Medicine and Health Sciences Commons^™

Complexes Of Ghrelin Ghs-R1a, Ghs-R1b, And Dopamine D1 Receptors Localized In The Ventral Tegmental Area As Main Mediators Of The Dopaminergic Effects Of Ghrelin, Gemma Navarro, William Rea, César Quiroz, Estefanía Moreno, Devan Gomez, Cody J. Wenthur, Vicent Casadó, Lorenzo Leggio, Matthew C. Hearing, Sergi Ferré

Biomedical Sciences Faculty Research and Publications

Ghrelin receptor, also known as growth hormone secretagogue receptor (GHS-R1a), is coexpressed with its truncated isoform GHS-R1b, which does not bind ghrelin or signal, but oligomerizes with GHS-R1a, exerting a complex modulatory role that depends on its relative expression. D₁ dopamine receptor (D1R) and D5R constitute the two D₁-like receptor subtypes. Previous studies showed that GHS-R1b also facilitates oligomerization of GHS-R1a with D1R, conferring GHS-R1a distinctive pharmacological properties. Those include a switch in the preferred coupling of GHS-R1a from Gq to Gs and the ability of D1R/D5R agonists and antagonists to counteract GHS-R1a signaling. Activation of ghrelin …

Organic Cation Transporter 3 And The Dopamine Transporter Differentially Regulate Catecholamine Uptake In The Basolateral Amygdala And Nucleus Accumbens, Katherine M. Holleran, Jamie H. Rose, Steven C. Fordahl, Kelsey C. Benton, Kayla E. Rohr, Paul J. Gasser, Sara R. Jones

Biomedical Sciences Faculty Research and Publications

Regional alterations in kinetics of catecholamine uptake are due in part to variations in clearance mechanisms. The rate of clearance is a critical determinant of the strength of catecholamine signaling. Catecholamine transmission in the nucleus accumbens core (NAcc) and basolateral amygdala (BLA) is of particular interest due to involvement of these regions in cognition and motivation. Previous work has shown that catecholamine clearance in the NAcc is largely mediated by the dopamine transporter (DAT), but clearance in the BLA is less DAT‐dependent. A growing body of literature suggests that organic cation transporter 3 (OCT3) also contributes to catecholamine clearance in …

Organic Cation Transporter 3: A Cellular Mechanism Underlying Rapid, Non-Genomic Glucocorticoid Regulation Of Monoaminergic Neurotransmission, Physiology, And Behavior, Paul J. Gasser, Christopher A. Lowry

Biomedical Sciences Faculty Research and Publications

Corticosteroid hormones act at intracellular glucocorticoid receptors (GR) and mineralocorticoid receptors (MR) to alter gene expression, leading to diverse physiological and behavioral responses. In addition to these classical genomic effects, corticosteroid hormones also exert rapid actions on physiology and behavior through a variety of non-genomic mechanisms, some of which involve GR or MR, and others of which are independent of these receptors. One such GR-independent mechanism involves corticosteroid-induced inhibition of monoamine transport mediated by “uptake₂” transporters, including organic cation transporter 3 (OCT3), a low-affinity, high-capacity transporter for norepinephrine, epinephrine, dopamine, serotonin and histamine. Corticosterone directly and acutely inhibits …

Endogenous Dopamine And Endocannabinoid Signaling Mediate Cocaine-Induced Reversal Of Ampar Synaptic Potentiation In The Nucleus Accumbens Shell, Anna E. Ingebretson, Matthew C. Hearing, Ethan D. Huffington, Mark J. Thomas

Biomedical Sciences Faculty Research and Publications

Repeated exposure to drugs of abuse alters the structure and function of neural circuits mediating reward, generating maladaptive plasticity in circuits critical for motivated behavior. Within meso-corticolimbic dopamine circuitry, repeated exposure to cocaine induces progressive alterations in AMPAR-mediated glutamatergic synaptic transmission. During a 10–14 day period of abstinence from cocaine, AMPAR signaling is potentiated at synapses on nucleus accumbens (NAc) medium spiny neurons (MSNs), promoting a state of heightened synaptic excitability. Re-exposure to cocaine during abstinence, however, rapidly reverses and depotentiates enhanced AMPAR signaling. To understand how re-exposure to cocaine alters AMPAR synaptic transmission, we investigated the roles of dopamine …

Corticosterone Regulates Both Naturally Occurring And Cocaine‐Induced Dopamine Signaling By Selectively Decreasing Dopamine Uptake, Daniel S. Wheeler, Amanda L. Ebben, Beliz Kurtoglu, Marissa E. Lovell, Austin T. Bohn, Isabella A. Jasek, David A. Baker, John R. Mantsch, Paul J. Gasser, Robert A. Wheeler

