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Biochemical Pharmacology Oct 2012The dopamine D3 receptor (D3R) has been investigated as a potential target for medication development to treat substance use disorders (SUDs) with a particular focus on... (Review)
Review
The dopamine D3 receptor (D3R) has been investigated as a potential target for medication development to treat substance use disorders (SUDs) with a particular focus on cocaine and methamphetamine. Currently, there are no approved medications to treat cocaine and methamphetamine addiction and thus developing pharmacotherapeutics to complement existing behavioral strategies is a fundamental goal. Novel compounds with high affinity and D3R selectivity have been evaluated in numerous animal models of drug abuse and favorable outcomes in nonhuman primate models of self-administration and relapse have provided compelling evidence to advance these agents into the clinic. One approach is to repurpose drugs that share the D3R mechanism and already have clinical utility, and to this end buspirone has been identified as a viable candidate for clinical trials. A second, but substantially more resource intensive and risky approach involves the development of compounds that exclusively target D3R, such as GSK598809 and PG 619. Clinical investigation of these drugs or other novel D3R-selective agents will provide a better understanding of the role D3R plays in addiction and whether or not antagonists or partial agonists that are D3R selective are effective in achieving abstinence in this patient population.
Topics: Animals; Cocaine; Cocaine-Related Disorders; Disease Models, Animal; Dopamine Agonists; Dopamine Antagonists; Humans; Methamphetamine; Molecular Structure; Receptors, Dopamine D3; Substance-Related Disorders
PubMed: 22781742
DOI: 10.1016/j.bcp.2012.06.023 -
Psychopharmacology Sep 2022Learning the association between rewards and predictive cues is critical for appetitive behavioral responding. The mesolimbic dopamine system is thought to play an...
RATIONALE
Learning the association between rewards and predictive cues is critical for appetitive behavioral responding. The mesolimbic dopamine system is thought to play an integral role in establishing these cue-reward associations. The dopamine response to cues can signal differences in reward value, though this emerges only after significant training. This suggests that the dopamine system may differentially regulate behavioral responding depending on the phase of training.
OBJECTIVES
The purpose of this study was to determine whether antagonizing dopamine receptors elicited different effects on behavior depending on the phase of training or the type of Pavlovian task.
METHODS
Separate groups of male rats were trained on Pavlovian tasks in which distinct audio cues signaled either differences in reward size or differences in reward rate. The dopamine receptor antagonist flupenthixol was systemically administered prior to either the first ten sessions of training (acquisition phase) or the second ten sessions of training (expression phase), and we monitored the effect of these manipulations for an additional ten training sessions.
RESULTS
We identified acute effects of dopamine receptor antagonism on conditioned responding, the latency to respond, and post-reward head entries in both Pavlovian tasks. Interestingly, dopamine receptor antagonism during the expression phase produced persistent deficits in behavioral responding only in rats trained on the reward size Pavlovian task.
CONCLUSIONS
Together, our results illustrate that dopamine's control over behavior in Pavlovian tasks depends upon one's prior training experience and the information signaled by the cues.
