Medical Neurobiology Commons^™

In Search Of The Locus Coeruleus: Guidelines For Identifying Anatomical Boundaries And Electrophysiological Properties Of The Blue Spot In Mice, Fish, Finches, And Beyond, Amelien Vreven, Gary Aston-Jones, Anthony E Pickering, Gina R Poe, Barry Waterhouse, Nelson K Totah

Rowan-Virtua School of Osteopathic Medicine Departmental Research

Our understanding of human brain function can be greatly aided by studying analogous brain structures in other organisms. One brain structure with neurochemical and anatomical homology throughout vertebrate species is the locus coeruleus (LC), a small collection of norepinephrine (NE)-containing neurons in the brainstem that project throughout the central nervous system. The LC is involved in nearly every aspect of brain function, including arousal and learning, which has been extensively examined in rats and nonhuman primates using single-unit recordings. Recent work has expanded into putative LC single-unit electrophysiological recordings in a nonmodel species, the zebra finch. Given the importance of …

Differential Roles Of Key Brain Regions: Ventral Tegmental Area, Locus Coeruleus, Dorsal Raphe, Nucleus Accumbens, Caudate Nucleus, And Prefrontal Cortex In Regulating Response To Methylphenidate: Insights From Neuronal And Behavioral Studies In Freely Behaving Rats, Nachum Dafny, Catherine Claussen, Emilee Frazier, Yin Liu

Faculty, Staff and Student Publications

A total of 3102 neurons were recorded before and following acute and chronic methylphenidate (MPD) administration. Acute MPD exposure elicits mainly increases in neuronal and behavioral activity in dose–response characteristics. The response to chronic MPD exposure, as compared to acute 0.6, 2.5, or 10.0 mg/kg MPD administration, elicits electrophysiological and behavioral sensitization in some animals and electrophysiological and behavioral tolerance in others when the neuronal recording evaluations were performed based on the animals’ behavioral responses, or amount of locomotor activity, to chronic MPD exposure. The majority of neurons recorded from those expressing behavioral sensitization responded to chronic MPD with further …

Caldendrin Is A Repressor Of Piezo2 Channels And Touch Sensation In Mice, Josue A Lopez, Luis O Romero, Wai-Lin Kaung, J Wesley Maddox, Valeria Vásquez, Amy Lee

Faculty, Staff and Student Publications

The sense of touch is crucial for cognitive, emotional, and social development and relies on mechanically activated (MA) ion channels that transduce force into an electrical signal. Despite advances in the molecular characterization of these channels, the physiological factors that control their activity are poorly understood. Here, we used behavioral assays, electrophysiological recordings, and various mouse strains (males and females analyzed separately) to investigate the role of the calmodulin-like Ca2+ sensor, caldendrin, as a key regulator of MA channels and their roles in touch sensation. In mice lacking caldendrin (Cabp1 KO), heightened responses to tactile stimuli correlate with enlarged …

Potential Value Of A Rapid Syndromic Multiplex Pcr For The Diagnosis Of Native And Prosthetic Joint Infections: A Real-World Evidence Study, Stéphanie Pascual, Brooklyn Noble, Nusreen Ahmad-Saeed, Catherine Aldridge, Simone Ambretti, Sharon Amit, Rachel Annett, Shaan Ashk O'Shea, Anna Maria Barbui, Gavin Barlow, Lucinda Barrett, Mario Berth, Alessandro Bondi, Nicola Boran, Sara E Boyd, Catarina Chaves, Martin Clauss, Peter Davies, Ileana T Dianzo-Delgado, Jaime Esteban, Stefan Fuchs, Lennart Friis-Hansen, Daniel Goldenberger, Andrej Golle, Juha O Groonroos, Ines Hoffmann, Tomer Hoffmann, Harriet Hughes, Marina Ivanova, Peter Jezek, Gwennan Jones, Zeynep Ceren Karahan, Cornelia Lass-Flörl, Frédéric Laurent, Laura Leach, Matilde Lee Horsbøll Pedersen, Caroline Loiez, Maureen Lynch, Robert J Maloney, Martin Marsh, Olivia Milburn, Shanine Mitchell, Luke S P Moore, Lynn Moffat, Marianna Murdjeva, Michael E Murphy, Deepa Nayar, Giacomo Nigrisoli, Fionnuala O'Sullivan, Büşra Öz, Teresa Peach, Christina Petridou, Mojgan Prinz, Mitja Rak, Niamh Reidy, Gian Maria Rossolini, Anne-Laure Roux, Patricia Ruiz-Garbajosa, Kordo Saeed, Llanos Salar-Vidal, Carlos Salas Venero, Mathyruban Selvaratnam, Eric Senneville, Peter Starzengruber, Ben Talbot, Vanessa Taylor, Rihard Trebše, Deborah Wearmouth, Birgit Willinger, Marjan Wouthuyzen-Bakker, Brianne Couturier, Florence Allantaz

