Discovery of new tetracyclic tetrahydrofuran derivatives as potential broad-spectrum psychotropic agents

Ligand-Controlled Cobalt-Catalyzed Regio-, Enantio-, and Diastereoselective Oxyheterocyclic Alkene Hydroalkylation

Metal-hydride-catalyzed alkene hydroalkylation has been developed as an efficient method for C(sp3)-C(sp3) coupling with broad substrate availability and high functional group compatibility. However, auxiliary groups, a conjugated group or a chelation-directing group, are commonly required to attain high regio- and enantioselectivities. Herein, we reported a ligand-controlled cobalt-hydride-catalyzed regio-, enantio-, and diastereoselective oxyheterocyclic alkene hydroalkylation without chelation-directing groups. This reaction enables the hydroalkylation of conjugated and unconjugated oxyheterocyclic alkenes to deliver C2- or C3-alkylated tetrahydrofuran or tetrahydropyran in uniformly good yields and with high regio- and enantioselectivities. In addition, hydroalkylation of C2-substituted 2,5-dihydrofuran resulted in the simultaneous construction of 1,3-distereocenters, providing convenient access to polysubstituted tetrahydrofuran with multiple enantioenriched C(sp3) centers.

Molecular dynamics and free energy calculations of clozapine bound to D2 and H1 receptors reveal a cardiometabolic mitigated derivative

Most atypical antipsychotics derive from a high dropout of drug treatments due to adverse cardiometabolic side effects. These side effects are caused, in part, by the H1 receptor blockade. The current work sought a clozapine derivative with a reduced affinity for the H1 receptor while maintaining its therapeutic effect linked to D2 receptor binding. Explicit molecular dynamics simulations and end-point free energy calculations of clozapine in complex with the D2 and H1 receptors embedded in cholesterol-rich lipid bilayers were performed to analyze the intermolecular interactions and address the relevance of clozapine-functional groups. Based on that, free energy perturbation calculations were performed to measure the change in free energy of clozapine structural modifications. Our results indicate the best clozapine derivative is the iodine atom substitution for chlorine. The latter is mainly due to electrostatic interaction loss for the H1 receptor, while the halogen orientation out of the D2 active site reduces the impact on the affinity.Communicated by Ramaswamy H. Sarma.

The effect and safety of probiotics on depression: a systematic review and meta-analysis of randomized controlled trials

PURPOSE

With the escalating social pressures, there has been a continuous rise in the prevalence of depression among the population, leading to substantial healthcare burdens. Moreover, conventional pharmacological interventions still exhibit certain limitations. Therefore, the primary objective of this study is to systematically evaluate the clinical efficacy of probiotics in the treatment of depression.

METHODS

Randomized controlled trials of probiotics in treating depressive symptoms were retrieved from Pubmed, Cochrane Library, Web of Science, Wan Fang database, and CNKI between the establishment of the database and March 2022. The primary outcome was Beck's depression rating scale (BDI) scores, while the secondary outcomes were depression scores on the DASS-21 scale, biochemical indicators (IL-6, NO, and TNF-α levels), and adverse events. In addition, Revman 5.3 was used for Meta-analysis and quality evaluation, and Stata 17 was used for the Egger test and Begg's test. A total of 776 patients, including 397 and 379 patients in the experimental and control groups, respectively, were included.

RESULTS

The total BDI score of the experimental group was lower than that of the control group (MD = - 1.98, 95%CI - 3.14 to - 0.82), and the score of DASS (MD = 0.90, 95%CI - 1.17 to 2.98), the IL-6 level (SMD = - 0.55, 95%CI - 0.88 to - 0.23), the NO level (MD = 5.27, 95% CI 2.51 to 8.03), and the TNF-α level (SMD = 0.19, 95% CI - 0.25 to 0.63).

CONCLUSION

The findings substantiate the therapeutic potential of probiotics in mitigating depressive symptoms by significantly reducing Beck's Depression Inventory (BDI) scores and alleviating the overall manifestation of depression.

Molecular Docking Assessment of Cathinones as 5-HT2AR Ligands: Developing of Predictive Structure-Based Bioactive Conformations and Three-Dimensional Structure-Activity Relationships Models for Future Recognition of Abuse Drugs

Commercially available cathinones are drugs of long-term abuse drugs whose pharmacology is fairly well understood. While their psychedelic effects are associated with 5-HT2AR, the enclosed study summarizes efforts to shed light on the pharmacodynamic profiles, not yet known at the receptor level, using molecular docking and three-dimensional quantitative structure-activity relationship (3-D QSAR) studies. The bioactive conformations of cathinones were modeled by AutoDock Vina and were used to build structure-based (SB) 3-D QSAR models using the Open3DQSAR engine. Graphical inspection of the results led to the depiction of a 3-D structure analysis-activity relationship (SAR) scheme that could be used as a guideline for molecular determinants by which any untested cathinone molecule can be predicted as a potential 5-HT2AR binder prior to experimental evaluation. The obtained models, which showed a good agreement with the chemical properties of co-crystallized 5-HT2AR ligands, proved to be valuable for future virtual screening campaigns to recognize unused cathinones and similar compounds, such as 5-HT2AR ligands, minimizing both time and financial resources for the characterization of their psychedelic effects.

