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Dopamine D2

Roee Admon, Roselinde H Kaiser, Daniel G Dillon, Miranda Beltzer, Franziska Goer, David P Olson, Gordana Vitaliano, Diego A Pizzagalli
OBJECTIVE: Major depressive disorder is characterized by reduced reward-related striatal activation and dysfunctional reward learning, putatively reflecting decreased dopaminergic signaling. The goal of this study was to test whether a pharmacological challenge designed to facilitate dopaminergic transmission can enhance striatal responses to reward and improve reward learning in depressed individuals. METHOD: In a double-blind placebo-controlled design, 46 unmedicated depressed participants and 43 healthy control participants were randomly assigned to receive either placebo or a single low dose (50 mg) of the D2/D3 receptor antagonist amisulpride, which is believed to increase dopamine signaling through presynaptic autoreceptor blockade...
October 24, 2016: American Journal of Psychiatry
Junji Uno, Keisuke Obara, Hiroko Suzuki, Satomi Miyatani, Daisuke Chino, Takashi Yoshio, Yoshio Tanaka
BACKGROUND/AIMS: To investigate the potential inhibitory effects of 18 clinically available antidepressants on acetylcholine (ACh)-induced contractions in guinea pig urinary bladder smooth muscle (UBSM) in order to predict whether they may induce voiding impairment. METHODS: Concentration-response curves for ACh-induced contractions in guinea pig UBSM strips were obtained in the absence or presence of selected antidepressants. When inhibitory effects indicated competitive antagonism, pA2 values against ACh were calculated and compared to plausible antidepressant blood concentrations...
October 22, 2016: Pharmacology
Eliane Brito Cortez Lima, Caren Nádia Soares de Sousa, Lucas Nascimento Meneses, Yuri Freitas E Silva Pereira, Natália Castelo Branco Matos, Rayanne Brito de Freitas, Nycole Brito Cortez Lima, Manoel Cláudio Azevedo Patrocínio, Luzia Kalyne Almeida Moreira Leal, Glauce Socorro Barros Viana, Silvânia Maria Mendes Vasconcelos
Extracts from the husk fiber of Cocos nucifera are used in folk medicine, but their actions on the central nervous system have not been studied. Here, the anxiolytic and antidepressant effects of the standardized hydroalcoholic extract of C. nucifera husk fiber (HECN) were evaluated. Male Swiss mice were treated with HECN (50, 100, or 200 mg/kg) 60 min before experiments involving the plus maze test, hole-board test, tail suspension test, and forced swimming test (FST). HECN was administered orally (p.o.) in acute and repeated-dose treatments...
October 21, 2016: Journal of Natural Medicines
Amanda R de Oliveira, Adriano E Reimer, Fernando M C V Reis, Marcus L Brandão
Considering the complexity of aversive information processing and defensive response expression, a combined action of stress modulators may be required for an optimal performance during threatening situations. Dopamine is now recognized as one of the most active modulators underlying states of fear and anxiety. On the other hand, activation of hypothalamic-pituitary-adrenocortical (HPA) axis, which leads to the release of corticosterone in rodents, has been considered a key part of the stress response. The current study is an extension of prior work investigating modulatory effects of dopamine and corticosterone on conditioned fear expression...
October 20, 2016: Experimental Brain Research. Experimentelle Hirnforschung. Expérimentation Cérébrale
Samuele Maramai, Sandra Gemma, Simone Brogi, Giuseppe Campiani, Stefania Butini, Holger Stark, Margherita Brindisi
D3 receptors represent a major focus of current drug design and development of therapeutics for dopamine-related pathological states. Their close homology with the D2 receptor subtype makes the development of D3 selective antagonists a challenging task. In this review, we explore the relevance and therapeutic utility of D3 antagonists or partial agonists endowed with multireceptor affinity profile in the field of central nervous system disorders such as schizophrenia and drug abuse. In fact, the peculiar distribution and low brain abundance of D3 receptors make them a valuable target for the development of drugs devoid of motor side effects classically elicited by D2 antagonists...
2016: Frontiers in Neuroscience
Laurence D Picton, Keith T Sillar
Dopamine plays important roles in the development and modulation of motor control circuits. Here we show that dopamine exerts potent effects on the central pattern generator circuit controlling locomotory swimming in post-embryonic Xenopus tadpoles. Dopamine (0.5-100 μM) reduced fictive swim bout occurrence and caused both spontaneous and evoked episodes to become shorter, slower and weaker. The D2-like receptor agonist quinpirole mimicked this repertoire of inhibitory effects on swimming, whilst the D4 receptor antagonist, L745,870, had the opposite effects...
October 20, 2016: Scientific Reports
Davide Amato, Clare L Beasley, Margaret K Hahn, Anthony C Vernon
Antipsychotic drugs, all of which block the dopamine D2 receptor to a greater or lesser extent, are the mainstay for the pharmacological treatment of schizophrenia. Engaging in a deeper understanding of how antipsychotics act on the brain and body, at the cellular, molecular and physiological level is vital to comprehend both the beneficial and potentially harmful actions of these medications and stimulate development of novel therapeutics. To address this, we review recent advances in our understanding of neuroadaptations to antipsychotics, focusing on (1) treatment efficacy, (2) impact on brain volume and (3) evidence from human post-mortem studies that attempt to dissect neuropathological effects of antipsychotic drugs from organic schizophrenia neurobiology and (4) cardio-metabolic side effects...
