This study examined the effects of footshock stress and reexposure to cues previously associated with footshock on expression of brain-derived neurotrophic factor (BDNF) mRNA in the hippocampus of male rats. Exposure to twenty 0.5-s 0.4-mA footshocks co-terminating withBrain-derived neurotrophic factor (BDNF) is a member of the neurotrophin family of growth factors, which also includes nerve growth factor and neurotrophins 3 and 4. BDNF as well as these other neurotrophins, plays an important role in neuronal growth and differentiation during development, and also contributes to the survival, function, and plasticity of neurons in the adult brain (Lewin and Barde 1996). Thus, through a variety of mechanisms in different brain regions, BDNF has been implicated in emergent phenomena such as learning and memory (Patterson et al. 1996;Mu et al. 1999) and even contributes to the modulation of overt behaviors such as aggression (Lyons et al. 1999). The ability of BDNF to influence these processes is related, in part, to the activity dependent regulation of BDNF expression in adult brain (Lewin and Barde 1996).BDNF is also thought to play a role in the cellular and behavioral responses to stress (Duman et al. , 2000. Exposure to physical stress, such as immobilization, downregulates BDNF expression in the hippocampus (Smith et al. 1995, Vaidya et al. 1997 (Duman et al. , 2000. Moreover, downregulation of BDNF could contribute to the hippocampal pathology observed in psychiatric disorders such as post-traumatic stress disorder (PTSD) and depression (Bremner et al. 2000;Mervaala et al. 2000;Vakili et al. 2000). This possibility is supported by the observation that these disorders are sensitive to stressful experiences (Breslau et al. 1995;Kendler et al. 2000). Based on these observations and findings, we became interested in determining whether psychological stress has a measurable impact on hippocampal BDNF expression similar to the effects of physical stressors that have been reported.We therefore tested the effects of psychological stress produced by exposures to cues previously paired with footshock on BDNF mRNA levels in the dentate gyrus of the hippocampus. We hypothesized that re-exposure to cues associated with footshock stress, as well as footshock itself, would decrease BDNF mRNA in the dentate gyrus. The results demonstrate that this type of psychological stress produces a heightened sensitivity to previously neutral cues that results in downregulation of BDNF, and suggest that psychological stress, such as that experienced in association with PTSD and depression, as well as other disorders, could result in decreased neurotrophic support of the hippocampus. MATERIAL AND METHODS AnimalsAdult male Sprague-Dawley rats were kept in a 12:12 h light-dark cycle (lights on at 7:00 A . M .) for 7-10 days before each experiment. The animals were housed two or three per cage and fed ad libitum. Experiments were conducted between 9:00 A . M . and 6:00 P . M . To control for possible effects of diurnal variation on hippoca...

D-Arabinofurans, attached to either a galactofuran or a lipomannan, are the primary constituents of mycobacterial cell wall, forming the unique arabinogalactan (AG) and lipoarabinomannan (LAM), respectively. Emerging data indicate that the arabinans of AG and LAM are distinguished by virtue of the additional presence of linear termini in LAM, which entails some unknown feature of the EmbC protein for proper synthesis. In common with the two paralogous EmbA and EmbB proteins functionally implicated for the arabinosylation of AG, EmbC is predicted to carry 13 transmembrane spanning helices in an integral N-terminal domain followed by a hydrophilic extracytoplasmic C-terminal domain. To delineate the function of this C-terminal domain, the embC knock-out mutant of Mycobacterium smegmatis was complemented with plasmids expressing truncated embC genes. The expression level of serially truncated EmbC protein thus induced was examined by EmbC-specific peptide antibody, and their functional implications were inferred from ensuing detailed structural analysis of the truncated LAM variants synthesized. Apart from critically showing that the smaller arabinans are mostly devoid of the linear terminal motif, beta-D-Araf(1-->2)-alpha-D-Araf(1-->5)-alpha-D-Araf(1-->5)-alpha-D-Araf, our studies clearly implicate the C-terminal domain of EmbC in the chain extension of LAM. For the first time a full range of arabinan chains as large as 18-22 Araf residues and beyond could be released intact by the use of an endogenous endo-D-arabinanase from M. smegmatis, profiled, and sequenced directly by tandem mass spectrometry. In conjunction with NMR studies, our results unequivocally show that the LAM-specific linear termini are an extension on a well defined inner branched Ara-(18-22) core. This hitherto unrecognized feature not only allows a significant revision of the structural model of LAM-arabinan since its first description a decade ago but also furnishes a probable molecular basis of selectivity in biosynthesis, as conferred by the EmbC protein.

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BackgroundIschemia/reperfusion injury plays a crucial role in renal transplantation, and represents a significant risk factor for acute renal failure and delayed graft function. The pathophysiological contribution of endoplasmic reticulum and mitochondria stress to ischemia/reperfusion injury has also been highlighted. Berberine (BBR) has been showed to attenuate ischemia/reperfusion injury by inhibiting oxidative stress. The study was carried out to investigate whether the pretreatment of BBR could reduce hypoxia/reoxygenation (H/R)-induced injury by inhibiting mitochondria stress and endoplasmic reticulum stress pathways.MethodsThe cultured human renal proximal tubular cell line HK-2 cells were exposed to 24 h hypoxia (5% CO2, 1% O2, 94% N2) followed by 3 h reoxygenation (5% CO2, 21% O2, 74% N2). And BBR was added to the culture medium 2h prior to the treatment. Then the cell viability, oxidative stress level, morphological change of apoptosis and apoptotic rate were determined. In addition, Western blot analysis was performed to identify the expression of apoptotic pathway parameters, including Bcl-2, Bax and cytochrome C involved in mitochondrial-dependent pathway and ER stress hallmarks such as glucose-regulated protein 78 and CCAAT/enhancer binding protein homologous protein.ResultsH/R produced dramatic injuries in HK-2 cells. The cell viability and the oxidative stress level in group H/R was significantly decreased. The classical morphological change of apoptosis was found, while the apoptotic rate and the expression of proteins involved in mitochondrial stress and endoplasmic reticulum stress pathways increased (p<0.05). Administration of BBR significantly inhibited these H/R induced changes (p<0.05).ConclusionThis study revealed that BBR pretreatment serves a protective role against H/R induced apoptosis of human renal proximal tubular cells, and the mechanism is related to suppression of mitochondrial stress and endoplasmic reticulum stress pathways.