Regulation Of Aggressive Behavior Research Articles

Genetic Variability of <i>MAOA</i> Gene among Aggressive Animals from the Non-Canonical Behavioral Model <i>Neogale vison</i>

The MAOA gene is widely known regulator of aggressive behavior among human and animals. Here, we analyzed the genetic variability of the MAOA gene and its promoter region in non-canonical behavioral model – American mink (Neogale vison). We didn’t observe any significant genetic variations among animals with aggressive behavior, that suggests the presence of genetic and/or epigenetic variations in other systems involved in regulation of aggression in this model.

Serotonin and dopamine regulate the aggressiveness of swimming crabs (Portunus trituberculatus) in different ways

Bioamines act as a pivotal part in the regulation of aggressive behavior in animals as a type of neuroendocrine, but the patterns of how they regulate aggressiveness in crustaceans are still unclear due to species-specific responses. To determine the effects of serotonin (5-HT) and dopamine (DA) on the aggressiveness of swimming crabs (Portunus trituberculatus), we quantified their behavioral and physiological characteristics. The results showed that an injection of 5-HT at 0.5 mmol L−1 and 5 mmol L−1 could significantly enhance the aggressiveness of swimming crabs, as well as an injection of DA at 5 mmol L-1. The regulation of 5-HT and DA on aggressiveness is dose-dependent, and these two bioamines have different concentration thresholds that can trigger aggressiveness changes. 5-HT could up-regulate the 5-HTR1 gene expression and increase lactate content at the thoracic ganglion as the aggressiveness enhances, suggesting that 5-HT may activate related receptors and neuronal excitability to regulate aggressiveness. As a result of DA injection at 5 mmol L-1, lactate content in the chela muscle and hemolymph increased, glucose content in the hemolymph increased, and the CHH gene was significantly up-regulated. Pyruvate kinase and hexokinase enzyme activities in the hemolymph increased, which accelerated the glycolysis process. These results demonstrate that DA regulates the lactate cycle, which provides substantial short-term energy for aggressive behavior. Both 5-HT and DA can mediate aggressive behavior in the crab by activating calcium regulation in muscle tissue. We conclude that the enhancement of aggressiveness is a process of energy consumption, in which 5-HT acts on the central nervous system to induce aggressive behavior, and DA affects muscle and hepatopancreas tissue to provide a large amount of energy. This study expands upon the knowledge of regulatory mechanisms of aggressiveness in crustaceans and offers a theoretical foundation for enhancing crab culture management.

Identification and Characterization of 5-HT Receptor 1 from Scylla paramamosain: The Essential Roles of 5-HT and Its Receptor Gene during Aggressive Behavior in Crab Species.

Biogenic amines (BAs) play an important role in the aggressive behavior of crustaceans. In mammals and birds, 5-HT and its receptor genes (5-HTRs) are characterized as essential regulators involved in neural signaling pathways during aggressive behavior. However, only one 5-HTR transcript has been reported in crabs. In this study, the full-length cDNA of the 5-HTR1 gene, named Sp5-HTR1, was first isolated from the muscle of the mud crab Scylla paramamosain using the reverse-transcription polymerase chain reaction (RT-PCR) and rapid-amplification of cDNA ends (RACE) methods. The transcript encoded a peptide of 587 amino acid residues with a molecular mass of 63.36 kDa. Western blot results indicate that the 5-HTR1 protein was expressed at the highest level in the thoracic ganglion. Furthermore, the results of quantitative real-time PCR show that the expression levels of Sp5-HTR1 in the ganglion at 0.5, 1, 2, and 4 h after 5-HT injection were significantly upregulated compared with the control group (p < 0.05). Meanwhile, the behavioral changes in 5-HT-injected crabs were analyzed with EthoVision. After 0.5 h of injection, the speed and movement distance of the crab, the duration of aggressive behavior, and the intensity of aggressiveness in the low-5-HT-concentration injection group were significantly higher than those in the saline-injection and control groups (p < 0.05). In this study, we found that the Sp5-HTR1 gene plays a role in the regulation of aggressive behavior by BAs, including 5-HT in the mud crab. The results provide reference data for the analysis of the genetic mechanism of aggressive behaviors in crabs.

