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PubMed1998

Folliculogenesis, onset of puberty and fecundity of mink (Mustela vision Schreb) selectively bred for docility or aggressiveness.

It has been suggested that selective breeding of animals for docile behavior is correlated with early onset of puberty and improved fertility. We wished to test the hypothesis that mink bred for docility would show earlier onset of puberty and greater fecundity than mink bred for aggressiveness. We used farm-raised, 7-mo-old mink females that had been selectively bred for 7 to 10 generations on the basis of behavior towards humans. Onset of puberty was estimated once (between 15 and 20 December) by vaginal smears and was said to start wtih preponderance of cornified epithelial cells in the cytological specimen. Fecundity was measured by litter size and rate of folliculogenesis, with and without hCG stimulation, by histomorphometric examination of ovaries and uteri. A total of 43/100 (43%) docile females achieved proestrus and estrus as compared to 16/136 (12%) of the aggressive ones. Overall pregnancy rate, survival to 5 d after whelping and litter size did not differ between the docile and aggressive females. Docile females showed significantly higher numbers (P < 0.05 and < 0.001) of growing, maturing and atretic follicles than the aggressive ones, however the latter showed a highly significant (P < 0.001) folliculogenic response to hCG. The response of the ovary of aggressive females to hCG is particularly dramatic because in most aggressive females the ovaries contained none or only few follicles of any kind. The inhibition of folliculogenesis in aggressive mink is similar to that reported in Silverblue and Sapphire mink homozygous for the Stuart factor. The paradoxical response to hCG may be an indication that selective breeding for aggression may be correlated with the disturbance at the early stages of folliculogenesis which creates a deficiency of follicles that are sensitive to LH-type stimulation.

Aggression↗
PubMed1998

Testosterone and its metabolites modulate 5HT1A and 5HT1B agonist effects on intermale aggression.

Our understanding of the neurochemical and neuroendocrine systems' regulating the display of offensive intermale aggression has progressed substantially over the past twenty years. Pharmacological studies have shown that serotonin, via its action at 5HT1A and/or 5HT1B receptor sites, modulates the display of intermale aggressive behavior and that its effects serve to decrease behavioral expression. Neuroendocrine investigations, in turn, have demonstrated that male-typical aggression is testosterone-dependent and studies of genetic effects, metabolic function and steroid receptor binding have shown that facilitation of behavioral displays can occur via independent androgen-sensitive or estrogen-sensitive pathways. Remarkably, there have been virtually no studies that examined the interrelationship between these facilitative and inhibitory systems. As an initial step toward characterizing the interaction between the systems, studies were conducted that assessed hormonal modulation of serotonin function at 5HT1A and 5HT1B receptor sites. They demonstrated: (1) that the androgenic and estrogenic metabolites of testosterone differentially modulate the ability of systemically administered 8-OH-DPAT (a 5HT1A agonist) and CGS12066B (a 5HT1B agonist) to decrease offensive aggression; and (2) when microinjected into the lateral septum (LS) or medial preoptic area (MPO), the aggression-attenuating effects of 1A and 1B agonists differ regionally and vary with the steroidal milieu. In general, the results suggest that estrogens establish a restrictive environment for attenuation of T-dependent aggression by 8-OH-DPAT and CGS 12066B, while androgens either do not inhibit, or perhaps even facilitate, the ability of 5HT1A and 5HT1B agonists to reduce aggression. Potential mechanisms involved in the production of these steroidal effects are discussed and emerging issues that may impact on efforts to develop an integrative neurobiological model of offensive, intermale aggression are considered.

Aggression↗
PubMed2001

Aggressive behavioral phenotypes in mice.

