Dopamine receptor D1, also known as DRD1. It is one of the two types of D1-like receptor family — receptors D1 and D5. It is a protein that in humans is encoded by the DRD1 gene. [5] [6] [7] [8]
Dopamine receptor D1, also known as DRD1. It is one of the two types of D1-like receptor family — receptors D1 and D5. It is a protein that in humans is encoded by the DRD1 gene. [5] [6] [7] [8]
D1 receptors are the most abundant kind of dopamine receptor in the central nervous system.
Northern blot and in situ hybridization show that the mRNA expression of DRD1 is highest in the dorsal striatum (caudate and putamen) and ventral striatum (nucleus accumbens and olfactory tubercle). [9]
Lower levels occur in the basolateral amygdala, cerebral cortex, septum, thalamus, and hypothalamus. [9]
D1 receptors regulate the memory, learning, and the growth of neurons, also is used in the reward system and locomotor activity, mediating some behaviors and modulating dopamine receptor D2-mediated events. [10] [8]
They play a role in addiction by facilitating the gene expression changes that occur in the nucleus accumbens during addiction.
They are Gs coupled and can stimulate neurons by activation of cyclic AMP-dependent protein kinase.
The DRD1 gene expresses primarily in the caudate putamen in humans, and in the caudate putamen, the nucleus accumbens and the olfactory tubercle in mouse. Gene expression patterns from the Allen Brain Atlases in mouse and human can be found here.
There are a number of ligands selective for the D1 receptors. To date, most of the known ligands are based on dihydrexidine or the prototypical benzazepine partial agonist SKF-38393 (one derivative being the prototypical antagonist SCH-23390). [11] D1 receptor has a high degree of structural homology to another dopamine receptor, D5, and they both bind similar drugs. [12] As a result, none of the known orthosteric ligands is selective for the D1 vs. the D5 receptor, but the benzazepines generally are more selective for the D1 and D5 receptors versus the D2-like family. [11] Some of the benzazepines have high intrinsic activity whereas others do not. In 2015 the first positive allosteric modulator for the human D1 receptor was discovered by high-throughput screening. [13]
Several D1 receptor agonists are used clinically. These include apomorphine, pergolide, rotigotine, and terguride. All of these drugs are preferentially D2-like receptor agonists. Fenoldopam is a selective D1 receptor partial agonist that does not cross the blood-brain-barrier and is used intravenously in the treatment of hypertension. Dihydrexidine and adrogolide (ABT-431) (a prodrug of A-86929 with improved bioavailability) are the only selective, centrally active D1-like receptor agonists that have been studied clinically in humans. [16] The selective D1 agonists give profound antiparkinson effects in humans and primate models of PD, and yield cognitive enhancement in many preclinical models and a few clinical trials. The most dose-limiting feature is profound hypotension, but the clinical development was impeded largely by lack of oral bioavailability and short duration of action. [16] [17] [18] In 2017, Pfizer made public information about pharmaceutically-acceptable non-catechol selective D1 agonists that are in clinical development.
Many typical and atypical antipsychotics are D1 receptor antagonists in addition to D2 receptor antagonists. But asenapine has shown stronger D1 receptor affinity compared to other antipsychotics. No other D1 receptor antagonists have been approved for clinical use. Ecopipam is a selective D1-like receptor antagonist that has been studied clinically in humans in the treatment of a variety of conditions, including schizophrenia, cocaine abuse, obesity, pathological gambling, and Tourette's syndrome, with efficacy in some of these conditions seen. The drug produced mild-to-moderate, reversible depression and anxiety in clinical studies however and has yet to complete development for any indication.
