Neuroendocrine response to meta-chlorophenylpiperazine and ipsapirone in relation to anxiety and aggression

Anxiolytic-like effects of extremely low frequency electric field in stressed rats: involvement of 5-HT2C receptors

BACKGROUND

Possible modulatory effects of noninvasive brain stimulation have gained interest recently. In our study, the effect of low frequency electric fields (LF-EF) on stress-induced electrophysiological, behavioral changes and the possible involvement of serotonergic 5-HT2C receptors were investigated.

MATERIALS AND METHODS

A total of eight groups including the control groups were formed by applying LF-EF with or without a 5-HT2C receptor agonist to naïve or acute stress exposed rats to demonstrate the effects of LF-EF. LF-EF administration at 10 kV/m was started 30 min before acute stress application and lasted for 1 h in total. Anxiety levels and social interaction were evaluated using the elevated plus maze test and social interaction test, respectively. Auditory evoked potentials (AEP) were recorded by using ascending loudness paradigms. Loudness dependence AEP (LDAEP) was calculated by using amplitude values to analyze serotonergic transmission. Serotonin and glucocorticoid levels were measured in the frontal cortex and hippocampus.

RESULTS

It was observed that the applied LF-EF reduced the anxiety behavior, and attenuated the LDAEP responses in stress and/or 5-HT2C receptor agonist applied groups. In parallel, an increase in serotonin levels and a decrease in glucocorticoid levels were observed. However, LF-EF exposure was ineffective in impaired social interaction.

CONCLUSIONS

Our findings show that 10 kV/m LF-EF administration may modulate the neural network and physiological responses associated with mild acute stress. 5-HT2C receptor dependent functions are thought to play a role in the anxiolytic effect of LF-EF.

Azapirones versus placebo for panic disorder in adults

BACKGROUND

Panic disorder is common in the general population. It is often associated with other psychiatric disorders, such as drug dependence, major depression, bipolar disorder, social phobia, specific phobia and generalised anxiety disorder. Azapirones are a class of drugs used as anxiolytics. They are associated with less drowsiness, psychomotor impairment, alcohol potentiation and potential for addiction or abuse than benzodiazepines. However, azapirones are not widely used in the treatment of panic disorder and evidence for their efficacy is unclear. It is important to find out if azapirones are effective and acceptable in the treatment of panic disorder.

OBJECTIVES

To assess the effects of azapirones on panic disorder in adults, specifically:1. to determine the efficacy of azapirones in alleviating symptoms of panic disorder, with or without agoraphobia, in comparison with placebo;2. to review the acceptability of azapirones in panic disorder, with or without agoraphobia, in comparison with placebo; and3. to investigate adverse effects of azapirones in panic disorder with or without agoraphobia, including general prevalence of adverse effects, compared with placebo.

SEARCH METHODS

We searched the Cochrane Depression Anxiety and Neurosis Group Trials Specialised Register (CCDANCTR, search date: 10th January 2014), which includes relevant randomised controlled trials from The Cochrane Library (all years), MEDLINE (1950-), EMBASE (1974-), and PsycINFO (1967-).

SELECTION CRITERIA

Randomised controlled trials that compared azapirones with placebo for panic disorder in adults.

DATA COLLECTION AND ANALYSIS

Three review authors independently identified studies, assessed trial quality and extracted data. We contacted study authors for additional information.

MAIN RESULTS

Three studies involving 170 participants compared the azapirone buspirone with placebo. No study provided enough usable information on our primary efficacy outcome (response). For our primary acceptability outcome, moderate-quality evidence indicated that azapirones had lower acceptability than placebo: risk ratio (RR) for dropouts for any reason 2.13 (95% confidence interval (CI) 1.11 to 4.07; 3 studies, 170 participants. Evidence for secondary efficacy outcomes were of low quality. Results on efficacy between azapirone and placebo in terms of agoraphobia (standardised mean difference (SMD) -0.01, 95% CI -0.56 to 0.53; 1 study, 52 participants), general anxiety (mean difference (MD) -2.20, 95% CI -5.45 to 1.06; 2 studies, 115 participants) and depression (MD -1.80, 95% CI -5.60 to 2.00; 1 study, 52 participants) were uncertain. None of the studies provided information for the assessment of allocation concealment or sequence generation. Conflicts of interest were not explicitly expressed. The risk of attrition bias was rated high for all three studies. Information on adverse effects other than dropouts for any reason was insufficient to include in the analyses.

