Medicine and Health Sciences Commons^™

Levo-Tetrahydropalmatine Attenuates Cocaine Self-Administration Under A Progressive-Ratio Schedule And Cocaine Discrimination In Rats, John R. Mantsch, Samantha Wisniewski, Oliver Vranjkovic, Corey Peters, Amanda Becker, Abbey Valentine, Shi-Jiang Li, David A. Baker, Zheng Yang

Biomedical Sciences Faculty Research and Publications

Levo-tetrahydropalmatine (l-THP) is an alkaloid found in many traditional Chinese herbal preparations and has a unique pharmacological profile that includes dopamine receptor antagonism. Previously we demonstrated that l-THP attenuates fixed-ratio (FR) cocaine self-administration (SA) and cocaine-induced reinstatement in rats at doses that do not alter food-reinforced responding. This study examined the effects of l-THP on cocaine and food SA under progressive-ratio (PR) schedules of reinforcement and the discriminative stimulus effects of cocaine. In adult male Sprague–Dawley rats self-administering cocaine (0.5 or 1.0 mg/kg/inf), l-THP significantly reduced breaking points at the 1.875, 3.75 and 7.5 mg/kg …

Effects Of Hypothyroidism On Cell Proliferation And Neuroblasts In The Hippocampal Dentate Gyrus In A Rat Model Of Type 2 Diabetes, Sun Shin Yi, In Koo Hwang, Ji Won Choi, Moo-Ho Won, Je Kyung Seong, Yeo Sung Yoon

Biomedical Sciences Faculty Research and Publications

We observed how the hypothyroid state affects diabetic states and modifies cell proliferation and neuroblast differentiation in the hippocampal dentate gyrus (DG). For this, 0.03% methimazole, an anti-thyroid drug, was administered to 7-week-old, pre-diabetic Zucker diabetic fatty (ZDF) rats by drinking water for 5 weeks, and the animals were sacrificed at 12 weeks of age. At this age, corticosterone levels were significantly increased in the ZDF rats compared to those in the control (Zucker lean control, ZLC) rats. Methimazole (methi) treatment in the ZDF rats (ZDF-methi rats) significantly decreased corticosterone levels and diabetes-induced hypertrophy of adrenal glands. In the DG, …

Molecular Requirements For Ethanol Differential Allosteric Modulation Of Ligand-Gated Ion Channels Based On Selective G Beta Gamma Modulation, Gonzalo E. Yevenes, Gustavo Moraga-Cid, Ariel Avila, Leonardo Guzman, Maximiliano Figueroa, Robert W. Peoples, Luis G. Aguayo

Biomedical Sciences Faculty Research and Publications

It is now believed that the allosteric modulation produced by ethanol in glycine receptors (GlyRs) depends on alcohol binding to discrete sites within the protein structure. Thus, the differential ethanol sensitivity of diverse GlyR isoforms and mutants was explained by the presence of specific residues in putative alcohol pockets. Here, we demonstrate that ethanol sensitivity in two LGIC members, the GlyR adult alpha1 and embryonic alpha2 subunits, can be modified through selective mutations that rescued or impaired Gbetagamma modulation. Even though that both isoforms were able to physically interact with Gbetagamma, only the alpha1 GlyR was functionally modulated by Gbetagamma …

Transcriptional Profiles For Glutamate Transporters Reveal Differences Between Organophosphates But Similarities With Unrelated Neurotoxicants, Theodore A. Slotkin, Doug Lobner, Frederic J. Seidler

Biomedical Sciences Faculty Research and Publications

The developmental neurotoxicity of organophosphates involves mechanisms other than their shared property as cholinesterase inhibitors, among which are excitotoxicity and oxidative stress. We used PC12 cells as a neurodevelopmental model to compare the effects of chlorpyrifos and diazinon on the expression of genes encoding glutamate transporters. Chlorpyrifos had a greater effect in cells undergoing nerve growth factor-induced neurodifferentiation as compared to undifferentiated PC12 cells, with peak sensitivity at the initiation of differentiation, reflecting a global upregulation of all the glutamate transporter genes expressed in this cell line. In differentiating cells, chlorpyrifos had a significantly greater effect than did diazinon and …

Toxicity Of Flow Line, Durafill Vs, And Dycal To Dental Pulp Cells: Effects Of Growth Factors, Alyssa Furey, Julie Hjelmhaug, Doug Lobner

Biomedical Sciences Faculty Research and Publications

Introduction

The objective was to determine the effects of growth factor treatment on dental pulp cell sensitivity to toxicity of 2 composite restoration materials, Flow Line and Durafill VS, and a calcium hydroxide pulp capping material, Dycal.

