Neurochemical profile of eltoprazine

5-HT1A agonists for levodopa-induced dyskinesia in Parkinson's disease

Levodopa is the most effective agent for treating the symptoms of Parkinson's disease (PD). However, levodopa-induced dyskinesia remains a significant complication that manifests after few years of treatment, for which therapeutic options remain limited. Several agonists of the serotonin type 1A (5-HT_1A) receptor with varying levels of efficacy and interaction at other sites, have been tested in the clinic. Clinical trials testing 5-HT_1A agonists have yielded inconsistent results in alleviating dyskinesia, especially that the antidyskinetic benefit observed was often accompanied by an adverse effect on motor function. In this article, we summarize and analyze the various clinical trials performed with 5-HT_1A agonists in PD patients with dyskinesia and offer perspectives on the future of this class of agents in PD.

Pharmacotherapy of Primary Impulsive Aggression in Violent Criminal Offenders

Primary impulsive aggression (PIA) can be implicated as a common factor that results in an arrest, disciplinary, and restraint measures during confinement, and criminal recidivism after release. Evidence suggests that anti-impulsive aggression agents (AIAAs) can diminish or prevent impulsive aggression even when occurring with personality pathology such as borderline or antisocial personality disorder (ASPD), common conditions in offender populations. A previous review identified agents that have been subjected to controlled drug trials of sufficient quality, and subsequently, a decisional algorithm was developed for selecting an AIAA for individuals with IA. This selection process began with the five agents that showed efficacy in two or more quality studies from the earlier review. Today, 8 years after the quality review study, the present authors undertook this follow-up literature review. The aims of the present review were to survey the literature to identify and assess: (1) drug trials of comparable quality published since the 2013 review, including trials of the previously identified AIAAs as well as trials of agents not included in the earlier review; (2) severity of aggressive outbursts; (3) the materiality of risks or side-effects that are associated with individual AIAAs as well as antipsychotic agents commonly used to control clinical aggression; (4) efficacy of these agents in special populations (e.g., females); and (5) cost and convenience of each agent. Improved pharmacotherapy of PIA by addressing risks, side effects and practicality as well as the efficacy of AIAAs, should promote the rehabilitation and reintegration of some pathologically aggressive offenders back into the community.

Arene Amination Instead of Fluorination: Substitution Pattern Governs the Reactivity of Dialkoxybenzenes with Selectfluor

Arene substitution patterns are well-known to affect the regioselectivity of a given transformation but not necessarily the type of reactivity. Herein, we report that the substitution pattern of alkoxyarenes dictates whether a putative one-electron or two-electron reaction predominates in reactions with Selectfluor. A series of amination products is presented, resulting from the single-electron oxidation of electron-rich arenes followed by direct C-H to C-N bond formation. We demonstrate the ability of this transformation to synthesize medicinally and biologically relevant nitrogen heterocycles. Lastly, this unusual "mechanistic switch" is probed with computational chemistry and competition experiments.

Recent developments in geriatric psychopharmacology

INTRODUCTION

There is a tremendous growing need to address the burden of geriatric psychiatric disorders. Recent developments relevant to geriatric psychiatry have focused on Alzheimer's disease (AD), severe/refractory depression, and cancer/end of life care.

AREAS COVERED

This is a non-systematic, narrative review (databases and websites for search: PubMed, Google Scholar, Medscape, ClinicalTrials.gov; focusing on the last 6 years), and covers developments in disease-modifying therapies for AD, diagnostic radiotracers for AD, medications for neuropsychiatric symptoms of dementia, ketamine/esketamine, psychedelics, and cannabinoids.

EXPERT OPINION

The focus of on-going trials of anti-amyloid agents has been on individuals with very early stage AD; several agents are under phase 3 investigation, and aducanumab is under FDA review. Amyloid and tau PET scans have been approved by the FDA to assist in the diagnoses of AD. Promising pharmaceuticals for neuropsychiatric symptoms of dementia include pimavanserin, brexpiprazole, escitalopram, dextromethorphan/quinidine, and lithium. Esketamine, although approved for treatment-resistant depression in general adults, failed to demonstrate efficacy in elderly patients in a phase 3 trial. There is preliminary evidence for benefit of psychedelic-assisted psychotherapy in end-of-life and cancer-related depression/anxiety. Evidence for the use of cannabinoids is currently lacking.

