Background-Strengthening the macrophage glutathione redox buffer reduces macrophage content and decreases the severity of atherosclerotic lesions in LDL receptor-deficient (LDLR Ϫ/Ϫ ) mice, but the underlying mechanisms were not clear. This study examined the effect of metabolic stress on the thiol redox state, chemotactic activity in vivo, and the recruitment of macrophages into atherosclerotic lesions and kidneys of LDL-R Ϫ/Ϫ mice in response to mild, moderate, and severe metabolic stress. Methods and Results-Reduced glutathione (GSH) and glutathione disulfide (GSSG) levels in peritoneal macrophages isolated from mildly, moderately, and severe metabolically-stressed LDL-R Ϫ/Ϫ mice were measured by HPLC, and the glutathione reduction potential (E h ) was calculated. Macrophage E h correlated with the macrophage content in both atherosclerotic (r 2 ϭ0.346, Pϭ0.004) and renal lesions (r 2 ϭ0.480, Pϭ0.001) in these mice as well as the extent of both atherosclerosis (r 2 ϭ0.414, Pϭ0.001) and kidney injury (r 2 ϭ0.480, Pϭ0.001). Compared to LDL-R Ϫ/Ϫ mice exposed to mild metabolic stress, macrophage recruitment into MCP-1-loaded Matrigel plugs injected into LDL-R Ϫ/Ϫ mice increased 2.6-fold in moderately metabolically-stressed mice and 9.8-fold in severely metabolically-stressed mice. The macrophage E h was a strong predictor of macrophage chemotaxis (r 2 ϭ0.554, PϽ0.001). Conclusion-Thiol oxidative stress enhances macrophage recruitment into vascular and renal lesions by increasing the responsiveness of macrophages to chemoattractants. This novel mechanism contributes at least in part to accelerated atherosclerosis and kidney injury associated with dyslipidemia and diabetes in mice. Key Words: glutathione Ⅲ macrophage recruitment Ⅲ metabolic stress Ⅲ atherosclerosis Ⅲ inflammation M etabolic disorders such as hypercholesterolemia and diabetes are strongly associated with both macro-and microvascular diseases, a common feature of which is the recruitment of blood monocyte-derived macrophages to sites of vascular injury. Whereas most studies exploring the mechanisms underlying atherosclerosis and other vascular pathologies have focused on the impact of a dysregulated metabolism on the vasculature itself, a number of more recent studies suggest that metabolic disorders may also directly impact monocytes and alter their functionalities in ways that promote and accelerate the disease process. Phenotypic abnormalities in blood monocytes of diabetic patients have been reported, including altered metabolism, 1-3 phagocytosis, 4,5 and cytokine release. 6 -8 Furthermore, peritoneal macrophages isolated from either atherosclerosis-prone mice or diabetic mice show altered cytokine and chemokine responses compared with macrophages from healthy control mice. 9,10 However, it is not yet well-understood to what extent monocyte dysfunction induced by metabolic diseases contributes to macrophage recruitment and vascular diseases such as atherosclerosis.The recruitment of blood monocyte-derived macrophages into the vessel wall is co...

Thorny excrescences are the postsynaptic components of synapses between mossy fibers of granule cells and dendrites of CA3 pyramidal neurons in the hippocampal formation. Very little quantitative data on the number and distribution of excrescences in adult rats are available because, first, the vast majority are grouped into clusters and it is not possible to identify single excrescences within these clusters at the light microscope level. Second, clusters are of varying lengths and are distributed over hundreds of micrometers, making ultrastructural analysis prohibitively time-consuming. Here, by using three-dimensional analysis techniques at the light microscope level, we quantified the number, length, and distribution of excrescence clusters on proximal and midfield pyramidal neurons in the rat. Results indicated that proximal neurons had similar numbers of clusters on their apical and basal trees, and that cluster length was also similar. In contrast, midfield neurons had more apical than basal clusters, and apical clusters were longer. For neurons in both regions, basal clusters were located about 50% closer to somata. Overall, proximal neurons had more clusters than did midfield neurons, but the clusters were shorter; thus, proximal and midfield neurons had about the same total cluster length, and presumably the same number of single excrescences. Based on these data and on published ultrastructural measurements of single excrescences, we estimated an average of 41 excrescences/neuron, and suggest that a pyramidal neuron can be contacted by a maximum of 41 mossy fiber boutons, each from a different granule cell.

Previous studies have demonstrated that cortical spreading depression (CSD) induces neuronal tolerance to a subsequent episode of ischemia. The objective of the present investigation was to determine whether CSD alters levels of mRNA coding for putative neuroprotective proteins. Unilateral CSD was evoked in male Wistar rats by applying 2 mol/L KCl over the frontal cortex for 2 hours. After recovery for 0, 2, or 24 hours, levels of several mRNA coding for neuroprotective proteins were measured bilaterally in parietal cortex using Northern blot analysis. Levels of c-fos mRNA and brain-derived neurotrophic factor (BDNF) mRNA were markedly elevated at 0 and 2 hours, but not 24 hours after CSD. Tissue plasminogen activator (tPA) mRNA levels were also significantly increased at 0 and 2 hours, but not 24 hours after CSD. Levels of the 72-kDa heat-shock protein (hsp72) mRNA were not significantly increased by CSD, except for a small elevation (20%) at 2 hours recovery. Levels of the 73-kDa heat-shock cognate (hsc73) mRNA were slightly, but significantly, increased at 2 and 24 hours of recovery. Finally, levels of mRNA for protease nexin-1 and glutamine synthetase were not significantly altered by CSD at any time studied. The current results support the hypothesis that neuronal tolerance to ischemia after CSD may be mediated by increased expression of FOS, BDNF, or tPA, but not by increased expression of hsp72, hsc73, nexin-1, or glutamine synthetase.

No abstract