A Novel Gliotransmitter, L-β-Aminoisobutyric Acid, Contributes to Pathophysiology of Clinical Efficacies and Adverse Reactions of Clozapine

Clozapine is listed as one of the most effective antipsychotics and has been approved for treating treatment-resistant schizophrenia (TRS); however, several type A and B adverse reactions, including weight gain, metabolic complications, cardiotoxicity, convulsions, and discontinuation syndromes, exist. The critical mechanisms of clinical efficacy for schizophrenia, TRS, and adverse reactions of clozapine have not been elucidated. Recently, the GABA isomer L-β-aminoisobutyric acid (L-BAIBA), a protective myokine in the peripheral organs, was identified as a candidate novel transmission modulator in the central nervous system (CNS). L-BAIBA activates adenosine monophosphate-activated protein kinase (AMPK) signalling in both the peripheral organs and CNS. Activated AMPK signalling in peripheral organs is an established major target for treating insulin-resistant diabetes, whereas activated AMPK signalling in the hypothalamus contributes to the pathophysiology of weight gain and metabolic disturbances. Clozapine increases L-BAIBA synthesis in the hypothalamus. In addition, the various functions of L-BAIBA in the CNS have recently been elucidated, including as an activator of GABA-B and group-III metabotropic glutamate (III-mGlu) receptors. Considering the expressions of GABA-B and III-mGlu receptors (localised in the presynaptic regions), the activation of GABA-B and III-mGlu receptors can explain the distinct therapeutic advantages of clozapine in schizophrenia or TRS associated with N-methyl-D-aspartate (NMDA) receptor disturbance compared with other atypical antipsychotics via the inhibition of the persistent tonic hyperactivation of thalamocortical glutamatergic transmission in the prefrontal cortex. L-BAIBA has also been identified as a gliotransmitter, and a detailed exploration of the function of L-BAIBA in tripartite synaptic transmission can further elucidate the pathophysiology of effectiveness for treating TRS and/or specific adverse reactions of clozapine.

G protein-coupled receptors in neurodegenerative diseases and psychiatric disorders

Neuropsychiatric disorders are multifactorial disorders with diverse aetiological factors. Identifying treatment targets is challenging because the diseases are resulting from heterogeneous biological, genetic, and environmental factors. Nevertheless, the increasing understanding of G protein-coupled receptor (GPCR) opens a new possibility in drug discovery. Harnessing our knowledge of molecular mechanisms and structural information of GPCRs will be advantageous for developing effective drugs. This review provides an overview of the role of GPCRs in various neurodegenerative and psychiatric diseases. Besides, we highlight the emerging opportunities of novel GPCR targets and address recent progress in GPCR drug development.

Therapeutic Potential and Limitation of Serotonin Type 7 Receptor Modulation

Although a number of mood-stabilising atypical antipsychotics and antidepressants modulate serotonin type 7 receptor (5-HT7), the detailed contributions of 5-HT7 function to clinical efficacy and pathophysiology have not been fully understood. The mood-stabilising antipsychotic agent, lurasidone, and the serotonin partial agonist reuptake inhibitor, vortioxetine, exhibit higher binding affinity to 5-HT7 than other conventional antipsychotics and antidepressants. To date, the initially expected rapid onset of antidepressant effects-in comparison with conventional antidepressants or mood-stabilising antipsychotics-due to 5-HT7 inhibition has not been observed with lurasidone and vortioxetine; however, several clinical studies suggest that 5-HT7 inhibition likely contributes to quality of life of patients with schizophrenia and mood disorders via the improvement of cognition. Furthermore, recent preclinical studies reported that 5-HT7 inhibition might mitigate antipsychotic-induced weight gain and metabolic complication by blocking other monoamine receptors. Further preclinical studies for the development of 5-HT7 modulation against neurodevelopmental disorders and neurodegenerative diseases have been ongoing. To date, various findings from various preclinical studies indicate the possibility that 5-HT7 modifications can provide two independent strategies. The first is that 5-HT7 inhibition ameliorates the dysfunction of inter-neuronal transmission in mature networks. The other is that activation of 5-HT7 can improve transmission dysfunction due to microstructure abnormality in the neurotransmission network-which could be unaffected by conventional therapeutic agents-via modulating intracellular signalling during the neurodevelopmental stage or via loss of neural networks with aging. This review attempts to describe the current and novel clinical applications of 5-HT7 modulation based on preclinical findings.

Discovery of new chemotypes of dual 5-HT2A/D2 receptor antagonists with a strategy of drug design methodologies

Aim: Through the application of structure- and ligand-based methods, the authors aimed to create an integrative approach to developing a computational protocol for the rational drug design of potent dual 5-HT_2A/D₂ receptor antagonists without off-target activities on H₁ receptors. Materials & methods: Molecular dynamics and virtual docking methods were used to identify key interactions of the structurally diverse antagonists in the binding sites of the studied targets, and to generate their bioactive conformations for further 3D-quantitative structure-activity relationship modeling. Results & conclusion: Toward the goal of finding multi-potent drugs with a more effective and safer profile, the obtained results led to the design of a new set of dual antagonists and opened a new perspective on the therapy for complex brain diseases.