Management of Dementia-Related Psychosis, Agitation and Aggression: A Review of the Pharmacology and Clinical Effects of Potential Drug Candidates

Along with cognitive decline, 90% of patients with dementia experience behavioral and psychological symptoms of dementia, such as psychosis, aggression, agitation, and depression. Atypical antipsychotics are commonly prescribed off-label to manage certain symptoms, despite warnings from the regulatory agencies regarding the increased risk of mortality associated with their use in elderly patients. Moreover, these compounds display a limited clinical efficacy, mostly owing to the fact that they were developed to treat schizophrenia, a disease characterized by neurobiological deficits. Thus, to improve clinical efficacy, it has been suggested that patients with dementia should be treated with exclusively designed and developed drugs that interact with pharmacologically relevant targets. Within this context, numerous studies have suggested druggable targets that might achieve therapeutically acceptable pharmacological profiles. Based on this, several different drug candidates have been proposed that are being investigated in clinical trials for behavioral and psychological symptoms of dementia. We highlight the recent advances toward the development of therapeutic agents for dementia-related psychosis and agitation/aggression and discuss the relationship between the relevant biological targets and their etiology. In addition, we review the compounds that are in the early stage of development (discovery or preclinical phase) and those that are currently being investigated in clinical trials for dementia-related psychosis and agitation/aggression. We also discuss the mechanism of action of these compounds and their pharmacological utility in patients with dementia.

Receptor Ligands as Helping Hands to L-DOPA in the Treatment of Parkinson's Disease

Levodopa (LD) is the most effective drug in the treatment of Parkinson’s disease (PD). However, although it represents the “gold standard” of PD therapy, LD can cause side effects, including gastrointestinal and cardiovascular symptoms as well as transient elevated liver enzyme levels. Moreover, LD therapy leads to LD-induced dyskinesia (LID), a disabling motor complication that represents a major challenge for the clinical neurologist. Due to the many limitations associated with LD therapeutic use, other dopaminergic and non-dopaminergic drugs are being developed to optimize the treatment response. This review focuses on recent investigations about non-dopaminergic central nervous system (CNS) receptor ligands that have been identified to have therapeutic potential for the treatment of motor and non-motor symptoms of PD. In a different way, such agents may contribute to extending LD response and/or ameliorate LD-induced side effects.

Serotonergic targets for the treatment of L-DOPA-induced dyskinesia

Dopamine (DA) replacement therapy with L-3,4-dihydroxyphenylalanine (L-DOPA) continues to be the gold-standard treatment for Parkinson's disease (PD). Despite clear symptomatic benefit, long-term L-DOPA use often results in the development of L-DOPA-induced dyskinesia (LID), significantly reducing quality of life and increasing costs for PD patients and their caregivers. Accumulated research has demonstrated that several pre- and post-synaptic mechanisms contribute to LID development and expression. In particular, raphe-striatal hyperinnervation and unregulated DA release from 5-HT terminals is postulated to play a central role in LID manifestation. As such, manipulation of the 5-HT system has garnered considerable attention. Both pre-clinical and clinical research has supported the potential of modulating the 5-HT system for LID prevention and treatment. This review discusses the rationale for continued investigation of several potential anti-dyskinetic strategies including 5-HT stimulation of 5-HT1A and 5-HT1B receptors and blockade of 5-HT2A receptors and SERT. We present the latest findings from experimental and clinical investigations evaluating these 5-HT targets with the goal of identifying those with translational promise and the challenges associated with each.

Serotonergic Approaches in Parkinson's Disease: Translational Perspectives, an Update

Parkinson's disease (PD) has long been seen as a disorder caused by degeneration of the dopaminergic system, leading to the classic motor manifestations of the disease. However, there is now overwhelming evidence that PD is more than a disease merely caused by dopamine depletion. It is well-known that a myriad of other neurotransmitters are affected by the disease process. One such neurotransmitter is serotonin (5-HT). 5-HT has been shown to play a role in several motor and nonmotor manifestations of PD, including tremor, cognition, depression and psychosis. 5-HT also seems to play a critical role in L-3,4-dihydroxyphenylalanine (L-DOPA)-induced dyskinesia. A breadth of preclinical studies and clinical trials have been conducted that aimed at modulating the 5-HT system in order to alleviate depression, cognitive deficits, psychosis, and dyskinesia. In this Review, we summarize recent advances in the 5-HT field in PD, but with a translational emphasis. We start by presenting a novel nonhuman primate model of PD that presents with dual dopamine and 5-HT lesions. We then present preclinical and clinical data that introduce new concepts, such as the use of biased and partial agonists, as well as molecules recently introduced to the field of PD, such as eltoprazine, pimavanserin, nelotanserin, and SYN-120, to enhance therapeutic benefit while minimizing adverse events, notably on parkinsonian disability.

