Medicine and Health Sciences Commons^™

Altered Gating Of KV1.4 In The Nucleus Accumbens Suppresses Motivation For Reward, Bernadette O'Donovan, Adewale Adeluyi, Erin L Anderson, Robert D. Cole, Jill R. Turner, Pavel I. Ortinski

Neuroscience Faculty Publications

Deficient motivation contributes to numerous psychiatric disorders, including withdrawal from drug use, depression, schizophrenia, and others. Nucleus accumbens (NAc) has been implicated in motivated behavior, but it remains unclear whether motivational drive is linked to discrete neurobiological mechanisms within the NAc. To examine this, we profiled cohorts of Sprague-Dawley rats in a test of motivation to consume sucrose. We found that substantial variability in willingness to exert effort for reward was not associated with operant responding under low-effort conditions or stress levels. Instead, effort-based motivation was mirrored by a divergent NAc shell transcriptome with differential regulation at potassium and dopamine …

Minocycline Protects Developing Brain Against Ethanol-Induced Damage, Xin Wang, Kai Zhang, Fanmuyi Yang, Zhenhua Ren, Mei Xu, Jacqueline A. Frank, Zun-Ji Ke, Jia Luo

Pharmacology and Nutritional Sciences Faculty Publications

Fetal alcohol spectrum disorders (FASD) are caused by ethanol exposure during the pregnancy and is the leading cause of mental retardation. Ethanol exposure during the development results in the loss of neurons in the developing brain, which may underlie many neurobehavioral deficits associated with FASD. It is important to understand the mechanisms underlying ethanol-induced neuronal loss and develop appropriate therapeutic strategies. One of the potential mechanisms involves neuroimmune activation. Using a third trimester equivalent mouse model of ethanol exposure, we demonstrated that ethanol induced a wide-spread neuroapoptosis, microglial activation, and neuroinflammation in C57BL/6 mice. Minocycline is an antibiotic that inhibits …

Hne-Modified Proteins In Down Syndrome: Involvement In Development Of Alzheimer Disease Neuropathology, Eugenio Barone, Elizabeth Head, D. Allan Butterfield, Marzia Perluigi

Sanders-Brown Center on Aging Faculty Publications

Down syndrome (DS), trisomy of chromosome 21, is the most common genetic form of intellectual disability. The neuropathology of DS involves multiple molecular mechanisms, similar to AD, including the deposition of beta-amyloid (Aβ) into senile plaques and tau hyperphosphorylating in neurofibrillary tangles. Interestingly, many genes encoded by chromosome 21, in addition to being primarily linked to amyloid-beta peptide (Aβ) pathology, are responsible for increased oxidative stress (OS) conditions that also result as a consequence of reduced antioxidant system efficiency. However, redox homeostasis is disturbed by overproduction of Aβ, which accumulates into plaques across the lifespan in DS as well as …

Carisbamate Blockade Of T-Type Voltage-Gated Calcium Channels, Do Young Kim, Fang-Xiong Zhang, Stan T. Nakanishi, Timothy Mettler, Ik-Hyun Cho, Younghee Ahn, Florian Hiess, Lina Chen, Patrick G. Sullivan, S. R. Wayne Chen, Gerald W. Zamponi, Jong M. Rho

Spinal Cord and Brain Injury Research Center Faculty Publications

Objectives

Carisbamate (CRS) is a novel monocarbamate compound that possesses antiseizure and neuroprotective properties. However, the mechanisms underlying these actions remain unclear. Here, we tested both direct and indirect effects of CRS on several cellular systems that regulate intracellular calcium concentration [Ca²⁺]_i.

Methods

We used a combination of cellular electrophysiologic techniques, as well as cell viability, Store Overload‐Induced Calcium Release (SOICR), and mitochondrial functional assays to determine whether CRS might affect [Ca²⁺]_i levels through actions on the endoplasmic reticulum (ER), mitochondria, and/or T‐type voltage‐gated Ca²⁺ channels.