Studies of the engagement for serotonergic system in regulation of aggressive behavior in two behavioral models on rats

Studies of the engagement for serotonergic system in regulation of aggressive behavior in two behavioral models on rats

Identification of functional single nucleotide polymorphisms in the porcine SLC6A4 gene associated with aggressive behavior in weaned pigs after mixing.

Variation in genes of the serotonergic system influences aggressive behavior by affecting serotonin levels in the central and cortical nervous system. SLC6A4 (serotonin transporter) is a master regulator of 5-HT signaling and involved in the regulation of aggressive behavior in humans and rodents. To identify potential functional single nucleotide polymorphisms (SNPs) for the porcine SLC6A4 gene associated with aggressive behavior, a total of 500 pigs (268 barrows and 232 gilts) were selected and mixed in 51 pens. Their behavior was recorded and observed for 72 h after mixing. Based on a composite aggressive score (CAS), the most aggressive and the least aggressive pigs within each pen were selected separately (a total of 204 pigs). Ear tissue was sampled to extract genomic DNA. Eight SNPs in the 5'-flanking region, coding region, and 3'-untranslated region (3'-UTR) of SLC6A4 were genotyped, of which 6 SNPs had significant differences (P < 0.05) in allele frequency between the most aggressive and least aggressive pigs. Luciferase activity was greater in plasmids of genotype GG than plasmids of genotype CC of rs345058216 (P < 0.01). Computational analysis nominated MAZ as putative transcription factor (TF) with higher probability to bind the SLC6A4 promoter at the SNP (rs345058216) site. Also, we demonstrated that MAZ overexpression modulates SLC6A4 promoter activity in allele-specific manner with an in vitro assay. In addition, we demonstrated that SLC6A4 was a direct target of miR-671-5p. The dual luciferase reporter gene assay and cell transfection were performed to examine the role of miR-671-5p in regulating SLC6A4 expression. The luciferase assays revealed that the SNP rs332335871 affects regulation of miR-671-5p in SLC6A4 expression. After overexpression of miR-671-5p in porcine primary neural cells, the SLC6A4 mRNA levels can be significantly reduced. In conclusion, we here found that miR-671-5p and MAZ mediated porcine SLC6A4 expression level, which provides the possible molecular mechanism of aggressive behavior.

Structural covariance of amygdala subregions is associated with trait aggression and endogenous testosterone in healthy individuals

Many studies point toward volume reductions in the amygdala as a potential neurostructural marker for trait aggression. However, most of these findings stem from clinical samples, rendering unclear whether the findings generalize to non-clinical populations. Furthermore, the notion of neural networks suggests that interregional correlations in gray matter volume (i.e., structural covariance) can explain individual differences in aggressive behavior beyond local univariate associations. Here, we tested whether structural covariance between amygdala subregions and the rest of the brain is associated with self-reported aggression in a large sample of healthy young students (n = 263; 49% women). Salivary testosterone concentrations were measured for a subset of n = 40 male and n = 36 female subjects, allowing us to investigate the influence of endogenous testosterone on structural covariance. Aggressive individuals showed enhanced covariance between left superficial amygdala (SFA) and left dorsal anterior insula (dAI), but lower covariance between right laterobasal amygdala (LBA) and right dorsolateral prefrontal cortex (dlPFC). These structural patterns overlap with functional networks involved in the genesis and regulation of aggressive behavior, respectively. With increasing endogenous testosterone, we observed stronger structural covariance between right centromedial amygdala (CMA) and right medial prefrontal cortex in men and between left CMA and bilateral orbitofrontal cortex in women. These results speak for structural covariance of amygdala subregions as a robust correlate of trait aggression in healthy individuals. Moreover, regions that showed structural covariance with the amygdala modulated by either testosterone or aggression did not overlap, suggesting a complex role of testosterone in human social behavior beyond facilitating aggressiveness.