Faculty, Staff and Student Publications

Introduction: The BIOFIRE Joint Infection (JI) Panel is a diagnostic tool that uses multiplex-PCR testing to detect microorganisms in synovial fluid specimens from patients suspected of having septic arthritis (SA) on native joints or prosthetic joint infections (PJIs). Methods: A study was conducted across 34 clinical sites in 19 European and Middle Eastern countries from March 2021 to June 2022 to assess the effectiveness of the BIOFIRE JI Panel. Results: A total of 1527 samples were collected from patients suspected of SA or PJI, with an overall agreement of 88.4 % and 85 % respectively between the …

Mechanosensory Encoding In Ex Vivo Muscle–Nerve Preparations, Stephen N. Housley, Evelyn A. Gardolinski, Paul Nardelli, J'Ana Reed, Mark M. Rich, Timothy C. Cope

Neuroscience, Cell Biology & Physiology Faculty Publications

Our objective was to evaluate an ex vivo muscle-nerve preparation used to study mechanosensory signalling by low threshold mechanosensory receptors (LTMRs). Specifically, we aimed to assess how well the ex vivo preparation represents in vivo firing behaviours of the three major LTMR subtypes of muscle primary sensory afferents, namely type Ia and II muscle spindle (MS) afferents and type Ib tendon organ afferents. Using published procedures for ex vivo study of LTMRs in mouse hindlimb muscles, we replicated earlier reports on afferent firing in response to conventional stretch paradigms applied to non-contracting, that is passive, muscle. Relative to in vivo …

Voltage- And Calcium-Gated Membrane Currents Tune The Plateau Potential Properties Of Multiple Neuron Types, Curtis L Neveu, Paul Smolen, Douglas A Baxter, John H Byrne

Faculty, Staff and Student Publications

Many neurons exhibit regular firing that is limited to the duration and intensity of depolarizing stimuli. However, some neurons exhibit all-or-nothing plateau potentials that, once elicited, can lead to prolonged activity that is independent of stimulus intensity or duration. To better understand this diversity of information processing, we compared the voltage-gated and Ca²⁺-gated currents of three identified neurons from hermaphroditic Aplysia californica. Two of these neurons, B51 and B64, generated plateau potentials and a third neuron, B8, exhibited regular firing and was incapable of generating a plateau potential. With the exception of the Ca²⁺-gated potassium …

Caudal Dmn Neurons Innervate The Spleen And Release Cart Peptide To Regulate Neuroimmune Function, Nobuhide Kobori, Anthony N Moore, John B Redell, Pramod K Dash

Faculty, Staff and Student Publications

BACKGROUND: Inflammation is a fundamental biological response to injury and infection, which if unregulated can contribute to the pathophysiology of many diseases. The vagus nerve, which primarily originates from the dorsal motor nucleus (DMN), plays an important role in rapidly dampening inflammation by regulating splenic function. However, direct vagal innervation of the spleen, which houses the majority of immune and inflammatory cells, has not been established. As an alternative to direct innervation, an anti-inflammatory reflex pathway has been proposed which involves the vagus nerve, the sympathetic celiac ganglion, and the neurotransmitter norepinephrine. Although sympathetic regulation of inflammation has been shown, …

Cortex-Wide Neural Dynamics Predict Behavioral States And Provide A Neural Basis For Resting-State Dynamic Functional Connectivity, Somayeh Shahsavarani, David N Thibodeaux, Weihao Xu, Sharon H Kim, Fatema Lodgher, Chinwendu Nwokeabia, Morgan Cambareri, Alexis J Yagielski, Hanzhi T Zhao, Daniel A Handwerker, Javier Gonzalez-Castillo, Peter A Bandettini, Elizabeth M C Hillman