Topics: Animals; Conditioning, Classical; Conditioning, Operant; Cues; Dopamine; Dopamine Antagonists; Male; Rats; Rats, Sprague-Dawley; Receptors, Dopamine; Reward
PubMed: 35796814
DOI: 10.1007/s00213-022-06182-w -
PLoS Biology Jun 2024Difficulties in reasoning about others' mental states (i.e., mentalising/Theory of Mind) are highly prevalent among disorders featuring dopamine dysfunctions (e.g.,... (Randomized Controlled Trial)
Randomized Controlled Trial
Difficulties in reasoning about others' mental states (i.e., mentalising/Theory of Mind) are highly prevalent among disorders featuring dopamine dysfunctions (e.g., Parkinson's disease) and significantly affect individuals' quality of life. However, due to multiple confounding factors inherent to existing patient studies, currently little is known about whether these sociocognitive symptoms originate from aberrant dopamine signalling or from psychosocial changes unrelated to dopamine. The present study, therefore, investigated the role of dopamine in modulating mentalising in a sample of healthy volunteers. We used a double-blind, placebo-controlled procedure to test the effect of the D2/D3 antagonist haloperidol on mental state attribution, using an adaptation of the Heider and Simmel (1944) animations task. On 2 separate days, once after receiving 2.5 mg haloperidol and once after receiving placebo, 33 healthy adult participants viewed and labelled short videos of 2 triangles depicting mental state (involving mentalistic interaction wherein 1 triangle intends to cause or act upon a particular mental state in the other, e.g., surprising) and non-mental state (involving reciprocal interaction without the intention to cause/act upon the other triangle's mental state, e.g., following) interactions. Using Bayesian mixed effects models, we observed that haloperidol decreased accuracy in labelling both mental and non-mental state animations. Our secondary analyses suggest that dopamine modulates inference from mental and non-mental state animations via independent mechanisms, pointing towards 2 putative pathways underlying the dopaminergic modulation of mental state attribution: action representation and a shared mechanism supporting mentalising and emotion recognition. We conclude that dopaminergic pathways impact Theory of Mind, at least indirectly. Our results have implications for the neurochemical basis of sociocognitive difficulties in patients with dopamine dysfunctions and generate new hypotheses about the specific dopamine-mediated mechanisms underlying social cognition.
Topics: Humans; Receptors, Dopamine D2; Male; Adult; Haloperidol; Female; Receptors, Dopamine D3; Double-Blind Method; Young Adult; Theory of Mind; Dopamine; Dopamine Antagonists; Mentalization
PubMed: 38870319
DOI: 10.1371/journal.pbio.3002652 -
The International Journal of... Mar 2004Clinician choice of an atypical antipsychotic may depend on a number of factors such as perceived efficacy, tolerability and cost. It is also important that the choice... (Review)
Review
Clinician choice of an atypical antipsychotic may depend on a number of factors such as perceived efficacy, tolerability and cost. It is also important that the choice of treatment takes into consideration the previous response to treatment, experience of side-effects and personal clinical characteristics. The receptor-affinity profiles of the atypical antipsychotics differ; with the exception of amisulpride, a selective D2/D3 antagonist, all the atypical antipsychotics exhibit a greater affinity for the serotonin-2A receptors than dopamine receptors. However, there is no evidence that the variation in receptor affinities is relevant to efficacy. Indeed, the crucial factor may be fast dissociation from low affinity for the D2 receptor. Tolerability also varies between the atypical antipsychotics and the side-effect profile may be related to the receptor-affinity profile of the individual drugs. Extrapyramidal side-effects are generally less of a problem with most atypical drugs than with conventional drugs, but weight gain, loss of glycaemic control, sedation and hyperprolactinaemia remain problematic in some patients. Amisulpride is effective for the treatment of both positive and negative symptoms, and is well tolerated with regard to weight gain, glucose tolerance and sedation. In two clinical trials, the AMIRIS and SOLIANOL studies, amisulpride demonstrated clear advantages over some other atypical antipsychotics with respect to negative symptoms, depressive symptoms and weight gain.