Association of androgens and estrogens with agonistic behavior in the annual fish Austrolebias reicherti

Agonistic behavior governs the settlement of conflicts among conspecifics for limiting resources. Sex steroids play a critical role in the regulation of agonistic behavior which in turn may produce modulations in hormone titres. In this study we analyzed the association of androgens and estrogens with agonistic behavior in the annual fish Austrolebias reicherti. This native species inhabits temporary ponds that dry out completely during summer, having one of the shortest lifespans among vertebrates. They are highly sexually dimorphic and have a single breeding season during which they reproduce continuously. Here we measured plasma levels of 11-ketotestosterone (11KT) and 17β-estradiol (E2) in adult males after the resolution of a social conflict and assessed the role of the aromatase conversion of testosterone (T) to E2 in male aggression. Winners had higher levels of 11KT than losers yet; winner 11KT levels did not differ from those of males not exposed to a social challenge. E2 levels did not show differences among winners, losers or control males. However, fights under the aromatase inhibitor Fadrozole were overall less aggressive than control fights. Our results suggest an androgen response to losing a conflict and that the conversion of T to E2 is involved in the regulation of aggressive behavior. Annual fish extreme life history may give new insights on hormone-behavior interactions.

Regulation of Aggressive Behavior by Mossy Cells in the Caudal Dentate Gyrus

Regulation of Aggressive Behavior by Mossy Cells in the Caudal Dentate Gyrus

Expression Patterns of Serotonin Receptors 1А and 7 in the Brain of Rats with Genetically Determined Fear-Induced Aggressive Behavior or the Lack of Aggression

Abstract—Serotonin receptors of subtype 1А (5-HT1A) are involved in the regulation of aggressive behavior. New data show that 5-HT1A receptors are capable of heterodimerization and antagonistic interaction with type 7 serotonin receptors (5-HT7); hence, it is important to study the involvement of 5-НТ7 receptors in aggressive behavior. Specifically, it is necessary to study the patterns of co-expression of 5-НТ1А and 5-НТ7 receptors in the brains of animals that differ in the degree of genetically defined aggression. In this paper, we have studied the expression of serotonin 5-НТ1А and 5-НТ7 receptors in several cerebral structures of rats with genetically defined aggressive behavior or the lack of aggression. We have revealed significant changes in the expression of these receptors both at mRNA and receptor protein levels. Of particular interest is the changes in the levels of the membrane protein of 5-НТ1А and 5-НТ7 receptors in the midbrain and hippocampus of aggressive rats. A decrease in the level of 5-НТ1А receptors in the midbrain is associated with an increase in the level of this receptor in the hippocampus; meanwhile, the level of 5-НТ7 receptor is increased in the midbrain and decreased in the hippocampus of aggressive rats compared to tame animals. These data indicate interaction between 5-НТ7 and 5-НТ1А receptors. In addition, the expression of 5‑НТ7 receptors is increased in the frontal cortex and the mRNA level of the 5-НТ7 receptor gene is decreased in the hypothalamus of aggressive rats compared to tame animals. Therefore, significant changes in the expression of 5-НТ7 receptors in the brain of rats selected for a high level of fear-induced aggression towards humans have been revealed for the first time. Genotype-dependent peculiarities of combined expression of 5-НТ1А and 5-НТ7 receptors have been revealed in the investigated brain structures. Our data suggest that interaction between 5-НТ1А- and 5-НТ7-receptors may be an important factor in the regulation of genetically defined aggression.

