Proceedings of the National Academy of Sciences of the United States of America
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Proc. Natl. Acad. Sci. U.S.A. · Oct 2009
Inhibition of protein kinase C signaling protects prefrontal cortex dendritic spines and cognition from the effects of chronic stress.
The prefrontal cortex r regulates behavior, cognition, and emotion by using working memory. Prefrontal functions are impaired by stress exposure. Acute, stress-induced deficits arise from excessive protein kinase C (PKC) signaling, which diminishes prefrontal neuronal firing. ⋯ We found that inhibition of PKC rescued working memory impairments and reversed distal apical dendritic spine loss in layer II/III pyramidal neurons of rat prelimbic cortex. Greater spine density predicted better cognitive performance, the first direct correlation between pyramidal cell structure and working memory abilities. These findings suggest that PKC inhibitors may be neuroprotective in disorders with dysregulated PKC signaling such as bipolar disorder, schizophrenia, post-traumatic stress disorder, and lead poisoning--conditions characterized by impoverished prefrontal structural and functional integrity.
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Proc. Natl. Acad. Sci. U.S.A. · Sep 2009
Central role of TRAF-interacting protein in a new model of brain sexual differentiation.
Sexually dimorphic brain nuclei underlie gender-specific neural functions and susceptibility to disease, but the developmental basis of dimorphisms is poorly understood. In these studies, we focused on the anteroventral periventricular nucleus (AVPV), a nucleus that is larger in females and critical for the female-typical cyclic surge pattern of luteinizing hormone (LH) release. Sex differences in the size and function of the AVPV result from apoptosis that occurs preferentially in the developing male. ⋯ The male AVPV also had higher levels of bax and bad mRNA, but neither of these genes was regulated by either TNFalpha or TRIP. Finally, the trip gene was not expressed in the sexually dimorphic nucleus of the preoptic area (SDN-POA), a nucleus in which apoptosis is higher in females than males. These findings form the basis of a new model of sexual differentiation of the AVPV that may also apply to the development of other sexually dimorphic nuclei.
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Proc. Natl. Acad. Sci. U.S.A. · Sep 2009
Allogeneic human mesenchymal stem cells for treatment of E. coli endotoxin-induced acute lung injury in the ex vivo perfused human lung.
Recent studies have suggested that bone marrow-derived multipotent mesenchymal stem cells (MSCs) may have therapeutic applications in multiple clinical disorders including myocardial infarction, diabetes, sepsis, and hepatic and acute renal failure. Here, we tested the therapeutic capacity of human MSCs to restore alveolar epithelial fluid transport and lung fluid balance from acute lung injury (ALI) in an ex vivo perfused human lung preparation injured by E. coli endotoxin. ⋯ Using siRNA knockdown of potential paracrine soluble factors, secretion of keratinocyte growth factor was essential for the beneficial effect of MSCs on alveolar epithelial fluid transport, in part by restoring amiloride-dependent sodium transport. In summary, treatment with allogeneic human MSCs or the conditioned medium restores normal fluid balance in an ex vivo perfused human lung injured by E. coli endotoxin.
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Proc. Natl. Acad. Sci. U.S.A. · Sep 2009
The putative cannabinoid receptor GPR55 affects osteoclast function in vitro and bone mass in vivo.
GPR55 is a G protein-coupled receptor recently shown to be activated by certain cannabinoids and by lysophosphatidylinositol (LPI). However, the physiological role of GPR55 remains unknown. Given the recent finding that the cannabinoid receptors CB(1) and CB(2) affect bone metabolism, we examined the role of GPR55 in bone biology. ⋯ Consistent with the ability of GPR55 to suppress osteoclast formation but stimulate osteoclast function, histomorphometric and microcomputed tomographic analysis of the long bones from male GPR55(-/-) mice revealed increased numbers of morphologically inactive osteoclasts but a significant increase in the volume and thickness of trabecular bone and the presence of unresorbed cartilage. These data reveal a role of GPR55 in bone physiology by regulating osteoclast number and function. In addition, this study also brings to light an effect of both the endogenous ligand, LPI, on osteoclasts and of the cannabis constituent, CBD, on osteoclasts and bone turnover in vivo.
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Proc. Natl. Acad. Sci. U.S.A. · Sep 2009
Intrahippocampal injection of a lentiviral vector expressing Nrf2 improves spatial learning in a mouse model of Alzheimer's disease.
The amyloid hypothesis of Alzheimer's disease (AD) postulates that amyloid-beta (Abeta) deposition and neurotoxicity play a causative role in AD; oxidative injury is thought to be central in the pathogenesis. An endogenous defense system against oxidative stress is induced by binding of the transcription factor nuclear factor E2-related factor 2 (Nrf2) to the antioxidant response element (ARE) enhancer sequence. The Nrf2-ARE pathway is activated in response to reactive oxygen species to trigger the simultaneous expression of numerous protective enzymes and scavengers. ⋯ Memory improvement in APP/PS1 mice after Nrf2 transduction shifts the balance between soluble and insoluble Abeta toward an insoluble Abeta pool without concomitant change in total brain Abeta burden. Nrf2 gene transfer is associated with a robust reduction in astrocytic but not microglial activation and induction of Nrf2 target gene heme oxygenase 1, indicating overall activation of the Nrf2-ARE pathway in hippocampal neurons 6 months after injection. Results warrant further exploration of the Nrf2-ARE pathway for treatment of AD and suggest that the Nrf2-ARE pathway may represent a potential therapeutic strategy to pursue in AD in humans, particularly in view of the multiple mechanisms by which Nrf2 can exert its protective effects.