The Pharmacotherapy of Human Aggression: A Review

Aggression is a common treatment problem that may be associated with several disorders including schizophrenia, schizoaffective disorder, acute mania/bipolar disorder, personality disorders, substance abuse disorders, medical disorders, neurological disorders, and medication misadventures. Aggression is not a linear entity, it is a multidimensional problem influenced by a patient's environment and biological, psychological, and/or neurological status. It follows that if one has a multidimensional treatment problem, then a compre hensive treatment plan must be used to achieve optimal management. The comprehensive treatment of aggression should include a thorough baseline evaluation, regular objective measurement of aggression severity using a rating scale (eg, Overt Aggression Scale), psychological interventions, behavioral interventions, pharmacotherapy and, if necessary, seclusion and/or restraint. The pharmacotherapy of aggres sion includes the traditional antipsychotics and benzodiazepines, which are most commonly used; other pharmacotherapies frequently selected include the β-blockers, carbamazepine, and lithium. Despite these pharmacotherapeutic options and despite a pharmacological rationale for each one, the medications used for the treatment of aggression are at least in part nonspecific for aggression. The nonspecificity of these pharmacotherapies is best exemplified by the common use of multiple drug regimens. This may then lead to drug misadventures either in the form of drug-drug interactions, adverse effects, or toxicity. The serenics are a class of phenylpiperazine compounds that have exhibited some promise as being more selective anti- aggression drugs. Eltoprazine, the first member of this new class, is in early phases of human investigation. Copyright © 1996 by W.B. Saunders Company

The highly-selective 5-HT(1A) agonist F15599 reduces L-DOPA-induced dyskinesia without compromising anti-parkinsonian benefits in the MPTP-lesioned macaque

L-3,4-dihydroxyphenylalanine (L-DOPA) is the most effective anti-parkinsonian agent available, but upon chronic administration, patients with Parkinson's disease (PD) experience abnormal involuntary movements, dyskinesia. Modulation of serotonin 1A (5-HT1A) receptors is regarded as an effective way to alleviate dyskinesia, yet this approach has been marred by a reduction of the therapeutic effectiveness of L-DOPA. We hypothesised that highly-selective 5-HT1A stimulation might be a way to alleviate dyskinesia without compromising L-DOPA anti-parkinsonian action. F15599 (also known as NLX-101) is a highly-selective 5-HT1A agonist that displays over 1000 × selectivity over off-target receptors. Seven cynomolgus macaques were administered MPTP and developed severe parkinsonism. Following chronic administration of L-DOPA, they developed severe and reproducible dyskinesia. F15599 (0.003, 0.01, 0.03 and 0.1 mg/kg) or vehicle was administered in combination with L-DOPA and its effect on dyskinesia and L-DOPA anti-parkinsonian was assessed. In combination with L-DOPA, F15599 (0.1 mg/kg) reduced the severity of peak-dose dyskinesia, by ≈45% (P < 0.001), compared to L-DOPA alone. F15599 (any dose) had no effect on duration of on-time or motor activity counts compared to L-DOPA alone. F15599 at 0.03 and 0.1 mg/kg significantly reduced duration of on-time with disabling dyskinesia (by ≈49% and ≈71%, P < 0.05 and P < 0.001, respectively). These results suggest that F15599, a highly-selective 5-HT1A receptor agonist, alleviates dyskinesia without exerting a deleterious effect on L-DOPA anti-parkinsonian action.

