Biological & pharmaceutical bulletin
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Berberine has a wide range of biochemical and pharmacologic effects, including antitumor activity, but the mechanisms involved in berberine-induced apoptosis remain unclear. The purpose of the present study was to investigate the changes in oxidative stress and endoplasmic reticulum (ER)-related molecules, which are closely associated with cell death-signaling transduction pathways, in human glioblastoma T98G cells treated with berberine. Berberine significantly decreased the cell viability of T98G cells in a dose-dependent manner. ⋯ Berberine also markedly enhanced apoptosis in T98G cells through the induction of a higher ratio of Bax/Bcl-2 proteins, disruption of the mitochondrial membrane potential, activation of caspase-9 and -3, and cleavage of the poly(ADP-ribose) polymerase (PARP). The inhibition of ER stress using salubrinal led to an increased the level of Bcl-2, whereas the level of Bax, cleavage of procaspase-9 and -3, and PARP were decreased when compared with cells treated with berberine alone, indicating that berberine-induced apoptosis is associated with mitochondrial dysfunction. These results demonstrate that berberine induces apoptosis via ER stress through the elevation of ROS and mitochondrial-dependent pathway in human glioblastoma T98G cells.
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The complex molecular cascades of ischemic tolerance in brain cells remain unclear. Recently, sphingolipid-related metabolite ceramide has been implicated as a second messenger in many biological functions, including neuronal survival and death. The present study, therefore, examined the roles of ceramide (Cer) in ischemic tolerance induced by preconditioning with sublethal oxygen-glucose deprivation (OGD) using primary cultured cortical neurons of rats. ⋯ Treatment with an inhibitor of de novo ceramide synthesis, fumonisin B(1), during the ischemic preconditioning period completely blocked preconditioning-induced ischemic tolerance. Moreover, application of a non-cytotoxic concentration of exogenous cell-permeable ceramide produced neuroprotection against lethal OGD. The results suggest that ceramides increased by sublethal OGD preconditioning play an important role in induction of ischemic tolerance.
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RhoA plays an important role in Ca(2+) sensitization of bronchial smooth muscle in antigen-induced airway hyperresponsiveness (AHR). Glucocorticoids are now the most effective anti-inflammatory treatment for asthma, and inhaled corticosteroids are the most effective long-term control therapy for persistent asthma. To determine the mechanism of the inhibitory action of glucocorticoids on AHR in allergic bronchial asthma, that of prednisolone on RhoA upregulation was investigated using cultured human bronchial smooth muscle cells (hBSMCs). ⋯ Prednisolone partly inhibited the IL-13-induced RhoA upregulation and RhoA promoter activity, although prednisolone had no effects on the activations of signal transducers and activators of transcription (STAT)6 and nuclear factor (NF)-kappaB. Increased expression and promoter activity of RhoA induced by TNF-alpha was completely inhibited by prednisolone, although the activation of NF-kappaB failed to be inhibited by prednisolone in hBSMCs. These findings suggest that prednisolone might inhibit NF-kappaB-induced transcription via interaction between glucocorticoid receptor (GR), resulting in an inhibition of RhoA upregulation induced by IL-13 and TNF-alpha.
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The present study was designed to investigate the ameliorative potential of pralidoxime in tibial and sural nerve transection-induced neuropathy in rats. Tibial and sural nerve transection was performed by sectioning tibial and sural nerve portions (2 mm) of the sciatic nerve, and leaving the common peroneal nerve intact. The pinprick, acetone, hot and cold tail immersion tests were performed to assess the degree of motor functions, mechanical hyperalgesia, cold allodynia, heat and cold hyperalgesia respectively. ⋯ However, administration of pralidoxime (10, 20 mg/kg intraperitoneally (i.p.)) for 14 d attenuated tibial and sural nerve transection-induced cold allodynia, mechanical, hot and cold hyperalgesia. Furthermore, pralidoxime also attenuated tibial and sural nerve transection induced increase in oxidative stress and calcium levels. It may be concluded that pralidoxime has ameliorative potential in attenuating the painful neuropathic state associated with tibial and sural nerve transection, which may possibly be attributed to decrease in oxidative stress and calcium levels.
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The radical scavenging effects and protective activities against oxidative stress of Korean mistletoe (Viscum album coloratum) lectin were investigated in vitro and with a cellular system using LLC-PK(1) renal epithelial cells. The Korean mistletoe lectin (KML) showed 1,1-diphenyl-2-picrylhydrazyl radical scavenging activity with an IC(50) value of 42.6 microg/ml. It also exerted nitric oxide (NO), superoxide anion (O(2)(-)), and hydroxyl radical scavenging activities in concentration-dependent manners. ⋯ Furthermore, overexpressions of cyclooxygenase-2 and inducible NO synthase induced by SIN-1 were observed, but KML down-regulated the expression levels of both genes. KML also reduced SIN-1-induced nuclear factor kappa B expression and the phosphorylation of inhibitor kappa B alpha in LLC-PK(1) cells. These results indicate that KML has protective activities against oxidative damage induced by free radicals.