Faculty, Staff and Student Publications

Although resting-state functional magnetic resonance imaging (fMRI) studies have observed dynamically changing brain-wide networks of correlated activity, fMRI's dependence on hemodynamic signals makes results challenging to interpret. Meanwhile, emerging techniques for real-time recording of large populations of neurons have revealed compelling fluctuations in neuronal activity across the brain that are obscured by traditional trial averaging. To reconcile these observations, we use wide-field optical mapping to simultaneously record pan-cortical neuronal and hemodynamic activity in awake, spontaneously behaving mice. Some components of observed neuronal activity clearly represent sensory and motor function. However, particularly during quiet rest, strongly fluctuating patterns of activity across …

Target Cell-Specific Synaptic Dynamics Of Excitatory To Inhibitory Neuron Connections In Supragranular Layers Of Human Neocortex, Mean-Hwan Kim, Cristina Radaelli, Elliot R Thomsen, Deja Monet, Thomas Chartrand, Nikolas L Jorstad, Joseph T Mahoney, Michael J Taormina, Brian Long, Katherine Baker, Trygve E Bakken, Luke Campagnola, Tamara Casper, Michael Clark, Nick Dee, Florence D'Orazi, Clare Gamlin, Brian E Kalmbach, Sara Kebede, Brian R Lee, Lindsay Ng, Jessica Trinh, Charles Cobbs, Ryder P Gwinn, C Dirk Keene, Andrew L Ko, Jeffrey G Ojemann, Daniel L Silbergeld, Staci A Sorensen, Jim Berg, Kimberly A Smith, Philip R Nicovich, Tim Jarsky, Hongkui Zeng, Jonathan T Ting, Boaz P Levi, Ed Lein

Faculty, Staff and Student Publications

Rodent studies have demonstrated that synaptic dynamics from excitatory to inhibitory neuron types are often dependent on the target cell type. However, these target cell-specific properties have not been well investigated in human cortex, where there are major technical challenges in reliably obtaining healthy tissue, conducting multiple patch-clamp recordings on inhibitory cell types, and identifying those cell types. Here, we take advantage of newly developed methods for human neurosurgical tissue analysis with multiple patch-clamp recordings, post-hoc fluorescent in situ hybridization (FISH), machine learning-based cell type classification and prospective GABAergic AAV-based labeling to investigate synaptic properties between pyramidal neurons and PVALB- …

Functional Neuronal Circuits Promote Disease Progression In Cancer, Anthony C Restaino, Austin Walz, Samuel J Vermeer, Jeffrey Barr, Attila Kovács, Robin R Fettig, Daniel W Vermeer, Hunter Reavis, Caitlin S Williamson, Christopher T Lucido, Tuany Eichwald, Dalia K Omran, Euihye Jung, Lauren E Schwartz, Maria Bell, Desirae M Muirhead, Jody E Hooper, William C Spanos, Ronny Drapkin, Sebastien Talbot, Paola D Vermeer

Faculty, Staff and Student Publications

The molecular and functional contributions of intratumoral nerves to disease remain largely unknown. We localized synaptic markers within tumors suggesting that these nerves form functional connections. Consistent with this, electrophysiological analysis shows that malignancies harbor significantly higher electrical activity than benign disease or normal tissues. We also demonstrate pharmacologic silencing of tumoral electrical activity. Tumors implanted in transgenic animals lacking nociceptor neurons show reduced electrical activity. These data suggest that intratumoral nerves remain functional at the tumor bed. Immunohistochemical staining demonstrates the presence of the neuropeptide, Substance P (SP), within the tumor space. We show that tumor cells express the …

Extravasated Brain-Reactive Autoantibodies Perturb Neuronal Surface Protein Expression In Alzheimer's Pathology, Wardah Bajwa, Mary Kosciuk, Randel L. Swanson, Anuradha Krishnan, Venkat Venkataraman, Robert Nagele, Nimish Acharya

Rowan-Virtua Research Day

Background: Increased blood-brain barrier (BBB) permeability is reported in both the neuropathological and in vivo studies in both Alzheimer’s Disease (AD) and age matched cognitively normal, no cognitive impairment (NCI), subjects. Impaired BBB allows various vascular components such as immunoglobulin G (IgG) to extravasate into the brain and specifically bind to various neuronal surface proteins (NSP), also known as brain reactive autoantibodies (BrABs). This interaction is predicted to further enhance deposition of amyloid plaques.