Serotonin: a never-ending story

The neurotransmitter serotonin is an evolutionary ancient molecule that has remarkable modulatory effects in almost all central nervous system integrative functions, such as mood, anxiety, stress, aggression, feeding, cognition and sexual behavior. After giving a short outline of the serotonergic system (anatomy, receptors, transporter) the author's contributions over the last 40 years in the role of serotonin in depression, aggression, anxiety, stress and sexual behavior is outlined. Each area delineates the work performed on animal model development, drug discovery and development. Most of the research work described has started from an industrial perspective, aimed at developing animals models for psychiatric diseases and leading to putative new innovative psychotropic drugs, like in the cases of the SSRI fluvoxamine, the serenic eltoprazine and the anxiolytic flesinoxan. Later this research work mainly focused on developing translational animal models for psychiatric diseases and implicating them in the search for mechanisms involved in normal and diseased brains and finding new concepts for appropriate drugs.

Revisiting the serotonin-aggression relation in humans: a meta-analysis

The inverse relation between serotonin and human aggression is often portrayed as "reliable," "strong," and "well established" despite decades of conflicting reports and widely recognized methodological limitations. In this systematic review and meta-analysis, we evaluate the evidence for and against the serotonin deficiency hypothesis of human aggression across 4 methods of assessing serotonin: (a) cerebrospinal fluid levels of 5-hydroxyindoleacetic acid (CSF 5-HIAA), (b) acute tryptophan depletion, (c) pharmacological challenge, and (d) endocrine challenge. Results across 175 independent samples and over 6,500 total participants were heterogeneous, but, in aggregate, revealed a small, inverse correlation between serotonin functioning and aggression, anger, and hostility (r = -.12). Pharmacological challenge studies had the largest mean weighted effect size (r = -.21), and CSF 5-HIAA studies had the smallest (r = -.06). Potential methodological and demographic moderators largely failed to account for variability in study outcomes. Notable exceptions included year of publication (effect sizes tended to diminish with time) and self- versus other-reported aggression (other-reported aggression was positively correlated to serotonin functioning). We discuss 4 possible explanations for the pattern of findings: unreliable measures, ambient correlational noise, an unidentified higher order interaction, and a selective serotonergic effect. Finally, we provide 4 recommendations for bringing much needed clarity to this important area of research: acknowledge contradictory findings and avoid selective reporting practices; focus on improving the reliability and validity of serotonin and aggression measures; test for interactions involving personality and/or environmental moderators; and revise the serotonin deficiency hypothesis to account for serotonin's functional complexity.

5-HT receptors and reward-related behaviour: a review

The brain's serotonin (5-HT) system is key in the regulation of reward-related behaviours, from eating and drinking to sexual activity. The complexity of studying this system is due, in part, to the fact that 5-HT acts at many receptor subtypes throughout the brain. The recent development of drugs with greater selectivity for individual receptor subtypes has allowed for rapid advancements in our understanding of this system. Use of these drugs in combination with animal models entailing selective reward measures (i.e. intracranial self-stimulation, drug self-administration, conditioned place preference) have resulted in a greater understanding of the pharmacology of reward-related processing and behaviour (particularly regarding drugs of abuse). The putative roles of each 5-HT receptor subtype in the pharmacology of reward are outlined and discussed here. It is concluded that the actions of 5-HT in reward are receptor subtype-dependent (and thus should not be generalized) and that all studied subtypes appear to have a unique profile which is determined by content (e.g. receptor function, localization - both throughout the brain and within the synapse) and context (e.g. type of behavioural paradigm, type of drug). Given evidence of altered reward-related processing and serotonergic function in numerous neuropsychiatric disorders, such as depression, schizophrenia, and addiction, a clearer understanding of the role of 5-HT receptor subtypes in this context may lead to improved drug development and therapeutic approaches.

5-HT(1B) receptors, ventral orbitofrontal cortex, and aggressive behavior in mice

RATIONALE

Systemic injections of 5-HT(1B) receptor agonists have been shown to have specific anti-aggressive effects in aggressive individuals. One site of action for these drugs is the 5-HT(1B) receptors in the ventral orbitofrontal cortex (VO PFC), an area that has been implicated in the inhibitory control of behavior and is a terminal region for 5-HT projections.

OBJECTIVE

To assess the anti-aggressive effects of the 5-HT(1B) receptor agonist CP-94,253 when microinjected into the VO PFC (0.1, 0.56, and 1.0 microg/0.2 microl) or into the infralimbic prefrontal cortex (IL PFC; 1.0 microg/0.2 microl) in separate groups of aggressive resident male mice. To confirm the 5-HT(1B) receptor as the critical site of action for the anti-aggressive effects, the 5-HT(1B/D) antagonist GR-127,935 was microinjected at 10.0 microg/0.2 microl into the VO PFC. After recovery from surgery, the anti-aggressive effects of microinjected CP-94,253 were studied during 5-min resident-intruder confrontations that were recorded and analyzed.

