Medicine and Health Sciences Commons^™

Oral Branched-Chain Amino Acid Supplements That Reduce Brain Serotonin During Exercise In Rats Also Lower Brain Catecholamines, Sujean Choi, Briana Disilvio, Madelyn H. Fernstrom, John D. Fernstrom

Biomedical Sciences Faculty Research and Publications

Exercise raises brain serotonin release and is postulated to cause fatigue in athletes; ingestion of branched-chain amino acids (BCAA), by competitively inhibiting tryptophan transport into brain, lowers brain tryptophan uptake and serotonin synthesis and release in rats, and reputedly in humans prevents exercise-induced increases in serotonin and fatigue. This latter effect in humans is disputed. But BCAA also competitively inhibit tyrosine uptake into brain, and thus catecholamine synthesis and release. Since increasing brain catecholamines enhances physical performance, BCAA ingestion could lower catecholamines, reduce performance and thus negate any serotonin-linked benefit. We therefore examined in rats whether BCAA would reduce both …

Primary Blast Traumatic Brain Injury In The Rat: Relating Diffusion Tensor Imaging And Behavior, Matthew D. Budde, Alok Shah, Michael Mccrea, William E. Cullinan, Frank A. Pintar, Brian D. Stemper

Biomedical Sciences Faculty Research and Publications

The incidence of traumatic brain injury (TBI) among military personnel is at its highest point in U.S. history. Experimental animal models of blast have provided a wealth of insight into blast injury. The mechanisms of neurotrauma caused by blast, however, are still under debate. Specifically, it is unclear whether the blast shockwave in the absence of head motion is sufficient to induce brain trauma. In this study, the consequences of blast injury were investigated in a rat model of primary blast TBI. Animals were exposed to blast shockwaves with peak reflected overpressures of either 100 or 450 kPa (39 and …

The Hiv-1 Protein Vpr Targets The Endoribonuclease Dicer For Proteasomal Degradation To Boost Macrophage Infection, Laurieann Klockow, Hamayun J. Sharifi, Xiaoyun Wen, Meg Flagg, Andrea K.M. Furuya, Michael Nekorchuk, Carlos M.C. De Noronha

Biomedical Sciences Faculty Research and Publications

The HIV-1 protein Vpr enhances macrophage infection, triggers G2 cell cycle arrest, and targets cells for NK-cell killing. Vpr acts through the CRL4^DCAF1 ubiquitin ligase complex to cause G2 arrest and trigger expression of NK ligands. Corresponding ubiquitination targets have not been identified. UNG2 and SMUG1 are the only known substrates for Vpr-directed depletion through CRL4^DCAF1. Here we identify the endoribonuclease Dicer as a target of HIV-1 Vpr-directed proteasomal degradation through CRL4^DCAF1. We show that HIV-1 Vpr inhibits short hairpin RNA function as expected upon reduction of Dicer levels. Dicer inhibits HIV-1 replication in T …

Environmental Circadian Disruption Elevates The Il-6 Response To Lipopolysaccharide In Blood, Kandis L. Adams, Oscar Castanon-Cervantes, Jennifer A. Evans, Alec J. Davidson

Biomedical Sciences Faculty Research and Publications

The immune system is regulated by circadian clocks within the brain and immune cells. Environmental circadian disruption (ECD), consisting of a 6-h phase advance of the light:dark cycle once a week for 4 weeks, elevates the inflammatory response to lipopolysaccharide (LPS) both in vivo and in vitro. This indicates that circadian disruption adversely affects immune function; however, it remains unclear how the circadian system regulates this response under ECD conditions. Here, we develop an assay using ex vivo whole-blood LPS challenge to investigate the circadian regulation of immune responses in mice and to determine the effects of ECD on these …

Corticosterone Acts In The Nucleus Accumbens To Enhance Dopamine Signaling And Potentiate Reinstatement Of Cocaine Seeking, Evan N. Graf, Robert A. Wheeler, David A. Baker, Amanda L. Ebben, Jonathan E. Hill, Jayme R. Mcreynolds, Mykel A. Robble, Daniel S. Wheeler, John Mantsch, Paul J. Gasser

Biomedical Sciences Faculty Research and Publications

Stressful life events are important contributors to relapse in recovering cocaine addicts, but the mechanisms by which they influence motivational systems are poorly understood. Studies suggest that stress may “set the stage” for relapse by increasing the sensitivity of brain reward circuits to drug-associated stimuli. We examined the effects of stress and corticosterone on behavioral and neurochemical responses of rats to a cocaine prime after cocaine self-administration and extinction. Exposure of rats to acute electric footshock stress did not by itself reinstate drug-seeking behavior but potentiated reinstatement in response to a subthreshold dose of cocaine. This effect of stress was …

