Medicine and Health Sciences Commons^™

The Tnfα-Transgenic Rat: Hippocampal Synaptic Integrity, Cognition, Function, And Post-Ischemic Cell Loss, L. Creed Pettigrew, Richard J. Kryscio, Christopher M. Norris

Sanders-Brown Center on Aging Faculty Publications

The cytokine, tumor necrosis factor α (TNFα), is a key regulator of neuroinflammation linked to numerous neurodegenerative conditions and diseases. The present study used transgenic rats that overexpress a murine TNFα gene, under the control of its own promoter, to investigate the impact of chronically elevated TNFα on hippocampal synaptic function. Neuronal viability and cognitive recovery in TNFα Tg rats were also determined following an ischemic insult arising from reversible middle cerebral artery occlusion (MCAO). Basal CA3-CA1 synaptic strength, recorded in acute brain slices, was not significantly different between eight-week-old TNFα Tg rats and non-Tg rats. In contrast, slices from …

AΒ40 Reduces P-Glycoprotein At The Blood-Brain Barrier Through The Ubiquitin-Proteasome Pathway, Anika M. S. Hartz, Yu Zhong, Andrea Wolf, Harry Levine Iii, David S. Miller, Björn Bauer

Sanders-Brown Center on Aging Faculty Publications

Failure to clear amyloid-β (Aβ) from the brain is in part responsible for Aβ brain accumulation in Alzheimer's disease (AD). A critical protein for clearing Aβ across the blood–brain barrier is the efflux transporter P-glycoprotein (P-gp) in the luminal plasma membrane of the brain capillary endothelium. P-gp is reduced at the blood–brain barrier in AD, which has been shown to be associated with Aβ brain accumulation. However, the mechanism responsible for P-gp reduction in AD is not well understood. Here we focused on identifying critical mechanistic steps involved in reducing P-gp in AD. We …

Mitochondria-Associated Micrornas In Rat Hippocampus Following Traumatic Brain Injury, Wang-Xia Wang, Nishant P. Visavadiya, Jignesh D. Pandya, Peter T. Nelson, Patrick G. Sullivan, Joe E. Springer

Sanders-Brown Center on Aging Faculty Publications

Traumatic brain injury (TBI) is a major cause of death and disability. However, the molecular events contributing to the pathogenesis are not well understood. Mitochondria serve as the powerhouse of cells, respond to cellular demands and stressors, and play an essential role in cell signaling, differentiation, and survival. There is clear evidence of compromised mitochondrial function following TBI; however, the underlying mechanisms and consequences are not clear. MicroRNAs (miRNAs) are small non-coding RNA molecules that regulate gene expression post-transcriptionally, and function as important mediators of neuronal development, synaptic plasticity, and neurodegeneration. Several miRNAs show altered expression following TBI; however, the …

Alzheimer's Therapeutics Targeting Amyloid Beta 1–42 Oligomers Ii: Sigma-2/Pgrmc1 Receptors Mediate Abeta 42 Oligomer Binding And Synaptotoxicity, Nicholas J. Izzo, Jinbin Xu, Chenbo Zeng, Molly J. Kirk, Kelsie Mozzoni, Colleen Silky, Courtney Rehak, Raymond Yurko, Gary Look, Gilbert Rishton, Hank Safferstein, Carlos Cruchaga, Alison Goate, Michael A. Cahill, Ottavio Arancio, Robert H. Mach, Rolf Craven, Elizabeth Head, Harry Levine Iii, Tara L. Spires-Jones, Susan M. Catalano

Sanders-Brown Center on Aging Faculty Publications

Amyloid beta (Abeta) 1-42 oligomers accumulate in brains of patients with Mild Cognitive Impairment (MCI) and disrupt synaptic plasticity processes that underlie memory formation. Synaptic binding of Abeta oligomers to several putative receptor proteins is reported to inhibit long-term potentiation, affect membrane trafficking and induce reversible spine loss in neurons, leading to impaired cognitive performance and ultimately to anterograde amnesia in the early stages of Alzheimer's disease (AD). We have identified a receptor not previously associated with AD that mediates the binding of Abeta oligomers to neurons, and describe novel therapeutic antagonists of this receptor capable of blocking Abeta toxic …