Hypothesis: Interaction between extravasated BrABs and its cognate NSPs lower the expression of that NSPs in AD patients.

Methods: We selected Western blotting technique to study …

Regeneration Of Neurons In Human Brain Tissue; A Revolutionary Concept With Therapeutic Potential, Mackenzie R. Dunn

Biomedical Sciences Undergraduate Research

There is current research to suggest that endogenous neuronal regeneration, exogenous neuronal stem cell transplantation and glial cell reprogramming could be prospective therapeutic treatments for neurodegeneration and traumatic injury. With these conditions, there is significant brain atrophy, loss of neurons and loss of synaptic connections which can have devastating effects on executive functioning, cognition, learning and memory. This review will examine these modern approaches to adult neurogenesis, and assess the viable mechanisms and future outlook of these three therapies for neurological regenerative medicine.

Intravital Imaging Of Cellular Response Due To Traumatic Brain Injury Using Confocal Microscopy, Enoch G. Kim, Jeffrey Horbatiuk, Carolyn Harris

Medical Student Research Symposium

Introduction: Cellular reaction to traumatic brain injury is complex and involves considerable interactions between cells and reactivity to foreign bodies. Our objective was to assess neurons, microglia, astrocytes, and intracellular Ca²⁺ signaling by creating a novel confocal microscopy technique involving an air immersed lens that does not sacrifice resolution and limits signal attenuation. This study aimed to create a consistent dynamic methodology to observe the cortical cellular response using real-time intravital imaging as trauma is being induced.

Methods: Once surgical plane was achieved, rodent cortices were exposed via craniotomy and blunt insertion with a silicone shunt catheter into the …

Positioning The Brainstem Within The Neural Network Of Threat Prediction, Xu O Zhang, Fabricio H Do Monte

Faculty, Staff and Student Publications

In a recent study, Strickland and McDannald dissected the role of brainstem networks in threat prediction. Using probabilistic threat discrimination in rats, the authors demonstrated that brainstem neurons estimate threat probability and generate positive aversive prediction errors after unexpected outcomes. Their findings suggest that, beyond organizing defensive behaviors, brainstem neurons are involved in threat prediction computations.

Genetic Targeting Of Adult Renshaw Cells Using A Calbindin 1 Destabilized Cre Allele For Intersection With Parvalbumin Or Engrailed1, Alicia R. Lane, Indeara C. Cogdell, Thomas M. Jessell, Jay B. Bikoff, Francisco J. Alvarez

Neuroscience, Cell Biology & Physiology Faculty Publications

Renshaw cells (RCs) are one of the most studied spinal interneurons; however, their roles in motor control remain enigmatic in part due to the lack of experimental models to interfere with RC function, specifically in adults. To overcome this limitation, we leveraged the distinct temporal regulation of Calbindin (Calb1) expression in RCs to create genetic models for timed RC manipulation. We used a Calb1 allele expressing a destabilized Cre (dgCre) theoretically active only upon trimethoprim (TMP) administration. TMP timing and dose influenced RC targeting efficiency, which was highest within the first three postnatal weeks, but specificity was low with …

The Effects Of Mapk Signaling On The Development Of Cerebellar Granule Cells, Kerry Morgan

Honors Scholar Theses

The granule cells are the most abundant neuronal type in the human brain. Rapid proliferation of granule cell progenitors results in dramatic expansion and folding of the cerebellar cortex during postnatal development. Mis-regulation of this proliferation process causes medulloblastoma, the most prevalent childhood brain tumor. In the developing cerebellum, granule cells are derived from Atoh1-expressing cells, which arise from the upper rhombic lip (the interface between the roof plate and neuroepithelium). In addition to granule cells, the Atoh1 lineage also gives rise to different types of neurons including cerebellar nuclei neurons. In the current study, I have investigated the …

