Aggression and anxiety: social context and neurobiological links.
TL;DR: Differences in the activity of the hypothalamic–pituitary–adrenal axis, brain arginine vasopressin, and the serotonin systems, among others, which contribute to the distinct behavioural phenotypes related to aggression and anxiety are discussed.
Abstract: Psychopathologies such as anxiety- and depression-related disorders are often characterized by impaired social behaviours including excessive aggression and violence. Excessive aggression and violence likely develop as a consequence of generally disturbed emotional regulation, such as abnormally high or low levels of anxiety. This suggests an overlap between brain circuitries and neurochemical systems regulating aggression and anxiety. In this review, we will discuss different forms of male aggression, rodent models of excessive aggression, and neurobiological mechanisms underlying male aggression in the context of anxiety. We will summarize our attempts to establish an animal model of high and abnormal aggression using rats selected for high (HAB) vs. low (LAB) anxiety-related behaviour. Briefly, male LAB rats and, to a lesser extent, male HAB rats show high and abnormal forms of aggression compared with non-selected (NAB) rats, making them a suitable animal model for studying excessive aggression in the context of extremes in innate anxiety. In addition, we will discuss differences in the activity of the hypothalamic-pituitary-adrenal axis, brain arginine vasopressin, and the serotonin systems, among others, which contribute to the distinct behavioural phenotypes related to aggression and anxiety. Further investigation of the neurobiological systems in animals with distinct anxiety phenotypes might provide valuable information about the link between excessive aggression and disturbed emotional regulation, which is essential for understanding the social and emotional deficits that are characteristic of many human psychiatric disorders.
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TL;DR: Shifting the balance between the neuropeptide systems towards oxytocin, by positive social stimuli and/or psychopharmacotherapy, may help to improve emotional behaviors and reinstate mental health.
764 citations
TL;DR: The mechanisms of OXT expression and release, expression and binding of the OXTR in brain and periphery, OX TR-coupled signaling cascades, and their involvement in behavioral outcomes are discussed to assemble a comprehensive picture of the central and peripheral OXT system.
Abstract: The many facets of the oxytocin (OXT) system of the brain and periphery elicited nearly 25,000 publications since 1930 (see FIGURE 1, as listed in PubMed), which revealed central roles for OXT and ...
510 citations
TL;DR: The status of peptide and non-peptide agonists and antagonists for the V1a, V1b and V2 receptors for arginine vasopressin (AVP) and the O2 receptor for oxytocin (OT) was reviewed in this paper.
Abstract: We recently reviewed the status of peptide and nonpeptide agonists and antagonists for the V1a, V1b and V2 receptors for arginine vasopressin (AVP) and the oxytocin receptor for oxytocin (OT). In the present review, we update the status of peptides and nonpeptides as: (i) research tools and (ii) therapeutic agents. We also present our recent findings on the design of fluorescent ligands for V1b receptor localisation and for OT receptor dimerisation. We note the exciting discoveries regarding two novel naturally occurring analogues of OT. Recent reports of a selective VP V1a agonist and a selective OT agonist point to the continued therapeutic potential of peptides in this field. To date, only two nonpeptides, the V2/V1a antagonist, conivaptan and the V2 antagonist tolvaptan have received Food and Drug Administration approval for clinical use. The development of nonpeptide AVP V1a, V1b and V2 antagonists and OT agonists and antagonists has recently been abandoned by Merck, Sanofi and Pfizer. A promising OT antagonist, Retosiban, developed at Glaxo SmithKline is currently in a Phase II clinical trial for the prevention of premature labour. A number of the nonpeptide ligands that were not successful in clinical trials are proving to be valuable as research tools. Peptide agonists and antagonists continue to be very widely used as research tools in this field. In this regard, we present receptor data on some of the most widely used peptide and nonpeptide ligands, as a guide for their use, especially with regard to receptor selectivity and species differences.
367 citations
TL;DR: The functional role of the brain oxytocin and vasopressin system in the context of maternal behavior, specifically maternal care and maternal aggression in rodents is discussed.
348 citations
TL;DR: The data indicate that the basal activity of the endogenous brain OT system is sufficient to promote natural occurring social preference in rodents while synthetic OT shows potential to reverse stress-induced social avoidance and might thus be of use for treating social phobia and social dysfunction in humans.
347 citations
Cites methods from "Aggression and anxiety: social cont..."
...For social defeat, male rats selectively bred for low anxiety-related behavior (LAB) which show a reliable high level of inter-male aggression (Beiderbeck et al, 2007; Neumann et al, 2010), were used as residents....
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References
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TL;DR: The prevalence of psychiatric disorders is greater than previously thought to be the case, and morbidity is more highly concentrated than previously recognized in roughly one sixth of the population who have a history of three or more comorbid disorders.
