dual inhibition of ERK1/2 and MMP-9 in exercised ischemic rats. Cerebral MMP-9 expression in ischemic rats with different treatment was determined at 6, 12 and 24 h reperfusion by real-time PCR for mRNA, Western blot for protein and zymography for enzyme activity. Exercise preconditioning significantly (p < 0.05) reduced apoptosis determined by caspase-3 and TUNEL. In non-exercised rats, doxycycline treatment had significant (p < 0.05) reductions in apoptosis after I/R injury. The dual ERK1/2–MMP-9 inhibited exercised animals had significantly (p < 0.05) reduced neuronal apoptosis that was similar to that seen in exercised ischemic rats. MMP-9 expression in I/R injury was significantly (p < 0.05) reduced in the exercised animals as compared to non-exercised controls. When ERK1/2 was inhibited, the reduced MMP-9 expression was reversed to the level seen in the non-exercised controls. This study has suggested that exercise-induced neuroprotection in I/R injury may be mediated by MMP-9 and ERK1/2 expression, leading to a reduction in neuronal apoptosis.     

A novel thermoelectric cooling device using Peltier modules for inducing local hypothermia of the spinal cord: the effect of local electrically controlled cooling for the treatment of spinal cord injuries in conscious rats

We developed a novel thermoelectric cooling device using Peltier modules for the treatment of spinal cord injury in rats. The extracorporeal electrically cooling component was attached to the aluminum arched plate which was placed on the surface of the spinal cord after the contusion injury in the 11th thoracic spinal cord. During the hypothermic treatment, rats were awake and could move in the cage. Hind limb motor function, evaluated using a BBB scale, in the hypothermic animals (33 °C for 48 h) was significantly higher than that in the normothermic animals from 2 weeks to 8 weeks after the injury.     

Glial activation in the spinal ventral horn caudal to cervical injury

Microglia and astrocytes play complex roles following spinal cord injury (SCI), contributing to inflammatory processes that both exacerbate injury and promote functional recovery by supporting neuro-protection and neuroplasticity. The crossed phrenic phenomenon (CPP) is an example of respiratory plasticity in which C₂ cervical hemisection (C₂HS) strengthens crossed-spinal synaptic pathways to phrenic motor neurons ipsilateral to injury. We hypothesized that microglia and astrocytes are activated in the phrenic motor nucleus caudal and ipsilateral to C₂HS, suggesting their potential for involvement in the CPP. To test this hypothesis, an incomplete cervical spinal hemisection (C₂ lateral injury; C₂LI) was performed, and rats were allowed to recover for 1, 3, 14 or 28 days before collecting perfused spinal tissues. Microglia (via OX42) and astrocytes [via glial fibrillary acidic protein (GFAP)] were visualized with immunofluorescence microscopy in the C₄-C₅ ventral horn, the region encompassing most of the phrenic motor nucleus. OX42-occupied fractional area ipsilateral to injury increased with C₂LI (vs. sham) at 1 (12.5 ± 1.8%, p < 0.001), 3 (29.0 ± 1.9%, p < 0.001), 14 (26.1 ± 3.1%, p < 0.001) and 28 (19.2 ± 2.0%, p < 0.001) days post-C₂LI. GFAP-occupied fractional area also increased with C₂LI at 3 (24.4 ± 3.2%, p < 0.001) and 14 (16.8 ± 8.3%, p = 0.012) days, but not at 1 (6.2 ± 3.9%, p = 0.262) or 28 (10.6 ± 3.9%, p = 0.059) days post-C₂LI. Thus, microglia and astrocytes are activated in the phrenic motor nucleus caudal to C₂LI, suggesting that they play a role in functional deficits and/or recovery following spinal injury.     