Alzheimer's Therapeutics Targeting Amyloid Beta 1-42 Oligomers I: Abeta 42 Oligomer Binding To Specific Neuronal Receptors Is Displaced By Drug Candidates That Improve Cognitive Deficits, Nicholas J. Izzo, Agnes Staniszewski, Lillian To, Mauro Fa, Andrew F. Teich, Faisal Saeed, Harrison Wostein, Thomas Walko Iii, Anisha Vaswani, Meghan Wardius, Zanobia Syed, Jessica Ravenscroft, Kelsie Mozzoni, Colleen Silky, Courtney Rehak, Raymond Yurko, Patricia Finn, Gary Look, Gilbert Rishton, Hank Safferstein, Miles Miller, Conrad Johanson, Edward Stopa, Manfred Windisch, Birgit Hutter-Paier, Mehrdad Shamloo, Ottavio Arancio, Harry Levine Iii, Susan M. Catalano

Sanders-Brown Center on Aging Faculty Publications

Synaptic dysfunction and loss caused by age-dependent accumulation of synaptotoxic beta amyloid (Abeta) 1-42 oligomers is proposed to underlie cognitive decline in Alzheimer's disease (AD). Alterations in membrane trafficking induced by Abeta oligomers mediates reduction in neuronal surface receptor expression that is the basis for inhibition of electrophysiological measures of synaptic plasticity and thus learning and memory. We have utilized phenotypic screens in mature, in vitro cultures of rat brain cells to identify small molecules which block or prevent the binding and effects of Abeta oligomers. Synthetic Abeta oligomers bind saturably to a single site on neuronal synapses and induce …

Expression Of Mir-15/107 Family Micrornas In Human Tissues And Cultured Rat Brain Cells, Wang-Xia Wang, Robert J. Danaher, Craig S. Miller, Joseph R. Berger, Vega G. Nubia, Bernard R. Wilfred, Janna H. Neltner, Christopher M. Norris, Peter T. Nelson

Sanders-Brown Center on Aging Faculty Publications

The miR-15/107 family comprises a group of 10 paralogous microRNAs (miRNAs), sharing a 5' AGCAGC sequence. These miRNAs have overlapping targets. In order to characterize the expression of miR-15/107 family miRNAs, we employed customized TaqMan Low-Density micro-fluid PCR-array to investigate the expression of miR-15/107 family members, and other selected miRNAs, in 11 human tissues obtained at autopsy including the cerebral cortex, frontal cortex, primary visual cortex, thalamus, heart, lung, liver, kidney, spleen, stomach and skeletal muscle. miR-103, miR-195 and miR-497 were expressed at similar levels across various tissues, whereas miR-107 is enriched in brain samples. We also examined the expression …

Inhibition Of Soluble Tumor Necrosis Factor Ameliorates Synaptic Alterations And Ca2+ Dysregulation In Aged Rats, Diana M. Sama, Hafiz Mohmmad Abdul, Jennifer L. Furman, Irina A. Artiushin, David E. Szymkowski, Stephen W. Scheff, Christopher M. Norris

Graduate Center for Gerontology Faculty Publications

The role of tumor necrosis factor α (TNF) in neural function has been investigated extensively in several neurodegenerative conditions, but rarely in brain aging, where cognitive and physiologic changes are milder and more variable. Here, we show that protein levels for TNF receptor 1 (TNFR1) are significantly elevated in the hippocampus relative to TNF receptor 2 (TNFR2) in aged (22 months) but not young adult (6 months) Fischer 344 rats. To determine if altered TNF/TNFR1 interactions contribute to key brain aging biomarkers, aged rats received chronic (4-6 week) intracranial infusions of XPro1595: a soluble dominant negative TNF that preferentially inhibits …

Microglial P38Α Mapk Is A Key Regulator Of Proinflammatory Cytokine Up-Regulation Induced By Toll-Like Receptor (Tlr) Ligands Or Beta-Amyloid (Aβ), Adam D. Bachstetter, Bin Xing, Lucia De Almeida, Edgardo R. Dimayuga, D. Martin Watterson, Linda J. Van Eldik