Results

In CA3 pyramidal neurons, kainic …

GabaB Receptor Attenuation Of GabaA Currents In Neurons Of The Mammalian Central Nervous System, Wen Shen, Changlong Nan, Peter T. Nelson, Harris Ripps, Malcolm M. Slaughter

Pathology and Laboratory Medicine Faculty Publications

Ionotropic receptors are tightly regulated by second messenger systems and are often present along with their metabotropic counterparts on a neuron's plasma membrane. This leads to the hypothesis that the two receptor subtypes can interact, and indeed this has been observed in excitatory glutamate and inhibitory GABA receptors. In both systems the metabotropic pathway augments the ionotropic receptor response. However, we have found that the metabotropic GABA_B receptor can suppress the ionotropic GABA_A receptor current, in both the in vitro mouse retina and in human amygdala membrane fractions. Expression of amygdala membrane microdomains in Xenopus oocytes by microtransplantation …

Selective Suppression Of The Α Isoform Of P38 Mapk Rescues Late-Stage Tau Pathology, Nicole Maphis, Shanya Jiang, Guixiang Xu, Olga N. Kokiko-Cochran, Saktimayee M. Roy, Linda J. Van Eldik, D. Martin Watterson, Bruce T. Lamb, Kiran Bhaskar

Sanders-Brown Center on Aging Faculty Publications

Background: Hyperphosphorylation and aggregation of tau protein are the pathological hallmarks of Alzheimer’s disease and related tauopathies. We previously demonstrated that the microglial activation induces tau hyperphosphorylation and cognitive impairment via activation of p38 mitogen-activated protein kinase (p38 MAPK) in the hTau mouse model of tauopathy that was deficient for microglial fractalkine receptor CX3CR1.

Method: We report an isoform-selective, brain-permeable, and orally bioavailable small molecule inhibitor of p38α MAPK (MW181) and its effects on tau phosphorylation in vitro and in hTau mice.

Results: First, pretreatment of mouse primary cortical neurons with MW181 completely blocked inflammation-induced p38α MAPK activation and AT8 …

Repeated Closed Head Injury In Mice Results In Sustained Motor And Memory Deficits And Chronic Cellular Changes, Amanda Nicholle Bolton Hall, Binoy Joseph, Jennifer M. Brelsfoard, Kathryn E. Saatman

Spinal Cord and Brain Injury Research Center Faculty Publications

Millions of mild traumatic brain injuries (TBIs) occur every year in the United States, with many people subject to multiple head injuries that can lead to chronic behavioral dysfunction. We previously reported that mild TBI induced using closed head injuries (CHI) repeated at 24h intervals produced more acute neuron death and glial reactivity than a single CHI, and increasing the length of time between injuries to 48h reduced the cumulative acute effects of repeated CHI. To determine whether repeated CHI is associated with behavioral dysfunction or persistent cellular damage, mice receiving either five CHI at 24h intervals, five CHI at …

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 …

Prefrontal Cortical Microcircuits Bind Perception To Executive Control, Ioan Opris, Lucas Santos, Greg A. Gerhardt, Dong Song, Theodore W. Berger, Robert E. Hampson, Sam A. Deadwyler

Neuroscience Faculty Publications

During the perception-to-action cycle, our cerebral cortex mediates the interactions between the environment and the perceptual-executive systems of the brain. At the top of the executive hierarchy, prefrontal cortical microcircuits are assumed to bind perceptual and executive control information to guide goal-driven behavior. Here, we tested this hypothesis by comparing simultaneously recorded neuron firing in prefrontal cortical layers and the caudate-putamen of rhesus monkeys, trained in a spatial-versus-object, rule-based match-to-sample task. We found that during the perception and executive selection phases, cell firing in the localized prefrontal layers and caudate-putamen region exhibited similar location preferences on spatial-trials, but less on …

Rod Microglia: Elongation, Alignment, And Coupling To Form Trains Across The Somatosensory Cortex After Experimental Diffuse Brain Injury, Jenna M. Ziebell, Samuel E. Taylor, Tuoxin Cao, Jordan L. Harrison, Jonathan Lifshitz

Neuroscience Faculty Publications

BACKGROUND: Since their discovery, the morphology of microglia has been interpreted to mirror their function, with ramified microglia constantly surveying the micro-environment and rapidly activating when changes occur. In 1899, Franz Nissl discovered what we now recognize as a distinct microglial activation state, microglial rod cells (Stäbchenzellen), which he observed adjacent to neurons. These rod-shaped microglia are typically found in human autopsy cases of paralysis of the insane, a disease of the pre-penicillin era, and best known today from HIV-1-infected brains. Microglial rod cells have been implicated in cortical 'synaptic stripping' but their exact role has remained unclear. This is …

