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[Change in certain forms of aggressive behavior and the concentration of monoamines in the brain during selection of wild rats for taming].

Norway rats have been selected during 20 generations by the absence of aggressive reaction to man (tamed rats). From 7 up to 20th generations of selection, different forms of aggressive behaviour (reaction to glove, intermale, shock-induced aggression and predatory aggression) were studied, and the level of noradrenaline, serotonin and its metabolite 5-hydroxyindoleacetic acid was determined in the brain. In the absence of aggressive reaction to glove in tamed rats, the shock-induced aggression considerably decreased while the predatory aggressiveness (mouse-killing behaviour) and intermale aggressiveness did not change. Beginning from 15-16th generation of selection, a higher level of the 5-hydroxyindoleacetic acid in the hypothalamus was established, in the 20th generation an increased content of serotonin was revealed in the hypothalamus and the midbrain. In some generations of selection an increased level of noradrenaline in the hypothalamus in comparison to wild rats was observed. A conclusion is made that the selection of animals by taming unequally influences different kinds of aggressiveness and is accompanied by inherited consolidated reorganization of the monoamine brain systems.

Aggression↗
PubMed1989

[Effect of electrical damage to catecholaminergic structures on aggressiveness in rats following administration of isoniazide].

The author studied the effect of INH administered in single and repeated doses on affective aggressiveness. INH's effect on predatory aggressiveness was evaluated following administration of the drug in a single dose in three different doses. Affective aggressiveness was provoked by pain stimulus, predatory aggression by chronic isolation. In order to evaluate the role of catecholaminergic neurons in INH's effect on affective aggression, electrical damage of structures known to have such neurons was carried out. INH was administered in a single and in multiple doses increasing affective aggressiveness in rats. This was intensified by destruction of the nucleus locus coeruleus and decreased by destroying ventral parts of the noradrenergic and dopaminergic pathways of the A-10 structure. INH decreased predatory aggressiveness of rats. The results of this study demonstrate the role of catecholamines in INH influence on aggression, showing also different roles of both studied neurological structures in regulation of aggression in rats.

Aggression↗
PubMed1981

[Aggression in peer groups during the second year of life].

1. Very little is known about the behaviour of children in their second year and even less in their Peer-group. Aggressive behaviour among peers seems to be established at this age and it is interesting to observe it within the Peer-groups. 2. A useful definition of aggression seems to be the following one: Aggression is any physical contact, direct or indirect, by which another person is hurt. 3. We observe five different forms of aggression: 3.1 Aggression by chance, without any aim, happening out of awkwardness and motoric clumsiness. This kind of aggression becomes rarer during the second year. 3.2 Manipulating one another, as shaking arm or leg of another child, pulling his hair, tapping his body and so on, giving the impression of the aggressor exploring his partner. This kind of aggression also becomes rarer during the second year. 3.3 Robbery of objects, i.e. toys being in the hands of another; the reaction of the victim is increasing during the second year. 3.4 Aggression in order to control the group and to establish leadership in connection with the development of a group hierarchy. 3.5 Pathologic Aggression, observed on a child of the group with brain dysfunction. The child overthrows others from behind, climbs on them and bites them in the ear, the neck or the cheek. 4. We still need more observation on Peer-groups of this age to know more about the beginning and development of the here described phenomena.

Aggression↗
PubMed1994

Risk factors for behavior-related euthanasia among dominant-aggressive dogs: 110 cases (1989-1992).

Establishing a prognosis for dogs with dominance-related aggression is difficult. Some dominant-aggressive dogs respond well to treatment; others continue to be serious risks for their owners. A study was performed to identify characteristics of dominance-related aggression and to identify risk factors associated with whether the aggressive behavior led to euthanasia. Medical records of 110 dogs with dominance-related aggression were examined retrospectively; characteristics of owner-directed aggression and eventual outcome of the dogs were recorded. By means of logistic regression, 2 different models were found to describe the association between behavior characteristics and outcome. In the first model, severe aggression in response to benign dominance challenges and body weight > 18.2 kg were associated with outcome. In the second model, unpredictability of aggression and a history of being purchased were associated with outcome. We concluded that dominance-related aggressive behavior can be subclassified according to severity and type and that outcome (ie, euthanasia) may be predictable in some cases.

Aggression↗
PubMed1994

[The concept of aggression in psychology and psychotherapy].