RESULTS

Microinjections of CP-94,253 (0.56 and 1.0 microg/0.2 microl) dose-dependently reduced the frequency of attack bites and sideways threats. This effect was behaviorally specific because non-aggressive motor activities were not significantly altered by the drug. In the IL vmPFC or in an area lateral to the VO PFC, CP-94,253 (1.0 microg/0.2 microl) did not have significant behavioral effects.

CONCLUSIONS

The results highlight the 5-HT(1B) receptors in the VO PFC as a particularly important site for the inhibition of species-typical aggressive behavior in male mice.

Agonist and inverse agonist efficacy at human recombinant serotonin 5-HT1A receptors as a function of receptor:G-protein stoichiometry

Membrane preparations were made from Chinese Hamster Ovary (CHO) cells expressing 1.6 and 4.2 pmol/mg of recombinant human 5-HT1A receptors, as determined by saturation binding with the selective antagonist, [3H]-S 15535 ([3H]-4-(benzodioxan-5-yl)]-(indan-2-yl)piperazine). There was no change in the number of G-proteins activated by the full agonist, serotonin (5-HT; approximately 1.1 pmol/mg in each preparation, measured by [35S]-GTP gamma S saturation binding), therefore increasing the receptor:G-protein ratio from approximately 1.4:1 (RGlow) to approximately 4:1 (RGhigh). Agonist efficacy was measured by stimulation of [35S]-GTP gamma S binding. The serotonergic agonist, eltoprazine, behaved as a partial agonist (Emax = 52.7%) at RGlow membranes but virtually as a full agonist (Emax = 93.2%) at RGhigh membranes, relative to 5-HT (= 100%). The latter exhibited a two-fold shift to the left in its concentration-response curve in RGhigh compared to RGlow membranes (P < 0.01). WAY 100,635 (N-¿2-[4-(2-methoxyphenyl)-1-piperazinyl]ethyl¿-N-(2-pyridinyl) -cyclo-hexane-carboxamide), did not alter [35S]-GTP gamma S binding from basal levels in either membrane preparation. In contrast, spiperone displayed inverse agonist activity, decreasing [35S]-GTP gamma S binding from basal levels by 17% in RGlow membranes but by 28% in RGhigh membranes. These data indicate that an increased receptor:G-protein ratio (i) augments the potency of full agonists, (ii) increases the efficacy of partial agonists and (iii) increases the negative efficacy of inverse agonists at recombinant human 5-HT1A receptors. Furthermore, these data suggest that spiperone induces, or stabilises, a G-protein-coupled, but inactive conformation of the receptor.

Chronic treatment with eltoprazine does not lead to tolerance in its anti-aggressive action, in contrast to haloperidol

The behavioral effects of eltoprazine and haloperidol during a 4 week treatment period were studied in the resident-intruder model of aggression in male rats. Eltoprazine, a serotonergic (5-HT1A/1B) agonist with specific anti-aggressive actions in animals, was compared to haloperidol, a neuroleptic often used to control behavioral disorders. Eltoprazine (1 or 3 mg/kg p.o.) and haloperidol (2 mg/kg p.o.) were given 60 min before a 10 min aggression test. Acutely, eltoprazine reduced aggression, without adversely affecting other behaviors. Eltoprazine (1 or 3 mg/kg p.o.) was subsequently given daily for 4 weeks and aggression tests were performed each week. The anti-aggressive effects of eltoprazine remained stable over the period of 4 weeks whereas exploration was increased. After a wash-out period of 1 week aggression had returned to baseline levels. Acutely given, haloperidol (2 mg/kg p.o.) completely reduced aggression concomitant with massive sedation. Significant tolerance developed to the sedatory actions of haloperidol over the 4 week treatment period. Aggression returned slowly, but remained below baseline values. One week after wash-out a new challenge with haloperidol (2 mg/kg p.o.) revealed significant tolerance. After 2 weeks wash-out aggression had returned to baseline. The data demonstrate persistent and specific anti-aggressive effects after eltoprazine showing no tolerance. In contrast, haloperidol showed tolerance and rebound effects for aggression. The development of tolerance after haloperidol has a different course for sedation than for the anti-aggressive action.