Dopamine receptor D1 has been shown to interact with:
The D1 receptor forms heteromers with the following receptors: dopamine D2 receptor, [37] dopamine D3 receptor, [37] [38] histamine H3 receptor, [39] μ opioid receptor, [40] NMDA receptor, [37] and adenosine A1 receptor. [37]
Several CryoEM structures of agonists bound to the dopamine D1 receptor complexed with the stimulatory heterotrimeric Gs protein have been determined. Agonist interact with extracellular loop 2 and extracellular regions of trans-membrane helices 2, 3, 6, and 7. Interactions between catechol-based agonists and three trans-membrane serine residues including S1985.42, S1995.43, and S2025.46 function as microswitches that are essential for receptor activation. [42]
A dopamine antagonist, also known as an anti-dopaminergic and a dopamine receptor antagonist (DRA), is a type of drug which blocks dopamine receptors by receptor antagonism. Most antipsychotics are dopamine antagonists, and as such they have found use in treating schizophrenia, bipolar disorder, and stimulant psychosis. Several other dopamine antagonists are antiemetics used in the treatment of nausea and vomiting.
Dihydrexidine (DAR-0100) is a moderately selective full agonist at the dopamine D1 and D5 receptors. It has approximately 10-fold selectivity for D1 and D5 over the D2 receptor. Although dihydrexidine has some affinity for the D2 receptor, it has functionally selective (highly biased) D2 signaling, thereby explaining why it lacks D2 agonist behavioral qualities.
SKF-38393 is a synthetic compound of the benzazepine chemical class which acts as a selective D1/D5 receptor partial agonist. It has stimulant and anorectic effects.
SKF-82,958 is a synthetic compound of the benzazepine class that acts as a D1/D5 receptor full agonist. SKF-82,958 and similar D1-like-selective full agonists like SKF-81,297 and 6-Br-APB produce characteristic anorectic effects, hyperactivity and self-administration in animals, with a similar but not identical profile to that of dopaminergic stimulants such as amphetamine. SKF-82,958 was also subsequently found to act as an agonist of ERα with negligible activity at ERβ, making it a subtype-selective estrogen.
A dopamine agonist is a compound that activates dopamine receptors. There are two families of dopamine receptors, D1-like and D2-like. They are all G protein-coupled receptors. D1- and D5-receptors belong to the D1-like family and the D2-like family includes D2, D3 and D4 receptors. Dopamine agonists are primarily used in the treatment of the motor symptoms of Parkinson's disease, and to a lesser extent, in hyperprolactinemia and restless legs syndrome. They are also used off-label in the treatment of clinical depression. Impulse control disorders are associated with the use of dopamine agonists for whatever condition.
Lisuride, sold under the brand name Dopergin among others, is a monoaminergic medication of the ergoline class which is used in the treatment of Parkinson's disease, migraine, and high prolactin levels. It is taken by mouth.
Rotigotine, sold under the brand name Neupro among others, is a dopamine agonist of the non-ergoline class of medications indicated for the treatment of Parkinson's disease and restless legs syndrome. It is formulated as a once-daily transdermal patch which provides a slow and constant supply of the drug over the course of 24 hours.
Dopamine receptor D2, also known as D2R, is a protein that, in humans, is encoded by the DRD2 gene. After work from Paul Greengard's lab had suggested that dopamine receptors were the site of action of antipsychotic drugs, several groups, including those of Solomon H. Snyder and Philip Seeman used a radiolabeled antipsychotic drug to identify what is now known as the dopamine D2 receptor. The dopamine D2 receptor is the main receptor for most antipsychotic drugs. The structure of DRD2 in complex with the atypical antipsychotic risperidone has been determined.
Dopamine receptor D5, also known as D1BR, is a protein that in humans is encoded by the DRD5 gene. It belongs to the D1-like receptor family along with the D1 receptor subtype.
Ecopipam is a dopamine antagonist which is under development for the treatment of Lesch-Nyhan syndrome, Tourette's syndrome, speech disorders, and restless legs syndrome. It is taken by mouth.