Clinical And Basic Research Investigations Into The Long‐Term Effects Of Prenatal Opioid Exposure On Brain Development, Taylor Boggess, W. Chris Risher

Biomedical Sciences

Coincident with the opioid epidemic in the United States has been a dramatic increase in the number of children born with neonatal abstinence syndrome (NAS), a form of withdrawal resulting from opioid exposure during pregnancy. Many research efforts on NAS have focused on short‐term care, including acute symptom treatment and weaning of the infants off their drug dependency prior to authorizing their release. However, investigations into the long‐term effects of prenatal opioid exposure (POE) on brain development, from the cellular to the behavioral level, have not been as frequent. Given the importance of the perinatal period for human brain development, …

Prefrontal Corticotropin-Releasing Factor (Crf) Neurons Act Locally To Modulate Frontostriatal Cognition And Circuit Function., Sofiya Hupalo, Andrea J Martin, Rebecca K Green, David M Devilbiss, Craig W Berridge

Rowan-Virtua School of Osteopathic Medicine Departmental Research

The PFC and extended frontostriatal circuitry support higher cognitive processes that guide goal-directed behavior. PFC-dependent cognitive dysfunction is a core feature of multiple psychiatric disorders. Unfortunately, a major limiting factor in the development of treatments for PFC cognitive dysfunction is our limited understanding of the neural mechanisms underlying PFC-dependent cognition. We recently demonstrated that activation of corticotropin-releasing factor (CRF) receptors in the caudal dorsomedial PFC (dmPFC) impairs higher cognitive function, as measured in a working memory task. Currently, there remains much unknown about CRF-dependent regulation of cognition, including the source of CRF for cognition-modulating receptors and the output pathways modulated …

Cell Specific Control Of The Pallidostriatal Pathway, Shubha Verma '19

Student Publications & Research

Parkinson’s Disease is a neurodegenerative disorder of the basal ganglia. The main cause for Parkinson’s Disease is the depletion of dopamine, a neurotransmitter. The basal ganglia contains four major nuclei: the substantia nigra, the subthalamic nucleus, the external globus pallidus, and the striatum. These nuclei communicate with each other by the use of neurons.

Persistent Stress-Induced Neuroplastic Changes In The Locus Coeruleus/Norepinephrine System, Olga Borodovitsyna, Neal Joshi, Daniel Chandler

Rowan-Virtua School of Osteopathic Medicine Departmental Research

Neural plasticity plays a critical role in mediating short- and long-term brain responses to environmental stimuli. A major effector of plasticity throughout many regions of the brain is stress. Activation of the locus coeruleus (LC) is a critical step in mediating the neuroendocrine and behavioral limbs of the stress response. During stressor exposure, activation of the hypothalamic-pituitary-adrenal axis promotes release of corticotropin-releasing factor in LC, where its signaling promotes a number of physiological and cellular changes. While the acute effects of stress on LC physiology have been described, its long-term effects are less clear. This review will describe how stress …

The Effect Of Caffeine On Migraine Headaches, Deborah Shimshoni

Honors Undergraduate Theses

As the most widely consumed drug around the globe, there is a vast array of contradicting research available on caffeine. One of the most debated and researched topics on caffeine is its effect on the brain. Meanwhile, the data on the neurological condition of migraine has information scattered throughout countless research articles and experiments.

Although neither migraine or caffeine are completely understood by the medical world, this analysis attempts to give a more coherent understanding of the relationship between the two. This is done by first understanding the known and theorized mechanisms of caffeine as well as the pathologies of …

Taranis Functions With Cyclin A And Cdk1 In A Novel Arousal Center To Control Sleep In Drosophila., Dinis J.S. Afonso, Die Liu, Daniel R. Machado, Huihui Pan, James E.C. Jepson, Dragana Rogulja, Kyunghee Koh

Department of Neuroscience Faculty Papers

Sleep is an essential and conserved behavior whose regulation at the molecular and anatomical level remains to be elucidated. Here, we identify TARANIS (TARA), a Drosophila homolog of the Trip-Br (SERTAD) family of transcriptional coregulators, as a molecule that is required for normal sleep patterns. Through a forward-genetic screen, we isolated tara as a novel sleep gene associated with a marked reduction in sleep amount. Targeted knockdown of tara suggests that it functions in cholinergic neurons to promote sleep. tara encodes a conserved cell-cycle protein that contains a Cyclin A (CycA)-binding homology domain. TARA regulates CycA protein levels and genetically …