Dopamine and Dopamine-Related Ligands Can Bind Not Only to Dopamine Receptors

The dopaminergic system is one of the most important neurotransmitter systems in the central nervous system (CNS). It acts mainly by activation of the D₁-like receptor family at the target cell. Additionally, fine-tuning of the signal is achieved via pre-synaptic modulation by the D₂-like receptor family. Some dopamine drugs (both agonists and antagonists) bind in addition to DRs also to α₂-ARs and 5-HT receptors. Unfortunately, these compounds are often considered subtype(s) specific. Thus, it is important to consider the presence of these receptor subtypes in specific CNS areas as the function virtually elicited by one receptor type could be an effect of other—or the co-effect of multiple receptors. However, there are enough molecules with adequate specificity. In this review, we want to give an overview of the most common off-targets for established dopamine receptor ligands. To give an overall picture, we included a discussion on subtype selectivity. Molecules used as antipsychotic drugs are reviewed too. Therefore, we will summarize reported affinities and give an outline of molecules sufficiently specific for one or more subtypes (i.e., for subfamily), the presence of DR, α₂-ARs, and 5-HT receptors in CNS areas, which could help avoid ambiguous results.

Synthesis and Investigations of Building Blocks with Dibenzo[b,f] Oxepine for Use in Photopharmacology

The synthesis of photoswitchable azo-dibenzo[b,f]oxepine derivatives and microtubule inhibitors were described. Subsequently, we examined the reaction of methoxy derivative 3-nitrodibenzo[b,f]oxepine with different aldehydes and in the presence of BF3·OEt2 as a catalyst. Our study provided a very concise method for the construction of the azo-dibenzo[b,f]oxepine skeleton. The analysis of products was run using experimental and theoretical methods. Next, we evaluated the E/Z isomerization of azo-dibenzo[b,f]oxepine derivatives, which could be photochemically controlled using visible-wavelength light.

Design, Sustainable Synthesis and Biological Evaluation of a Novel Dual α2A/5-HT7 Receptor Antagonist with Antidepressant-Like Properties

The complex pathophysiology of depression, together with the limits of currently available antidepressants, has resulted in the continuous quest for alternative therapeutic strategies. Numerous findings suggest that pharmacological blockade of α₂-adrenoceptor might be beneficial for the treatment of depressive symptoms by increasing both norepinephrine and serotonin levels in certain brain areas. Moreover, the antidepressant properties of 5-HT₇ receptor antagonists have been widely demonstrated in a large set of animal models. Considering the potential therapeutic advantages in targeting both α₂-adrenoceptors and 5-HT₇ receptors, we designed a small series of arylsulfonamide derivatives of (dihydrobenzofuranoxy)ethyl piperidines as dually active ligands. Following green chemistry principles, the designed compounds were synthesized entirely using a sustainable mechanochemical approach. The identified compound 8 behaved as a potent α_2A/5-HT₇ receptor antagonist and displayed moderate-to-high selectivity over α₁-adrenoceptor subtypes and selected serotonin and dopaminergic receptors. Finally, compound 8 improved performance of mice in the forced swim test, displaying similar potency to the reference drug mirtazapine.

Effects of Subchronic Administrations of Vortioxetine, Lurasidone, and Escitalopram on Thalamocortical Glutamatergic Transmission Associated with Serotonin 5-HT7 Receptor

The functional suppression of serotonin (5-HT) type 7 receptor (5-HT7R) is forming a basis for scientific discussion in psychopharmacology due to its rapid-acting antidepressant-like action. A novel mood-stabilizing atypical antipsychotic agent, lurasidone, exhibits a unique receptor-binding profile, including a high affinity for 5-HT7R antagonism. A member of a novel class of antidepressants, vortioxetine, which is a serotonin partial agonist reuptake inhibitor (SPARI), also exhibits a higher affinity for serotonin transporter, serotonin receptors type 1A (5-HT1AR) and type 3 (5-HT3R), and 5-HT7R. However, the effects of chronic administration of lurasidone, vortioxetine, and the selective serotonin reuptake inhibitor (SSRI), escitalopram, on 5-HT7R function remained to be clarified. Thus, to explore the mechanisms underlying the clinical effects of vortioxetine, escitalopram, and lurasidone, the present study determined the effects of these agents on thalamocortical glutamatergic transmission, which contributes to emotional/mood perception, using multiprobe microdialysis and 5-HT7R expression using capillary immunoblotting. Acute local administration of a 5-HT7R agonist and antagonist into the mediodorsal thalamic nucleus (MDTN) enhanced and reduced thalamocortical glutamatergic transmission, induced by N-methyl-D-aspartate (NMDA)/glutamate receptor inhibition in the reticular thalamic nucleus (RTN). Acute local administration of a relevant therapeutic concentration of vortioxetine and lurasidone into the MDTN suppressed the thalamocortical glutamatergic transmission via 5-HT7R inhibition, whereas that of escitalopram activated 5-HT7R. Subchronic administration of effective doses of vortioxetine and lurasidone (for 7 days) reduced the thalamocortical glutamatergic transmission, but escitalopram did not affect it, whereas subchronic administration of these three agents attenuated the stimulatory effects of the 5-HT7R agonist on thalamocortical glutamatergic transmission. Subchronic administration of effective doses of vortioxetine, lurasidone, and escitalopram downregulated the 5-HT7R expression of the plasma membrane in the MDTN; the 5-HT7R downregulation induced by vortioxetine and lurasidone was observed at 3 days, but that induced by escitalopram required a longer duration of 7 days. These results indicate that chronic administration of vortioxetine, escitalopram, and lurasidone generate downregulation of 5-HT7R in the thalamus; however, the direct inhibition of 5-HT7R associated with vortioxetine and lurasidone generates more rapid downregulation than the indirect elevation of the extracellular serotonin level via serotonin transporter inhibition by escitalopram.