Methods

Toxicity of the dental materials to cultures of primary dental pulp cells was determined by the MTT metabolism assay. The ability of 6 different growth factors to influence the toxicity was tested.

Results

A 24-hour exposure to either Flow Line or Durafill VS caused approximately 40% cell death, whereas Dycal exposure caused approximately 80% cell death. The toxicity of Flow Line and …

Involvement Of Noradrenergic Neurotransmission In The Stress- But Not Cocaine-Induced Reinstatement Of Extinguished Cocaine-Induced Conditioned Place Preference In Mice: Role For Β-2 Adrenergic Receptors, John R. Mantsch, Andy Meyer, Oliver Vranjkovic, Chad E. Beyer, David A. Baker, Holly Caretta

Biomedical Sciences Faculty Research and Publications

The responsiveness of central noradrenergic systems to stressors and cocaine poses norepinephrine as a potential common mechanism through which drug re-exposure and stressful stimuli promote relapse. This study investigated the role of noradrenergic systems in the reinstatement of extinguished cocaine-induced conditioned place preference by cocaine and stress in male C57BL/6 mice. Cocaine- (15 mg/kg, i.p.) induced conditioned place preference was extinguished by repeated exposure to the apparatus in the absence of drug and reestablished by a cocaine challenge (15 mg/kg), exposure to a stressor (6-min forced swim (FS); 20–25°C water), or administration of the α-2 adrenergic receptor (AR) antagonists yohimbine …

Synaptotoxicity Of Alzheimer Beta Amyloid Can Be Explained By Its Membrane Perforating Property, Fernando Sepulveda, Jorge Parodi, Robert W. Peoples, Carlos Opazo, Luis G. Aguayo

Biomedical Sciences Faculty Research and Publications

The mechanisms that induce Alzheimer’s disease (AD) are largely unknown thereby deterring the development of disease-modifying therapies. One working hypothesis of AD is that Aβ excess disrupts membranes causing pore formation leading to alterations in ionic homeostasis. However, it is largely unknown if this also occurs in native brain neuronal membranes. Here we show that similar to other pore forming toxins, Aβ induces perforation of neuronal membranes causing an increase in membrane conductance, intracellular calcium and ethidium bromide influx. These data reveal that the target of Aβ is not another membrane protein, but that Aβ itself is the cellular target …

Pathologically Activated Neuroprotection Via Uncompetitive Blockade Of N-Methyl-D-Aspartate Receptors With Fast Off-Rate By Novel Multifunctional Dimer Bis(Propyl)-Cognitin, Jialie Luo, Wenming Li, Yuming Zhao, Hongjun Fu, Dik-Lung Ma, Jing Tang, Chaoying Li, Robert W. Peoples, Fushun Li, Qinwen Wang, Pingbo Huang, Jun Xia, Yuanping Pang, Yifan Han

Biomedical Sciences Faculty Research and Publications

Uncompetitive N-methyl-d-aspartate (NMDA) receptor antagonists with fast off-rate (UFO) may represent promising drug candidates for various neurodegenerative disorders. In this study, we report that bis(propyl)-cognitin, a novel dimeric acetylcholinesterase inhibitor and γ-aminobutyric acid subtype A receptor antagonist, is such an antagonist of NMDA receptors. In cultured rat hippocampal neurons, we demonstrated that bis(propyl)-cognitin voltage-dependently, selectively, and moderately inhibited NMDA-activated currents. The inhibitory effects of bis(propyl)-cognitin increased with the rise in NMDA and glycine concentrations. Kinetics analysis showed that the inhibition was of fast onset and offset with an off-rate time constant of 1.9 s. Molecular docking simulations showed moderate …

Drug-Induced Plasticity Contributing To Heightened Relapse Susceptibility: Neurochemical Changes And Augmented Reinstatement In High-Intake Rats, Aric Madayag, Kristen S. Kau, Doug Lobner, John R. Mantsch, Samantha Wisniewski, David A. Baker

Biomedical Sciences Faculty Research and Publications

A key in understanding the neurobiology of addiction and developing effective pharmacotherapies is revealing drug-induced plasticity that results in heightened relapse susceptibility. Previous studies have demonstrated that increased extracellular glutamate, but not dopamine, in the nucleus accumbens core (NAcc) is necessary for cocaine-induced reinstatement. In this report, we examined whether drug-induced adaptations that are necessary to generate cocaine-induced reinstatement also determine relapse vulnerability. To do this, rats were assigned to self-administer cocaine under conditions resulting in low (2 h/d; 0.5 mg/kg/infusion, i.v.) or high (6 h/d; 1.0 mg/kg/infusion, i.v.) levels of drug intake since these manipulations produce groups of rats …