Chronic mianserin or eltoprazine treatment in rats: effects on the elevated plus-maze test and on limbic 5-HT2C receptor levels

Rats were chronically treated with mianserin (10 mg/kg i.p.) or eltoprazine (1 mg/kg i.p.) and were tested in the elevated plus-maze test for anxiety. 5-HT2C (previously 5-HT1C, see Humphrey et al., 1993, Trends Pharmacol. Sci. 14, 223) binding sites and their mRNA were evaluated in limbic structures (i.e., amygdala, hippocampus, septum) of a sample of these rats by autoradiographic binding studies and in situ hybridization histochemistry. Mianserin and eltoprazine displayed opposite effects in the elevated plus-maze: mianserin induced anxiolytic-like effects, while eltoprazine showed anxiogenic-like ones. Within the amygdala, but not in other structures, the quantitative autoradiographic analysis of the 5-HT2C binding sites showed a differential effect: mianserin treatment induced a decrease in the number of these sites, while eltoprazine treatment resulted in an increase. In spite of this, neither mianserin- nor eltoprazine-treated rats displayed an alteration in the 5-HT2C receptor mRNA levels in the brain regions examined. Our results are suggestive of a relation between anxiolytic/anxiogenic-like effects and the level of 5-HT2C binding sites in the amygdala.

The effects of dorsal raphe administration of eltoprazine, TFMPP and 8-OH-DPAT on resident intruder aggression in the rat

To evaluate the role of somatodendritic 5-HT1A receptors in the mediation of aggressive behaviour, eltoprazine, TFMPP (1-(3-trifluoromethylphenyl)piperazine hydrochloride) and 8-OH-DPAT (8-hydroxy-2-(di-n-propylamino)tetralin) were administered locally into the dorsal raphe nucleus of rats. 8-OH-DPAT (1 and 10 micrograms) and eltoprazine (10 and 30 micrograms) reduced aggression, but concomitantly reduced social interest and increased inactivity. TFMPP (1 and 10 micrograms) did not reduce aggression. As 8-OH-DPAT and to a lesser extent eltoprazine affect 5-HT1A receptors, it is proposed that a general reduction of serotonergic neurotransmission by activation of somatodendritic serotonergic autoreceptor leads to a non-specific reduction of aggression. As TFMPP has a significantly lower affinity for 5-HT1A receptors than 8-OH-DPAT or eltoprazine, the lack of effect of TFMPP supports this view.

Dealing with sadness, madness and hostility. New psychotropic drug remedies for the future

The objective of this article is to present an overview of new forms of psychotropic drug therapy that may be expected to play a role in psychiatric practice in the 1990s. In predicting these future developments, three lines of approach have been followed. Firstly, progress in elucidating basic neuronal mechanisms is described. The radioligand receptor binding technique has proved to be an especially powerful tool in the search for novel psychoactive compounds. Secondly, those mental health problems most likely to undergo intensive study are discussed. It is likely that special attention will be devoted to organic mental disorders related to aging (dementia) or chronic exposure to toxic substances. In addition, research will be aimed at explaining and reducing the occurrence of auto-aggressive and hetero-aggressive behaviour. Thirdly, the types of newly designed agents and treatment strategies currently under investigation are outlined. In particular, the development of pharmacological agents that interfere with serotonergic molecular mechanisms has opened the way to improving existing psychotropic drugs, to inventing drugs that achieve known clinical effects via different mechanisms of action, and even to discovering entirely new categories of psychotropic drugs.

Effects of the 5-HT uptake inhibitors, femoxetine and paroxetine, and a 5-HT1A/B agonist, eltoprazine, on the behavioural satiety sequence

In rats allowed access to a 35% sucrose solution, following a 4-h period of food and water deprivation, an initial period of sucrose consumption was followed by a short period of grooming and exploratory behaviour, later superseded by resting. This "behavioural satiety sequence" was advanced in time by the 5-HT uptake inhibitors femoxetine and paroxetine and by the 5-HT1A/B agonist eltoprazine at anorectic and subanorectic doses. These effects, which are similar to those previously observed with another 5-HT uptake inhibitor, fluoxetine, are compatible with an increase in postprandial satiety.