Aggressiveness is one of the basic characteristics of human beings. It can be defined as a relatively constant individual disposition or group characteristic manifested by the frequency, intensity and mode of aggressive behaviour. Aggressiveness has an inborn basis but its frequency, intensity and form are acquired during life and can therefore be influenced by the environment, i.e. also by training and psychotherapy. With regard to the genesis and purpose we differentiate between reflex, instrumental aggression, aggression with an end in itself and aggression resulting from affection. Psychological theories on the genesis of aggression can be divided into endogenous, exogenous and the interaction approach. The author discusses in his paper also the relationship between aggression and the type of psychotherapeutic treatment, and expands in more detail on aggressiveness and its control within the framework of Rogers' approach (person-centered approach).

Aggression↗
PubMed1977

Validation of a laboratory play measure of child aggression.

The validity of laboratory play measures of aggression has been called into question. Critics have charged that laboratory findings on childhood aggression cannot be generalized to everyday aggression. In the present study, the validity of striking a Bobo clown as a measure of aggression was assessed by correlating the rate of this behavior with peer ratings, teaching ratings, and self-ratings of aggressiveness in a preschool. Laboratory aggression correlated significantly with both peer ratings, r = .76, p less than .01, and teacher ratings, r = .57, p less than .05, but not with self-ratings, r = .36. Laboratory aggression correlated more highly with aggression ratings for males (N = 9) than for females (N = 9), but not significantly so. The findings support the use of laboratory play as a valid measure of aggression in children.

Aggression↗
PubMed1996

Gender differences in children's normative beliefs about aggression: how do I hurt thee? Let me count the ways.

This research was designed to assess whether children view relationally manipulative behaviors (i.e., those behaviors labeled relational aggression in past research) as "aggressive." 2 studies were conducted to evaluate whether children view relationally manipulative behaviors as associated with 2 defining features of aggression, anger (Study 1) and intent to harm (Study 2). Results of Study 1 (n = 459, 9-12-year-olds) indicated that relational aggression was the most frequently cited angry behavior for girls' interactions whereas physical aggression was the most frequently cited angry behavior for boys' interactions. Results of Study 2 (n = 60, 9-11-year-olds) demonstrated that relational aggression and verbal insults were the most frequently cited harmful behaviors for girls whereas physical aggression and verbal insults were the most frequently cited harmful behaviors for boys. These studies provide the first evidence that children view relationally manipulative acts (relational aggression) as angry, harmful behaviors (i.e., as "aggressive").

Aggression↗
PubMed1996

Social information-processing mechanisms in reactive and proactive aggression.

Theories of aggressive behavior and ethological observations in animals and children suggest the existence of distinct forms of reactive (hostile) and proactive (instrumental) aggression. Toward the validation of this distinction, groups of reactive aggressive, proactive aggressive, and nonaggressive children were identified (n = 624 9-12-year-olds). Social information-processing patterns were assessed in these groups by presenting hypothetical vignettes to subjects. 3 hypotheses were tested: (1) only the reactive-aggressive children would demonstrate hostile biases in their attributions of peers' intentions in provocation situations (because such biases are known to lead to reactive anger); (2) only proactive-aggressive children would evaluate aggression and its consequences in relatively positive ways (because proactive aggression is motivated by its expected external outcomes); and (3) proactive-aggressive children would select instrumental social goals rather than relational goals more often than nonaggressive children. All 3 hypotheses were at least partially supported.

Aggression↗
PubMed1995

[Characteristics of dementia patients with aggressive behaviors].

Aggressive behaviors are found in dementia patients and pose major problems for their caregivers and may be amenable to treatment. The present study aims to determine the frequency of aggressive behaviors in dementia patients and to test whether there is a relationship with the psychiatric symptoms. Ninety-one dementia patients from a geriatric psychiatry unit were surveyed for the aggressive behaviors and psychiatric symptoms by semi-structured interview with the patients and their caregivers. Major findings included that 53.8% of these patients had aggressive behaviors; these patients were older and had later onset of dementia; the presence of hallucination, misidentification and wandering were significant predictors of physical aggression; the association of aggressive behaviors with the cognitive test and delusion was not significant. These observations suggest that dementia patients have a high prevalence rate of aggressive behaviors that warrants the prevention and intervention. Hallucination, misidentification and wandering are risk factors for physical aggression and potentially trestable. Further research is needed to identify the cause and the management of aggressive behaviors in dementia patients.

Aged↗
PubMed1998

Differences in alcohol expectancy between aggressive and nonaggressive social drinkers.