Early Stage Drug Treatment That Normalizes Proinflammatory Cytokine Production Attenuates Synaptic Dysfunction In A Mouse Model That Exhibits Age-Dependent Progression Of Alzheimer's Disease-Related Pathology, Adam D. Bachstetter, Christopher M. Norris, Pradoldej Sompol, Donna M. Wilcock, Danielle Goulding, Janna H. Neltner, Daret St. Clair, D. Martin Watterson, Linda J. Van Eldik

Sanders-Brown Center on Aging Faculty Publications

Overproduction of proinflammatory cytokines in the CNS has been implicated as a key contributor to pathophysiology progression in Alzheimer's disease (AD), and extensive studies with animal models have shown that selective suppression of excessive glial proinflammatory cytokines can improve neurologic outcomes. The prior art, therefore, raises the logical postulation that intervention with drugs targeting dysregulated glial proinflammatory cytokine production might be effective disease-modifying therapeutics if used in the appropriate biological time window. To test the hypothesis that early stage intervention with such drugs might be therapeutically beneficial, we examined the impact of intervention with MW01-2-151SRM (MW-151), an experimental therapeutic that …

In Vitro Amplification Of Misfolded Prion Protein Using Lysate Of Cultured Cells, Charles E. Mays, Jihyun Yeom, Hae-Eun Kang, Jifeng Bian, Vadim Khaychuk, Younghwan Kim, Jason C Bartz, Glenn C Telling, Chongsuk Ryou

Microbiology, Immunology, and Molecular Genetics Faculty Publications

Protein misfolding cyclic amplification (PMCA) recapitulates the prion protein (PrP) conversion process under cell-free conditions. PMCA was initially established with brain material and then with further simplified constituents such as partially purified and recombinant PrP. However, availability of brain material from some species or brain material from animals with certain mutations or polymorphisms within the PrP gene is often limited. Moreover, preparation of native PrP from mammalian cells and tissues, as well as recombinant PrP from bacterial cells, involves time-consuming purification steps. To establish a convenient and versatile PMCA procedure unrestricted to the availability of substrate sources, we attempted to …

Increased Mitochondrial Calcium Sensitivity And Abnormal Expression Of Innate Immunity Genes Precede Dopaminergic Defects In Pink1-Deficient Mice, Ravi S. Akundi, Zhenyu Huang, Joshua Eason, Jignesh D. Pandya, Lianteng Zhi, Wayne A. Cass, Patrick G. Sullivan, Hansruedi Büeler

Neuroscience Faculty Publications

BACKGROUND: PTEN-induced kinase 1 (PINK1) is linked to recessive Parkinsonism (EOPD). Pink1 deletion results in impaired dopamine (DA) release and decreased mitochondrial respiration in the striatum of mice. To reveal additional mechanisms of Pink1-related dopaminergic dysfunction, we studied Ca²⁺ vulnerability of purified brain mitochondria, DA levels and metabolism and whether signaling pathways implicated in Parkinson's disease (PD) display altered activity in the nigrostriatal system of Pink1⁻/⁻ mice.

METHODS AND FINDINGS: Purified brain mitochondria of ^Pink1⁻/⁻ mice showed impaired Ca²⁺ storage capacity, resulting in increased Ca²⁺ induced mitochondrial permeability transition (mPT) that was rescued by cyclosporine A. …

Dopamine Neuron Stimulating Actions Of A Gdnf Propeptide, Luke H. Bradley, Josh Fuqua, April Richardson, Jadwiga Turchan-Cholewo, Yi Ai, Kristen A. Kelps, John D. Glass, Xiuquan He, Zhiming Zhang, Richard Grondin, O. Meagan Littrell, Peter Huettl, Francois Pomerleau, Don M. Gash, Greg A. Gerhardt

Neuroscience Faculty Publications

BACKGROUND: Neurotrophic factors, such as glial cell line-derived neurotrophic factor (GDNF), have shown great promise for protection and restoration of damaged or dying dopamine neurons in animal models and in some Parkinson's disease (PD) clinical trials. However, the delivery of neurotrophic factors to the brain is difficult due to their large size and poor bio-distribution. In addition, developing more efficacious trophic factors is hampered by the difficulty of synthesis and structural modification. Small molecules with neurotrophic actions that are easy to synthesize and modify to improve bioavailability are needed.

