Journal of neurochemistry
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Journal of neurochemistry · Jun 2009
Tamoxifen attenuates inflammatory-mediated damage and improves functional outcome after spinal cord injury in rats.
Tamoxifen has been found to be neuroprotective in both transient and permanent experimental ischemic stroke. However, it remains unknown whether this agent shows a similar beneficial effect after spinal cord injury (SCI), and what are its underlying mechanisms. In this study, we investigated the efficacy of tamoxifen treatment in attenuating SCI-induced pathology. ⋯ The myelin loss and the increase in production of myelin-associated axonal growth inhibitors were also found to be significantly attenuated at day 3 post-injury. Furthermore, rats treated with tamoxifen scored much higher on the locomotor rating scale after SCI than did vehicle-treated rats, suggesting improved functional outcome after SCI. Together, these results demonstrate that tamoxifen provides neuroprotective effects for treatment of SCI-related pathology and disability, and is therefore a potential neuroprotectant for human spinal cord injury therapy.
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Journal of neurochemistry · Jun 2009
Distinct modulation of voltage-gated and ligand-gated Ca2+ currents by PPAR-gamma agonists in cultured hippocampal neurons.
Type 2 diabetes mellitus is a metabolic disorder characterized by hyperglycemia and is especially prevalent in the elderly. Because aging is a risk factor for type 2 diabetes mellitus, and insulin resistance may contribute to the pathogenesis of Alzheimer's disease (AD), anti-diabetic agents (thiazolidinediones-TZDs) are being studied for the treatment of cognitive decline associated with AD. These agents normalize insulin sensitivity in the periphery and can improve cognition and verbal memory in AD patients. ⋯ Rosiglitazone, but not pioglitazone reduced VGCC currents. In contrast, NMDAR-mediated currents were significantly reduced by pioglitazone but not rosiglitazone. These results show that TZDs modulate Ca(2+)-dependent pathways in the brain and have different inhibitory profiles on two major Ca(2+) sources, potentially conferring neuroprotection to an area of the brain that is particularly vulnerable to the effects of aging and/or AD.
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Journal of neurochemistry · Jun 2009
A synthetic NCAM-derived mimetic peptide, FGL, exerts anti-inflammatory properties via IGF-1 and interferon-gamma modulation.
Microglial cell activity increases in the rat hippocampus during normal brain aging. The neural cell adhesion molecule (NCAM)-derived mimetic peptide, FG loop (FGL), acts as an anti-inflammatory agent in the hippocampus of the aged rat, promoting CD200 ligand expression while attenuating glial cell activation and subsequent pro-inflammatory cytokine production. The aim of the current study was to determine if FGL corrects the age-related imbalance in hippocampal levels of insulin-like growth factor-1 (IGF-1) and pro-inflammatory interferon-gamma (IFNgamma), and subsequently attenuates the glial reactivity associated with aging. ⋯ Finally, the proclivity of FGL to attenuate IFNgamma-induced glial cell activation in vitro is IGF-1-dependent. Overall, these findings suggest that FGL, by correcting the age-related imbalance in hippocampal levels of IGF-1 and IFNgamma, attenuates glial cell activation associated with aging. These findings also highlight a novel mechanism by which FGL can impact on neuronal CD200 ligand expression and subsequently on glial cell activation status.
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Journal of neurochemistry · Jun 2009
Inhibiting astrocytic activation: a novel analgesic mechanism of ketamine at the spinal level?
Although ketamine is widely used as an analgesic agent and has an anti-allodynic effect on neuropathic pain, the underlying analgesic mechanisms are not fully explained by the modern 'neuronal-based' theories. As emerging studies have focused on the critical role of spinal astrocytes in the pathological pain states, we have hypothesized that there exist some 'astrocytes-related' mechanisms in the analgesic function of ketamine. ⋯ Using quantitative Western blot analysis, our report showed that intrathecal ketamine down-regulated glial fibrillary acidic protein expression, suggesting inhibition of SNL-induced astrocytic activation, which wasn't influenced by intraperitoneal administration. We conclude that intraperitoneal ketamine could alleviate SNL-induced neuropathic pain via the classical 'neuronal-based' mechanisms, but in addition, 'astrocytes-related' mechanisms were also important underlying the anti-allodynic effect of intrathecal ketamine.
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Journal of neurochemistry · Jun 2009
Prenatal stress alters glutamatergic system responsiveness in adult rat prefrontal cortex.
Exposure to stress during gestation alters brain development resulting in permanent alterations that may increase susceptibility to subsequent cognitive or neuropsychiatric disorders. In this manuscript we examined the effects of prenatal stress on critical determinants of the glutamatergic synapse under basal conditions as well as in response to acute stress. The main finding of this work is that gestational stress altered the responsiveness of the glutamatergic system following a challenge at adulthood. ⋯ Changes were also observed in the phosphorylation of the alpha-amino-3-hydroxy-5-methylisoxazole-4-propionate subunit GluR-1(Ser831) which, however, relied on the acute stress exposure and were independent of gestational stress. These effects point to a unique interference of chronic prenatal stress with the responsiveness of specific determinants of the glutamatergic synapse at adulthood in a region specific manner. The inability to mount an homeostatic glutamatergic response to subsequent stress at adulthood may impair the normal responses of the cell to challenging situations.