Aggressive behavior in male and female mice occurs in conflicts with intruding rivals, most often for the purpose of suppressing the reproductive success of the opponent. The behavioral repertoire of fighting is composed of intricately sequenced bursts of species-typical elements, with the resident displaying offensive and the intruder defensive acts and postures. The probability of occurrence as well as the frequency, duration, temporal and sequential patterns of aggressive behavior can be quantified with ethological methods. Classic selection and strain comparisons show the heritability of aggressive behavior, and point to the influence of several genes, including some of them on the Y chromosome. However, genetic effects on aggressive behavior critically depend upon the background strain, maternal environment and the intruder. These factors are equally important in determining changes in aggressive behavior in mice with a specific gene deletion. While changes in aggression characterize mutant mice involving a variety of genes, no pattern has emerged that links particular gene products (i.e. enzyme, peptide, receptor) to either an increase or a decrease in aggressive behavior, but rather emphasizes polygenic influences. A potentially common mechanism may be some components of the serotonin system, since alterations in 5-HT neurotransmission have been found in several of the KO mice that display unusual aggressive behavior.

Aggression↗
PubMed2001

Mid-latency evoked potentials in self-reported impulsive aggression.

The present study was conducted to examine psychophysiological differences in arousability among individuals who display impulsive aggressive outbursts. Amplitude and latency for the mid-latency evoked potentials (P1, N1 and P2) were obtained at scalp electrode sites. The evoking stimuli were three intensities (low, medium, high) of photic stimulation. Compared to non-aggressive controls, impulsive aggressive subjects showed significantly reduced P1 amplitude, which is indicative of an inefficient sensory gating mechanism. In addition, these subjects exhibited significantly larger N1 amplitude implying an enhanced orienting of attention to stimuli. Impulsive aggressive subjects also exhibited shorter P1, N1 and P2 peak latency. These results suggest that impulsive aggressive individuals may display quicker orienting and processing of stimuli in an attempt to compensate for low resting arousal levels. Finally, impulsive aggressive subjects augmented the P1-N1 component more frequently than controls, which is consistent with previous studies examining impulsivity and sensation seeking. Together, these findings extend previous work concerning the underlying physiology of impulsive aggression. It has been suggested that impulsive aggressive individuals may attempt to compensate for low resting arousal levels by engaging in stimulus seeking behaviors. Accordingly, the present findings imply similar physiological compensatory responses as demonstrated by heightened orienting of attention, processing and arousability. In addition, a compromised sensory gating system in impulsive aggressors may exacerbate such circumstances, and lead to later cognitive processing deficits.

Aggression↗
PubMed1997

Early androgen effects on aggression in children and adults with congenital adrenal hyperplasia.

Males are more likely than females to show aggressive behavior across species, ages, and situations, and these differences may be partly influenced by early hormones. We studied aggression in three samples of subjects with congenital adrenal hyperplasia (CAH), who were exposed to high levels of androgen in the prenatal and early postnatal periods. Controls were siblings and first cousins similar in age. In Sample 1, adolescents and adults completed the Multidimensional Personality Questionnaire (MPQ), which includes an Aggression scale. In Sample 2, adolescents and adults completed the MPQ and a paper-and-pencil version of Reinisch's Aggression Inventory. In Sample 3, parents rated the aggression of children aged 3-12, using a modification of Reinisch's Inventory. In all three samples, control males had higher aggression scores than control females. Further, as predicted, females with CAH had higher aggression than control females, but the difference was significant only in adolescents and adults. These results suggest that early androgens contribute to variability in human aggression.

Adolescent↗
PubMed2002

Irritability, acute alcohol consumption and aggressive behavior in men and women.