Rolipram attenuates acute oligodendrocyte death in the adult rat ventrolateral funiculus following contusive cervical spinal cord injury

Rolipram, an inhibitor of phosphodiesterase 4 (PDE4) proteins that hydrolyze cAMP, increases axonal regeneration following spinal cord injury (SCI). Recent evidence indicate that rolipram also protects against a multitude of apoptotic signals, many of which are implicated in secondary cell death post-SCI. In the present study, we used immunohistochemistry and morphometry to determine potential spinal cord targets of rolipram and to test its protective potential in rats undergoing cervical spinal cord contusive injury. We found that 3 PDE4 subtypes (PDE4A, B, D) were expressed by spinal cord oligodendrocytes. OX-42 immunopositive microglia only expressed the PDE4B subtype. Oligodendrocyte somata were quantified within the cervical ventrolateral funiculus, a white matter region critical for locomotion, at varying time points after SCI in rats receiving rolipram or vehicle treatments. We show that rolipram significantly attenuated oligodendrocyte death at 24 h post-SCI continuing through 72 h, the longest time point examined. These results demonstrate for the first time that spinal cord glial cells express PDE4 subtypes and that the PDE4 inhibitor rolipram protects oligodendrocytes from secondary cell death following contusive SCI. They also indicate that further investigations into neuroprotection and axonal regeneration with rolipram are warranted for treating SCI.     

Low-frequency H-reflex depression in trained human soleus after spinal cord injury

After spinal cord injury (SCI), widespread reorganization occurs within spinal reflex systems. Regular muscle activity may influence reorganization of spinal circuitry after SCI. The purpose of this study is to investigate the effects of long-term soleus training on H-reflex depression in humans after SCI. Seven subjects with acute (<7 weeks) SCI (AC group) underwent testing of H-reflex depression at several frequencies of repetitive stimulation. Eight subjects (including 3 from AC) stimulated one soleus muscle daily, leaving the other leg as an untrained within-subject control. Trained limb H-reflexes were assessed during year 1 (TR1) and year 2 (TR2) of training. Untrained limbs were tested during year 2 (UN). H-reflex amplitude was lower at 1, 2 and 5 Hz than at 0.1 or 0.2 Hz (p < 0.05). The pattern of depression differed between AC and UN (p < 0.05), but not between TR2 and UN (p > 0.05) despite significant adaptations in torque and fatigue resistance (p < 0.05). Three subjects who began training very early after SCI retained H-reflex post activation depression, suggesting that early intervention of daily muscular activity may be important.     

Role of spinal metabotropic glutamate receptors in regulation of lower urinary tract function in the decerebrate unanesthetized rat

The role of spinal metabotropic glutamate receptors (mGluRs) in control of lower urinary tract functions was evaluated in rats using an mGluR antagonist administered via the intrathecal route. Cystometrograms in combination with external urethral sphincter (EUS) EMG recordings were performed on 13 decerebrate unanesthetized Sprague–Dawley female rats (n = 6 for spinal cord intact rats; n = 7 for spinal cord transected rats). In spinal cord intact rats, a group I/II mGluR antagonist, (±)-alpha-methyl-4-carboxyphenylglycine (MCPG), at doses of 3–30 μg, changed neither bladder nor EUS EMG activity, whereas a larger dose (100 μg) produced a significant facilitation of EUS EMG activity (41% increase in the peak activity) with little effect on bladder contractions. In chronically spinal cord transected rats, MCPG (3–100 μg) had no effect on bladder and EUS EMG activity. The results suggest that group I/II mGluRs are likely to be involved in inhibition of the excitatory pathway to the EUS but not involved in the control of the bladder. The lack of effect of MCPG on the EUS EMG activity in chronic spinal cord transected rats indicates that mGluR-mediated inhibitory control of the EUS was eliminated after spinal cord injury.     