Sanders-Brown Center on Aging Faculty Publications

BACKGROUND: Overproduction of proinflammatory cytokines from activated microglia has been implicated as an important contributor to pathophysiology progression in both acute and chronic neurodegenerative diseases. Therefore, it is critical to elucidate intracellular signaling pathways that are significant contributors to cytokine overproduction in microglia exposed to specific stressors, especially pathways amenable to drug interventions. The serine/threonine protein kinase p38α MAPK is a key enzyme in the parallel and convergent intracellular signaling pathways involved in stressor-induced production of IL-1β and TNFα in peripheral tissues, and is a drug development target for peripheral inflammatory diseases. However, much less is known about the quantitative …

Cx3cl1 Reduces Neurotoxicity And Microglial Activation In A Rat Model Of Parkinson's Disease, Mibel M. Pabon, Adam D. Bachstetter, Charles E. Hudson, Carmelina Gemma, Paula C. Bickford

Sanders-Brown Center on Aging Faculty Publications

BACKGROUND: Parkinson's disease is characterized by a progressive loss of dopaminergic neurons in the substantia nigra. The cause of the neurodegeneration is unknown. Neuroinflammation has been clearly shown in Parkinson's disease and may be involved in the progressive nature of the disease. Microglia are capable of producing neuronal damage through the production of bioactive molecules such as cytokines, as well as reactive oxygen species (ROS), and nitric oxide (NO). The inflammatory response in the brain is tightly regulated at multiple levels. One form of immune regulation occurs via neurons. Fractalkine (CX3CL1), produced by neurons, suppresses the activation of microglia. CX3CL1 …

Focus On Rna Isolation: Obtaining Rna For Microrna (Mirna) Expression Profiling Analyses Of Neural Tissue, Wang-Xia Wang, Bernard R. Wilfred, Donald A. Baldwin, R. Benjamin Isett, Na Ren, Arnold J. Stromberg, Peter T. Nelson

Sanders-Brown Center on Aging Faculty Publications

MicroRNAs (miRNAs) are present in all known plant and animal tissues and appear to be somewhat concentrated in the mammalian nervous system. Many different miRNA expression profiling platforms have been described. However, relatively little research has been published to establish the importance of 'upstream' variables in RNA isolation for neural miRNA expression profiling. We tested whether apparent changes in miRNA expression profiles may be associated with tissue processing, RNA isolation techniques, or different cell types in the sample. RNA isolation was performed on a single brain sample using eight different RNA isolation methods, and results were correlated using a conventional …

Focal Cerebral Ischemia In The Tnfalpha-Transgenic Rat, L. Creed Pettigrew, Mark S. Kindy, Stephen W. Scheff, Joe E. Springer, Richard J. Kryscio, Yizhao Li, David S. Grass

Sanders-Brown Center on Aging Faculty Publications

BACKGROUND: To determine if chronic elevation of the inflammatory cytokine, tumor necrosis factor-alpha (TNFalpha), will affect infarct volume or cortical perfusion after focal cerebral ischemia.

METHODS: Transgenic (TNFalpha-Tg) rats overexpressing the murine TNFalpha gene in brain were prepared by injection of mouse DNA into rat oocytes. Brain levels of TNFalpha mRNA and protein were measured and compared between TNFalpha-Tg and non-transgenic (non-Tg) littermates. Mean infarct volume was calculated 24 hours or 7 days after one hour of reversible middle cerebral artery occlusion (MCAO). Cortical perfusion was monitored by laser-Doppler flowmetry (LDF) during MCAO. Cortical vascular density was quantified by stereology. …

Neuroprotective Action Of Cycloheximide Involves Induction Of Bcl-2 And Antioxidant Pathways, Katsutoshi Furukawa, Steven Estus, Weiming Fu, Robert J. Mark, Mark P. Mattson

Sanders-Brown Center on Aging Faculty Publications

The ability of the protein synthesis inhibitor cycloheximide (CHX) to prevent neuronal death in different paradigms has been interpreted to indicate that the cell death process requires synthesis of “killer” proteins. On the other hand, data indicate that neurotrophic factors protect neurons in the same death paradigms by inducing expression of neuroprotective gene products. We now provide evidence that in embryonic rat hippocampal cell cultures, CHX protects neurons against oxidative insults by a mechanism involving induction of neuroprotective gene products including the antiapoptotic gene bcl-2 and antioxidant enzymes. Neuronal survival after exposure to glutamate, FeSO₄, and amyloid β-peptide …