D2 Ligands Research Articles

Characterization of behavioral changes in T-maze alternation from dopamine D1 agonists with different receptor coupling mechanisms.

Dopamine D1 receptor agonists have been shown to improve working memory, but often have a non-monotonic (inverted-U) dose-response curve. One hypothesis is that this may reflect dose-dependent differential engagement of D1 signaling pathways, a mechanism termed functional selectivity or signaling bias. To test this hypothesis, we compared two D1 ligands with different signaling biases in a rodent T-maze alternation task. Both tested ligands (2-methyldihydrexidine and CY208243) have high intrinsic activity at cAMP signaling, but the former also has markedly higher intrinsic activity at D1-mediated recruitment of β-arrestin. The spatial working memory was assessed via the alternation behavior in the T-maze where the alternate choice rate quantified the quality of the memory and the duration prior to making a choice represented the decision latency. Both D1 drugs changed the alternate rate and the choice latency in a dose-dependent manner, albeit with important differences. 2-Methyldihydrexidine was somewhat less potent but caused a more homogeneous improvement than CY208243 in spatial working memory. The maximum changes in the alternate rate and the choice latency tended to occur at different doses for both drugs. These data suggest that D1 signaling bias in these two pathways (cAMP vs β-arrestin) has complex effects on cognitive processes as assessed by T-maze alternation. Understanding these mechanisms should allow the identification or discovery of D1 agonists that can provide superior cognitive enhancement.

Approach to the specificity and selectivity between D2 and D3 receptors by mutagenesis and binding experiments part I: Expression and characterization of D2 and D3 receptor mutants.

D3/D2 sub-specificity is a complex problem to solve. Indeed, in the absence of easy structural biology of the G-protein coupled receptors, and despite key progresses in this area, the systematic knowledge of the ligand/receptor relationship is difficult to obtain. Due to these structural biology limitations concerning membrane proteins, we favored the use of directed mutagenesis to document a rational towards the discovery of markedly specific D3 ligands over D2 ligands together with basic binding experiments. Using our methodology of stable expression of receptors in HEK cells, we constructed the gene encoding for 24 mutants and 4 chimeras of either D2 or D3 receptors and expressed them stably. Those cell lines, expressing a single copy of one receptor mutant each, were stably constructed, selected, amplified and the membranes from them were prepared. Binding data at those receptors were obtained using standard binding conditions for D2 and D3 dopamine receptors. We generated 26 new molecules derived from D2 or D3 ligands. Using 8 reference compounds and those 26 molecules, we characterized their binding at those mutants and chimeras, exemplifying an approach to better understand the difference at the molecular level of the D2 and D3 receptors. Although all the individual results are presented and could be used for minute analyses, the present report does not discuss the differences between D2 and D3 data. It simply shows the feasibility of the approach and its potential.

Synthesis and evaluation of cyclic diamino benzamide based D3 receptor ligands

Dopamine (1) is a key neurotransmitter whose impact on pharmacological processes is mediated by a family of dopamine receptors designated D1, D2, D3, D4, and D5. Various diseases and conditions such as schizophrenia, drug abuse, depression, restless leg syndrome, Parkinson’s disease (PD), and inflammatory diseases have been linked to aberrant D3 activity. Herein, we report a series of novel D3 ligands with improved solubility over our previous lead compound, MC25-41 (2).

Functional Selectivity of Dopamine D1 Receptor Signaling: Retrospect and Prospect.

Research progress on dopamine D1 receptors indicates that signaling no longer is limited to G protein-dependent cyclic adenosine monophosphate phosphorylation but also includes G protein-independent β-arrestin-related mitogen-activated protein kinase activation, regulation of ion channels, phospholipase C activation, and possibly more. This review summarizes recent studies revealing the complexity of D1 signaling and its clinical implications, and suggests functional selectivity as a promising strategy for drug discovery to magnify the merit of D1 signaling. Functional selectivity/biased receptor signaling has become a major research front because of its potential to improve therapeutics through precise targeting. Retrospective pharmacological review indicated that many D1 ligands have some degree of mild functional selectivity, and novel compounds with extreme bias at D1 signaling were reported recently. Behavioral and neurophysiological studies inspired new methods to investigate functional selectivity and gave insight into the biased signaling of several drugs. Results from recent clinical trials also supported D1 functional selectivity signaling as a promising strategy for discovery and development of better therapeutics.