Mechanisms involved in tributyltin-enhanced aggressive behaviors and fear responses in male zebrafish

Tributyltin (TBT), an aromatase inhibitor, has been found to disrupt gametogenesis and reproductive behavior in several fish species. However, whether TBT is capable of affecting other behaviors such as aggressive behavior and fear response in fish and the underlying mode(s) of action remain unclear. To study aggressive behavior, adult zebrafish (Danio rerio) males were continuously exposed to two nominal concentrations of TBT (TBT-low, 100 ng/L and TBT-high, 500 ng/L) for 28 days. To study the fear response, the fish were divided into four groups (Blank and Control, 0 ng/L TBT; TBT-low, 100 ng/L; and TBT-high, 500 ng/L). The fish were then treated with DW (Blank) or with alarm substance (AS) (Control, TBT-low and TBT-high). After exposure, the aggressive behavior of the fish was tested using the mirror test (mirror-biting frequency, approaches to the mirror and duration in approach zone).and fighting test (fish-biting frequency) The mirror-biting frequency, approaches to the mirror, duration in approach zone and fish-biting frequency of the TBT-exposed fish increased significantly compared to those of the control fish, indicating enhanced aggressive behavior. The fear response parameters tested using the novel tank dive test (onset time to the higher half, total duration in the lower half and the frequency of turning) of the TBT-exposed fish were also significantly increased after AS administration, suggesting an enhanced fear response. Further investigation revealed that TBT treatment elevated the plasma level of 11-ketotestosterone (11-KT) and decreased the plasma level of estradiol (E2) in a concentration-dependent manner. Moreover, TBT up-regulated the mRNA levels of ar, c-fos and bdnf1, and suppressed the expression of btg-2 in fish. In addition, exposure to AS increased the plasma level of cortisol and down-regulated the mRNA expression levels of genes involved in 5-HT synthesis (such as tph1b and pet1) in both control and TBT-treated fish. AS significantly suppressed the mRNA level of tph1b, tph2, pet1 and npy in the TBT-high group compared to the control fish. The present study demonstrates that TBT enhances aggressive behavior and fear responses in male zebrafish probably through altering plasma levels of 11-KT, E2 and cortisol and altering the expression of genes involved in the regulation of aggressive behavior (ar, c-fos, bdnf1 and btg-2) and fear responses (tph1b, tph2, pet1 and npy). The present study greatly extends our understanding of the behavioral toxicity of TBT to fish.

Juvenile hormone manipulation affects female reproductive status and aggressiveness in a non-social parasitoid wasp

In vertebrates, titers of androgens such as testosterone are known to upregulate aggressive behaviors associated with reproduction. In insects, juvenile hormone (JH) is a good candidate for studying the flexibility of insect endocrine responses because it has important effects on both reproductive processes and behavior. JH has a gonadotropic effect across a broad range of insect species, increasing ovarian development in females, and may have a role in the regulation of aggressive behavior during competition. In Hymenoptera, the functions of JH have been studied in facultatively eusocial species such as polistine wasps, bumblebees, ants and bees. Surprisingly, no work has yet focused on the relationship between JH, reproduction and aggressiveness in a non-social Hymenoptera, although it may help to understand how JH actions have evolved across taxa with different degrees of sociality. Here, we explored how JH treatment influenced: i) female reproductive status, and ii) the intensity (aggressiveness) and resolution of conflict, in Eupelmus vuilleti (Hymenoptera: Eupelmidae), a solitary ectoparasitoid wasp in which females fight over hosts. We demonstrated that intra-abdominal injections of JH increased the number of mature eggs in females after 24 h. In addition, the number of aggressive behaviors displayed by females was affected by the interaction between JH treatment and the number of mature eggs in their abdomen, but mature egg load alone predicted the outcome of staged contests. Wasps were more aggressive when they had more ready-to-lay eggs, with this effect being stronger when females were injected with JH. Moreover, females won more frequently when they had higher mature egg load. Our results highlight how JH affects egg maturation and aggressive behaviors in Eupelmus vuilleti females. To our knowledge, this is the first study showing that hormone manipulation can modulate females’ reproduction status and behavior during intraspecific competition over hosts in a non-social hymenopteran parasitoid.