The effects of intraventricular administration of eltoprazine, 1-(3-trifluoromethylphenyl)piperazine hydrochloride and 8-hydroxy-2-(di-n-propylamino)tetralin on resident intruder aggression in the rat

Various serotonergic agents may reduce aggression in rats, but how they act in different parts of the brain is unknown. This study attempted to unravel part of this question by application of different serotonergic ligands into the lateral ventricle (i.c.v.) of male rats (resident-intruder aggression). 8-OH-DPAT (8-hydroxy-2-(di-n-propylamino)tetralin; 1 and 10 micrograms), a specific 5-HT1A agonist, affected neither aggression nor any other behaviour. The mixed 5-HT1A,B,C agonist, TFMPP (1-(3-trifluoromethylphenyl)piperazine hydrochloride), and the 5-HT1A/1B agonist, eltoprazine ((1-(2,3)-dihydro-1,4-benzodioxin-5-yl)piperazine hydrochloride), suppressed aggression at i.c.v. doses of 10 and 30 micrograms. This reduction was not caused by sedation. These data suggest a role of postsynaptic 5-HT1B receptors in mediating the anti-aggressive effects of mixed 5-HT1 agonists.

Dose-proportionality of eltoprazine. Pharmacokinetics of single oral doses in healthy subjects

Eltoprazine. HCl belongs to a new class of psychotropic drug, the serenics. The dose-proportionality and pharmacokinetics of eltoprazine HCl has been investigated after single oral doses of 5, 10, 20 mg (18 subjects) and 30 mg (12 subjects) in a partly randomized, cross-over design. Eltoprazine was well tolerated and there were no relevant changes in safety parameters. All subjects showed irregular plasma-concentration-time profiles, some subjects demonstrating secondary peaks. The mean half-life was calculated to be about 6.5 h. The renal excretion of eltoprazine was characterized by net tubular secretion. AUC, peak plasma concentrations and the amount excreted unchanged in the urine were linearly related to the dose. Renal clearance and t1/2 were independent of dose. Thus, eltoprazine HCl was well tolerated orally and exhibited a linear pharmacokinetic profile.

Postsynaptic 5-HT1 receptors and offensive aggression in rats: a combined behavioural and autoradiographic study with eltoprazine

The present study was designed to assess whether the antiaggressive effects of eltoprazine are mediated via presynaptic and/or postsynaptic 5-HT1 receptors. We describe the effects of central 5-HT depletion 1) on the behaviour of resident TMD-S3 rats in a territorial situation, 2) on the efficacy of eltoprazine to inhibit offensive aggression, and 3) on the 5-HT1A, 5-HT1B and 5-HT1C receptor binding in brains of rats previously used in behavioural studies. Male resident rats were given combined 5,7-dihydroxytryptamine (5,7-DHT) injections into the dorsal and median raphe nuclei. Two to four weeks after the lesions, rats were confronted with an intruder Wiser rat in their home cage for a 10-min period. The 5,7-DHT treatment resulted in a modest reduction of offensive behaviour, while having no effects on other social and nonsocial behaviours. Oral administration of eltoprazine (1 mg/kg) specifically reduced offensive aggression in both sham- and 5,7-DHT-lesioned animals, leaving social interest and exploration intact or even increasing it. A low dose (0.3 mg/kg) of eltoprazine did not affect the behavioural repertoire of sham-operated rats, whereas this dose significantly reduced offense behaviours in the 5,7-DHT-lesioned residents. Quantitative autoradiographic studies 5 weeks after 5,7-DHT treatment revealed a significant increase in radioligand binding to 5-HT1A, 5-HT1B and 5-HT1C sites in many brain regions studied, except for the raphe nuclei where [3H]8-OH-DPAT binding to 5-HT1A sites was markedly reduced. The concentrations of 5-HT and 5-HIAA in frontal cortex were reduced to approximately 10% of controls. The results indicate that serotonin has a stimulatory rather than an inhibitory influence on offensive aggressive behaviour. Central 5-HT depletion does not prevent the antiaggressive effects of eltoprazine, indicating a role for postsynaptic 5-HT1 receptors in the modulation of offensive aggression. The 5,7-DHT-induced overall upregulation of 5-HT1A, 5-HT1B and 5-HT1C binding sites suggests that these three receptor subtypes receive a tonic serotonergic influence. It is conceivable that this postsynaptic 5-HT1 receptor supersensitivity is reflected by the increased efficacy of eltoprazine to inhibit offensive aggression.