An Attempt to Achieve Hydrated Imidazoline Ring Expansion (HIRE) of Diarene-Fused [1,4]Diazepinones Delivers Selective Dopamine D2 Receptor Ligands

AbstractAttempts to extend the hydrated imidazoline ring expansion (HIRE) strategy to a series of diarene-fused [1,4]diazepinones (earlier applied successfully to bis-pyrido substrate nevirapine) did not result in ring expansion but, rather, led to 2-aminoethyl side chain expulsion. This seeming setback (setting the limitations to the HIRE methodology substrate scope) led to the discovery of selective dopamine D2 ligands with elements of structure–activity relationships.

Radiosynthesis and evaluation of 18F-labeled dopamine D4-receptor ligands

IntroductionThe dopamine D4 receptor (D4R) has attracted considerable attention as potential target for the treatment of a broad range of central nervous system disorders. Although many efforts have been made to improve the performance of putative radioligand candidates, there is still a lack of D4R selective tracers suitable for in vivo PET imaging. Thus, the objective of this work was to develop a D4-selective PET ligand for clinical applications. MethodsFour compounds based on previous and new lead structures were prepared and characterized with regard to their D4R subtype selectivity and predicted lipophilicity. From these, 3-((4-(2-fluorophenyl)piperazin-1-yl)methyl)-1H-pyrrolo[2,3-b]pyridine I and (S)-4-(3-fluoro-4-methoxybenzyl)-2-(phenoxymethyl)morpholine II were selected for labeling with fluorine-18 and subsequent evaluation by in vitro autoradiography to assess their suitability as D4 radioligand candidates for in vivo imaging. ResultsThe radiosynthesis of [18F]I and [18F]II was successfully achieved by copper-mediated radiofluorination with radiochemical yields of 7% and 66%, respectively. The radioligand [18F]II showed specific binding in areas where D4 expression is expected, whereas [18F]I did not show any uptake in distinct brain regions and exhibited an unacceptable degree of non-specific binding. ConclusionsThe compounds studied exhibited high D4R subtype selectivity and logP values compatible with high brain uptake, but only ligand [18F]II showed low non-specific binding and is therefore a good candidate for further evaluation. Advances in knowledgeThe discovery of new lead structures for high-affinity D4 ligands opens up new possibilities for the development of suitable PET-radioligands. Implications for patientPET-imaging of dopamine D4-receptors could facilitate understanding, diagnosis and treatment of neuropsychiatric and neurodegenerative diseases.

Dopamine D1 Agonists, Working Memory, and the Prefrontal Cortex: Effect of Receptor Functional Selectivity/Signaling Bias

Dopamine D1 agonists produce an ‘inverted‐U’ dose‐response on working memory‐related behavioral tasks (i.e., low doses improve but high doses have no effect or tend to impair performance). This dose‐dependency has been observed at the single neuron level in the prefrontal cortex, where the cellular basis of working memory is represented. Few studies, however, have examined this process at the neuron population level and its signaling mechanism(s) is still unclear. In the current study, two D1 agonists, 2‐methyldihydrexidine (2MDHX) and CY208,243 (CY208), were examined and compared in rats performing a spatial working memory‐related T‐maze task. 2MDHX is a full agonist at adenylate cyclase and a super‐agonist at β‐arrestin recruitment, whereas CY208 has relatively high intrinsic activity at adenylate cyclase, but much lower at β‐arrestin recruitment. Both compounds had inverted U‐dose response curves at both the behavioral and prefrontal neuron population level, albeit with distinct differences. At behavioral level, they both caused similar improvement with high potency (10 nmol/kg). Conversely, the right‐hand (descending) part of the inverted U dose‐response curve had a great slope for 2MDHX than for CY208, suggesting an extended effective range for a compound with lower β‐arrestin activity. At the neuron population level, both drugs affected the percentage, uniformity, and ensemble strength of sensitivity in a dose‐dependent manner, but 2MDHX influenced neuron activity more before the choice in the T‐maze task whereas CY208 influenced it more after the choice. As the off‐target effects were not likely engaged at the very low doses (i.e., nmol/kg range) utilized in the current study, the differences between 2MDHX and CY208 most likely are related to their specific D1 functional selectivity profiles. The ‘inverted‐U’ dose‐response of D1 agonists on cognitive performance has been observed in many of animal models and confirmed in humans. Although the cognitive improvement at the optimal dose is impressive, the biphasic effect complicates potential clinical use of D1 drugs. Our data indicate that differential signaling may play a role in D1‐related dose‐dependent regulation of cognition, and suggest that D1‐related dose‐dependent regulation of working memory could be modified by functionally selective/biased ligands. This may help guide the discovery of novel D1 compounds that may yield a more monotonic response and therefore translate to the clinic more readily.Support or Funding InformationBrain & Behavior Research Foundation Young Investigator Grant # 19469 to YY, the 2017 Children’s Miracle Network Research Grant #10 to YY and RBM, the Penn State Translational Brain Research Center, and R01 NS105471 to RBM. Conflict of interest: Dr. Mailman is an inventor on patents related to D1 ligand discovery, and this conflict is disclosed and managed by the Penn State College of Medicine.