Fus Transgenic Rats Develop The Phenotypes Of Amyotrophic Lateral Sclerosis And Frontotemporal Lobar Degeneration., Cao Huang, Hongxia Zhou, Jianbin Tong, Han Chen, Yong-Jian Liu, Dian Wang, Xiaotao Wei, Xu-Gang Xia

Department of Pathology, Anatomy, and Cell Biology Faculty Papers

Fused in Sarcoma (FUS) proteinopathy is a feature of frontotemporal lobar dementia (FTLD), and mutation of the fus gene segregates with FTLD and amyotrophic lateral sclerosis (ALS). To study the consequences of mutation in the fus gene, we created transgenic rats expressing the human fus gene with or without mutation. Overexpression of a mutant (R521C substitution), but not normal, human FUS induced progressive paralysis resembling ALS. Mutant FUS transgenic rats developed progressive paralysis secondary to degeneration of motor axons and displayed a substantial loss of neurons in the cortex and hippocampus. This neuronal loss was accompanied by ubiquitin aggregation and …

Dopaminergic Neurons Derived From Human Induced Pluripotent Stem Cells Survive And Integrate Into 6-Ohda-Lesioned Rats., Jingli Cai, Ming Yang, Elizabeth Poremsky, Sarah Kidd, Jay S Schneider, Lorraine Iacovitti

Farber Institute for Neuroscience Faculty Papers

Cell replacement therapy could be an important treatment strategy for Parkinson's disease (PD), which is caused by the degeneration of dopamine neurons in the midbrain (mDA). The success of this approach greatly relies on the discovery of an abundant source of cells capable of mDAergic function in the brain. With the paucity of available human fetal tissue, efforts have increasingly focused on renewable stem cells. Human induced pluripotent stem (hiPS) cells offer great promise in this regard. If hiPS cells can be differentiated into authentic mDA neuron, hiPS could provide a potential autologous source of transplant tissue when generated from …

Interaction Of The Mu-Opioid Receptor With Gpr177 (Wntless) Inhibits Wnt Secretion: Potential Implications For Opioid Dependence., Jay Jin, Saranya Kittanakom, Victoria Wong, Beverly A S Reyes, Elisabeth J Van Bockstaele, Igor Stagljar, Wade Berrettini, Robert Levenson

Department of Neurosurgery Faculty Papers

BACKGROUND: Opioid agonist drugs produce analgesia. However, long-term exposure to opioid agonists may lead to opioid dependence. The analgesic and addictive properties of opioid agonist drugs are mediated primarily via the mu-opioid receptor (MOR). Opioid agonists appear to alter neuronal morphology in key brain regions implicated in the development of opioid dependence. However, the precise role of the MOR in the development of these neuronal alterations remains elusive. We hypothesize that identifying and characterizing novel MOR interacting proteins (MORIPs) may help to elucidate the underlying mechanisms involved in the development of opioid dependence. RESULTS: GPR177, the mammalian ortholog of Drosophila …

Mitochondrial Mislocalization Underlies Abeta42-Induced Neuronal Dysfunction In A Drosophila Model Of Alzheimer's Disease., Kanae Iijima-Ando, Stephen A Hearn, Christopher Shenton, Anthony Gatt, Lijuan Zhao, Koichi Iijima

Department of Biochemistry and Molecular Biology Faculty Papers

The amyloid-beta 42 (Abeta42) is thought to play a central role in the pathogenesis of Alzheimer's disease (AD). However, the molecular mechanisms by which Abeta42 induces neuronal dysfunction and degeneration remain elusive. Mitochondrial dysfunctions are implicated in AD brains. Whether mitochondrial dysfunctions are merely a consequence of AD pathology, or are early seminal events in AD pathogenesis remains to be determined. Here, we show that Abeta42 induces mitochondrial mislocalization, which contributes to Abeta42-induced neuronal dysfunction in a transgenic Drosophila model. In the Abeta42 fly brain, mitochondria were reduced in axons and dendrites, and accumulated in the somata without severe mitochondrial …