Topics: Adverse Drug Reaction Reporting Systems; Amisulpride; Antipsychotic Agents; Clinical Trials as Topic; Dopamine Antagonists; Humans; Psychiatric Status Rating Scales; Schizophrenia; Schizophrenic Psychology; Sulpiride; Treatment Outcome; Weight Gain
PubMed: 14972081
DOI: 10.1017/S1461145704004134 -
Yakugaku Zasshi : Journal of the... 2016The characteristics and functional roles of opioids originally present in vivo (endogenous opioids) in guinea-pig ileum were investigated. The release of endogenous... (Review)
Review
The characteristics and functional roles of opioids originally present in vivo (endogenous opioids) in guinea-pig ileum were investigated. The release of endogenous opioids was determined by the inhibitory twitch response evoked by 0.1 Hz stimulation after 10 Hz stimulation (post-tetanic twitch inhibition). The effects of peptidase inhibitors increased the post-tetanic twitch inhibition, prevented by β-funaltrexamine and nor-binaltorphimine, which are selective μ- and κ-opioid receptor subtype antagonists, respectively. Dopamine receptor antagonists (haloperidol, sultopride and domperidone) increased the post-tetanic twitch inhibition. These results suggest that dopamine receptors are involved in modulation of the ileal opioid system, so as to diminish endogenous opioid release by tetanic stimulation, and dopamine antagonists increase the opioid action, that might depend more on the increased release of endogenous opioids. The post-tetanic twitch inhibition was inhibited by adrenalectomy, and showed the supersensitivity of the opioid receptors, resulting from a decrease of endogenous opioids by adrenalectomy. These findings suggest that the increase in morphine-analgesia by adrenalectomy was due to this process. In the presence of naloxone, an opioid antagonist, an increase in basal tension after tetanic stimulation (10 Hz stimulation) (post-tetanic contraction) was observed, and was blocked by spantide, a substance P antagonist, and indomethacin, a prostaglandins-biosynthesis inhibitor. This contraction increased with morphine or peptidase inhibitor exposure, depending on the length of time the ileum was exposed to the morphine or peptidase inhibitor. Post-tetanic contraction might be a useful indicator of the formation of physical dependence to morphine or endogenous opioids in the ileum.
Topics: Animals; Dopamine Antagonists; Humans; Ileum; Morphine; Morphine Dependence; Muscle Contraction; Muscle, Smooth; Naloxone; Narcotic Antagonists; Opioid Peptides; Protease Inhibitors; Receptors, Dopamine; Receptors, Opioid, kappa; Receptors, Opioid, mu; Time Factors
PubMed: 27040344
DOI: 10.1248/yakushi.15-00265 -
Journal of B.U.ON. : Official Journal... 2020In the effort to improve treatment effectiveness in glioblastoma, this short note reviewed collected data on the pathophysiology of glioblastoma with particular... (Review)
Review
In the effort to improve treatment effectiveness in glioblastoma, this short note reviewed collected data on the pathophysiology of glioblastoma with particular reference to intersections with the pharmacology of perphenazine. That study identified five areas of potentially beneficial intersection. Data showed seemingly 5 independent perphenazine attributes of benefit to glioblastoma treatment - i) blocking dopamine receptor 2, ii) reducing centrifugal migration of subventricular zone cells by blocking dopamine receptor 3, iii) blocking serotonin receptor 7, iv) activation of protein phosphatase 2, and v) nausea reduction. Perphenazine is fully compatible with current chemoirradiation protocols and with the commonly used ancillary medicines used in clinical practice during the course of glioblastoma. All these attributes argue for a trial of perphenazine's addition to current standard treatment with temozolomide and irradiation. The subventricular zone seeds the brain with mutated cells that become recurrent glioblastoma after centrifugal migration. The current paper shows how perphenazine might reduce that contribution. Perphenazine is an old, generic, cheap, phenothiazine antipsychotic drug that has been in continuous clinical use worldwide since the 1950's. Clinical experience and research data over these decades have shown perphenazine to be well-tolerated in psychiatric populations, in normals, and in non-psychiatric, medically ill populations for whom perphenazine is used to reduce nausea. For now (Summer, 2020) the nature of glioblastoma requires a polypharmacy approach until/unless a core feature and means to address it can be identified in the future. Conclusions: Perphenazine possesses a remarkable constellation of attributes that recommend its use in GB treatment.