Identification of C10 nitrogen-containing aporphines with dopamine D1 versus D5 receptor selectivity

New aporphines containing C10 nitrogen substituents (viz. nitro, aniline or amide moieties), were synthesized and evaluated for affinity at human serotonin 5-HT1A and 5-HT2A receptors and at human dopamine D1, D2 and D5 receptors. Two series of analogs were investigated: series A which contain a sole C10 nitrogen substituent on the tetracyclic aporphine core and series B which are 1,2,10-trisubstituted aporphines. Remarkably, compounds from both series lacked affinity for the D5 receptor, thus attaining D1 versus D5 selectivity. Compound 20c was the most potent D1 ligand identified. Docking studies at D1 and D5 receptors indicate that the binding mode of 20c at the D1 receptor allows for stronger hydrophobic contacts, (primarily with Phe residues) as compared to the D5 receptor, accounting for its D1 versus D5 selectivity. Considering the lack of affinity for the D5 receptor (and low affinity at other receptors tested), compound 20c represents an interesting starting point for further structural diversification of aporphines as sub-type selective D1 receptor tools.

Design, synthesis, and evaluation of N-(4-(4-phenyl piperazin-1-yl)butyl)-4-(thiophen-3-yl)benzamides as selective dopamine D3 receptor ligands.

As part of our on-going effort to explore the role of dopamine receptors in drug addiction and identify potential novel therapies for this condition, we have a identified a series of N-(4-(4-phenyl piperazin-1-yl)butyl)-4-(thiophen-3-yl)benzamide D3 ligands. Members of this class are highly selective for D3 versus D2, and we have identified two compounds (13g and 13r) whose rat in vivo IV pharmacokinetic properties that indicate that they are suitable for assessment in in vivo efficacy models of substance use disorders.

Design, synthesis and molecular modelling of new bulky Fananserin derivatives with altered pharmacological profile as potential antidepressants

It is now known that many neurotransmitter systems are responsible for diseases of the central nervous system (CNS). One of the most common CNS disease is depression. Considering that in the treatment and the genesis of depression, the most important are the serotonin receptors from 5-HT1A, 5-HT2A, 5-HT6 and 5-HT7 groups, and dopamine D2R this article describes searching for group of new ligands for mentioned receptors. In the searching for potentially useful compound, we decided to start from the structure of well-known Fananserin. We tried to developed new derivatives, with changed profile of activity compared to Fananserin. Literature analysis and virtual screening emerged group of halogenated long-chain arylpiperazines derivatives of 1,8 naphthosultam/lactam with hexyl carbon chain to synthesis. The compounds obtaining method was developed with a microwave assisted synthesis. Reactions were carried out in acetonitrile, water or in solvent-free conditions. The obtained compounds were tested for their affinity for the serotonin receptors mentioned above. The work managed to obtain compounds acting on selected serotonin receptors, including multifunctional 5-HT1A/5-HT7/D2 ligand 5k, dual 5-HT1A/D2 ligand 5j and selective 5-HT1A ligands 5r and 5c. The SAR analysis showed a visible dependence of affinity for the 5-HT6 receptors from structure of ligands. This relationship was discussed using molecular docking methods. A conformal analysis was also performed for selected ligands and the Fukui indexes were calculated using the DFT (B3LYP/6-311+G (d,p) level of theory) methods. The conducted research and analysis using molecular docking methods allows for selecting further pathways of structural modifications in the design of new ligands for serotonin receptors belonging to the group mentioned. What is more, conducted research show the potential using of Fukui indices to predict the biological activity of new molecules.