Aggression in BALB/cJ mice is differentially predicted by the volumes of anterior and midcingulate cortex

Anterior cingulate cortex (ACC) and midcingulate cortex (MCC) have been implicated in the regulation of aggressive behaviour. For instance, patients with conduct disorder (CD) show increased levels of aggression accompanied by changes in ACC and MCC volume. However, accounts of ACC/MCC changes in CD patients have been conflicting, likely due to the heterogeneity of the studied populations. Here, we address these discrepancies by studying volumetric changes of ACC/MCC in the BALB/cJ mouse, a model of aggression, compared to an age- and gender-matched control group of BALB/cByJ mice. We quantified aggression in BALB/cJ and BALB/cByJ mice using the resident–intruder test, and related this to volumetric measures of ACC/MCC based on Nissl-stained coronal brain slices of the same animals. We demonstrate that BALB/cJ behave consistently more aggressively (shorter attack latencies, more frequent attacks, anti-social biting) than the control group, while at the same time showing an increased volume of ACC and a decreased volume of MCC. Differences in ACC and MCC volume jointly predicted a high amount of variance in aggressive behaviour, while regression with only one predictor had a poor fit. This suggests that, beyond their individual contributions, the relationship between ACC and MCC plays an important role in regulating aggressive behaviour. Finally, we show the importance of switching from the classical rodent anatomical definition of ACC as cingulate area 2 and 1 to a definition that includes the MCC and is directly homologous to higher mammalian species: clear behaviour-related differences in ACC/MCC anatomy were only observed using the homologous definition.

Right ventrolateral prefrontal cortex involvement in proactive and reactive aggression: a transcranial direct current stimulation study.

To investigate whether modulation of the excitability of the right ventrolateral prefrontal cortex (rVLPFC) using transcranial direct current stimulation (tDCS) would alter proactive aggression, reactive aggression, or both. The Taylor Aggression Paradigm, considered to provide measures indicative of the two types of aggression, was presented with delivery of either anodal tDCS or sham tDCS over rVLPFC. Participants were required to select levels of negative feedback to delivery should they win on a competitive reaction-time task and the levels selected on initial trials (with no feedback from the opponent) were taken as measures of proactive aggression, whereas levels on subsequent trials (with feedback from the opponent) were indicators of reactive aggression. The 'opponent' throughout was actually computer controlled. tDCS delivered over rVLPFC was associated with significantly lower levels of negative feedback being selected for both types of trials, suggesting reduction of proactive and reactive aggression. The results are consistent with rVLPFC playing a general role in the regulation of aggressive behavior. Further work to evaluate the site-related specificity of this would be beneficial.

Recent advances in genetics of aggressive behavior

One of the most important problems of modern neurobiology and medicine is an understanding of the mechanisms of normal and pathological behavior of a person. Aggressive behavior is an integral part of the human psyche. However, environmental risk factors, mental illness and somatic diseases can lead to increased aggression to be the biological basis of antisocial behavior in a human society. An important role in development of aggressive behavior belongs to the hereditary factors that may be linked to abnormal functioning of neurotransmitter systems in the brain yet the underlying genetic mechanisms remain unclear, which is due to a large number of single nucleotide polymorphisms, insertions and deletions in the structure of genes that encode the components of the neurotransmitter systems. The most studied candidate genes for aggressive behavior are serotonergic (TPH1, TPH2, HTR2A, SLC6A4) and dopaminergic (DRD4, SLC6A3) system genes, as well as the serotonin or catecholamine metabolizing enzyme genes (COMT, MAOA). In addition, there is evidence that the hypothalamic-pituitary system genes (OXT, OXTR, AVPR1A, AVPR1B), the sex hormone receptors genes (ER1, AR), neurotrophin (BDNF) and neuronal apoptosis genes (CASP3, BAX) may also be involved in development of aggressive behavior. The results of Genome-Wide Association Studies (GWAS) have demonstrated that FYN, LRRTM4, NTM, CDH13, DYRK1A and other genes are involved in regulation of aggressive behavior. These and other evidence suggest that genetic predisposition to aggressive behavior may be a very complex process.