METHODS AND FINDINGS: Here we present the neurobiological actions of dopamine …

Detection Of Sub-Clinical Cwd Infection In Conventional Test-Negative Deer Long After Oral Exposure To Urine And Feces From Cwd+ Deer, Nicholas J. Haley, Candace K. Mathiason, Mark D. Zabel, Glenn C. Telling, Edward A Hoover

Microbiology, Immunology, and Molecular Genetics Faculty Publications

BACKGROUND: Chronic wasting disease (CWD) of cervids is a prion disease distinguished by high levels of transmissibility, wherein bodily fluids and excretions are thought to play an important role. Using cervid bioassay and established CWD detection methods, we have previously identified infectious prions in saliva and blood but not urine or feces of CWD+ donors. More recently, we identified very low concentrations of CWD prions in urine of deer by cervid PrP transgenic (Tg[CerPrP]) mouse bioassay and serial protein misfolding cyclic amplification (sPMCA). This finding led us to examine further our initial cervid bioassay experiments using sPMCA.

OBJECTIVES: We sought …

Striatal Neuroinflammation Promotes Parkinsonism In Rats, Dong-Young Choi, Mei Liu, Randy L. Hunter, Wayne A. Cass, Jignesh D. Pandya, Patrick G. Sullivan, Eun-Joo Shin, Hyoung-Chun Kim, Don M. Gash, Guoying Bing

Neuroscience Faculty Publications

BACKGROUND: Sporadic Parkinson's disease (PD) is a progressive neurodegenerative disorder with unknown cause, but it has been suggested that neuroinflammation may play a role in pathogenesis of the disease. Neuroinflammatory component in process of PD neurodegeneration was proposed by postmortem, epidemiological and animal model studies. However, it remains unclear how neuroinflammatory factors contribute to dopaminergic neuronal death in PD.

FINDINGS: In this study, we analyzed the relationship among inducible nitric oxide synthase (iNOS)-derived NO, mitochondrial dysfunction and dopaminergic neurodegeneration to examine the possibility that microglial neuroinflammation may induce dopaminergic neuronal loss in the substantia nigra. Unilateral injection of lipopolysaccharide (LPS) …

Pioglitazone Inhibition Of Lipopolysaccharide-Induced Nitric Oxide Synthase Is Associated With Altered Activity Of P38 Map Kinase And Pi3k/Akt, Bin Xing, Tao Xin, Randy Lee Hunter, Guoying Bing

Neuroscience Faculty Publications

BACKGROUND: Previous studies have suggested that peroxisome proliferator activated receptor-gamma (PPAR-gamma)-mediated neuroprotection involves inhibition of microglial activation and decreased expression and activity of inducible nitric oxide synthase (iNOS); however, the underlying molecular mechanisms have not yet been well established. In the present study we explored: (1) the effect of the PPAR-gamma agonist pioglitazone on lipopolysaccharide (LPS)-induced iNOS activity and nitric oxide (NO) generation by microglia; (2) the differential role of p38 mitogen-activated protein kinase (p38 MAPK), c-Jun NH(2)-terminal kinase (JNK), and phosphoinositide 3-kinase (PI3K) on LPS-induced NO generation; and (3) the regulation of p38 MAPK, JNK, and PI3K by pioglitazone. …

Expansion Of The Calcium Hypothesis Of Brain Aging And Alzheimer's Disease: Minding The Store, Olivier Thibault, John C. Gant, Philip W. Landfield

Pharmacology and Nutritional Sciences Faculty Publications

Evidence accumulated over more than two decades has implicated Ca2+ dysregulation in brain aging and Alzheimer's disease (AD), giving rise to the Ca2+ hypothesis of brain aging and dementia. Electrophysiological, imaging, and behavioral studies in hippocampal or cortical neurons of rodents and rabbits have revealed aging-related increases in the slow afterhyperpolarization, Ca2+ spikes and currents, Ca2+transients, and L-type voltage-gated Ca2+ channel (L-VGCC) activity. Several of these changes have been associated with age-related deficits in learning or memory. Consequently, one version of the Ca2+ hypothesis has been that increased L-VGCC activity drives many of the other Ca2+-related biomarkers of hippocampal aging. …