Neuroprotective ferulic acid (FA)–glycol chitosan (GC) nanoparticles for functional restoration of traumatically injured spinal cord

An urgent unmet need exists for early-stage treatment of spinal cord injury (SCI). Currently methylprednisolone is the only therapeutic agent used in clinics, for which the efficacy is controversial and the side effect is well-known. We demonstrated functional restoration of injured spinal cord by self-assembled nanoparticles composed of ferulic acid modified glycol chitosan (FA–GC). Chitosan and ferulic acid are strong neuroprotective agents but their systemic delivery is difficult. Our data has shown a prolonged circulation time of the FA–GC nanoparticles allowing for effective delivery of both chitosan and ferulic acid to the injured site. Furthermore, the nanoparticles were found both in the gray matter and white matter. The in vitro tests demonstrated that nanoparticles protected primary neurons from glutamate-induced excitotoxicity. Using a spinal cord contusion injury model, significant recovery in locomotor function was observed in rats that were intravenously administered nanoparticles at 2 h post injury, as compared to non-improvement by methylprednisolone administration. Histological analysis revealed that FA–GC treatment significantly preserved axons and myelin and also reduced cavity volume, astrogliosis, and inflammatory response at the lesion site. No obvious adverse effects of nanoparticles to other organs were found. The restorative effect of FA–GC presents a promising potential for treating human SCIs.     

Pituitary adenylate cyclase-activating polypeptide prevents cell death in the spinal cord with traumatic injury

Pituitary adenylyl cyclase-activating polypeptide (PACAP) is a potent factor in the regulation of neurotransmission, neuroprotection, neurogenesis and anti-inflammation. We here examined the neuroprotective effect of PACAP on injury to the spinal cord tissue of adult rats, induced by dropping a 10 g NYU impactor from the height of 25 mm (moderate injury) or 50 mm (severe injury). PACAP was found to effectively attenuate cell apoptosis in the spinal cord with moderate injury. However, treatment with PACAP had a lesser effect on decreasing DNA fragmentation in the lesion center of the spinal cord with severe contusion injury. Yet, greater extended neural fibers and motor neurons were observed in the rostral and caudal regions of the PACAP-treated spinal cord when compared to that seen in the PBS-treated control. Our findings indicate the beneficial effect of PACAP for the treatment of spinal cord injury (SCI).     

Protective effect of N,N′-dialkylated analogs of 4,4′-diaminodiphenylsulfone in a model of intrastriatal quinolinic acid induced-excitotoxicity

The bacteriostatic agent 4,4′-diaminodiphenylsulfone or dapsone (DDS) and some of its N,N′-dialkylated analogs have shown anticonvulsant and neuroprotective properties in different experimental models. In this study, we tested the ability of five DDS analogs (N,N′-dimethyldapsone, N,N′-diethyldapsone, N,N′-dipropyldapsone, N,N′-dibutyldapsone and N,N′-ditosyldapsone) to attenuate quinolinic acid-induced toxicity in vivo. Male Wistar rats were treated with either DDS or analogs (12.5 mg/kg and equimolar doses respectively) 30 min before quinolinic acid intrastriatal stereotaxic injection (240 nmol/μl). Six days after injury, circling behavior was evaluated by counting ipsilateral turns for 1 h after apomorphine challenge (1 mg/kg, sc). Twenty-four hours later, rats were sacrificed and their corpora striata were dissected out to determine GABA content. Hemotoxicity of the analogs was assessed as the ability to produce methemoglobin (MHb) in vivo. Blood was sampled from tail vein within 18 h after drugs administration. Methemoglobin levels were determined by visible spectrophotometry and mean profiles of MHb-percentage versus time were obtained. All of the analogs tested decreased the number of ipsilateral turns/hour, reducing up to 67% the turns counting (p < 0.05) when compared to those induced in animals receiving quinolinic acid with no treatment. N,N′-dimethylated, N,N′-diethylated and N,N′-dibutylated analogs significantly prevented the decrease of intrastriatal GABA content (p < 0.05). Methemoglobin produced by the administration of analogs was significantly lower than the levels of the group receiving dapsone (p < 0.05). The neuroprotective effect of analogs and their diminished hemotoxicity make them potential candidates for therapeutic applications.     