Investigation of lipophilicity and pharmacokinetic properties of 2-(methoxy)phenylpiperazine dopamine D2 ligands

Reversed-phase thin-layer chromatography and micellar thin-layer chromatography were used in order to investigate retention behaviour and to determine lipophilicity of series of 2-(methoxy)phenylpiperazine dopamine D2 ligands with different size, shape and rigidity. The retention mechanism was discussed. The lipophilicity parameters obtained in conventional reversed-phase systems expressed as RM0 and C0, as well as RM values determined in microemulsion reversed-phase systems were correlated with in silico determined lipophilicity values. In silico pharmacokinetic properties of 2-(methoxy)phenylpiperazine dopamine D2 ligands revealed the importance of experimentally determined lipophilicity values besides the molecular weight, on the blood–brain barrier permeability process. Also, the experimentally determined lipophilicity was found as a very important factor in plasma protein binding process of 2-(methoxy)phenylpiperazine dopamine D2 ligands. Besides, the Lipinski's rule of five indicates that examined ligands satisfy the criterion of drug-like molecules. The principal component analysis was performed on the experimentally determined and calculated lipophilicity values as well on the molecular descriptors which describe the pharmacokinetic properties in order to provide basic insights into similarities among the studied ligands.

Ultra-large library docking for discovering new chemotypes.

Despite intense interest in expanding chemical space, libraries of hundreds-of-millions to billions of diverse molecules have remained inaccessible. Here, we investigate structure-based docking of 170 million make-on-demand compounds from 130 well-characterized reactions. The resulting library is diverse, representing over 10.7 million scaffolds otherwise unavailable. The library was docked against AmpC β-lactamase and the D4 dopamine receptor. From the top-ranking molecules, 44 and 549 were synthesized and tested, respectively. This revealed an unprecedented phenolate inhibitor of AmpC, which was optimized to 77 nM, the most potent non-covalent AmpC inhibitor known. Crystal structures of this and other new AmpC inhibitors confirmed the docking predictions. Against D4, hit rates fell monotonically with docking score, and a hit-rate vs. score curve predicted 453,000 D4 ligands in the library. Of 81 new chemotypes discovered, 30 were sub-micromolar, including a 180 pM sub-type selective agonist.

Effects on brain-derived neurotrophic factor signalling of chronic mild stress, chronic risperidone and acute intracranial dopamine receptor challenges.

We have previously reported the effects of intracranial injections of dopamine D1, D2 and D3 ligands in animals subjected to the Novel Object Recognition (NOR) test following exposure to chronic mild stress (CMS) and chronic treatment with risperidone (RSP). Here, we present some molecular biological data from the same animals. It was predicted that brain-derived neurotrophic factor (BDNF) signalling in the prefrontal cortex (PFC) would reflect behavioural performance, implying an increase following acute administration of a D2 agonist or a D3 antagonist, blockade of this effect by CMS and its restoration by chronic RSP. In separate cohorts, animals were injected within the PFC or the hippocampus (HPC) with either the D1 agonist SKF-81297, the D2 agonist quinpirole or the D3 antagonist SB-277,011, following exposure to control conditions or CMS and chronic treatment with saline or RSP. Intracranial injections followed an exposure trial in the NOR test, with a retention trial 24 h later. Immediately afterwards, the animals were killed and expression of BDNF and TRKβ protein, and their respective mRNAs, was measured in PFC and HPC samples. CMS decreased the expression of TRKβ in both PFC and HPC. Several effects associated with intracranial injection were noted, but they were inconsistent and unrelated to CMS exposure. The effects of CMS on TRKβ are consistent with a decrease in BDNF signalling, albeit that expression of BDNF itself did not change significantly. There was no evidence for an involvement of the BDNF-TRKβ system in responses to RSP or dopamine ligands in animals exposed to CMS. However, there was a 24 h delay between the intracranial injection and tissue harvesting, meaning that brief early drug effects could have been missed.

Return of D4 Dopamine Receptor Antagonists in Drug Discovery.

The dopamine D4 receptor garnered a great deal of interest in the early 1990s when studies showed the atypical antipsychotic clozapine possessed higher affinity for D4, relative to other dopamine receptor subtypes, and that this activity might underlie the unique clinical efficacy of clozapine. Unfortunately, D4 antagonists that were developed for schizophrenia failed in the clinic. Thus, D4 fell out of favor as a therapeutic target, and work in this area was silent for decades. Recently, D4 ligands with improved selectivity for D4 against not only D1-3,5 but also other biogenic amine targets have emerged, and D4 is once again in the spotlight as a novel target for both addiction and Parkinson's disease (PD), as well as other emerging diseases. This report will review the historical data for D4, review the known D4 ligands, and then highlight new data supporting a role for D4 inhibition in addiction, PD, and cancer.