Current Limitations and Candidate Potential of 5-HT7 Receptor Antagonism in Psychiatric Pharmacotherapy

Several mood-stabilizing atypical antipsychotics and antidepressants weakly block serotonin (5-HT) receptor type-7 (5-HT7R); however, the contributions of 5-HT7R antagonism to clinical efficacy and pathophysiology are yet to be clarified. A novel mood-stabilizing antipsychotic agent, lurasidone exhibits predominant binding affinity to 5-HT7R when compared with other monoamine receptors. To date, we have failed to discover the superior clinical efficacy of lurasidone on schizophrenia, mood, or anxiety disorders when compared with conventional mood-stabilizing atypical antipsychotics; however, numerous preclinical findings have indicated the possible potential of 5-HT7R antagonism against several neuropsychiatric disorders, as well as the generation of novel therapeutic options that could not be expected with conventional atypical antipsychotics. Traditional experimental techniques, electrophysiology, and microdialysis have demonstrated that the effects of 5-HT receptor type-1A (5-HT1AR) and 5-HT7R on neurotransmission are in contrast, but the effect of 5-HT1AR is more predominant than that of 5-HT7R, resulting in an insufficient understanding of the 5-HT7R function in the field of psychopharmacology. Accumulating knowledge regarding the pharmacodynamic profiles of 5-HT7R suggests that 5-HT7R is one of the key players in the establishment and remodeling of neural development and cytoarchitecture during the early developmental stage to the mature brain, and dysfunction or modulation of 5-HT7R is linked to the pathogenesis/pathophysiology of neuropsychiatric and neurodevelopmental disorders. In this review, to explore candidate novel applications for the treatment of several neuropsychiatric disorders, including mood disorders, schizophrenia, and other cognitive disturbance disorders, we discuss perspectives of psychopharmacology regarding the effects of 5-HT7R antagonism on transmission and intracellular signaling systems, based on preclinical findings.

Development of novel derivatives of stilbene and macrocyclic compounds as potent of anti-microtubule factors

Microtubules (composed of α- and β-tubulin heterodimers) ubiquitous cellular polymers are important components of the cytoskeleton and play diverse roles within the cell, such as maintenance of cell structure, protein trafficking or chromosomal segregation during cell division. The polymers of tubulin play a pivotal role in mitosis and are regarded as an excellent target for chemotherapeutic agents to treat cancer. This review presents a brief overview of the synthesis and mechanism of action of new compounds targeting the dynamic of microtubule - tubulin polymerization/depolymerization. It is divided into the following parts: section I concerns targeting microtubules- tubulin-binding drugs derivatives of stilbene. In section II there are presented photoswitchable inhibitors of microtubule dynamics. Section III concerns using macrocyclic compounds as tubulin inhibitors. In this review, the authors focused primarily on reports produced inthe last five years and the latest strategies in this field.

The Benefits of Olanzapine in Palliating Symptoms

OPINION STATEMENT

Olanzapine has become a major drug in the management of chemotherapy-induced nausea and vomiting as a prophylactic agent. In addition, a recent randomized trial has demonstrated its benefits in treating nausea and vomiting associated with advanced cancer. The added benefit to olanzapine is that it also stimulates appetite. As a result, since it treats multiple symptoms associated with advanced cancer, it is likely to become the antiemetic of choice in palliative care at least in the USA. The added benefit of treating insomnia and the avoidance of benzodiazepines should place olanzapine in at the top of the list of drugs to use for patients who do complain of insomnia. There is no good evidence that it potentiates the respiratory depression of opioids unlike benzodiazepines. The evidence is weak that olanzapine in as an adjuvant analgesic. Hopefully, future trials will explore this in greater depth. The benefits of adding olanzapine to potent opioids are that it may reduce craving, drug cues, and opioid misuse. Other symptoms like anxiety and depression may be addressed by the addition of olanzapine to standard antidepressants.

Immunoendocrine Peripheral Effects Induced by Atypical Antipsychotics

Atypical antipsychotics (AAP) or second-generation antipsychotics are the clinical option for schizophrenia treatment during acute psychoses, but they are also indicated for maintenance during lifetime, even though they are being used for other psychiatric conditions in clinical practice such as affective disorders and autism spectrum disorder, among others. These drugs are differentiated from typical antipsychotics based on their clinical profile and are a better choice because they cause fewer side effects regarding extrapyramidal symptoms (EPS). Even though they provide clear therapeutic benefits, AAP induce peripheral effects that trigger phenotypic, functional, and systemic changes outside the Central Nervous System (CNS). Metabolic disease is frequently associated with AAP and significantly impacts the patient's quality of life. However, other peripheral changes of clinical relevance are present during AAP treatment, such as alterations in the immune and endocrine systems as well as the intestinal microbiome. These less studied alterations also have a significant impact in the patient's health status. This manuscript aims to revise the peripheral immunological, endocrine, and intestinal microbiome changes induced by AAP consumption recommended in the clinical guidelines for schizophrenia and other psychiatric disorders.

