Emodin promotes fibroblast apoptosis and prevents epidural fibrosis through PERK pathway in rats.

BACKGROUND: Laminectomy is usually classed as a common orthopedic surgery, but postoperative epidural fibrosis often leads to less-than-desirable clinical outcomes. As demonstrated by prior studies, emodin (EMO) exerts an anti-fibrotic effect. Here, we carried out investigation into the inhibitory effect created by EMO application on epidural fibrosis after laminectomy in rats. METHODS: The paper conducts a series of experiment. In vitro, we observed the effect of EMO on fibroblasts by Cell Counting Kit-8 (CCK-8) assay. Apoptosis of fibroblasts induced by EMO was detected by western blot, TUNEL assay, and flow cytometry. The results revealed that EMO was capable of inducing fibroblast apoptosis, and the proteins of PERK pathway also changed accordingly. In vivo, the effect of EMO on epidural fibrosis in 12 male Sprague-Dawley rats was observed by histological staining. RESULTS: CCK-8 assay indicated that EMO was effective in reducing fibroblast viability in a time- and a dose-dependent manner. TUNEL assay and flow cytometry analysis have demonstrated that the apoptotic rate of fibroblasts increased as the EMO concentration rose. Western blot analysis proved that EMO promoted the relative expression of p-perk and p-eIF2α and that the expression of its downstream proteins CHOP and GRP78 was also enhanced. The expression of apoptotic protein Bax and cleaved PARP was upregulated, whereas the expression of anti-apoptotic protein Bcl-2 was downregulated. In addition, histological and immunohistochemical analysis demonstrated that EMO functioned to inhibit epidural fibrosis and increase GRP78 expression in fibrous tissue by promoting apoptosis of fibroblasts. CONCLUSIONS: EMO could have inhibitory effect on epidural fibrosis in a concentration-dependent manner. The potential mechanism might be through PERK signaling pathway to promote fibroblast apoptosis. It has a possibility to be taken as a novel method for the treatment of epidural fibrosis.

Hemostasis vs. epidural fibrosis?: A comparative study on an experimental rat model of laminectomy.

AIM: The aim of this study was to evaluate the histopathological and biochemical impact and effectiveness of two hemostatic agents, Ankaferd blood stopper (ABS) and Microporous Polysaccharide Hemospheres (MPH), on epidural fibrosis in an experimental rat laminectomy model. MATERIAL AND METHODS: Twenty adult Wistar albino rats were divided into MPH-treated (n=6), ABS-treated (n=6) and control (n=8) groups. Laminectomy of the lumbar spine was performed in all animals and treatment groups were exposed to MPH and ABS while closure was applied in control group as per usual. Epidural fibrosis was evaluated in all groups macroscopically, histopathologically, biochemically and with electron microscopy four weeks later. RESULTS: Statistically, it was found that MPH-treated group had significantly less epidural fibrosis compared to ABS-treated and control groups. CONCLUSION: We compared two hemostatic agents for their propensity to cause adhesions in the present study. Our results show that MPH significantly reduces epidural scar formation and dural adhesion in a rat model of laminectomy while ABS increases postoperative fibrosis.

Elevation of extracellular glutamate in the final, ischemic stage of progressive epidural mass lesion in cats.

Epidural mass lesions may cause ischemia due to progressive intracranial hypertension. In order to investigate the impact of intracranial pressure on accumulation of neuroactive substances, we gradually raised intracranial pressure in five halothane anesthetized cats by inflation of an epidural balloon. We evaluated in the parietal cortex contralateral to the site of balloon inflation, alterations of extracellular glutamate and purine catabolites and of the lactate/pyruvate ratio in relation to changes of intracranial, cerebral perfusion and mean arterial blood pressure. In a complementary experiment, regional cerebral blood flow was assessed by sequential positron emission tomography. In this simplified mass lesion model, extracellular glutamate increased in all cats at a late, critical stage after tentorial herniation, when intracranial pressure had increased to more than 90 mm Hg, cerebral perfusion pressure had decreased below 40-50 mm Hg. Positron emission tomography assessments revealed that the ischemic threshold for glutamate accumulation was in the range of 15-20 mL/100 g/min. Purine catabolites and the lactate/pyruvate ratio increased somewhat earlier than glutamate, but also after reaching the critical, terminal stage. We conclude that in this model of progressive epidural compression, glutamate-mediated excitotoxic processes at sites remote from the initial focal lesion depend on processes such as delayed ischemia in combination with tentorial herniation and systemic hypotension. These processes seem to be initiated by a decrease of cerebral perfusion pressure below a threshold of 40-50 mm Hg.