AUTHORS' CONCLUSIONS

The efficacy of azapirones is uncertain due to the lack of meta-analysable data for the primary outcome and low-quality evidence for secondary efficacy outcomes. A small amount of moderate-quality evidence suggested that the acceptability of azapirones for panic disorder was lower than for placebo. However, only trials of one azapirone (namely buspirone) were included in this review; this, combined with the small sample size, limits our conclusions. If further research is to be conducted, studies with larger sample sizes, with different azapirones and with less risk of bias are necessary to draw firm conclusions regarding azapirones for panic disorder.

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.

RNA splicing and editing modulation of 5-HT(2C) receptor function: relevance to anxiety and aggression in VGV mice

Changes in serotonin(2C) receptor (5-HTR2c) editing, splicing and density were found in conditions such as depression and suicide, but mechanisms explaining the changes in 5-HTR2c function are unknown. Thus, mice expressing only the fully edited VGV isoform of 5-HTR2c, in which clinically relevant behavioral changes are associated with alterations in splicing and receptor density, were studied. VGV mice displayed enhanced anxiety-like behavior in response to a preferential 5-HTR2c agonist in the social interaction test. Nearly half of interactions between pairs of VGV congeners consisted of fighting behaviors, whereas no fighting occurred in wild-type (WT) mice. VGV mice also exhibited a striking increase in freezing behaviors in reaction to an innately aversive ultrasonic stimulus. This behavioral phenotype occurred in conjunction with decreased brain 5-HT turnover during stress. These functional data were put in relation with the 5-HTR2c mRNA splicing process generating a truncated protein (5-HTR2c-Tr) in addition to the full-length receptor (5-HTR2c-Fl). 5-HTR2c-Tr mRNA was less abundant in many brain regions of VGV mice, which concomitantly had more 5-HTR2c than WT mice. Fluorescence resonance energy transfer and bioluminescence resonance energy transfer studies in transfected living HEK293T cells showed that 5-HTR2c-Tr interacts with 5-HTR2c-Fl. The 5-HTR2c-Tr was localized in the endoplasmic reticulum where it retained 5-HTR2c-Fl, preventing the latter to reach the plasma membrane. Consequently, 5-HTR2c-Tr decreased (3)H-mesulergine binding to 5-HTR2c-Fl at the plasma membrane in a concentration-dependent manner and more strongly with edited 5-HTR2c-Fl. These results suggest that 5-HTR2c pre-mRNA editing and splicing are entwined processes determining increased 5-HTR2c levels in pathological conditions through a deficit in 5-HTR2c-Tr.

Effects of sub-chronic nandrolone administration on hormonal adaptive response to acute stress in rats

Androgenic-anabolic steroid (AAS) misuse has been associated with depression. It has been proposed that stress has a role in depression and that serotonin is involved in both endocrine responses to stress and depressive physiopathology. Although reports demonstrate that AAS chronic administration modifies components of stress-responsive hypothalamic-pituitary-adrenal axis (HPAA), no study has evaluated AAS effect on the response to stressful stimuli. We studied the effects of the subchronic administration (once a day for 14 days in rats) of a supratherapeutical dose of nandrolone decanoate (ND) on HPAA and cortical serotoninergic system response to acute restraint stress (RS). Acute RS produced the following effects: increase in CORT (in blood) and ACTH (both in blood and in pituitary corticotropes), GR depletion in hippocampus and hypothalamus cytosol and GR translocation in hippocampus nuclear fraction, cortical serotonin re-uptake stimulation and hippocampus cytosolic ERK2 activation. ND by itself, i.e. in non-stressed rats, did not modify these parameters, except for a decrease of plasma CORT and ACTH levels and an increase in hippocampus cytosolic phospho-ERK1/2. On the contrary, in stressed rats ND affected stress-induced plasma ACTH increase and prevented all other above reported stress effects, except the increase in pituitary ACTH positive cell density. Our results show that the prolonged administration of a supratherapeutical dose of ND in rats, albeit did not affect in a notable way HPAA and serotonin transporter activity in the absence of stress, may deregulate the stress-induced hormonal cascade which plays a crucial role in depressive psychopathology.