Antipsychotic Treatment of Behavioral and Psychological Symptoms of Dementia (BPSD): Management of Extrapyramidal Side Effects

Antipsychotic drugs are often used for the treatment of behavioral and psychological symptoms of dementia (BPSD), especially psychosis and behavioral disturbances (e.g., aggression and agitation). They are prescribed alone or in conjunction with anti-dementia (e.g., anti-Alzheimer’s disease drugs) and other psychotropic drugs (e.g., antidepressants). However, antipsychotic drugs frequently produce serious extrapyramidal side effects (EPS) including Parkinsonian symptoms (e.g., bradykinesia, akinesia, tremor, and muscle rigidity). Therefore, appropriate drug choice and combination strategy are important in the treatment of BPSD. Among anti-Alzheimer’s disease drugs, cholinesterase inhibitors (ChEIs, e.g., donepezil and galantamine) have a propensity to potentiate EPS associated with antipsychotic treatment in a synergistic manner. In contrast, the NMDA receptor antagonist memantine reduces antipsychotic-induced EPS. Antidepressant drugs, which inhibit 5-HT reuptake into the nerve terminals, also synergistically augment antipsychotic-induced EPS, while mirtazapine (α₂, 5-HT₂ and 5-HT₃ antagonist) reduces the EPS induction. Importantly, previous studies showed that multiple 5-HT receptors play crucial roles in modulating EPS associated with antipsychotic treatment. Specifically, activation of 5-HT_1A receptors or blockade of 5-HT₂, 5-HT₃ and 5-HT₆ receptors can alleviate EPS induction both by antipsychotics alone and by combined antipsychotic treatments with ChEIs or 5-HT reuptake inhibitors. In this article, we review antipsychotic use in treating BPSD and discuss the favorable drug selection in terms of the management of antipsychotic-induced EPS.

Synthesis of medium-sized (6-7-6) ring compounds by iron-catalyzed C-H activation/annulation [corrected]

In this report, we have described a FeCl3-catalyzed process involving intramolecular annulation of o-phenoxy diarylacetylenes via hydroarylation to afford a series of biologically potent fused seven-membered (6-7-6) ring compounds under mild reaction conditions. This reaction was believed to proceed through Friedel-Crafts type sequential carbometallation followed by protonation to produce phenyldibenz[b,f]oxepines. This method was also extended to synthesize seven-membered rings that are fused with coumarins.

Pharmacologically distinct pramipexole-mediated akinesia vs. risk-taking in a rat model of Parkinson's disease

Pramipexole and ropinirole are dopamine agonists that are efficacious in treating motor disturbances of neuropathologies, e.g., Parkinson's disease and restless legs syndrome. A significant portion of treated patients develop impulsive/compulsive behaviors. Current treatment is dose reduction or switching to an alternative dopamine replacement, both of which can undermine the motor benefits. Needed is a preclinical model that can assist in identifying adjunct treatments to dopamine agonist therapy that reduce impulsive/compulsive behaviors without interfering with motor benefits of the dopamine agonist. Toward that objective, the current study implemented a rat model of Parkinson's disease to behaviorally profile chronically administered pramipexole. This was accomplished with male Sprague-Dawley rats wherein (i) 6-hydroxydopamine-induced lesions of the dorsolateral striatum produced Parkinson's disease-like akinesia, measured in the forelimbs, (ii) intracranial self-stimulation-mediated probability discounting indicated impulsivity/risk-taking, and (iii) two doses of pramipexole were continuously administered for 14-28days via osmotic minipumps to mirror the chronic, stable exposure achieved with extended release formulations. The atypical antidepressant, mirtazapine, is known to reduce behaviors associated with drug addiction in rats; thus, we demonstrated model utility here by determining the effects of mirtazapine on pramipexole-induced motor improvements versus probability discounting. We observed that forelimb akinesia subsequent to striatal lesions was attenuated by both pramipexole doses tested (0.3 and 1.2mg/kg/day) within 4h of pump implant dispensing 0.3mg/kg/day and 1h by 1.2mg/kg/day. By contrast, 12-14days of infusion with 0.3mg/kg/day did not alter discounting, but increases were obtained with 1.2mg/kg/day pramipexole, with 67% of 1.2mg/kg/day-treated rats meeting categorical criteria for 'high risk-taking'. Insertion of a second minipump delivering mirtazapine did not alter motor function during 14days of co-administration with pramipexole, but was sufficient to attenuate risk-taking. These outcomes revealed distinct probability discounting and anti-akinesia profiles for pramipexole, indicating that pharmacotherapy, (e.g., mirtazapine treatments), can be developed that reduce risk-taking while leaving motor benefits intact.

Polypharmacology of dopamine receptor ligands

Most neurological diseases have a multifactorial nature and the number of molecular mechanisms discovered as underpinning these diseases is continuously evolving. The old concept of developing selective agents for a single target does not fit with the medical need of most neurological diseases. The development of designed multiple ligands holds great promises and appears as the next step in drug development for the treatment of these multifactorial diseases. Dopamine and its five receptor subtypes are intimately involved in numerous neurological disorders. Dopamine receptor ligands display a high degree of cross interactions with many other targets including G-protein coupled receptors, transporters, enzymes and ion channels. For brain disorders like Parkinsońs disease, schizophrenia and depression the dopaminergic system, being intertwined with many other signaling systems, plays a key role in pathogenesis and therapy. The concept of designed multiple ligands and polypharmacology, which perfectly meets the therapeutic needs for these brain disorders, is herein discussed as a general ligand-based concept while focusing on dopaminergic agents and receptor subtypes in particular.