October 15, 2016: Neuroscience and Biobehavioral Reviews
P Seeman
Although all current antipsychotics act by interfering with the action of dopamine at dopamine D2 receptors, two recent reports showed that 800 to 1000 mg of cannabidiol per day alleviated the signs and symptoms of schizophrenia, although cannabidiol is not known to act on dopamine receptors. Because these recent clinical findings may indicate an important exception to the general rule that all antipsychotics interfere with dopamine at dopamine D2 receptors, the present study examined whether cannabidiol acted directly on D2 receptors, using tritiated domperidone to label rat brain striatal D2 receptors...
October 18, 2016: Translational Psychiatry
Ursula F Bailer, Julie C Price, Carolyn C Meltzer, Angela Wagner, Chester A Mathis, Anthony Gamst, Walter H Kaye
OBJECTIVE: Individuals with anorexia nervosa (AN) have anxious and inhibited temperaments with high concern for consequences. Studies using either positron emission tomography (PET) or functional magnetic resonance imaging (fMRI) suggest involvement of the middle and dorsal caudate (DC) in individuals recovered (REC) from AN. For example, dopamine (DA) D2/D3 receptor binding in the middle caudate and DC was associated with anxiety and harm avoidance, and blood-oxygen-level-dependent (BOLD) response in the DC was positively related to trait anxiety...
October 18, 2016: International Journal of Eating Disorders
Jeffery F Rocca, Joshua G Lister, Richard J Beninger
Rats repeatedly exposed to the bar test following injections with a dopamine D2-like receptor antagonist such as haloperidol show increased descent latencies, suggesting that contextual stimuli may lose their ability to elicit approach and other responses. Here, we showed that rats took progressively longer to initiate descent from a horizontal bar across sessions following daily intraperitoneal treatment (paired group) with the D2-like receptor antagonist, spiroperidol (0.125 and 0.25 mg/kg), but not in the control group that received 0...
September 29, 2016: Behavioural Pharmacology
Lei-Fang Cao, Xiao-Yan Peng, Ya Huang, Bing Wang, Feng-Ming Zhou, Ruo-Xiao Cheng, Li-Hua Chen, Wei-Feng Luo, Tong Liu
In the present study, we investigated whether restoring descending noradrenergic inhibitory tone can attenuate pain in a PD rat model, which was established by stereotaxic infusion of 6-hydroxydopamine (6-OHDA) into the bilateral striatum (CPu). PD rats developed thermal and mechanical hypersensitivity at the 4th week after surgery. HPLC analysis showed that NE content, but not dopamine or 5-HT, significantly decreased in lumbar spinal cord in PD rats. Additional noradrenergic depletion by injection of N-(2-chloroethyl)-N-ethyl-2-bromobenzylamine (DSP-4) aggravated pain hypersensitivity in PD rats...
2016: Neural Plasticity
Tarek K Rajji, Benoit H Mulsant, Shinichiro Nakajima, Fernando Caravaggio, Takefumi Suzuki, Hiroyuki Uchida, Philip Gerretsen, Wanna Mar, Bruce G Pollock, David C Mamo, Ariel Graff-Guerrero
OBJECTIVES: To assess the impact of reducing the dose of antipsychotics on cognition and dopaminergic D2 receptor availability in the whole striatum, and identify their relationship in patients with schizophrenia aged 50 years or older. DESIGN: Open-label prospective PET [(11)C]-raclopride study. SETTING: A tertiary care center outpatient setting. PARTICIPANTS: Thirty-seven clinically stable participants with schizophrenia or schizoaffective disorder, aged 50 years or greater, and having been treated with olanzapine or risperidone monotherapy at the same dose for at least 6 months...
August 2, 2016: American Journal of Geriatric Psychiatry
Kayoko Kanamitsu, Ryosuke Arakawa, Yuichi Sugiyama, Tetsuya Suhara, Hiroyuki Kusuhara
The effect of drugs in the central nervous system (CNS) is closely related to occupancy of their target receptor. In this study, we integrated plasma concentrations, in vitro/in vivo data for receptor or protein binding, and in silico data, using a physiologically based pharmacokinetic model, to examine the predictability of receptor occupancy in humans. The occupancy of the dopamine D2 receptor and the plasma concentrations of the antipsychotic drugs quetiapine and perospirone in humans were collected from the literature or produced experimentally...