Piperazine compounds as drugs of abuse

Synthetic drugs are among the most commonly abused drugs in the world. This abuse is widespread among young people, especially in the dance club and rave scenes. Over the last several years, piperazine derived drugs have appeared, mainly available via the internet, and sold as ecstasy pills or under the names of "Frenzy", "Bliss", "Charge", "Herbal ecstasy", "A2", "Legal X" and "Legal E". Although in the market piperazine designer drugs have the reputation of being safe, several experimental and epidemiological studies indicate risks for humans. Piperazine designer drugs can be divided into two classes, the benzylpiperazines such as N-benzylpiperazine (BZP) and its methylenedioxy analogue 1-(3,4-methylenedioxybenzyl)piperazine (MDBP), and the phenylpiperazines such as 1-(3-chlorophenyl)piperazine (mCPP), 1-(3-trifluoromethylphenyl)piperazine (TFMPP), and 1-(4-methoxyphenyl)piperazine (MeOPP). Toxicokinetic properties, including metabolic pathways, actions and effects in animals and humans, with some hypothesis of mechanism of action, and analytical approaches for the identification of these drugs are summarized in this review.

Cortisol responses to ipsapirone challenge correlate with aggression, while basal cortisol levels correlate with impulsivity, in personality disorder and healthy volunteer subjects

BACKGROUND

This study was performed to test the hypothesis that 5-HT-1a receptors, as assessed by the cortisol (post-synaptic) and temperature (pre-synaptic) responses to the 5-HT-1a agonist, Ipsapirone (IPSAP), play a role in the regulation of impulsive aggressive behavior in human subjects.

METHODS

Fifty-two healthy subjects (28 with Personality Disorder: PD; 24 Healthy Volunteers: HV) underwent acute challenge with the selective 5-HT-1a agonist, ipsaprione (IPSAP: .3 mg/kg po). Residual Peak Delta Cortisol (ΔCORT[IPSAP]-R; after removal of Basal CORT and IPSAP plasma levels) was used as the primary 5-HT-1a post-synaptic receptor variable. Residual Nadir Delta Temperature (ΔTEMP[IPSAP]-R; after removal of Basal TEMP) was used as the primary 5-HT-1a somatodendritic (pre-synaptic) receptor variable. Measures of trait aggression included the Aggression scales of the Buss-Durkee Hostility Inventory (BDHI) and the Life History of Aggression (LHA); trait impulsivity was assessed with the Impulsivity scale of the Eysenck Personality Questionnaire (EPQ-II).

RESULTS

Correlations between ΔCORT[IPSAP]-R responses and BDHI Aggression scores varied by group. Specifically, BDHI Aggression correlated inversely with ΔCORT[IPSAP]-R values in PD subjects but directly in HV subjects. While EPQ-II Impulsivity did not correlate with ΔCORT[IPSAP]-R responses, this measure of impulsivity correlated directly with Basal CORT levels in all subjects. ΔTEMP[IPSAP]-R responses did not correlate with measures of trait aggression or trait impulsivity.

CONCLUSION

Physiologic responses of 5-HT-1a post-synaptic receptors may be reduced as a function of trait aggression, but not impulsivity, in PD subjects. In contrast, pre-synaptic 5-HT-1a receptors may not play a role in the regulation of aggression or impulsivity in human subjects.

The response of neurons in the bed nucleus of the stria terminalis to serotonin: implications for anxiety

Substantial evidence has suggested that the activity of the bed nucleus of the stria terminalis (BNST) mediates many forms of anxiety-like behavior in human and non-human animals. These data have led many investigators to suggest that abnormal processing within this nucleus may underlie anxiety disorders in humans, and effective anxiety treatments may restore normal BNST functioning. Currently some of the most effective treatments for anxiety disorders are drugs that modulate serotonin (5-HT) systems, and several decades of research have suggested that the activation of 5-HT can modulate anxiety-like behavior. Despite these facts, relatively few studies have examined how activity within the BNST is modulated by 5-HT. Here we review our own investigations using in vitro whole-cell patch-clamp electrophysiological methods on brain sections containing the BNST to determine the response of BNST neurons to exogenous 5-HT application. Our data suggest that the response of BNST neurons to 5-HT is complex, displaying both inhibitory and excitatory components, which are mediated by 5-HT(1A), 5-HT(2A), 5-HT(2C) and 5-HT(7) receptors. Moreover, we have shown that the selective activation of the inhibitory response to 5-HT reduces anxiety-like behavior, and we describe data suggesting that the activation of the excitatory response to 5-HT may be anxiogenic. We propose that in the normal state, the function of 5-HT is to dampen activity within the BNST (and consequent anxiety-like behavior) during exposure to threatening stimuli; however, we suggest that changes in the balance of the function of BNST 5-HT receptor subtypes could alter the response of BNST neurons to favor excitation and produce a pathological state of increased anxiety.