Brain-Derived Steroids, Behavior and Endocrine Conflicts Across Life History Stages in Birds: A Perspective

Biological steroids were traditionally thought to be synthesized exclusively by the adrenal glands and gonads. Recent decades have seen the discovery of neurosteroid production that acts locally within the central nervous system to affect physiology and behavior. These actions include, for example, regulation of aggressive behavior, such as territoriality, and locomotor movement associated with migration. Important questions then arose as to how and why neurosteroid production evolved and why similar steroids of peripheral origin do not always fulfill these central roles? Investigations of free-living vertebrates suggest that synthesis and action of bioactive steroids within the brain may have evolved to regulate expression of specific behavior in different life history stages. Synthesis and secretion of these hormones from peripheral glands is broadcast throughout the organism via the blood stream. While widespread, general actions of steroids released into the blood might be relevant for regulation of morphological, physiological, and behavioral traits in one life history stage, such hormonal release may not be appropriate in other stages. Specific and localized production of bioactive steroids in the brain, but not released into the periphery, could be a way to avoid such conflicts. Two examples are highlighted. First, we compare the control of territorial aggression of songbirds in the breeding season under the influence of gonadal steroids with autumnal (non-breeding) territoriality regulated by sex steroid production in the brain either from circulating precursors such as dehydroepiandrosterone or local central production of sex steroids de novo from cholesterol. Second, we outline the production of 7α-hydroxypregnenolone within the brain that appears to affect locomotor behavior in several contexts. Local production of these steroids in the brain may provide specific regulation of behavioral traits throughout the year and independently of life history stage.

S173. GREY MATTER VOLUME DEFFICITS IN PATIENTS WITH A FIRST EPISODE NON-AFFECTIVE PSYCHOSIS AND SUICIDE RELATED BEHAVIOUR

BackgroundSuicide represents the main cause of premature dead in first episode psychosis (FEP) patients. However, our understanding of suicidal behaviour in this population is limited. During the last decade, several works have related suicidal behaviour in FEP patients with structural abnormalities in frontal and temporal areas as well as specific structures such as hippocampus, insula and amygdala. The main aim of this work was to analyse the possible structural brain abnormalities associated with suicide-related-behaviour in a large sample of FEP patients.MethodsWe use a voxel-based morphometry (VBM) analysis in 146 FEP individuals: 24 FEP with and 122 without suicidal behaviour. All images were taken in the same 3T Phillips scanner. The CAT 12 toolbox, which is implemented in SPM12 was used for VBM analysis of the data. A two-sample t-test was set with sex, age, handedness, total intracraneal volume and global disability score as nuisance covariables. We applied threshold-free cluster enhancement (TFCE) with 5000 permutations and corrected for multiple comparisons (FWE) at p<0.05.ResultsA gradual reduction of grey matter volume related to presence of suicide-related-behaviour was found in frontal area, specifically in superior frontal gyrus, middle frontal gyrus, precentral gyrus, inferior frontal gyrus and orbital gyrus. In addition, significant reduction was found in middle temporal gyrus as well as in posterior cingulate gyrus and precuneus.DiscussionOur results are in line with previous works which related suicidal behaviours with reduced frontal regions. Frontal areas are involved in: i) cognitive analysis; ii) foresight and weighing consequences of behaviour; iii) considering future and making predictions; iv) impulse control; v) delaying gratification; vi) inhibiting inappropriate behaviour; vii) initiating appropriate behaviour. Reestructuraria esta frase asi: On the other hand, precuneus is involved in: i) episode memories; ii) reflective self-awareness; iii) executive function; and iv) it is activated during judgements. Finally, cingulate gyrus has been strongly associated with emotional responses to pain, regulation of aggressive behaviour and decision making. Finally, middle temporal gyrus appears to play an important role in retrieving semantic information.This study provides some insights about brain abnormalities associated with suicide-related-behaviours in FEP patients. In particular, the areas reported in this study are related with important functions such as impulsivity, emotional processing information, responses to pain and aggressiveness which are strongly associated with suicide-related-behaviours. Further studies are necessary to replicate the relevance of these structures in suicidal behaviour in FEP patients.