Topics: Dopamine Antagonists; Glioblastoma; Humans; Perphenazine
PubMed: 33099901
DOI: No ID Found -
Dopamine antagonists and brief vision distinguish lens-induced- and form-deprivation-induced myopia.Experimental Eye Research Nov 2011In eyes wearing negative lenses, the D2 dopamine antagonist spiperone was only partly effective in preventing the ameliorative effects of brief periods of vision (Nickla... (Comparative Study)
Comparative Study
In eyes wearing negative lenses, the D2 dopamine antagonist spiperone was only partly effective in preventing the ameliorative effects of brief periods of vision (Nickla et al., 2010), in contrast to reports from studies using form-deprivation. The present study was done to directly compare the effects of spiperone, and the D1 antagonist SCH-23390, on the two different myopiagenic paradigms. 12-day old chickens wore monocular diffusers (form-deprivation) or -10 D lenses attached to the feathers with matching rings of Velcro. Each day for 4 days, 10 μl intravitreal injections of the dopamine D2/D4 antagonist spiperone (5 nmoles) or the D1 antagonist SCH-23390, were given under isoflurane anesthesia, and the diffusers (n = 16; n = 5, respectively) or lenses (n = 20; n = 6) were removed for 2 h immediately after. Saline injections prior to vision were done as controls (form-deprivation: n = 11; lenses: n = 10). Two other saline-injected groups wore the lenses (n = 12) or diffusers (n = 4) continuously. Axial dimensions were measured by high frequency A-scan ultrasonography at the start, and on the last day immediately prior to, and 3 h after the injection. Refractive errors were measured at the end of the experiment using a Hartinger's refractometer. In form-deprived eyes, spiperone, but not SCH-23390, prevented the ocular growth inhibition normally effected by the brief periods of vision (change in vitreous chamber depth, spiperone vs saline: 322 vs 211 μm; p = 0.01). By contrast, neither had any effect on negative lens-wearing eyes given similar unrestricted vision (210 and 234 μm respectively, vs 264 μm). The increased elongation in the spiperone-injected form-deprived eyes did not, however, result in a myopic shift, probably due to the inhibitory effect of the drug on anterior chamber growth (drug vs saline: 96 vs 160 μm; p < 0.01). Finally, spiperone inhibited the vision-induced transient choroidal thickening in form-deprived eyes, while SCH-23390 did not. These results indicate that the dopaminergic mechanisms mediating the protective effects of brief periods of unrestricted vision differ for form-deprivation versus negative lens-wear, which may imply different growth control mechanisms between the two.
Topics: Animals; Animals, Newborn; Axial Length, Eye; Benzazepines; Chickens; Choroid; Contact Lenses; Dopamine Antagonists; Dopamine D2 Receptor Antagonists; Eye; Intravitreal Injections; Light; Myopia; Receptors, Dopamine D1; Receptors, Dopamine D4; Sensory Deprivation; Spiperone; Ultrasonography
PubMed: 21872586
DOI: 10.1016/j.exer.2011.08.001 -
The Journal of Neuroscience : the... Oct 2020Meso-diencephalic dopaminergic neurons are known to modulate locomotor behaviors through their ascending projections to the basal ganglia, which in turn project to the...
Meso-diencephalic dopaminergic neurons are known to modulate locomotor behaviors through their ascending projections to the basal ganglia, which in turn project to the mesencephalic locomotor region, known to control locomotion in vertebrates. In addition to their ascending projections, dopaminergic neurons were found to increase locomotor movements through direct descending projections to the mesencephalic locomotor region and spinal cord. Intriguingly, fibers expressing tyrosine hydroxylase (TH), the rate-limiting enzyme of dopamine synthesis, were also observed around reticulospinal neurons of lampreys. We now examined the origin and the role of this innervation. Using immunofluorescence and tracing experiments, we found that fibers positive for dopamine innervate reticulospinal neurons in the four reticular nuclei of lampreys. We identified the dopaminergic source using tracer injections in reticular nuclei, which retrogradely labeled dopaminergic neurons in a caudal diencephalic nucleus (posterior tuberculum [PT]). Using voltammetry in brain preparations isolated , we found that PT stimulation evoked dopamine release in all four reticular nuclei, but not in the spinal cord. In semi-intact preparations where the brain is accessible and the body moves, PT stimulation evoked swimming, and injection of a D receptor antagonist within the middle rhombencephalic reticular nucleus was sufficient to decrease reticulospinal activity and PT-evoked swimming. Our study reveals that dopaminergic neurons have access to command neurons that integrate sensory and descending inputs to activate spinal locomotor neurons. As such, our findings strengthen the idea that dopamine can modulate locomotor behavior both via ascending projections to the basal ganglia and through descending projections to brainstem motor circuits. Meso-diencephalic dopaminergic neurons play a key role in modulating locomotion by releasing dopamine in the basal ganglia, spinal networks, and the mesencephalic locomotor region, a brainstem region that controls locomotion in a graded fashion. Here, we report in lampreys that dopaminergic neurons release dopamine in the four reticular nuclei where reticulospinal neurons are located. Reticulospinal neurons integrate sensory and descending suprareticular inputs to control spinal interneurons and motoneurons. By directly modulating the activity of reticulospinal neurons, meso-diencephalic dopaminergic neurons control the very last instructions sent by the brain to spinal locomotor circuits. Our study reports on a new direct descending dopaminergic projection to reticulospinal neurons that modulates locomotor behavior.