Abstract: Background: This study presents estimates of lifetime and 12-month prevalence of 14 DSM-III-R psychiatric disorders from the National Comorbidity Survey, the first survey to administer a structured psychiatric interview to a national probability sample in the United States. Methods: The DSM-III-R psychiatric disorders among persons aged 15 to 54 years in the noninstitutionalized civilian population of the United States were assessed with data collected by lay interviewers using a revised version of the Composite International Diagnostic Interview. Results: Nearly 50% of respondents reported at least one lifetime disorder, and close to 30% reported at least one 12-month disorder. The most common disorders were major depressive episode, alcohol dependence, social phobia, and simple phobia. More than half of all lifetime disorders occurred in the 14% of the population who had a history of three or more comorbid disorders. These highly comorbid people also included the vast majority of people with severe disorders. Less than 40% of those with a lifetime disorder had ever received professional treatment, and less than 20% of those with a recent disorder had been in treatment during the past 12 months. Consistent with previous risk factor research, it was found that women had elevated rates of affective disorders and anxiety disorders, that men had elevated rates of substance use disorders and antisocial personality disorder, and that most disorders declined with age and with higher socioeconomic status. Conclusions: The prevalence of psychiatric disorders is greater than previously thought to be the case. Furthermore, this morbidity is more highly concentrated than previously recognized in roughly one sixth of the population who have a history of three or more comorbid disorders. This suggests that the causes and consequences of high comorbidity should be the focus of research attention. The majority of people with psychiatric disorders fail to obtain professional treatment. Even among people with a lifetime history of three or more comorbid disorders, the proportion who ever obtain specialty sector mental health treatment is less than 50%. These results argue for the importance of more outreach and more research on barriers to professional help-seeking.
11,648 citations
"Aggression and anxiety: social cont..." refers background in this paper
...The lifetime prevalence of anxiety disorders, like panic disorder or general anxiety disorder, is about 17% (Somers et al., 2006) with social anxiety disorder, like social phobia, being the most common one (Kessler et al., 1994)....
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TL;DR: It is shown that an epigenomic state of a gene can be established through behavioral programming, and it is potentially reversible, suggesting a causal relation among epigenomicState, GR expression and the maternal effect on stress responses in the offspring.
Abstract: Here we report that increased pup licking and grooming (LG) and arched-back nursing (ABN) by rat mothers altered the offspring epigenome at a glucocorticoid receptor (GR) gene promoter in the hippocampus. Offspring of mothers that showed high levels of LG and ABN were found to have differences in DNA methylation, as compared to offspring of 'low-LG-ABN' mothers. These differences emerged over the first week of life, were reversed with cross-fostering, persisted into adulthood and were associated with altered histone acetylation and transcription factor (NGFI-A) binding to the GR promoter. Central infusion of a histone deacetylase inhibitor removed the group differences in histone acetylation, DNA methylation, NGFI-A binding, GR expression and hypothalamic-pituitary-adrenal (HPA) responses to stress, suggesting a causal relation among epigenomic state, GR expression and the maternal effect on stress responses in the offspring. Thus we show that an epigenomic state of a gene can be established through behavioral programming, and it is potentially reversible.
5,514 citations
TL;DR: A novel test for the selective identification of anxiolytic and anxiogenic drug effects in the rat is described, using an elevated + -maze consisting of two open arms and two enclosed arms, which showed that behaviour on the maze was not clearly correlated either with exploratory head-dipping or spontaneous locomotor activity.
5,391 citations
"Aggression and anxiety: social cont..." refers background in this paper
...A high level of anxiety is expressed by avoidance of these aversive zones, i.e. the open, bright or unprotected compartments/arms of the test apparatus, which can be validated with established anxiolytic as well as anxiogenic substances (Pellow et al., 1985)....
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...the open, bright or unprotected compartments/arms of the test apparatus, which can be validated with established anxiolytic as well as anxiogenic substances (Pellow et al., 1985)....
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TL;DR: The short variant of the polymorphism reduces the transcriptional efficiency of the 5-HTT gene promoter, resulting in decreased 5HTT expression and 5HT uptake in lymphoblasts as discussed by the authors, which is the site of action of widely used uptake-inhibiting antidepressant and antianxiety drugs.
Abstract: Transporter-facilitated uptake of serotonin (5-hydroxytryptamine or 5-HT) has been implicated in anxiety in humans and animal models and is the site of action of widely used uptake-inhibiting antidepressant and antianxiety drugs. Human 5-HT transporter (5-HTT) gene transcription is modulated by a common polymorphism in its upstream regulatory region. The short variant of the polymorphism reduces the transcriptional efficiency of the 5-HTT gene promoter, resulting in decreased 5-HTT expression and 5-HT uptake in lymphoblasts. Association studies in two independent samples totaling 505 individuals revealed that the 5-HTT polymorphism accounts for 3 to 4 percent of total variation and 7 to 9 percent of inherited variance in anxiety-related personality traits in individuals as well as sibships.
5,072 citations
"Aggression and anxiety: social cont..." refers background in this paper
...Furthermore, variations in the 5-HT reuptake transporter gene are known to infl uence emotional and social behaviours (Lesch et al., 1996, 1997)....
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TL;DR: In response to stress, the brain activates several neuropeptide-secreting systems, which eventually leads to the release of adrenal corticosteroid hormones, which subsequently feed back on the brain and bind to two types of nuclear receptor that act as transcriptional regulators as mentioned in this paper.
Abstract: In response to stress, the brain activates several neuropeptide-secreting systems. This eventually leads to the release of adrenal corticosteroid hormones, which subsequently feed back on the brain and bind to two types of nuclear receptor that act as transcriptional regulators. By targeting many genes, corticosteroids function in a binary fashion, and serve as a master switch in the control of neuronal and network responses that underlie behavioural adaptation. In genetically predisposed individuals, an imbalance in this binary control mechanism can introduce a bias towards stress-related brain disease after adverse experiences. New candidate susceptibility genes that serve as markers for the prediction of vulnerable phenotypes are now being identified.
3,727 citations