Serotonin genes and gene-gene interactions in borderline personality disorder in a matched case-control study

Lines of evidence suggest serotonin genes are susceptibility candidates in borderline personality disorder (BPD). However, few molecular genetic studies on BPD have been reported, especially an overall lack of study on epistatic interactions. We genotyped 27 polymorphisms in 7 serotonin genes in 113 Caucasian BPD patients and matched (sex, age and ethnicity) controls. Program UNPHASED was used to perform association analyses for genotypes, alleles and haplotypes with a permutation test of 10,000 simulations. The Multifactor Dimensionality Reduction analysis was used to examine gene-gene interactions in serotonin system, including three other genes (5-HTT, 5-HT2A and MAOA) that we previously reported. Genotype and allele analyses showed that BPD significantly associated with 5-HT2C and TPH2. BPD patients had high frequencies of the 5-HT2C rs6318G allele (p=0.021) and G/G genotype (OR=2.25); and TPH2 rs2171363T allele (p=0.001) and T containing genotypes (OR=3.40). The 5-HT1A, 5-HT1B, 5-HT1D, 5-HT3A and TPH1 showed no significant association with BPD for genotype, allele and haplotype analyses. We also detected significant interactions between 5-HT2C and TPH2 (p=0.001), and among 5-HT2C, 5-HTT, MAOA and TPH2 (p=0.001) in BPD. Patients with 5-HT2C rs6318G/G genotype had a high frequency of TPH2 rs2171363C/T genotype compared with controls. Our study indicates ""that serotonin genes and their interactions may play a role in the susceptibility to borderline personality disorder.

Corticosteroid-serotonin interactions in the neurobiological mechanisms of stress-related disorders

Among psychiatric disorders, depression and generalized anxiety are probably the most common stress-related illnesses. These diseases are underlain, at least partly, by dysfunctions of neurotransmitters and neurohormones, especially within the serotoninergic (5-HT) system and the hypothalamo-pituitary-adrenal (HPA) axis, which are also the targets of drugs used for their treatment. This review focuses on the nature of the interactions between central 5-HT and corticotrope systems in animal models, in particular those allowing the assessment of serotoninergic function following experimental manipulation of the HPA axis. The review provides an overview of the HPA axis and the 5-HT system organization, focusing on the 5-HT(1A) receptors, which play a pivotal role in the 5-HT system regulation and its response to stress. Both molecular and functional aspects of 5-HT/HPA interactions are then analyzed in the frame of psychoaffective disorders. The review finally examines the hippocampal neurogenesis response to experimental paradigms of stress and antidepressant treatment, in which neurotrophic factors are considered to play key roles according to the current views on the pathophysiology of depressive disorders.

HTR2C and HTR1A gene variants in German and Italian suicide attempters and completers

The serotonin 2C (HTR2C) and 1A (HTR1A) receptors have been involved in suicide-related behaviors. We studied gene variants of both receptors in suicide attempters and completers. The sample was composed of 167 German suicide attempters (affective spectrum n = 107, schizophrenia spectrum n = 35, borderline personality disorder n = 25), 92 Caucasian individuals who committed suicide, 312 German healthy subjects, 152 Italian suicide attempters (major depression n = 68 and bipolar disorder n = 84), and 131 Italian healthy volunteers. HTR2C (SNP: rs547536, rs2192372, rs6318, rs2428707, rs4272555, rs1801412) and HTR1A (SNP: rs1423691, rs878567, and rs6295) variants were analyzed in the German sample. HTR2C rs6318 and HTR1A rs6295 were analyzed in the Italian sample. Haplotype analysis in relation to suicidal behaviors did not reveal any significant association. Single markers and haplotypes were not or only marginally associated with other related features, such as violence of suicide attempt, family history for suicide attempt or State-Trait Anger Expression Inventory (STAXI) and Questionnaire for Measuring Factors of Aggression (FAF) scores. In conclusion, our study does not support the notion that HTR2C and HTR1A gene variants are major contributors to suicide-, anger-, or aggression-related behaviors in our sample.