The purpose of this study was to investigate the influence of irritability on alcohol-related aggression in men and women. Subjects were 204 (111 men and 93 women) healthy social drinkers between 21 and 35 years of age. Irritability was measured using the Caprara Irritability Scale. Following the consumption of either an alcohol or a placebo beverage, subjects were tested on a modified version of the Taylor Aggression Paradigm in which mild electric shocks were received from, and administered to, a fictitious opponent during a competitive task. Aggressive behavior was operationalized as the shock intensities administered to the fictitious opponent under conditions of low and high provocation. Of all the variables, provocation was the strongest elicitor of aggression. Overall, irritability was positively related to aggression for all subjects. The finding of greatest importance was that alcohol increased aggression for persons with higher, as opposed to lower, levels of irritability. However, this pattern of results was only evident for men. The results highlight the fact that alcohol consumption does not increase aggression in all persons and in all situations. An important goal for future research is to identify which individual differences and which contextual factors are most important in determining who will, and who will not, behave in an aggressive manner when intoxicated.

Acute Disease↗
PubMedDate not supplied

Aggression and psychopathology in persons with severe or profound mental retardation.

We examined aggression and psychopathology in persons with severe or profound mental retardation. Most aggressive episodes were directed toward other clients, and ratings of aggression were positively correlated with self-injury, stereotypic behavior, and being ambulatory. In a linear regression analysis of psychopathological correlates, aggression was most consistently predicted by dependent personality and psychosis. To better describe the construct of aggression, we also developed an Aggression-psychopathology scale. Persons with mental retardation and aggression were more likely to be impulsive, attention-seeking, dependent, socially inadequate, and anxious. Intensive efforts to modify the psychopathological correlates of aggression may improve treatment planning and outcome.

Adolescent↗
PubMed2000

Somatodendritic 5-HT(1A) autoreceptors mediate the anti-aggressive actions of 5-HT(1A) receptor agonists in rats: an ethopharmacological study with S-15535, alnespirone, and WAY-100635.

To elucidate the relative contribution of somatodendritic 5-HT(1A) autoreceptors and postsynaptic 5-HT(1A) receptors in the specific anti-aggressive properties of 5-HT(1A) receptor agonists, the influence of the novel benzodioxopiperazine compound S-15535, which behaves in vivo as a competitive antagonist at postsynaptic 5-HT(1A) receptors and as an agonist at 5-HT(1A) autoreceptors, upon offensive and defensive aggression was investigated in wild-type rats using a resident-intruder paradigm. S-15535 exerted a potent dose-dependent decrease in offensive, but not defensive, aggressive behavior (inhibitory dose (ID)(50) = 1.11 mg/kg). This anti-aggressive profile was roughly similar to that of the potent pre- and postsynaptic 5-HT(1A) full agonist alnespirone (ID(50) = 1. 24). The drug's profound anti-aggressive actions were not accompanied by sedative side effects or signs of the "5-HT(1A) receptor-mediated behavioral syndrome," which are characteristically induced by prototypical 5-HT(1A) receptor agonists like 8-OH-DPAT and buspirone. The selective pre- and postsynaptic 5-HT(1A) antagonist WAY-100635, which was inactive given alone, abolished the anti-aggressive effects of S-15535 and alnespirone, thereby confirming the involvement of 5-HT(1A) receptors. Furthermore, combined administration of S-15535 and alnespirone elicited an additive anti-aggressive effect, providing further support for somatodendritic 5-HT(1A) receptor involvement. Finally, the postsynaptic 5-HT(1A) antagonistic properties of S-15535 were confirmed by showing blockade of the alnespirone-induced hypothermia, a postsynaptic 5-HT(1A) mediated response in the rat. These data provide extensive evidence that the anti-aggressive effects of 5-HT(1A) receptor agonists are expressed via their action on somatodendritic 5-HT(1A) autoreceptors, thereby most likely attenuating intruder-activated serotonergic neurotransmission.

Aggression↗
PubMed2002

Laboratory-measured aggressive behavior of women: acute tryptophan depletion and augmentation.