Previous reports have shown that drinkers with aggressive personalities not only hold the strongest beliefs that alcohol facilitates aggressive behavior, but they also display the greatest increases in laboratory aggression after receiving alcohol. Given that several studies have demonstrated that a portion of the behavioral and subjective effects of alcohol are due to psychological expectancy, this study explored whether aggressive drinkers have elevated intoxication expectancies from laboratory beverages with unknown alcohol content. The rates of aggressive responses emitted in a money subtraction aggression model under baseline conditions were used to select an aggressive group and a nonaggressive group, each with five male and five female participants. Subjects then ingested and rated each of three placebo (1 ml alcohol) beverages administered hourly during a subsequent laboratory visit, and rated a series of three 0.35 g/kg of alcohol beverages the following day. Whereas nonaggressive subjects clearly discriminated the relative alcohol content of alcohol and placebo drinks, aggressive subjects gave progressively elevated shot equivalent ratings to placebo drinks, similar to their ratings of alcohol doses. However, despite similar self-reported drinking histories, aggressive subjects reported anticipating only half the intoxication from the alcohol doses (and in fact achieved a lower peak breath alcohol concentration) than was expected by nonaggressive subjects.

Adult↗
PubMed2001

Juvenile hormone and aggression in honey bees.

We determined whether defense by individual bees against non-nestmates in honey bees (Apis mellifera) is correlated with their juvenile hormone (JH) titers, which are known to vary developmentally and seasonally. We bioassayed winter and summer bees for aggressive and non-aggressive individuals. Bees in winter could not be distinguished by task group, but bees in summer were segregated into nurses and guards. JH titers were correlated with aggressive behavior at two levels. First, winter bees and summer nurses, known to have lower JH titers, both showed less aggression toward foreign bees than did summer guards. Second, aggressive individuals had significantly higher JH titers than did non-aggressive bees within each colony. Inter-colonial variation in aggressiveness was maintained during summer and winter, suggesting a genetic basis for these differences. An alarm pheromone test further substantiated the existence of inter-colonial differences. We found significant variation in JH titers among different colonies, but this variation was not significantly associated with colony-level aggressiveness. The correlation between JH and levels of aggressiveness within a colony suggests a regulatory role for JH, but variation among colonies involves factors other than JH.

Journal Article↗
PubMed2003

Timing of presentation of an audience: aggressive priming and audience effects in male displays of Siamese fighting fish (Betta splendens).

Studies of animal communication often underestimate the presence of individuals other than the signaller-receiver dyad. Signalling interactions often occur in the presence of non-participating individuals (audiences); the effect of these individuals upon the dynamics of interactions has been called the audience effect. Recent studies of fighting fish Betta splendens have shown that the presence of a male audience can increase aggression during interactions. However, in many of these studies males were allowed to see the audience prior to the interaction, thus such pre-exposure may have facilitated aggressive behaviour (aggressive priming). Here we present results of two experiments designed to examine the relative importance of priming and audience effects on the dynamics of aggressive interactions. Males that were pre-exposed showed higher levels of aggression during subsequent interactions regardless of the presence or absence of an audience. When only one of the interactants had been pre-exposed to the audience, the non-exposed male showed similar increases in aggressive behaviour, i.e. matching the level of aggression showed by his opponent. Taken together these results suggest that aggressive priming may have resulted in an over-estimation of the audience effect in previous studies. The results still highlight the importance of social environment in determining the dynamics and outcomes of aggressive contests.

Journal Article↗
PubMed2001

Expression and functional significance of VE-cadherin in aggressive human melanoma cells: role in vasculogenic mimicry.

We recently have introduced the term vasculogenic mimicry to describe the unique ability of aggressive melanoma tumor cells to form tubular structures and patterned networks in three-dimensional culture, which "mimics" embryonic vasculogenic networks formed by differentiating endothelial cells. In the current study, we address the biological significance of several endothelial-associated molecules (revealed by microarray analysis) with respect to expression and function in highly aggressive and poorly aggressive human cutaneous melanoma cell lines (established from the same patient). In a comparative analysis, CD31 was not expressed by any of the melanoma cell lines, whereas TIE-1 (tyrosine kinase with Ig and epidermal growth factor homology domains-1) was strongly expressed in the highly aggressive tumor cells with a low level of expression in one of the poorly aggressive cell lines. Vascular endothelial (VE)-cadherin was exclusively expressed by highly aggressive melanoma cells and was undetectable in the poorly aggressive tumor cells, suggesting the possibility of a vasculogenic switch. Down-regulation of VE-cadherin expression in the aggressive melanoma cells abrogated their ability to form vasculogenic networks and directly tested the hypothesis that VE-cadherin is critical in melanoma vasculogenic mimicry. These results highlight the plasticity of aggressive melanoma cells and call into question their possible genetic reversion to an embryonic phenotype. This finding could pose a significant clinical challenge in targeting tumor cells that may masquerade as circulating endothelial cells or other embryonic-like stem cells.

