Antioxidant and antiapoptotic effects of darbepoetin-α against traumatic brain injury in rats

Introduction

In this study, we tried to determine whether darbepoetin-α would protect the brain from oxidative stress and apoptosis in a rat traumatic brain injury model.

Material and methods

The animals were randomized into four groups; group 1 (sham), group 2 (trauma), group 3 (darbepoetin α), group 4 (methylprednisolone). In the sham group only the skin incision was performed. In all the other groups, a moderate traumatic brain injury modelwas applied.

Results

Following trauma both glutathione peroxidase, superoxide dismutase levels decreased (p < 0.001 for both); darbepoetin-α increased the activity of both antioxidant enzymes (p = 0.001 and p < 0.001 respectively). Trauma caused significant elevation in the nitric oxide synthetase and xanthine oxidase levels (p < 0.001 for both). Administration of darbepoetin-α significantly decreased the levels of nitric oxide synthetase and xanthine oxidase (p < 0.001 for both). Also, trauma caused significant elevation in the nitric oxide levels (p < 0.001); darbepoetin-α administration caused statistically significant reduction in the nitric oxide levels (p < 0.001). On the other hand, malondialdehyde levels were increased following trauma (p < 0.001), and darbepoetin α significantly reduced the malondialdehyde levels (p < 0.001). Due to the elevated apoptotic activity following the injury, caspase-3 activity increased significantly. Darbepoetin-α treatment significantly inhibited apoptosis by lowering the caspase-3 activity (p < 0.001). In the darbepoetin group, histopathological score was lower than the trauma group (p = 0.016).

Conclusions

In this study, darbepoetin-α was shown to be at least as effective as methylprednisolone in protecting brain from oxidative stress, lipid peroxidation and apoptosis.     

Elevated expression of liver X receptor alpha (LXRα) in myocardium of streptozotocin-induced diabetic rats

The present study was designed to investigate the myocardial expression of liver X receptor alpha (LXRα) in a streptozotocin (STZ)-induced diabetic rat model. Immunohistochemical staining, quantitative real-time RT-PCR, and Western blot analysis were used to determine the expression of LXRα in the myocardium of STZ-induced diabetic rats. The myocardial expression of LXRα target genes, long-chain acyl-CoA synthetase 3 (ACSL3), fatty acid transporter protein (FAT/CD36), ATP-binding cassette transporter A1 (ABCA1), and ABCG1 were also detected. Bisulfite sequencing analysis was employed to examine the methylation status of the CpG island at the LXRα promoter region in the myocardium of STZ-induced diabetic rats. We found that LXRα mRNA and protein expression in the left ventricles, right ventricles, and atria of diabetic rats were gradually increased during the progression of diabetic cardiomyopathy (DCM). The mRNA expression levels of ACSL3 and FAT/CD36 and the protein expression levels of ABCA1 and ABCG1 were also markedly increased in different heart chambers of diabetic rats. Moreover, there was a significant difference in the methylation status of LXRα gene between the ventricles of control and diabetic rats (P < 0.05). Our findings suggest that elevated expression of LXRα may be involved in the progression of DCM, and demethylation of LXRα is likely to be responsible for its increased expression in myocardial tissues.     

Introduction of calpain inhibitors in traumatic brain injury: A novel approach?

Traumatic brain injury (TBI) is a major cause of death and disability throughout the world. In recent years, researchers focused on the pathological significance of calcium accumulation in the brain after TBI. Neuronal calcium homeostasis disturbances may result in the activation of calpain a ubiquitous calcium-sensitive protease. The calpain family has a well-established causal role in neuronal cell death following acute brain injury: their activation has been observed to progressively increase after either contusive or diffuse brain trauma in animals, suggesting calpain to be a mediator of early neuronal damage. We hypothesize that pretreatment with the calpain inhibitors in population at objective risk (military soldiers' pre combat) in appropriate dose would open therapeutic time window expected to prevent and reduce extensive brain damage by providing optimal TBI neuroprotection. Additional therapeutic strategy for TBI, based on calpain modulating actions such as pretreatment with calpain inhibitors has been proposed. Since calpain overexpression has been well established in acute neuronal injury and further subsequent neurodegeneration, from a clinical viewpoint, we speculate that if this hypothesis proves correct pretreatment inhibitors introduction may become a therapeutic option for different brain pathologies to be approached and treated with.     

Bazedoxifene protects cerebral autoregulation after traumatic brain injury and attenuates impairments in blood–brain barrier damage: involvement of anti-inflammatory pathways by blocking MAPK signaling

Inflammation Research - Traumatic brain injury (TBI) is a significant cause of death and long-term deficits in motor and cognitive functions for which there are currently no effective...     