Plasma L-tryptophan (Trp) reductions have been related to aggression increases in men. Impairment of serotonin synthesis and neurotransmission is one explanation. Using repeated-measures, this Trp manipulation study measured laboratory-induced aggression in 12 women after Trp augmentation (T+), depletion (T-), and food-restricted (fasting control) conditions. Participants were provoked with periodic subtraction of money from their task earnings by a (fictitious) partner. Aggression was defined as the number of point subtractions participants made from their fictitious partner. Participants completed five testing sessions under each condition. T+ decreased aggressive responses and T- increased aggressive responses. Post-hoc analyses showed changes in aggressive behavior were specific to women with higher fasting control plasma Trp, which is consistent with research demonstrating that men with higher levels of baseline Trp are more aggressive. These findings indicate that both T+ and T- can influence aggressive behavior and that certain subgroups of women may be more susceptible to serotonin manipulation.

Adolescent↗
PubMed2001

Alcohol use and workplace aggression: an examination of perpetration and victimization.

PURPOSE: The purpose of the present investigation was to examine the relationship between victimization from and perpetration of workplace aggression between coworkers and frequency of alcohol use during the last year. METHODS: Civilian employees (N = 300) selected from the US population were interviewed over the telephone with psychometrically sound measures of workplace aggression and alcohol use frequency during the last year. Hierarchical regression analyses were used to examine the relationship between alcohol use and workplace aggression, after controlling for sociodemographic variables. RESULTS: Both percentage of days of any drinking and percentage of days of heavy drinking during the last year were positively related to (a) victimization from verbal and physical aggression at work and (b) perpetration of verbal and physical aggression at work. IMPLICATIONS: Consistent with research studies spanning the sociobehavioral literature, the present investigation found alcohol use was associated with perpetration of and victimization from verbal and physical workplace aggression. Although the study established an association exists between alcohol use and workplace aggression, future investigations should attempt to understand employee alcohol use in the context of a multifaceted model that includes other likely factors that contribute to the incidence of aggressive behavior on the job.

Adolescent↗
PubMed2005

Characteristics of aggression in clinically referred children.

OBJECTIVE: We investigated the phenomenology of aggression in a group of psychiatrically referred children and in a comparison group of children. INTRODUCTION: Children (N=275) were evaluated at a pediatric psychopharmacology clinic in an academic medical center and compared with 100 non-referred children from the community. To assess the influence of several predictors on the child's level of clinical impairment we conducted stepwise regression analyses. RESULTS: Aggression occurred across many different psychiatric diagnoses in psychiatrically referred children. Aggression in referred children was more frequent, physical, intense, lasted for a longer duration per episode, was more resistant to intervention, and occurred at an earlier age of onset in contrast with comparison children. Controlling for psychiatric diagnosis and demographic variables, family income and number of aggressive episodes in the last 6 months were the only significant predictors of child impairment. DISCUSSION: Phenomenologically, aggression may be more maladaptive in children with a psychiatric disorder compared with non-referred youths. These phenomenological differences in characteristics of aggression support the concept of an aggressive syndrome in psychiatrically referred children. CONCLUSION: Results support the need for development of specific treatment interventions for excessive maladaptive aggression independent of psychiatric diagnosis in referred children and adolescents.

Adolescent↗
PubMed2000

Cannibalism and intraguild predation among phytoseiid mites: are aggressiveness and prey preference related to diet specialization?

We tested whether specialist and generalist phytoseiid mites differ in aggressiveness and prey choice in cannibalism and intraguild predation. Specialists tested were Galendromus occidentalis, Neoseiulus longispinosus, Phytoseiulus persimilis, and P. macropilis; generalists tested were Amblyseius andersoni, Euseius finlandicus, E. hibisci, Kampimodromus aberrans, Neoseiulus barkeri, N. californicus, N. cucumeris, NM fallacis, and Typhlodromus pyri. Aggressiveness of cannibalistic females against larvae was not related to diet specialization except that highly aggressive species were exclusively generalists. Seldom to moderately cannibalizing species occurred in both generalist and specialist phytoseiids. In contrast to aggressiveness in cannibalism, generalists and specialists differed in aggressiveness in intraguild predation. Adult females of specialists were only slightly aggressive against heterospecific larvae, whereas adult females of all generalists except T. pyri were highly aggressive. Adult females of generalists were able to discriminate between con- and heterospecific larvae and preferentially consumed the latter when given a choice. Adult females of specialists except G. occidentalis showed no preference when given a choice between con- and heterospecific larvae. We conclude that aggressiveness in intraguild predation, species recognition and subsequent preferential consumption of heterospecifics when given a choice is common in generalist but not specialist phytoseiids. We discuss the evolutionary pathways that might have led to the difference between specialists and generalists in species discrimination.