Effects of Acute and Chronic Treatments with Dopamine D2 and D3 Receptor Ligands on Cocaine versus Food Choice in Rats.

Dopamine D3 receptor ligands are potential medications for psychostimulant addiction. Medication assessment may benefit from preclinical studies that evaluate chronic medication effects on choice between an abused drug and an alternative, nondrug reinforcer. This study compared acute and chronic effects of dopamine D2- and D3-preferring ligands on choice between intravenous cocaine and palatable food in rats. Under baseline conditions, cocaine maintained dose-dependent increases in cocaine choice and reciprocal decreases in food choice. Acutely, the D2 agonist R-(-)-norpropylapomorphine (NPA) and antagonist L-741,626 [3-[[4-(4-chlorophenyl)-4-hydroxypiperidin-l-yl]methyl-1H-indole] produced leftward and rightward shifts in cocaine dose-effect curves, respectively, whereas the partial agonist terguride had no effect. All three drugs dose-dependently decreased food-maintained responding. Chronically, the effects of R-(-)-norpropylapomorphine and L-741,626 on cocaine self-administration showed marked tolerance, whereas suppression of food-reinforced behavior persisted. Acute effects of the D3 ligands were less systematic and most consistent with nonselective decreases in cocaine- and food-maintained responding. Chronically, the D3 agonist PF-592,379 [5-[(2R,5S)-5-methyl-4-propylmorpholin-2-yl]pyridin-2-amine] increased cocaine choice, whereas an intermediate dose of the D3 antagonist PG01037 [N-[(E)-4-[4-(2,3-dichlorophenyl)piperazin-1-yl]but-2-enyl]-4-pyridin-2-ylbenzamide] produced a therapeutically desirable decrease in cocaine choice early in treatment; however, tolerance to this effect developed, and lower and higher doses were ineffective. D3 ligands failed to significantly modify total cocaine intake but caused persistent decreases in food intake. Thus, D2-and D3-preferring ligands showed distinct profiles, consistent with different pharmacological actions. In addition, these results highlight the role of acute versus chronic treatment as a determinant of test drug effects. With the possible exception of the D3 antagonist PG01037, no ligand was promising in terms of cocaine addiction treatment.

Opposing effects of dopamine D1- and D2-like agonists on intracranial self-stimulation in male rats.

Dopamine acts through dopamine Type I receptors (comprising D1 and D5 subtypes) and dopamine Type II receptors (comprising D2, D3, and D4 subtypes). Intracranial self-stimulation (ICSS) is 1 experimental procedure that can be used to evaluate abuse-related effects of drugs targeting dopamine receptors. This study evaluated effects of dopamine receptor ligands on ICSS in rats using experimental procedures that have been used previously to examine abused indirect dopamine agonists such as cocaine and amphetamine. Male Sprague-Dawley rats responded under a fixed-ratio 1 schedule for electrical stimulation of the medial forebrain bundle, and frequency of stimulation varied from 56-158 Hz in 0.05 log increments during each experimental session. Drug potency and time course were determined for the D1 ligands A77636, SKF82958, SKF38393, fenoldopam, and SCH39166 and the D2/3 ligands sumanirole, apomorphine, quinpirole, PD128907, pramipexole, aripiprazole, eticlopride, and PG01037. The high-efficacy D1 agonists A77636 and SKF82958 produced dose-dependent, time-dependent, and abuse-related facilitation of ICSS. Lower efficacy D1 ligands and all D2/3 ligands failed to facilitate ICSS at any dose or pretreatment time. A mixture of SKF82958 and quinpirole produced a mixture of effects produced by each drug alone. Quinpirole also failed to facilitate ICSS after regimens of repeated treatment with either quinpirole or cocaine. These studies provide more evidence for divergent effects of dopamine D1- and D2-family agonists on ICSS procedure in rats and suggest that ICSS may be a useful complement to other approaches for preclinical abuse potential assessment, in part because of the reproducibility of results. (PsycINFO Database Record

Structure-Based Virtual Screening for Dopamine D2 Receptor Ligands as Potential Antipsychotics.