Blunted hormone responses to Ipsapirone are associated with trait impulsivity in personality disorder patients

Impulsive aggression is associated with central serotonergic dysfunction. Animal models particularly implicate the 5-HT(1A) receptor in this behavior. We tested the hypothesis that central 5-HT(1A) receptor function is impaired in impulsive aggressive personality disorder patients. A total of 52 individuals with DSM-III-R personality disorders, all medically healthy adult outpatients without concurrent psychiatric medication treatment, underwent serial plasma cortisol, prolactin, and temperature measurements before and after ipsapirone 20 mg oral administration. Subjects completed self-report measures of impulsivity, hostility, depression and anxiety, and childhood maltreatment. Stepwise regression analysis revealed impulsivity alone among symptom measures to be associated with significantly decreased peak cortisol and prolactin responses. Diagnoses of borderline personality disorder (BPD) and intermittent explosive disorder-revised (IED-R) were associated with significantly increased and decreased cortisol responses, respectively. However, post hoc analyses indicated that impulsivity was significantly negatively correlated with cortisol responses in the BPD group, and may mediate the association of both BPD and IED-R with altered cortisol responses. Temperature response was associated with neither diagnostic nor symptom measures. Neither diagnostic nor dimensional measures of depression or anxiety, nor severity of childhood maltreatment, were significantly associated with cortisol, prolactin, or temperature responses. Impulsivity is related to impaired function at (or downstream to) postsynaptic 5-HT(1A) receptors, and this relationship may be partly responsible for the association of impaired serotonergic function with diagnoses such as BPD and IED-R. In addition, D(2) receptor dysfunction may play a role in impulsivity, whereas 5-HT(1A) cell-body autoreceptor function may be spared in these disorders.

The cognitive paradox in posttraumatic stress disorder: a hypothesis

Posttraumatic stress disorder (PTSD) is characterized by a peculiar cognitive state. The traumatic event(s) are partly hypermemorized, partly blurred, whereas the ability to store and retrieve new information is impaired. The question is raised as to what the biological systems might be that 'carry' this cognitive paradox. Four possible candidate systems are discussed. It is concluded that understimulation of the corticosteroid receptors, particularly the glucocorticoid receptors (GRs), overactivity of the noradrenaline (NA) and vasopressin (VA) systems, and deficits in the 5-Hydroxytryptamine (5-HT) system, particularly the 5-HT(1A) system, could generate a cognitive syndrome similar to the one observed in PTSD. A dual hypothesis is launched holding that (a) in PTSD, downregulation of the 5-HT(1A) receptor system is the primary lesion, while the other dysfunctions mentioned are subsidiaries and that (b) underdevelopment of or damage to the 5-HT(1A) receptor system will make a person PTSD-prone.

Chronic treatment with fluvoxamine desensitizes 5-HT2C receptor-mediated hypolocomotion in rats

The effectiveness of fluvoxamine, a selective serotonin re-uptake inhibitor (SSRI), in the treatment of anxiety disorders, such as obsessive-compulsive, panic and social anxiety disorders, has been confirmed in clinical studies. The hypersensitivity of 5-HT2C receptors has been reported in subjects with these disorders, and SSRIs have been suggested to have therapeutic effects in such cases through the desensitization of the 5-HT2C receptor function. In the present study, we investigated whether chronic administration of fluvoxamine desensitizes 5-HT2C receptors using a putative in vivo rat model of 5-HT2C receptor function. Acute treatment with fluvoxamine or another SSRI, paroxetine, reduced spontaneous locomotion, as observed with the administration of m-chlorophenylpiperazine (mCPP). This effect of fluvoxamine was reversed by treatment with a selective 5-HT2C receptor antagonist, SB 242084. On the other hand, chronic treatment with fluvoxamine or paroxetine inhibited mCPP-induced hypolocomotion, while they had no effects in control rats. In addition, chronic treatment with these drugs had no effects on the mCPP concentration in the rat brain. These results suggest that 5-HT2C receptors are desensitized by chronic treatment with fluvoxamine, as well as paroxetine. Thus, the clinical efficacy of fluvoxamine on anxiety disorders might involve the normalization of the 5-HT2C receptor function.