Antigens, CD↗
PubMed2000

Aggressive angiomyxoma of pelvic parts exhibits oestrogen and progesterone receptor positivity.

AIMS: Aggressive angiomyxoma of pelvic parts is a distinctive soft tissue tumour that chiefly involves the vulvar and perineal region of female patients. Several previous reports have demonstrated oestrogen receptor (ER) and/or progesterone receptor (PR) positivity in this neoplasm. The aim of this study was to confirm whether ER and/or PR positivity is present in aggressive angiomyxoma. We also wished to ascertain whether positivity may be found in the stromal cells of normal vulval skin and in other lesions at this site that can cause diagnostic confusion with aggressive angiomyxoma. METHODS: Five aggressive angiomyxomas in female patients and one involving male pelvic soft parts were stained immunohistochemically with antibodies against ER and PR. Other samples studied were normal vulval skin (n = 7), fibroepithelial polyps of vulva (n = 7), vulval smooth muscle neoplasms (n = 5), vulval nerve sheath tumours (n = 2), vaginal angiomyofibroblastoma (n = 1), and pelvic myxoma (n = 1). Nuclear staining was classified as negative, weak, moderate, or strong and the proportion of positively staining cells was categorised as 0, < 10%, 10-50%, or > 50%. RESULTS: All five cases of aggressive angiomyxoma in female patients were positive for ER (two with weak intensity involving < 10% of cells and three with moderate intensity involving 10-50% of cells) and four of five cases were strongly positive for PR in > 50% of cells. The other case was negative for PR. There was no staining with antibodies to ER or PR in the single male patient with aggressive angiomyxoma. Other samples exhibiting positivity of the stromal cells for either ER or PR were normal vulval skin (five of seven, ER; two of seven, PR), fibroepithelial polyps (four of seven, ER; five of seven, PR), smooth muscle neoplasms (three of five, ER; four of five, PR), nerve sheath tumours (one of two, ER; one of two, PR), angiomyofibroblastoma (one of one, ER; one of one, PR), and pelvic myxoma (one of one, PR). CONCLUSIONS: All cases of aggressive angiomyxoma of pelvic soft parts in female patients exhibited positivity for ER and/or PR. Because of its propensity to occur in female patients during the reproductive years, it is possible that aggressive angiomyxoma is a hormonally responsive neoplasm. However, dermal fibroblasts in normal vulval skin and stromal cells in a variety of vulval lesions can also be positive. ER or PR immunoreactivity cannot be used to distinguish aggressive angiomyxoma and its histological mimics.

Biomarkers, Tumor↗
PubMed1995

Provocation frequency and its role in determining the effects of smoked marijuana on human aggressive responding.

Five male subjects participated in an experiment to determine how variations in provocation frequency, manipulated before and after smoking marijuana, would affect free-operant aggressive responding. Two response buttons, A and B, were available. Pressing button A was maintained by a fixed-ratio 100 schedule of point presentation. Subjects were instructed that the completion of each fixed-ratio 10 on button B resulted in a point subtraction from a second subject (who was in fact fictitious). Button B responses were defined as aggressive, since they ostensibly resulted in the presentation of an aversive stimulus (i.e., point subtraction) to another person. Aggressive responding was engendered by a random-time schedule of point subtraction and maintained by the initiation of intervals free from point subtraction. Points subtracted from the subjects were attributed to the fictitious other subject. The effects of smoking placebo and 3.58% w/w Delta-9-tetrahydro-canabinol marijuana cigarettes, on aggressive responding under four different provocation conditions, were studied: (1) low provocation before and low provocation after smoking; (2) low provocation before and high provocation after smoking; (3) high provocation before and low provocation after smoking; and (4) high provocation before and after smoking. Manipulating the level of provocation frequency immediately before smoking marijuana had no effect on the number of aggressive responses emitted after smoking marijuana. Rather, the provocation frequency immediately after smoking marijuana was important. After smoking active marijuana cigarettes, aggressive responding was significantly suppressed, relative to placebo, under the high provocation condition but not under the low provocation condition. As a result, the effects of marijuana on aggression appear to be largely determined by the environmental conditions (i.e., level of provocation frequency and/or rate of aggressive responding) present immediately after smoking marijuana. This finding may help to account for some of the inconsistencies observed in previous studies, where marijuana has been found to both increase and decrease aggressive responding.