Structure-based virtual screening using a D2 receptor homology model was performed to identify dopamine D2 receptor ligands as potential antipsychotics. From screening a library of 6.5 million compounds, 21 were selected and were subjected to experimental validation. From these 21 compounds tested, ten D2 ligands were identified (47.6% success rate, among them D2 receptor antagonists, as expected) that have additional affinity for other receptors tested, in particular 5-HT2A receptors. The affinity (Ki values) of the compounds ranged from 58 nm to about 24 μM. Similarity and fragment analysis indicated a significant degree of structural novelty among the identified compounds. We found one D2 receptor antagonist that did not have a protonatable nitrogen atom, which is a key structural element of the classical D2 pharmacophore model necessary for interaction with the conserved Asp(3.32) residue. This compound exhibited greater than 20-fold binding selectivity for the D2 receptor over the D3 receptor. We provide additional evidence that the amide hydrogen atom of this compound forms a hydrogen bond with Asp(3.32), as determined by tests of its derivatives that cannot maintain this interaction.

Arylpiperazinylalkyl derivatives of 8-amino-1,3-dimethylpurine-2,6-dione as novel multitarget 5-HT/D receptor agents with potential antipsychotic activity

A series of new 7-arylpiperazinylalkyl-1,3-dimethyl-purine-2,6-dione derivatives with diversified 8-amino substituent in 8 position was synthesized and their 5-HT1A, 5-HT2A, 5-HT6, 5-HT7, and D2 receptor affinities were determined. The binding study allowed identifying some potent 5-HT1A/5-HT2A/5-HT7/D2 ligands. The most interesting because of their multireceptor profile were 8-piperidine (30–35) and 8-dipropylamine (45–47) analogs with four and five carbon aliphatic linkers. The selected compounds 24, 31, 34, 39, 41, 43, 45, and 46 in the functional in vitro evaluation for all targeted receptors showed significant partial D2 agonist, partial 5-HT1A agonist, and 5-HT2A antagonist properties. The advantageous in vitro affinity of compound 34 for 5-HT1A and D2 receptors has been explained by means of molecular modeling, taking into consideration its partial agonist activity towards the latter one. In behavioral studies, compounds 32 and 34 revealed antipsychotic-like properties, significantly decreasing d-amphetamine-induced hyperactivity in mice.

Dopamine D<sub>4</sub> Receptor Antagonists for the Treatment of Cocaine Use Disorders

The identification of effective medications for the management of cocaine use disorders remains an unmet public health challenge. In view of the prominent role of dopaminergic mechanisms in cocaine's abuse-related effects, research has focused on the development of subtype-selective dopamine D1-4 receptor antagonists. Here, we briefly recap the current status of this research effort, with a focus on several aspects of D4 research that may be pertinent to the consideration of D4 ligands in the development of candidate medications. Additionally, we present data from self administration studies in nonhuman primates showing that intravenous cocaine-maintained behavior is moderately, though non-significantly, decreased by doses of the D4-selective partial agonist Ro10-5824 and dramatically reduced by the D4- selective receptor antagonist NGD-94-1. The effects of these D4 ligands on cocaine self-administration were consistent among subjects and occurred in the absence of comparable effects on food-maintained responding. These data suggest that available D4 receptor antagonists should be investigated further as candidate medications for the management of cocaine use disorders.

New arylpiperazinylalkyl derivatives of 8-alkoxy-purine-2,6-dione and dihydro[1,3]oxazolo[2,3-f]purinedione targeting the serotonin 5-HT1A /5-HT2A /5-HT7 and dopamine D2 receptors.

To obtain potential antidepressants and/or antipsychotics, a series of new long-chain arylpiperazine derivatives of 8-alkoxy-purine-2,6-dione (10-24) and dihydro[1,3]oxazolo[2,3-f]purinedione (30-34) were synthesized and their serotonin (5-HT1A , 5-HT2A , 5-HT6 , 5-HT7 ) and dopamine (D2 ) receptor affinities were determined. The study allowed the identification of some potent 5-HT1A /5-HT7 /D2 ligands with moderate affinity for 5-HT2A sites. The binding mode of representative compounds from both chemical classes (11 and 31) in the site of 5-HT1A receptor was analyzed in computational studies. In functional in vitro studies, the selected compounds 15 and 16 showed antagonistic properties for the evaluated receptors. 8-Methoxy-7-{4-[4-(2-methoxyphenyl)-piperazin-1-yl]-butyl}-1,3-dimethyl-purine-2,6-dione (15) showed a lack of activity in terms and under the conditions of the forced swim, four plate and amphetamine-induced hyperactivity tests in mice, probably as a result of its high first pass effect in the liver.