Reprint of “Rearing piglets in multi-litter group lactation systems: Effects on piglet aggression and injuries post-weaning”

This experiment investigated the effects of rearing piglets in a multi-litter lactation system on piglet aggression at weaning. The following four pre-weaning treatments were applied to 72 sows and their litters (n=642 piglets); (1) Farrowing crate (‘FC’ − n=24 sows), (2) PigSAFE pens, in which sows and piglets are loose housed, (‘PS’ − n=24 sows), (3) Farrowing crate and group lactation (‘GLFC’ − n=12 sows), and (4) PigSAFE and group lactation (‘GLPS’ − n=12 sows). FC and PS piglets remained in treatment from birth (day 0) until weaning (day 27). GLFC and GLPS piglets were housed in FC and PS, respectively, from day 0 to 14 after which they were transferred (with their dams) to group lactation pens (n=6 sows and litters/pen), where they remained until weaning. Piglet weights were recorded at day 13 and 26. At weaning piglets were mixed into pens of four litters from FC, PS, or GL (2 GLFC litters and 2 GLPS litters) treatments and behaviour was continuously recorded for 2h. Aggression (reciprocal and non-reciprocal aggression of duration <5s) and fights (reciprocal aggression of duration ≥5s; frequency; total and average duration, latency to fight) were recorded for each litter. Six piglets from each litter were randomly selected for skin lesion scoring on day 26 and 24h post-weaning. GLFC and GLPS piglets had a lower growth rate than FC and PS piglets from day 13 to 26 (P<0.01) but there was no difference in weight at day 13 (P=0.11) or day 26 (P=0.17), or in skin lesions at day 26 (P=0.26). GL piglets delivered fewer bouts of aggression (P<0.01), fought less frequently in the 2h post-mixing at weaning (P<0.01) and had sustained fewer skin lesions 24h later (P<0.01) than FC or PS piglets. GL piglets also had shorter fights (P<0.01) and spent less total time fighting (P=0.04) than FC, but not than PS, piglets. These results highlight the possible importance of the early social environment on the development and regulation of aggressive behaviour in the pig. Due to the implications of aggression and injury on both animal welfare and productivity, there is a need for further investigation into the effects of housing piglets in multi-litter lactation systems.

5-HT1A receptor: Role in the regulation of different types of behavior

Serotonin, a brain neurotransmitter, acting via 14 types of serotonin (5-HT) receptors regulates different forms of both normal and pathological behavior. All 5-HT receptors (except for 5-HT3 representing an ion channel (ionotropic receptor)) belong to a superfamily of metabotropic receptors coupled with G-proteins. Each receptoris characterized by a unique gene, spectrum of affinity to different agonists and antagonists, specific distribution in the brain, and a set of controlled functions. Among this diversity of 5-HT receptors, the evolutionarily most ancient 5-HT1A receptor is of a special interest since it plays a key role in autoregulating of the brain 5-HT system. This role of 5-HT1A receptors is caused by the peculiarities of their localization (pre- or postsynaptically on 5-HT neurons), depending on which they can exert the opposite effect on the functional activity of the 5-HT system. The review is devoted to the data of the literature and the results obtained by the authors about the factors regulating the expression and functional activity of 5-HT1A receptors and their influence on behavior. The structure of the 5-HT1A receptor gene was described; and the latest data on the posttranslational regulation of the activity of 5-HT1A receptors and interaction of 5-HT receptors were given. Special attention was paid to the role of the 5-HT1A receptor’s heterodimerization with the 5-HT7 serotonin receptor and the functional inactivation of the 5-HT1A receptor. The involvement of 5-HT1A receptors in regulation of aggressive behavior, catalepsy, anxiety, depression, and unique natural adaptation (hibernation) was demonstrated. Special attention was paid to the involvement of these receptors in regulation of (1)—fear-induced defensive aggression the base of thedomestication process; (2) intermale aggression resulting in the establishment of a dominant–subordinant relationship in the animal community and underlying human asocial behavior; and (3) the mechanisms of depression and the effect of clinically efficient antidepressants of the serotonin reuptake inhibitors group. The role of 5-HT1A/5-HT7 heterodimerization in the mechanism of the antidepressants effect was hypothesized.