Glutathione monoethyl ester improves functional recovery, enhances neuron survival, and stabilizes spinal cord blood flow after spinal cord injury in rats

Secondary damage after spinal cord (SC) injury remains without a clinically effective drug treatment. To explore the neuroprotective effects of cell-permeable reduced glutathione monoethyl ester (GSHE), rats subjected to SC contusion using the New York University impactor were randomly assigned to receive intraperitoneally GSHE (total dose of 12 mg/kg), methylprednisolone sodium succinate (total dose of 120 mg/kg), or saline solution as vehicle. Motor function, assessed using the Basso-Beattie-Bresnahan scale for 8 weeks, was significantly better in GSHE (11.2+/-0.6, mean+/-S.E.M., n=8, at 8 weeks) than methylprednisolone (9.3+/-0.6) and vehicle (9.4+/-0.7) groups. The number of neurons in the red nuclei labeled with FluoroRuby placed caudally to the injury site was significantly higher in GSHE (158+/-9.3 mean+/-S.E.M., n=4) compared with methylprednisolone (53+/-14.7) and vehicle (46+/-16.4) groups. Differences in the amount of spared SC tissue at the epicenter and neighboring areas were not significant among experimental groups. In a second series of experiments, using similar treatment groups (n=6), regional changes in microvascular SC blood flow were evaluated for 100 min by laser-Doppler flowmetry after clip compression injury. SC blood flow fell in vehicle-treated rats 20% below baseline and increased significantly with methylprednisolone approximately 12% above baseline; changes were not greater than 5% in rats given GSHE. In conclusion, GSHE given to rats early after moderate SC contusion/compression improves functional outcome and red nuclei neuron survival significantly better than methylprednisolone and vehicle, and stabilizes SC blood flow. These results support further investigation of reduced glutathione supplementation after acute SC injury for future clinical application.     

Comparative effects of risedronate,atorvastatin, estrogen and SERMs on bone mass and strength in ovariectomized rats

Objective

The aim of this study was to investigate bone protective effects of risedronate, atorvastatin, raloxifene and clomiphene citrate in ovariectomized rats.

Methods

Our study was conducted on 63 rats at Experimental Research Center of Celal Bayar University. Six-month-old rats were divided into seven groups. There were five drug administered ovariectomized groups, one ovariectomized control group without drug administration and one non-ovariectomized control group without drug administration. Eight weeks postovariectomy, rats were treated with the bisphosphonate risedronate sodium, the statin atorvastatin, the estrogen 17β-estradiol and the selective estrogen receptor modulators (SERMs) raloxifene hydrochloride and clomiphene citrate by gavage daily for 8 weeks. At the end of the study, rats were killed under anesthesia. For densitometric evaluation, left femurs and tibiae were removed. Left femurs were also used to measure bone volume. Right femurs were used for three-point bending test.

Results

Compared to ovariectomized group, femur cortex volume increased significantly in non-ovariectomized group (p = 0.016). Compared to non-ovariectomized group, distal femoral metaphyseal and femur midshaft bone mineral density values were significantly lower in ovariectomized group (p = 0.047). In ovariectomy + atorvastatin group, whole femur and femur midshaft bone mineral density and three-point bending test maximal load values were significantly higher than ovariectomized group (p = 0.049, 0.05, and 0.018). When compared to the ovariectomized group, no significant difference was found with respect to femoral maximum load values in groups treated with risedronate, estrogen, raloxifene and clomiphene (p = 0.602, 0.602, 0.75, and 0.927). In ovariectomy + risedronate group, femur midshaft bone mineral density values were significantly higher than the values in ovariectomized group (p = 0.023). When compared to ovariectomized group, no significant difference was found with respect to femur midshaft bone mineral density values in groups treated with estrogen, raloxifene and clomiphene (p = 0.306, 0.808, and 0.095).

Conclusions

While risedronate sodium prevented the decrease in bone mineral density in ovariectomized rats, atorvastatin maintained mechanical characteristics of bone and also prevented the decrease in bone mineral density as risedronate sodium.     