Topics: Animals; Biomechanical Phenomena; Dopamine Antagonists; Dopaminergic Neurons; Electric Stimulation; Electrophysiological Phenomena; Lampreys; Locomotion; Nerve Fibers; Receptors, Dopamine D1; Reticular Formation; Spinal Cord; Swimming; Tyrosine 3-Monooxygenase
PubMed: 32998974
DOI: 10.1523/JNEUROSCI.2426-19.2020 -
Nutrients Apr 2019Inadequate breast milk supply is a frequently reported reason for early discontinuation of breastfeeding and represents a critical opportunity for intervening to improve... (Review)
Review
Inadequate breast milk supply is a frequently reported reason for early discontinuation of breastfeeding and represents a critical opportunity for intervening to improve breastfeeding outcomes. For women who continue to experience insufficient milk supply despite the utilisation of non-pharmacological lactation support strategies, pharmacological intervention with medications used to augment lactation, commonly referred to as galactagogues, is common. Galactagogues exert their pharmacological effects through altering the complex hormonal milieu regulating lactation, particularly prolactin and oxytocin. This narrative review provides an appraisal of the existing evidence regarding the efficacy and safety of pharmaceutical treatments for lactation insufficiency to guide their use in clinical practice. The greatest body of evidence surrounds the use of domperidone, with studies demonstrating moderate short-term improvements in breast milk supply. Evidence regarding the efficacy and safety of metoclopramide is less robust, but given that it shares the same mechanism of action as domperidone it may represent a potential treatment alternative where domperidone is unsuitable. Data on remaining interventions such as oxytocin, prolactin and metformin is too limited to support their use in clinical practice. The review provides an overview of key evidence gaps and areas of future research, including the impacts of pharmaceutical galactagogues on breast milk composition and understanding factors contributing to individual treatment response to pharmaceutical galactagogues.
Topics: Domperidone; Dopamine Antagonists; Female; Galactogogues; Humans; Lactation
PubMed: 31035376
DOI: 10.3390/nu11050974 -
Psychopharmacology Mar 2018In rodents, sucrose has been found to elicit addictive-like behaviours like the development of tolerance and the association with cues present at the time of...
In rodents, sucrose has been found to elicit addictive-like behaviours like the development of tolerance and the association with cues present at the time of consumption. Furthermore, the neurochemical response to sucrose binges is equivalent to the one observed in response to the abuse of addictive substances like cocaine. The experiments reported here address the effects of sucrose on an invertebrate model, the Platyhelminth brown planarian. The animals exposed to a 10% sucrose solution in one context developed a conditioned place preference (CPP) which was subsequently extinguished in the absence of the rewarding agent. However, one exposure to sucrose per se sufficed to reinstate the CPP response, suggesting sucrose-induced CPP can be characterised as a standard Pavlovian response. The same training procedure led to the development of context-specific tolerance to the effects of sucrose. However, comparing animals treated with dopamine D1 antagonist (SCH-23390) with control animals showed that the establishment of CPP, but not the development of tolerance, is mediated by the dopamine reward system.
Topics: Animals; Behavior, Addictive; Benzazepines; Cocaine; Conditioning, Classical; Disease Models, Animal; Dopamine Antagonists; Drug Tolerance; Male; Planarians; Reward; Sucrose
PubMed: 29197982
DOI: 10.1007/s00213-017-4801-8