A systematic methodology for large scale compound screening: A case study on the discovery of novel S1PL inhibitors

Decrease in sphingosine 1-phosphate (S1P) concentration induces migration of pathogenic T cells to the blood stream, disrupts the CNS and it is implicated in multiple sclerosis (MS), a progressive inflammatory disorder of the central nervous system (CNS), and Alzheimer's disease (AD). A promising treatment alternative for MS and AD is inhibition of the activity of the microsomal enzyme sphingosine 1-phosphate lyase (S1PL), which degrades intracellular S1P. This report describes an integrated systematic approach comprising virtual screening, molecular docking, substructure search and molecular dynamics simulation to discover novel S1PL inhibitors. Virtual screening of the ZINC database via ligand-based and structure-based pharmacophore models yielded 10000 hits. After molecular docking, common substructures of the top ranking hits were identified. The ligand binding poses were optimized by induced fit docking. MD simulations were performed on the complex structures to determine the stability of the S1PL-ligand complex and to calculate the binding free energy. Selectivity of the selected molecules was examined by docking them to hERG and cytochrome P450 receptors. As a final outcome, 15 compounds from different chemotypes were proposed as potential S1PL inhibitors. These molecules may guide future medicinal chemistry efforts in the discovery of new compounds against the destructive action of pathogenic T cells.

Learning from the past and looking to the future: Emerging perspectives for improving the treatment of psychiatric disorders

Modern neuropsychopharmacology commenced in the 1950s with the serendipitous discovery of first-generation antipsychotics and antidepressants which were therapeutically effective yet had marked adverse effects. Today, a broader palette of safer and better-tolerated agents is available for helping people that suffer from schizophrenia, depression and other psychiatric disorders, while complementary approaches like psychotherapy also have important roles to play in their treatment, both alone and in association with medication. Nonetheless, despite considerable efforts, current management is still only partially effective, and highly-prevalent psychiatric disorders of the brain continue to represent a huge personal and socio-economic burden. The lack of success in discovering more effective pharmacotherapy has contributed, together with many other factors, to a relative disengagement by pharmaceutical firms from neuropsychiatry. Nonetheless, interest remains high, and partnerships are proliferating with academic centres which are increasingly integrating drug discovery and translational research into their traditional activities. This is, then, a time of transition and an opportune moment to thoroughly survey the field. Accordingly, the present paper, first, chronicles the discovery and development of psychotropic agents, focusing in particular on their mechanisms of action and therapeutic utility, and how problems faced were eventually overcome. Second, it discusses the lessons learned from past successes and failures, and how they are being applied to promote future progress. Third, it comprehensively surveys emerging strategies that are (1), improving our understanding of the diagnosis and classification of psychiatric disorders; (2), deepening knowledge of their underlying risk factors and pathophysiological substrates; (3), refining cellular and animal models for discovery and validation of novel therapeutic agents; (4), improving the design and outcome of clinical trials; (5), moving towards reliable biomarkers of patient subpopulations and medication efficacy and (6), promoting collaborative approaches to innovation by uniting key partners from the regulators, industry and academia to patients. Notwithstanding the challenges ahead, the many changes and ideas articulated herein provide new hope and something of a framework for progress towards the improved prevention and relief of psychiatric and other CNS disorders, an urgent mission for our Century.

Symptomatic management for gastroparesis: antiemetics, analgesics, and symptom modulators

Although prokinetic agents typically are used for gastroparesis, antiemetic, analgesic, and neuromodulatory medications may help manage nausea, vomiting, pain, or discomfort. Antiemetic benefits are supported by few case reports. An open series reported symptom reductions with transdermal granisetron in gastroparesis. Opiates are not advocated in gastroparesis because they worsen nausea and delay emptying. Neuromodulators have theoretical utility, but the tricyclic agent nortriptyline showed no benefits over placebo in an idiopathic gastroparesis study raising doubts about this strategy. Neurologic and cardiac toxicities of these medications are recognized. Additional controlled study is warranted to define antiemetic, analgesic, and neuromodulator usefulness in gastroparesis.

Monoamine reuptake inhibitors in Parkinson's disease

The motor manifestations of Parkinson's disease (PD) are secondary to a dopamine deficiency in the striatum. However, the degenerative process in PD is not limited to the dopaminergic system and also affects serotonergic and noradrenergic neurons. Because they can increase monoamine levels throughout the brain, monoamine reuptake inhibitors (MAUIs) represent potential therapeutic agents in PD. However, they are seldom used in clinical practice other than as antidepressants and wake-promoting agents. This review article summarises all of the available literature on use of 50 MAUIs in PD. The compounds are divided according to their relative potency for each of the monoamine transporters. Despite wide discrepancy in the methodology of the studies reviewed, the following conclusions can be drawn: (1) selective serotonin transporter (SERT), selective noradrenaline transporter (NET), and dual SERT/NET inhibitors are effective against PD depression; (2) selective dopamine transporter (DAT) and dual DAT/NET inhibitors exert an anti-Parkinsonian effect when administered as monotherapy but do not enhance the anti-Parkinsonian actions of L-3,4-dihydroxyphenylalanine (L-DOPA); (3) dual DAT/SERT inhibitors might enhance the anti-Parkinsonian actions of L-DOPA without worsening dyskinesia; (4) triple DAT/NET/SERT inhibitors might exert an anti-Parkinsonian action as monotherapy and might enhance the anti-Parkinsonian effects of L-DOPA, though at the expense of worsening dyskinesia.