Journal Article↗
PubMed1995

Aggressive behaviour as a cause of psychiatric admission: a comparison between schizophrenic and affective disorder patients.

One hundred and fifty-six subjects were randomly chosen from 1,560 patients admitted to two psychiatric hospitals in Israel during 1991. The subjects' files were retrospectively studied to determine whether aggressive behaviour was the reason for psychiatric admission. We examined the relationship between aggressive behaviour, major psychiatric disorders (schizophrenia and affective disorder) and demographic variables (sex, age, family status and education). We also studied the monthly distribution of aggression throughout the year and the correlation to daily photoperiod duration. Forty-six per cent of the admissions related to aggressive behaviour. Schizophrenic patients were overly represented in the aggressive group. The monthly distribution of aggressive behaviour differed between schizophrenic and affective disorder patients. While the latter showed a seasonal pattern of aggressiveness, with a statistically significant peak during spring and winter, schizophrenic aggressive patients were distributed equally throughout the year. No statistically significant correlation was found between the incidence of aggression and the photoperiod duration.

Adult↗
PubMed2000

Reducing adolescents' aggressive and hostile behaviors: randomized trial effects of a brief family intervention 4 years past baseline.

OBJECTIVE: To examine the long-term effects of a brief family intervention on aggressive and hostile behaviors of adolescents in the general population. DESIGN: Randomized trial including 22 public schools assigned to the Iowa Strengthening Families Program or a control condition. Analyses supported sample representativeness and failed to show differential attrition effects 4 years after baseline. INTERVENTION: Seven-session intervention for parents and their sixth-grade children. MEASURES: The multi-informant, multimethod measures included independent observer ratings of adolescent aggressive and hostile behaviors in adolescent-parent interactions, family-member report of aggressive and hostile behaviors in those interactions, and adolescent self-report of aggressive and destructive conduct across settings. Data were collected during the 6th (preintervention and postintervention), 7th, 8th, and 10th grades. RESULTS: All measures showed a generally positive trend in intervention-control group differences over time. During 10th grade, significant intervention-control differences were found for adolescent self-report of aggressive and destructive conduct (P =. 01), with relative reduction rates ranging from 31.7% to 77.0%. Significant differences were shown for observer-rated aggressive and hostile behaviors in adolescent-parent interactions (P =.01); differences in family member reports of those behaviors were not significant. Supplemental analyses of both interactional behavior measures, specific to parent sex, indicated significant experimental group differences in interactions with mothers (P =.04 for both measures) but not with fathers. CONCLUSIONS: Brief family competency-training interventions designed for general populations can reduce aggressive and hostile behaviors in adolescents' interactions with parents and adolescent aggressive behaviors outside of the home setting. Thus, this type of intervention has important public health implications. Arch Pediatr Adolesc Med. 2000;154:1248-1257.

Adolescent↗
PubMed1992

Cerebrospinal fluid monoamine and adrenal correlates of aggression in free-ranging rhesus monkeys.

Clinical and preclinical studies involving several different mammalian species and research paradigms suggest a negative correlation between aggression and central serotonin activity. To test the generalizability of laboratory findings in rhesus monkeys that show a negative correlation between cerebrospinal fluid 5-hydroxyindoleacetic acid concentrations and aggression, we obtained cisternal cerebrospinal fluid and blood plasma samples from monkeys living in naturalistic conditions. During a semiannual trapping, 28 juvenile and adolescent male rhesus monkeys were chosen from a population of 4200 provisioned, free-ranging rhesus monkeys living on Morgan Island, a sea island located off the coast of South Carolina. Based on direct observations of participation or avoidance of aggressive behavior and examinations of apparent fight wounds, 18 monkeys were selected for cerebrospinal fluid taps and blood samples. The remaining 10 monkeys were selected at random. Descriptions of aggressive behavior and the number of old scars and recent wounds were carefully transcribed, and a photograph showing wounds and scars was obtained for each animal. Using the transcriptions and photographs, researchers experienced in rhesus monkey behavior, but blind to the subjects' monoamine and hormone concentrations, were asked to rank the monkeys from the most to the least aggressive. The results showed a significant negative correlation between high rankings for aggression and cerebrospinal fluid 5-hydroxyindoleacetic acid concentrations. There was evidence that aggression was associated with stress, in that cerebrospinal fluid, norepinephrine, and plasma corticotropin and cortisol concentrations were positively correlated with high rankings of aggression.

Adrenocorticotropic Hormone↗