Prefrontal Activity Links Nonoverlapping Events In Memory, Marieke R. Gilmartin, Hiroyuki Miyawaki, Fred J. Helmstetter, Kamran Diba

Biomedical Sciences Faculty Research and Publications

The medial prefrontal cortex (mPFC) plays an important role in memory. By maintaining a working memory buffer, neurons in prelimbic (PL) mPFC may selectively contribute to learning associations between stimuli that are separated in time, as in trace fear conditioning (TFC). Until now, evidence for this bridging role was largely descriptive. Here we used optogenetics to silence neurons in the PL mPFC of rats during learning in TFC. Memory formation was prevented when mPFC was silenced specifically during the interval separating the cue and shock. Our results provide support for a working memory function for these cells and indicate that …

Nr2a- And Nr2b-Containing Nmda Receptors In The Prelimbic Medial Prefrontal Cortex Differentially Mediate Trace, Delay, And Contextual Fear Conditioning, Marieke R. Gilmartin, Janine L. Kwapis, Fred J. Helmstetter

Biomedical Sciences Faculty Research and Publications

Activation of N-methyl-D-aspartate receptors (NMDAR) in the prelimbic medial prefrontal cortex (PL mPFC) is necessary for the acquisition of both trace and contextual fear memories, but it is not known how specific NR2 subunits support each association. The NR2B subunit confers unique properties to the NMDAR and may differentially regulate these two fear memories. Here we show that NR2A-containing NMDARs mediate trace, delay, and contextual fear memories, but NR2B-containing NMDARs are required only for trace conditioning, consistent with a role for PL mPFC in working memory.

Evidence For Covalent Linkage Between Some Plasma Α2-Antiplasmin Molecules And Aα Chains Of Circulating Fibrinogen, Michael W. Mosesson, Trudy Holyst, Irene Hernandez, Kevin R. Siebenlist

Biomedical Sciences Faculty Research and Publications

Plasma alpha₂-antiplasmin (α₂AP) is a single-chain serine protease inhibitor acting mainly through the fibrinolytic system. Its physiological importance is underscored by the observation that homozygous α₂AP deficiency results in a severe hemorrhagic disorder due to rapid fibrin clot lysis (hyperfibrinolysis).

Reduction In Phencyclidine Induced Sensorimotor Gating Deficits In The Rat Following Increased System Xc − Activity In The Medial Prefrontal Cortex, Victoria Lutgen, Krista Qualmann, Jon M. Resch, Linghai Kong, Sujean Choi, David A. Baker

Biomedical Sciences Faculty Research and Publications

Rationale: Aspects of schizophrenia, including deficits in sensorimotor gating, have been linked to glutamate dysfunction and/or oxidative stress in the prefrontal cortex. System x_c ⁻, a cystine–glutamate antiporter, is a poorly understood mechanism that contributes to both cellular antioxidant capacity and glutamate homeostasis.

Objectives: Our goal was to determine whether increased system x_c ⁻ activity within the prefrontal cortex would normalize a rodent measure of sensorimotor gating.

Methods: In situ hybridization was used to map messenger RNA (mRNA) expression of xCT, the active subunit of system x_c ⁻, in the prefrontal cortex. Prepulse inhibition was …

A Novel Alcohol-Sensitive Position In The M3 Domain Of The Nmda Receptor Glun2b Subunit, Robert W. Peoples

Biomedical Sciences Faculty Research and Publications

No abstract provided.

Sites Of Alcohol Action At The Glun1/Glun2b Nmda Receptor M3-M4 Domain Intersubunit Interfaces, Yuanhao Zhao, M. Wu, Hong Ren, Robert W. Peoples

Biomedical Sciences Faculty Research and Publications

The N-methyl-D-aspartate (NMDA) receptor has been shown to be one of the most important target sites of alcohol in the central nervous system. We and others have identified positions in the third and fourth membrane-associated (M) domains of both GluN1 and GluN2A subunits that influence alcohol sensitivity. In the structural model of the NMDA receptor based upon the related GluA2 receptor, the outward face of the M3 domain of one subunit type is oriented toward the M4 domain of the other subunit type. We recently reported that four pairs of alcohol-sensitive amino acid positions in GluN1/GluN2A NMDA receptors interact at …