3,5,4′-Tri-O-acetylresveratrol attenuates seawater aspiration-induced lung injury by inhibiting activation of nuclear factor-kappa B and hypoxia-inducible factor-1α

Resveratrol is a phytoalexin synthesized by a wide variety of plants, which has been proven to be effective in suppressing oxidative stress and inflammation. The aim of the present study was to investigate the effect of Resveratrol's prodrug: 3,5,4′-tri-O-acetylresveratrol, on seawater drowning-induced acute lung injury (SWD-ALI). Histological changes were assessed to study lung injuries; cytokines in lung samples were monitored by ELISA to reflect inflammation; T-SOD and MDA activity were detected to examine oxidative stress in lung tissues. Besides, we also tested the expression of NF-κB and HIF-1α to probe the possible protecting mechanism of 3,5,4′-tri-O-acetylresveratrol on AWD-ALI. The results showed that pretreatment with different doses of 3,5,4′-tri-O-acetylresveratrol improved seawater-induced lung histopathologic changes, alleviated lung edema, reduced the production of inflammatory mediators including TNF-α and IL-1β, inhibited MDA activity, and enhanced T-SOD activity, which was possibly associated with inhibition of NF-κB and HIF-1α. In conclusion, the current study demonstrated that 3,5,4′-tri-O-acetylresveratrol exhibited a protective effect on SWD-ALI by inhibiting of the inflammatory response, which may also involve the suppression of oxidative stress in lung tissues.     

Expression analysis of the early chemokine response 4?h after in vitro traumatic brain injury

Objective and design  

The importance of cytokine- and chemokine-mediated neuroinflammation in the progress of brain injury is becoming increasingly evident. We investigated the early local cytokine and chemokine expression and the development of tissue injury after moderate mechanical hippocampus trauma.     

Does edaravone (MCI- 186) act as an antioxidant and a neuroprotector in experimental traumatic brain injury?

Edaravone (MCI-186) is a novel synthetic free radical scavenger intended to have neuroprotective effect against ischemic insult. It is currently used on patients with cerebral infarction. Here, we note beneficial pharmaceutical effects of edaravone in rat experimental traumatic brain injury. Under specific experimental conditions, edaravone minimized traumatic brain injury by functioning as a synthetic antioxidant. Clinical trials testing the efficacy of edaravone are warranted.     

Bone marrow stromal cells in traumatic brain injury (TBI) therapy: true perspective or false hope?

Recent studies regard bone marrow stromal cells as a potential andidate for cellular therapy of traumatic brain injury and thus as an attractive alternative for embryonic and fetal stem cells. Numerous experiments indicate that bone marrow stromal cells play an important role in the repair of injured brain tissue and also support healing processes. Findings of in vitro and in vivo studies show that these cells have an ability to differentiate into cells of multiple tissues, including neurons and glial cells and to secrete an array of growth factors and cytokines, which have an influence on repair of damaged tissue. In addition, treatment of traumatic brain injury with bone marrow stromal cells promotes functional recovery of injured animals. Taking this into consideration, there is hope for using bone marrow stromal cells in brain injury therapy, which is very difficult because of specific events that occur in the pathological conditions. However, mechanisms responsible for the observed therapeutic potential of bone marrow stromal cells still remain unclear. The review presents achievements in studies on bone marrow stromal cells as a source of therapeutic benefits in treatment of traumatic brain injury and addresses the question of their possible future use in clinical trials.     

Effects of histamine andα-fluoromethylhistidine on brain tumor necrosis factor levels in rats

Besides the role of histamine (HA) as a neurotransmitter, a new concept has emerged presenting HA as an immunomodulator. Several studies have demonstrated interactions among HA, interleukin-1 (IL-1) and tumor necrosis factor (TNF), suggesting a possible bidirectional communication among them. In this study we have investigated the effects of i.p. administrations of HA diphosphate (6 µmol/kg) and-fluoromethylhistidine (FMH; 100 mg/kg) on TNF- levels in the hippocampus, hypothalamus, and posterior hypothalamic region of the rat brain. The concentrations of TNF- at 0 (Control, C) and 30 min after i.p. administration of HA were 0.26 ± 0.02 pg/mg and 0.32 ± 0.02 pg/mg in the hippocampus, 0.46 ± 0.04 pg/mg and 0.09 ± 0.006 pg/mg (p < 0.01) in the hypothalamus, and 0.47 ± 0.05 pg/mg and 0.26 ± 0.05 pg/mg in the posterior hypothalamic region. Three hours after FMH administration, an increase in the hippocampal levels of TNF- was observed (0.43 ± 0.04 pg/mg; p < 0.01), while in the hypothalamus (0.11 ± 0.02 pg/mg; p < 0.01) and in the posterior hypothalamic region (0.21 ± 0.04 pg/mg; p < 0.05) a decrease in TNF- levels was detected. These results suggest that changes in the histaminergic system influence TNF- production in the brain in an area-specific fashion.     