Biomedical Sciences Faculty Research and Publications

Stressful and aversive events promote maladaptive reward‐seeking behaviors such as drug addiction by acting, in part, on the mesolimbic dopamine system. Using animal models, data from our laboratory and others show that stress and cocaine can interact to produce a synergistic effect on reward circuitry. This effect is also observed when the stress hormone corticosterone is administered directly into the nucleus accumbens (NAc), indicating that glucocorticoids act locally in dopamine terminal regions to enhance cocaine's effects on dopamine signaling. However, prior studies in behaving animals have not provided mechanistic insight. Using fast‐scan cyclic voltammetry, we examined the effect of systemic …

Organic Cation Transporter 3 (Oct3) Is Localized To Intracellular And Surface Membranes In Select Glial And Neuronal Cells Within The Basolateral Amygdaloid Complex Of Both Rats And Mice, Paul J. Gasser, Matthew M. Hurley, June Chan, Virginia M. Pickel

Biomedical Sciences Faculty Research and Publications

Organic cation transporter 3 (OCT3) is a high-capacity, low-affinity transporter that mediates corticosterone-sensitive uptake of monoamines including norepinephrine, epinephrine, dopamine, histamine and serotonin. OCT3 is expressed widely throughout the amygdaloid complex and other brain regions where monoamines are key regulators of emotional behaviors affected by stress. However, assessing the contribution of OCT3 to the regulation of monoaminergic neurotransmission and monoamine-dependent regulation of behavior requires fundamental information about the subcellular distribution of OCT3 expression. We used immunofluorescence and immuno-electron microscopy to examine the cellular and subcellular distribution of the transporter in the basolateral amygdaloid complex of the rat and mouse brain. …

Drug Predictive Cues Activate Aversion-Sensitive Striatal Neurons That Encode Drug Seeking, Daniel S. Wheeler, Mykel A. Robble, Emily M. Hebron, Matthew J. Dupont, Amanda L. Ebben, Robert A. Wheeler

Biomedical Sciences Faculty Research and Publications

Drug-associated cues have profound effects on an addict’s emotional state and drug-seeking behavior. Although this influence must involve the motivational neural system that initiates and encodes the drug-seeking act, surprisingly little is known about the nature of such physiological events and their motivational consequences. Three experiments investigated the effect of a cocaine-predictive stimulus on dopamine signaling, neuronal activity, and reinstatement of cocaine seeking. In all experiments, rats were divided into two groups (paired and unpaired), and trained to self-administer cocaine in the presence of a tone that signaled the immediate availability of the drug. For rats in the paired group, …

Catecholamines In The Bed Nucleus Of The Stria Terminalis Reciprocally Respond To Reward And Aversion, Robert A. Wheeler

Biomedical Sciences Faculty Research and Publications

Background

Traditionally, norepinephrine has been associated with stress responses, whereas dopamine has been associated with reward. Both of these catecholamines are found within the bed nucleus of the stria terminalis (BNST), a brain relay nucleus in the extended amygdala between cortical/limbic centers, and the hypothalamic-pituitary-adrenal axis. Despite this colocalization, little is known about subsecond catecholamine signaling in subregions of the BNST in response to salient stimuli.

Methods

Changes in extracellular catecholamine concentration in subregions of the BNST in response to salient stimuli were measured within the rat BNST with fast-scan cyclic voltammetry at carbon-fiber microelectrodes.

Results

A discrete subregional distribution …

Oral Administration Of Levo-Tetrahydropalmatine Attenuates Reinstatement Of Extinguished Cocaine Seeking By Cocaine, Stress Or Drug-Associated Cues In Rats, Yazmin Figueroa-Guzman, Christopher R. Mueller, Oliver Vranjkovic, Samantha Wisniewski, Zheng Yang, Shi-Jiang Li, Colin Bohr, Evan N. Graf, David A. Baker, John R. Mantsch

Biomedical Sciences Faculty Research and Publications

Cocaine addiction is characterized by a persistently heightened susceptibility to drug relapse. For this reason, the identification of medications that prevent drug relapse is a critical goal of drug abuse research. Drug re-exposure, the onset of stressful life events, and exposure to cues previously associated with drug use have been identified as determinants of relapse in humans and have been found to reinstate extinguished cocaine seeking in rats. This study examined the effects of acute oral (gavage) administration of levo-tetrahydropalmatine (l-THP), a tetrahydroprotoberberine isoquinoline with a pharmacological profile that includes antagonism of D1, D2 and D3 dopamine receptors, …

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 …