Agonistic interactions elicit rapid changes in brain nonapeptide levels in zebrafish

The teleost fish nonapeptides, arginine vasotocin (AVT) and isotocin (IT), have been implicated in the regulation of social behavior. These peptides are expected to be involved in acute and transient changes in social context, in order to be efficient in modulating the expression of social behavior according to changes in the social environment. Here we tested the hypothesis that short-term social interactions are related to changes in the level of both nonapeptides across different brain regions. For this purpose we exposed male zebrafish to two types of social interactions: (1) real opponent interactions, from which a Winner and a Loser emerged; and (2) mirror-elicited interactions, that produced individuals that did not experience a change in social status despite expressing similar levels of aggressive behavior to those of participants in real-opponent fights. Non-interacting individuals were used as a reference group. Each social phenotype (i.e. Winners, Losers, Mirror-fighters) presented a specific brain profile of nonapeptides when compared to the reference group. Moreover, the comparison between the different social phenotypes allowed to address the specific aspects of the interaction (e.g. assessment of opponent aggressive behavior vs. self-assessment of expressed aggressive behavior) that are linked with neuropeptide responses. Overall, agonistic interactions seem to be more associated with the changes in brain AVT than IT, which highlights the preferential role of AVT in the regulation of aggressive behavior already described for other species.

5-HT1A receptor: its role in the regulation of different kinds of behavior

Brain serotonin (5-HT) is known to be involved in the control of a wide range of physiological functions as well as of different kinds of behavior. Such polyfunctionality of 5-HT is mediated by numerous 5-HT receptors. Currently, 14 different 5-HT receptor subtypes expressed in the mammals have been identified. The 5-HT1А receptor is one of the most extensively characterised members of the serotonin receptor family. Increased interest to the 5-HT1А receptor is based on (1) a key role in the autoregulation of the brain serotonergic system due to the postsynaptic and presynaptic localization, (2) a great body of data demonstrating implication of 5-HT1А receptor in the control of various physiological functions (3) involvement of 5-HT1А receptors in the mechanisms of depression, anxiety and suicide. The review describes literature and original data on factors affecting the expression and functional activity of 5-HT1А receptors and the involvement of 5-HT1А receptors in the regulation of normal and pathological behavior. The structure of the 5-HT1А receptor gene is described and new data on the posttranslational regulation of 5-HT1А receptor functional activity are provided. A special focus was given to the interaction between 5-HT1А and 5-HT7 receptors followed by heterodimer formation and the role of heterodimerization in the functional inactivation of the 5-HT1А receptor. The implication of 5-HT1А receptors in the regulation of aggressive behavior, catalepsy, anxiety, depression and hibernation was shown. Special attention is focused on the involvement of 5-HT1А receptors in the regulation of 1) fear-induced aggression towards man – the basis of domestication, 2) intermale aggression underling asocial behavior in men, 3) depression and in the mechanism of antidepressant action. The described data extend the idea on the 5-HT1А receptor as a key player in the brain 5-HT system.