Interleukin-1β of Red nucleus involved in the development of allodynia in spared nerve injury rats

Previous studies have indicated that interleukin-1β (IL-1β) is involved not only in immune modulation, but also in the modulation of pain in both the peripheral and central nervous systems. The current study investigated the expression of IL-1β in the brain of rats with spared nerve injury (SNI), using immunohistochemical technique. The results showed that immunoreactive-like IL-1β protein was significantly elevated in the Red nucleus (RN) 2 weeks after SNI. To further study the function of IL-1β in RN, different doses of IL-1β neutralizing antibody (10, 1.0 and 0.1 ng) were microinjected into the RN contralateral to the nerve injury side of neuropathic rats. The results indicated that the higher doses of anti-IL-1β antibody (10 and 1.0 ng) significantly attenuated the mechanical allodynia of neuropathic rats. However, administration of 0.1 ng anti-IL-1β antibody did not show anti-allodynia effect. These results suggest that IL-1β of RN is involved in the development of neuropathic pain in SNI rats.     

Transplantation of stromal-derived factor 1α and basic fibroblast growth factor primed insulin-producing cells reverses hyperglycaemia in diabetic rats

The defective insulin production is associated with severely reduced islet cell mass leading to diabetes. Growth factors preconditioned stem cells have arisen as an effective therapy to treat many diseases including diabetes. The current study was designed to assess the effect of pretreatment of ASCs derived IPCs with combination of stromal cell derived factor 1 alpha (SDF1α) and basic fibroblast growth factor (bFGF) in improving glucose tolerance in streptozotocin induced diabetic rats. The results showed maximally significant reduction in hyperglycaemia and fibrosis, while up-regulation of survival and pancreas-specific genes, insulin levels and homing of transplanted cells in SDF-1α?+?bFGF IPCs transplanted rats as compared with other groups. Moreover, increased expression of insulin, glucagon and Glut-2 in pancreas of the SDF-1α?+?bFGF IPCs transplanted group indicated more regeneration of pancreas. Hence, the use of IPCs preconditioned with SDF-1α?+?bFGF would be more effective for treating diabetes.     

The effects of inflammatory response associated with traumatic spinal cord injury in cutaneous wound healing and on expression of transforming growth factor-beta1 (TGF-β1) and platelet-derived growth factor (PDGF)-A at the wound site in rats

At the cellular level, spinal cord injury (SCI) provokes an inflammatory response that generates substantial secondary damage within the cord, but also may contribute to its repair. The aim of this study was to investigate the effects of inflammatory response associated with SCI in cutaneous wound healing and on expression of transforming growth factor-beta1 (TGF-β₁) and platelet-derived growth factor (PDGF)-A at the wound site in rats. At the 14th day analysis, the mean TGF-β₁ score in trauma group (I) was significantly lower than that in control group (C) (2.60 ± 0.90 vs. 3.64 ± 0.37, respectively; p < 0.05). The mean score for PDGF-A expression in group I was similar to the corresponding value in group C (2.42 ± 0.74 vs. 2.94 ± 0.72, respectively). Compared to group C, group I had significantly lower mean scores for epidermal and dermal regeneration, but higher mean scores for granulation tissue thickness and similar scores for angiogenesis. The dermal layer contains diffuse deposition of collagen fibers that are not organised as in control rat skin, and intraepidermal and subepidermal vasocongestion is distinct. Based on the results on the parameters evaluated in the study, experimental SCI in rats results in delay in wound healing and low intensity of TGF-β₁ in the dorsal wound-tissue specimens.     

Immunohistochemical study on caveolin-1α in regenerating process of tubular cells in gentamicin-induced acute tubular injury in rats

Caveolin-1, a principal component of caveolae, modulates growth signaling, endocytosis, and intracellular transport. We examined the expression of caveolin-1α and its relation to cell cycle and caveolin-interacting growth factor receptors in regenerating proximal tubules (PTs) after gentamicin-induced acute renal failure in rats. Caveolin-1α appeared in regenerating PTs as early as day 4 after last gentamicin, peaked at days 6 to 8, and showed cytoplasmic pattern after day 8. Immunoelectron microscopy revealed caveolin-1α-positive caveolae on the cell membrane and in cytoplasms in regenerating PTs at days 4 to 8 and caveolin-positivity confined to cytoplasms after day 10. The number of PT cells with proliferation markers peaked at day 6 and decreased afterwards as expression of cyclin-dependent kinase inhibitors increased. Platelet-derived growth factor receptor-β (PDGFR-β) and epidermal growth factor receptor (EGFR) were colocalized with caveolin-1α in proliferating PTs as early as day 4. Phosphorylated EGFR increased at day 8 and afterwards when caveolins dissociated from EGFR or decreased. In case of PDGFR-β, phosphorylation seemed to be associated with the increase and association of caveolins to the receptors. Our results suggest that transient expression of caveolin-1α in early regenerating PTs might contribute to the regenerating process of PTs through modulating growth factor receptors.