July 30, 2016: Drug Metabolism and Pharmacokinetics
Meg Waraczynski, Samantha Abbott, Alex V Schultz
Previous work in our laboratory has shown that stimulating D2 dopamine receptors in the central sublenticular extended amygdala (SLEAc) can render medial forebrain bundle (MFB) stimulation less rewarding. One of the many ways in which D2 stimulation could affect the activity status of SLEAc neurons is by indirectly blocking calcium ion (Ca(2+)) influx through CaV1.3 channels. He we directly investigate the effects of blocking CaV1.3 channels on the rewarding effect of MFB stimulation. In experiment one, CaV1...
October 13, 2016: Behavioural Brain Research
Rosario Pivonello, Marlijn Waaijers, Johan M Kros, Claudia Pivonello, Cristina de Angelis, Alessia Cozzolino, Annamaria Colao, Steven W J Lamberts, Leo J Hofland
The dopamine D2 receptor is the main dopamine receptor expressed in the human normal pituitary gland. The aim of the current study was to evaluate dopamine D2 receptor expression in the corticotroph cell populations of the anterior lobe and pars intermedia, as well as posterior lobe of the human normal pituitary gland by immunohistochemistry. Human normal pituitary gland samples obtained from routine autopsies were used for the study. In all cases, histology together with immunostaining for adrenocorticotropic hormone, melanocyte-stimulating hormone, prolactin, and neurofilaments were performed and compared to the immunostaining for D2 receptor...
October 13, 2016: Endocrine
Patricia Pilkinton, Carlos Berry, Seth Norrholm, Al Bartolucci, Badari Birur, Lori L Davis
OBJECTIVE: Selective serotonin reuptake inhibitors (SSRIs) remain the first-line treatment for posttraumatic stress disorder (PTSD). However, adjunctive atypical antipsychotics are often used to target residual or refractory symptoms. Asenapine is a novel atypical antipsychotic that possesses a high serotonin (5-HT2A) to dopamine (D2) affinity ratio and alpha-adrenergic antagonism, which may be advantageous in treating PTSD. This pilot study aimed to identify the therapeutic potential of asenapine as an adjunctive treatment for PTSD...
August 15, 2016: Psychopharmacology Bulletin
Chrislean Jun Botanas, Seong Shoon Yoon, June Bryan de la Peña, Irene Joy Dela Peña, Mikyung Kim, Taeseon Woo, Joung-Wook Seo, Choon-Gon Jang, Kyung-Tae Park, Young Hun Lee, Yong Sup Lee, Hee Jin Kim, Jae Hoon Cheong
The recreational use of synthetic cathinones has grown rapidly which prompted concerns from legal authorities and health care providers. However, in response to legislative regulations, synthesis of novel synthetic cathinones by introducing substituents in cathinone molecule has dramatically increased the diversity of these substances. Based on current trends, the aromatic ring is one of the popular sites in cathinone molecule being explored by designer-type modifications. In this study, we designed and synthesized a novel synthetic cathinone, 2-(methylamino)-1-(naphthalen-2-yl) propan-1-one (BMAPN), which has a naphthalene substituent on the aromatic ring...
October 11, 2016: Behavioural Brain Research
Martin J Bobak, Matthew W Weber, Melissa A Doellman, Douglas R Schuweiler, Jeana M Athens, Steven A Juliano, Paul A Garris
Modafinil (MOD) exhibits therapeutic efficacy for treating sleep and psychiatric disorders, but its mechanism is incompletely understood. Compared to other psychostimulants inhibiting dopamine (DA) uptake, MOD weakly interacts with the dopamine transporter (DAT) and modestly elevates striatal dialysate DA, suggesting additional targets besides DAT. However, the ability of MOD to induce wakefulness is abolished with DAT knockout, conversely suggesting that DAT is necessary for MOD action. Another psychostimulant target, but one not established for MOD, is activation of phasic DA signaling...
October 12, 2016: Journal of Pharmacology and Experimental Therapeutics
Jing Qiu, Zhongjun Yan, Kai Tao, Yansong Li, Yuqian Li, Jingchen Li, Yushu Dong, Dayun Feng, Huisheng Chen
BACKGROUND: Astrocyte-mediated neuroinflammation plays a critical role in ischemic stroke-induced secondary cerebral injury. Previous studies have suggested that the dopamine D2 receptor (DRD2) acts as a key target in regulating the neuroinflammatory response. However, the underlying molecular mechanisms are still unknown, and effective DRD2 agonists are lacking. In the present study, we examined the anti-inflammatory and neuroprotective effects of sinomenine (Sino), a monomeric compound with potential immunoregulatory properties in nervous system...
October 10, 2016: Journal of Neuroinflammation
William M Greenberg, Leslie Citrome
Lurasidone hydrochloride, a benzisothiazol derivative, is a second-generation (atypical) antipsychotic agent that has received regulatory approval for the treatment of schizophrenia in the US, Canada, the EU, Switzerland, and Australia, and also for bipolar depression in the US and Canada. In addition to its principal antagonist activity at dopamine D2 and serotonin 5-HT2A receptors, lurasidone has distinctive 5-HT7 antagonistic activity, and displays partial agonism at 5-HT1A receptors, as well as modest antagonism at noradrenergic α2A and α2C receptors...
October 8, 2016: Clinical Pharmacokinetics
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