Abeta42 Mutants With Different Aggregation Profiles Induce Distinct Pathologies In Drosophila., Koichi Iijima, Hsueh-Cheng Chiang, Stephen A Hearn, Inessa Hakker, Anthony Gatt, Christopher Shenton, Linda Granger, Amy Leung, Kanae Iijima-Ando, Yi Zhong

Department of Biochemistry and Molecular Biology Faculty Papers

Aggregation of the amyloid-beta-42 (Abeta42) peptide in the brain parenchyma is a pathological hallmark of Alzheimer's disease (AD), and the prevention of Abeta aggregation has been proposed as a therapeutic intervention in AD. However, recent reports indicate that Abeta can form several different prefibrillar and fibrillar aggregates and that each aggregate may confer different pathogenic effects, suggesting that manipulation of Abeta42 aggregation may not only quantitatively but also qualitatively modify brain pathology. Here, we compare the pathogenicity of human Abeta42 mutants with differing tendencies to aggregate. We examined the aggregation-prone, EOFAD-related Arctic mutation (Abeta42Arc) and an artificial mutation (Abeta42art) that …

Prolonged Cyclooxygenase-2 Induction In Neurons And Glia Following Traumatic Brain Injury In The Rat, Kenneth I. Strauss, Mary F. Barbe, Renee Marshall Demarest, Ramesh Raghupathi, Samir Mehta, Raj K. Narayan

Rowan-Virtua School of Osteopathic Medicine Departmental Research

Cyclooxygenase-2 (COX2) is a primary inflammatory mediator that converts arachidonic acid into precursors of vasoactive prostaglandins, producing reactive oxygen species in the process. Under normal conditions COX2 is not detectable, except at low abundance in the brain. This study demonstrates a distinctive pattern of COX2 increases in the brain over time following traumatic brain injury (TBI). Quantitative lysate ribonuclease protection assays indicate acute and sustained increases in COX2 mRNA in two rat models of TBI. In the lateral fluid percussion model, COX2 mRNA is significantly elevated (>twofold, p < 0.05, Dunnett) at 1 day postinjury in the injured cortex and bilaterally in the hippocampus, compared to sham-injured controls. In the lateral cortical impact model (LCI), COX2 mRNA peaks around 6 h postinjury in the ipsilateral cerebral cortex (fivefold induction, p < 0.05, Dunnett) and in the ipsilateral and contralateral hippocampus (two- and six-fold induction, respectively, p < 0.05, Dunnett). Increases are sustained out to 3 days postinjury in the injured cortex in both models. Further analyses use the LCI model to evaluate COX2 induction. Immunoblot analyses confirm increased levels of COX2 protein in the cortex and hippocampus. Profound increases in COX2 protein are observed in the cortex at 1-3 days, that return to sham levels by 7 days postinjury (p < 0.05, Dunnett). The cellular pattern of COX2 induction following TBI has been characterized using immunohistochemistry. COX2-immunoreactivity (-ir) rises acutely (cell numbers and intensity) and remains elevated for several days following TBI. Increases in COX2-ir colocalize with neurons (MAP2-ir) and glia (GFAP-ir). Increases in COX2-ir are observed in cerebral cortex and hippocampus, ipsilateral and contralateral to injury as early as 2 h postinjury. Neurons in the ipsilateral parietal, perirhinal and piriform cortex become intensely COX2-ir from 2 h to at least 3 days postinjury. In agreement with the mRNA and immunoblot results, COX2-ir appears greatest in the contralateral hippocampus. Hippocampal COX2-ir progresses from the pyramidal cell layer of the CA1 and CA2 region at 2 h, to the CA3 pyramidal cells and dentate polymorphic and granule cell layers by 24 h postinjury. These increases are distinct from those observed following inflammatory challenge, and correspond to brain areas previously identified with the neurological and cognitive deficits associated with TBI. While COX2 induction following TBI may result in selective beneficial responses, chronic COX2 production may contribute to free radical mediated cellular damage, vascular dysfunction, and alterations in cellular metabolism. These may cause secondary injuries to the brain that promote neuropathology and worsen behavioral outcome.