Delayed peripheral administration of the N-terminal tripeptide of IGF-1 (GPE) reduces brain damage following microsphere induced embolic damage in young adult and aged rats

We have previously reported that peripheral administration of GPE prevents neuronal injury after ischemic reperfusion injury in young adult rats. This study examined the ameliorating effects of GPE-treatment after embolic injury induced by microsphere injection in young adult and aged male rats. Unilateral injury was induced by injecting microspheres into the right internal carotid artery in both young adult (3–4 months) and aged (16–17 months) male rats. Either GPE (12 mg/kg) or the vehicle was infused intravenously over 1 h starting 3 h after embolic injury and the degree of brain injury, astrocytosis and vascular remodeling were examined using histological and immunohistochemical analysis 8 days later. Changes in core temperature, blood glucose concentration, oxygen saturation and heart rate were monitored. Microsphere injection induced multiple sites of focal damage in the ipsilateral subcortical regions. Massive numbers of microglia accumulated within the core of the tissue damage whereas astrocytes were located in the penumbra. There was no difference in the degree of brain injury between the young and aged control rats. However the aged rats showed less injury-induced astrocytosis and greater vascular remodeling. Intravenous infusion of GPE 3 h after the injury reduced overall damage scores in both young (p < 0.01) and aged rats (p < 0.05). GPE-treatment reduced astrocytosis in young, but not aged animals and did not significantly alter the vascular remodeling in either age group. The data suggested that the neuroprotection of the tripeptide is independent of cerebral reperfusion and is not age selective.     

Bradykinin preconditioning affects the number of degenerated neurons and the level of antioxidant enzymes in spinal cord ischemia in rabbits

Bradykinin preconditioning has been used for acquisition of tolerance after spinal cord ischemia. Rabbits were preconditioned intraperitoneally with bradykinin 48 h prior to 20 min of abdominal aorta ligation followed by 24 and 48 h of reperfusion. The activities of SOD and catalase were measured and Fluoro Jade B (FJB)-positive degenerated neurons were evaluated. The outcomes of Tarlov scoring system used to assess neurological functions showed significant improvement in bradykinin groups compared to the ischemic group. The number of FJB-positive degenerated neurons was decreased in ventral horns of both bradykinin groups. Significantly decreased activities of total SOD and mitochondrial Mn-SOD were also detected in both bradykinin groups versus ischemic group while CuZn-SOD and catalase activities were significantly decreased only in the bradykinin group after 24 h of reperfusion versus ischemic group. These findings suggest that one of the possibilities of the neuroprotective effect of delayed bradykinin preconditioning against spinal cord ischemic injury could be realized by mitochondrial protection and decreased synthesis of Mn-SOD as well as by promotion of neuronal survival.     

The neuroprotective effects of fibronectin mats and fibronectin peptides following spinal cord injury in the rat

We have shown previously that mats made from the glycoprotein fibronectin are permissive for axonal growth when implanted into the injured spinal cord. Recent evidence has indicated that fibronectin and its peptides also have neuroprotective effects in the CNS. We have therefore examined the neuroprotective effects of fibronectin applied to a spinal cord injury site. Adult rats with fibronectin mats implanted into a spinal cord lesion cavity had decreased apoptosis in the intact adjoining spinal cord tissue at 1 and 3 days post-injury compared to rats that had gelfoam implanted into the lesion cavity. Rats with fibronectin mat implants also showed enhanced hindlimb locomotor performance for the first 3 weeks post-surgery compared to control animals. To further examine the neuroprotective potential of fibronectin following spinal cord injury, we examined the effects of placing fibronectin mats over the site of a spinal cord hemisection or of delivering a solution derived from a dissolved fibronectin mat. The effects of these treatments were compared with control animals and animals that were treated with a fibronectin peptide (PRARIY) that has been shown to decrease secondary damage in a rodent model of cerebral ischemia. Results showed that both types of fibronectin mat treatment resulted in decreased lesion size, apoptosis, and axonal damage within the first week post-injury compared to control animals and were comparable in their neuroprotective efficacy to treatment with the fibronectin peptide. The results of the current study indicate that fibronectin based biomaterials have neuroprotective effects following spinal cord injury, in addition to their previously reported ability to promote axonal regeneration.