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Object Oxidative stress leading to lipid peroxidation is a major cause of secondary injury following spinal cord injury (SCI). The objectives of this study were to determine the duration of lipid peroxidation following acute SCI and the efficacy of short-and long-term administration of methylprednisolone on decreasing lipid peroxidation. Methods A total of 226 female Wistar rats underwent clip-compression induced SCI. In the first part of the study, spinal cords of untreated rats were assayed colorimetrically for malondialdehyde (MDA) to determine lipid peroxidation levels at various time points between 0 and 10 days. In the second part of the study, animals were treated with methylprednisolone for either 24 hours or 7 days. Control animals received equal volumes of normal saline. Treated and control rats were killed at various time points between 0 and 7 days. Results The MDA levels initially peaked 4 hours postinjury. By 12 hours, the MDA levels returned to baseline. A second increase was observed from 24 hours to 5 days. Both peak values differed statistically from the trough values (p < 0.008). The methylprednisolone reduced MDA levels (p < 0.04) within 12 hours of injury. No effect was seen at 24 hours or later. Conclusions The results of this study indicate that oxidative stress persists for 5 days following SCI in rats, and although methylprednisolone reduces MDA levels within the first 12 hours, it has no effect on the second lipid peroxidation peak.

Together, these results suggest that progenitorlike cells of the CB respond to cues associated with the loss of a single retinal cell type and that a subpopulation of those cells may differentiate into a cell that bears phenotypic resemblance to those seen in the retina.

Introduction:Transforming growth factor-β (TGF-β) and connective tissue growth factor (CTGF) are often described as the initial pro-fibrotic mediators upregulated early in fibrosis models dependent on angiotensin II (Ang-II). In the present study, we explore the mechanistic link between TGF-β and CTGF expression by using a novel TGF-β trap.Materials and methods:NIH/3T3 fibroblasts were subjected to TGF-β with or without TGF-β trap or 1D11 antibody, CTGF or CTGF plus TGF-β for six or 24 hours, and then used for quantitative real-time polymerase chain reaction (qRT-PCR) or immunocytochemistry. Male C57BL/6 mice were infused with Ang-II and randomly assigned TGF-β trap for six or 24 hours. Hearts were harvested for histological analyses, qRT-PCR and western blotting.Results:Exogenous TGF-β-induced fibroblasts resulted in significant upregulation of CTGF, TGF-β and type I collagen transcript levels in vitro. Additionally, TGF-β promoted the differentiation of fibroblasts into α-SMA+ myofibroblasts. CTGF expression was reduced by the addition of TGF-β trap or neutralizing antibody, confirming that its expression is dependent on TGF-β signaling. In contrast, exogenous CTGF did not appear to have an effect on fibroblast production of pro-fibrotic transcripts or fibroblast differentiation. Ang-II infusion in vivo led to a significant increase in TGF-β and CTGF mRNA expression at six and 24 hours with corresponding changes in Smad2 phosphorylation (pSmad2), indicative of increased TGF-β signaling. Ang-II animals that received the TGF-β trap demonstrated reduced CTGF mRNA levels and pSmad2 at six hours, suggesting that early CTGF expression is dependent on TGF-β signaling.Conclusions:We demonstrated that CTGF expression is dependent on TGF-β signaling both in vitro and in vivo in a model of myocardial fibrosis. This also suggests that early myocardial CTGF mRNA expression (six hours) after Ang-II exposure is likely dependent on latent TGF-β activation via the canonical Smad-dependent pathway in resident cardiac cells.

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