α2-Adrenoceptors are targets for antipsychotic drugs

RATIONALE

Almost all antipsychotic drugs (APDs), irrespective of whether they belong to the first-generation (e.g. haloperidol) or second-generation (e.g. clozapine), are dopamine D2 receptor antagonists. Second-generation APDs, which differ from first-generation APDs in possessing a lower propensity to induce extrapyramidal side effects, target a variety of monoamine receptors such as serotonin (5-hydroxytryptamine) receptors (e.g. 5-HT1A, 5-HT2A, 5-HT2C, 5-HT6, 5-HT7) and α1- and α2-adrenoceptors in addition to their antagonist effects at D2 receptors.

OBJECTIVE

This short review is focussed on the potential role of α2-adrenoceptors in the antipsychotic therapy.

RESULTS

Schizophrenia is characterised by three categories of symptoms: positive symptoms, negative symptoms and cognitive deficits. α2-Adrenoceptors are classified into three distinct subtypes in mammals, α2A, α2B and α2C. Whereas the α2B-adrenoceptor seems to play only a minor role in the brain, activation of postsynaptic α2A-adrenoceptors in the prefrontal cortex improves cognitive functions. Preclinical models such as D-amphetamine-induced locomotion, the conditioned avoidance response and the pharmacological N-methyl-D-aspartate receptor hypofunction model have shown that α2C-adrenoceptor blockade or the combination of D2 receptor antagonists with idazoxan (α2A/2C-adrenoceptor antagonist) could be useful in schizophrenia. A potential benefit of a treatment combination of first-generation APDs with the α2A/2C-adrenoceptor antagonists idazoxan or mirtazapine was also demonstrated in patients with schizophrenia.

CONCLUSIONS

It is concluded that α2-adrenoceptors may be promising targets in the antipsychotic therapy.

Synthesis of dibenzoxepine lactams via a Cu-catalyzed one-pot etherification/aldol condensation cascade reaction: application toward the total synthesis of aristoyagonine

A general synthesis of dibenzoxepine lactams has been developed using a one-pot Cu-catalyzed etherification/aldol condensation cascade reaction. The reaction of 4-hydroxyisoindolin-1-one with a wide range of 2-bromobenzaldehydes in the presence of a copper catalyst provided various aristoyagonine derivatives in good yields.

A framework to avoid irrational polypharmacy in psychiatry

Many patients with psychiatric disorders do not obtain remission from available pharmacological and psychotherapeutic treatments. Recent studies have demonstrated that there is a role for the rational use of 'combination therapy' when treating patients with serious and treatment-resistant mental illnesses. When prescribing multiple medications, it is easy, however, to fall into irrational polypharmacy. We present a framework that clinicians can use to avoid the pitfall of irrational polypharmacy. When using combination therapy, clinicians should consider: (a) pharmadynamic redundancy; (b) pharmacodynamic interactions; (c) pharmacokinetic interactions; and (d) avoid inadequate dosing of medications. Clinicians should also (e) regularly reassess the need for and benefit of continued combination therapy.

Modulation of antipsychotic-induced extrapyramidal side effects by medications for mood disorders

Antipsychotic drugs are widely used not only for schizophrenia, but also for mood disorders such as bipolar disorder and depression. To evaluate the interactions between antipsychotics and drugs for mood disorders in modulating extrapyramidal side effects (EPS), we examined the effects of antidepressants and mood-stabilizing drugs on haloperidol (HAL)-induced bradykinesia and catalepsy in mice and rats. The selective serotonin reuptake inhibitors (SSRIs), fluoxetine and paroxetine, and the tricyclic antidepressant (TCA) clomipramine, which showed no EPS by themselves, significantly potentiated HAL-induced bradykinesia and catalepsy in a dose-dependent manner. In contrast, the noradrenergic and specific serotonergic antidepressant (NaSSA) mirtazapine failed to augment, but rather attenuated HAL-induced bradykinesia and catalepsy. Mianserin also tended to reduce the EPS induction. In addition, neither treatment with lithium, sodium valproate nor carbamazepine potentiated HAL-induced EPS. Furthermore, treatment of animals with ritanserin (5-HT2A/2C antagonist), ondansetron (5-HT3 antagonist), and SB-258585 (5-HT6 antagonist) significantly antagonized the EPS augmentation by fluoxetine. Intrastriatal injection of ritanserin or SB-258585, but not ondansetron, also attenuated the EPS induction. The present study suggests that NaSSAs are superior to SSRIs or TCAs in combined therapy for mood disorders with antipsychotics in terms of EPS induction. In addition, 5-HT2A/2C, 5-HT3 and 5-HT6 receptors seem to be responsible for the augmentation of antipsychotic-induced EPS by serotonin reuptake inhibitors.