SKF-83,959, a synthetic benzazepine derivative used in scientific research, acts as an agonist at the D1–D2 dopamine receptor heteromer. It behaves as a full agonist at the D1 protomer and a high-affinity partial agonist at the D2 protomer. It was further shown to act as an allosteric modulator of the sigma-1 receptor. SKF-83,959 additionally inhibits sodium channels as well as delayed rectifier potassium channels. SKF-83,959 is a racemate that consists of the R-(+)- and S-(−)-enantiomers MCL-202 and MCL-201, respectively.
6-Br-APB is a synthetic compound that acts as a selective D1 agonist, with the (R)-enantiomer being a potent full agonist, while the (S) enantiomer retains its D1 selectivity but is a weak partial agonist. (R)-6-Br-APB and similar D1-selective full agonists like SKF-81,297 and SKF-82,958 produce characteristic anorectic effects, stereotyped behaviour and self-administration in animals, with a similar but not identical profile to that of dopaminergic stimulants such as amphetamine.
A-77636 is a synthetic drug which acts as a selective D1 receptor full agonist. It has nootropic, anorectic, rewarding and antiparkinsonian effects in animal studies, but its high potency and long duration of action causes D1 receptor downregulation and tachyphylaxis, and unlike other D1 full agonists such as SKF-82,958, it does not produce place preference in animals. A-77636 partially substituted for cocaine in animal studies, and has been suggested for use as a possible substitute drug in treating addiction, but it is better known for its use in studying the role of D1 receptors in the brain.
A-68930 is a synthetic compound that acts as a selective dopamine receptor D1 agonist. It is orally active and has antidepressant and anorectic effects in animals, producing wakefulness and tachycardia, but without stimulant effects, instead producing sedation. The difference in effects between A-68930 and other D1 agonists such as SKF-82958 may be due to their differing effects on the related D5 receptor.
SKF-81,297 is a synthetic drug of the benzazepine chemical class that acts as a selective dopamine D1/D5 receptor full agonist, and produces a characteristic stimulant-like pattern of anorexia, hyperactivity and self-administration in animals. This profile is shared with several related drugs such as 6-Br-APB and SKF-82,958, but not with certain other D1 full agonists such as A-77,636, reflecting functional selectivity of D1 activation. Newer findings reveal that SKF-81,297 additionally acts as a partial agonist at D1-D2 receptor heteromers.
A-86929 is a synthetic compound that acts as a selective dopamine receptor D1 agonist. It was developed as a possible treatment for Parkinson's disease, as well as for other applications such as treatment of cocaine addiction, but while it had reasonable efficacy in humans it also caused dyskinesias and has not been continued. It has mainly been used as its diacetate ester prodrug adrogolide (ABT-431), which has better bioavailability.
Dinapsoline is a drug developed for the treatment of Parkinson's disease, that acts as a selective full agonist at the dopamine D1 receptor.
Sumanirole (PNU-95,666) is a highly selective D2 receptor full agonist, the first of its kind to be discovered. It was developed for the treatment of Parkinson's disease and restless leg syndrome. While it has never been approved for medical use it is a highly valuable tool compound for basic research to identify neurobiological mechanisms that are based on a dopamine D2-linked (vs. D1-, D3-, D4-, and D5-linked) mechanism of action.
The D1–D2 dopamine receptor heteromer is a receptor heteromer consisting of D1 and D2 protomers.
Tavapadon is a dopamine receptor agonist which is under development for the treatment of Parkinson's disease. It is under development by Cerevel Therapeutics, which acquired tavapadon from Pfizer in 2018. It is taken by mouth.
Localization of the D1 receptor messenger ribonucleic acid (mRNA) expression has been mapped using Northern analysis and in situ hybridization (for a review, see [54]). Expression of D1 receptor mRNA is highest in the caudate putamen, nucleus accumbens, and olfactory tubercle. Lower levels of expression are found in the basolateral amygdala, cerebral cortex, septum pellucidum, thalamus, and hypothalamus.
This article incorporates text from the United States National Library of Medicine, which is in the public domain.