Effects of dopamine and serotonin antagonist injections into the striatopallidal complex of asymptomatic MPTP-treated monkeys

The cardinal symptoms of Parkinson's disease (PD), akinesia, rigidity and tremor, are only observed when the striatal level of dopamine (DA) is decreased by 60-80%. It is likely that compensatory mechanisms during the early phase of DA depletion delay the appearance of motor symptoms. In a previous study, we proposed a new PD monkey model with progressive MPTP intoxication. Monkeys developed all of the motor symptoms and then fully recovered despite a large DA cell loss in the substantia nigra (SN). Compensatory mechanisms certainly help to offset the dysfunction induced by the DA lesion, facilitating motor recovery in this model. Neurotransmitter measurements in the striatal sensorimotor and associative/limbic territories of these monkeys subsequently revealed that DA and serotonin (5-HT) could play a role in recovery mechanisms. To try to determine the involvement of these neurotransmitters in compensatory mechanisms, we performed local injections of DA and 5-HT antagonists (cis-flupenthixol and mianserin, respectively) into these two striatal territories and into the external segment of the globus pallidus (GPe). Injections were performed on monkeys that were in an asymptomatic state after motor recovery. Most parkinsonian motor symptoms reappeared in animals with DA antagonist injections either in sensorimotor, associative/limbic striatal territories or in the GPe. In contrast to the effects with DA antagonist, there were mild parkinsonian effects with 5-HT antagonist, especially after injections in sensorimotor territories of the striatum and the GPe. These results support a possible, but slight, involvement of 5-HT in compensatory mechanisms and highlight the possible participation of 5-HT in some behavioural disorders. Furthermore, these results support the notion that the residual DA in the different striatal territories and the GPe could be involved in important mechanisms of compensation in PD.

The serotonergic system in Parkinson's disease

Although the cardinal manifestations of Parkinson's disease (PD) are attributed to a decline in dopamine levels in the striatum, a breadth of non-motor features and treatment-related complications in which the serotonergic system plays a pivotal role are increasingly recognised. Serotonin (5-HT)-mediated neurotransmission is altered in PD and the roles of the different 5-HT receptor subtypes in disease manifestations have been investigated. The aims of this article are to summarise and discuss all published preclinical and clinical studies that have investigated the serotonergic system in PD and related animal models, in order to recapitulate the state of the current knowledge and to identify areas that need further research and understanding.

Molecular properties affecting fast dissociation from the D2 receptor

Dopamine D(2) receptor antagonism is the foundation of antipsychotic treatment. Antipsychotic agents vary in how fast they dissociate from the D(2) receptors. It has been proposed that the liability to exhibit side effects such as extra pyramidal symptoms may be the result of a slow rate of dissociation. Compounds with a faster rate of dissociation, while still blocking efficiently the D(2) receptors, will subsequently respond better to physiological surges in dopamine transmission. Therefore, work in our laboratories has focussed on identifying fast dissociating and selective D(2) antagonists. Biological screening was performed to measure the affinity and extent of dissociation for a large dataset of over 1800 D(2) antagonists. Subsequent univariate and multivariate statistical analysis revealed the molecular properties which differentiate fast and slow dissociating compounds. It is shown that faster dissociating antagonists are less lipophilic and have lower molecular weight. There was a clear and expected inverse relationship with extent of dissociation and binding affinity with more potent compounds tending to be slower dissociating. However, within a range of comparable affinity both fast and slow dissociating compounds were identified. After de-correlating affinity and dissociation the analysis revealed the important descriptors.

QSAR-CoMSIA applied to antipsychotic drugs with their dopamine D2 and serotonine 5HT2A membrane receptors

Antipsychotic drugs are psychiatric medication primarily used to manage psychosis (e.g., delusions or hallucinations), particularly in schizophrenia and bipolar disorder. First and second generations of antipshychotics tend to block receptors in the brain's dopamine pathways, but antipsychotic drugs encompass a wide range of receptor targets. The inhibition constant, Ki, at the level of membrane receptors is a major determinant of their pharmacokinetic behavior and, consequently, it can affect their antipsychotic activity. Here, predicted inhibition constants, Ki for 71 antipsychotics, already approved for clinical treatment, as well as representative new chemical structures which exhibit antipsychotic activity, were evaluated using 3D-QSAR-CoMSIA models. Significant values of the cross-validated correlation q2 (higher than 0.70) and the fitted correlation r2 (higher than 0.80) revealed that these models have reasonable power to predict the biological affinity of the 15 new risperidone and 12 new olanzapine derivatives in interactions with dopamine D2 and serotonin 5HT2A receptors; these compounds are suggested for further studies.

Serotonin 5-HT7 receptor agents: Structure-activity relationships and potential therapeutic applications in central nervous system disorders

Since its discovery in the 1940s in serum, the mammalian intestinal mucosa, and in the central nervous system, serotonin (5-HT) has been shown to be involved in virtually all cognitive and behavioral human functions, and alterations in its neurochemistry have been implicated in the etiology of a plethora of neuropsychiatric disorders. The cloning of 5-HT receptor subtypes has been of importance in enabling them to be classified as specific protein molecules encoded by specific genes. The 5-HT(7) receptor is the most recently classified member of the serotonin receptor family. Since its identification, it has been the subject of intense research efforts driven by its presence in functionally relevant regions of the brain. The availability of some selective antagonists and agonists, in combination with genetically modified mice lacking the 5-HT(7) receptor, has allowed for a better understanding of the pathophysiological role of this receptor. This paper reviews data on localization and pharmacological properties of the 5-HT(7) receptor, and summarizes the results of structure-activity relationship studies aimed at the discovery of selective 5-HT(7) receptor ligands. Additionally, an overview of the potential therapeutic applications of 5-HT(7) receptor agonists and antagonists in central nervous system disorders is presented.