Aggression↗
PubMed1998

Specificity of dating aggression and its justification among high-risk adolescents.

Ninety-five high-risk adolescents were studied to determine whether their dating aggression and its justification as a response to interpersonal problems were specific to the current partner, general to dating relationships, or part of a global age-mate (same-sex peers and opposite-sex dating partners) aggression problem. Approximately one-third of males and two-thirds of females reported physical aggression against their current dating partner. Males' aggression (and its justification) toward their current dating partner was part of a generalized pattern of dating aggression, whereas for females, physical aggression against a current dating partner (and its justification) was partner-specific and unrelated to aggression in other relationships. Findings are discussed with regard to intervention and future research on adolescent dating aggression.

Adolescent↗
PubMed2003

Effects of pairing aggressive and nonaggressive children in strategic peer affiliation.

Examined the behavior of 118 second graders who participated in a 6-week summer school program that incorporated strategic peer affiliation (a "buddy system"). Moderately aggressive children (the targets of the intervention) were paired with nonaggressive peers throughout the program. All participants were observed playing foosball with their buddies and with aggressive and nonaggressive nonbuddies as teammates. Aggressive children had lower levels of disruptive behavior when their teammate was nonaggressive, regardless of whether the teammate was a buddy. Nonaggressive children showed elevated disruptive behavior when playing with an aggressive nonbuddy, but not when playing with an aggressive buddy. The highest level of aggressive behavior was seen in pairs of aggressive teammates who were friends. One year later, no increase in peer-rated aggressive behavior was found in either group. Results suggest that unidirectional peer influence is possible and that strategic peer affiliation can be an effective intervention that does not put nonaggressive children at risk for acquiring undesired behaviors.

Aggression↗
PubMed2004

Association of normative beliefs and anger with aggression and antisocial behavior in Russian male juvenile offenders and high school students.

Examined the association of anger experience and two types of normative beliefs with physical aggression and nonaggressive antisocial behavior in 361 juvenile offenders and 206 high school students in Russia. All participants were male and ranged in age from 14 to 18 years. Higher frequency of aggressive acts was significantly associated with higher levels of anger and stronger beliefs that physical aggression is an appropriate course of action in conflicts. After statistically controlling for nonaggressive antisocial behavior, the relationship between physical aggression and antisocial beliefs was not significant. Similarly, with physical aggression controlled, nonaggressive antisocial behavior was uniquely associated with approval of deviancy, but not with anger or beliefs legitimizing aggression. Juvenile offenders reported higher levels of anger experience and higher frequency of aggression and antisocial behavior compared to high school students. There were no differences in normative beliefs between these two groups. This specificity of association of social-cognitive and emotion-regulation processes to aggressive and nonaggressive forms of antisocial behavior may be relevant to understanding the mechanisms of cognitive-behavioral therapy for conduct disorder and antisocial behavior.

Adolescent↗
PubMed2001

Differential gene expression in neutrophils from patients with generalized aggressive periodontitis.

Differential gene expression was investigated in neutrophils stimulated with N-formyl-methionyl-leucyl-phenylalanine using RNA fingerprinting by arbitrarily primed polymerase chain reaction (RAP-PCR). The cells were isolated from 3 groups of subjects: patients with generalized aggressive periodontitis (Aggressive-P. n = 6), generalized chronic periodontitis (Chronic-P, n = 6) and healthy controls (H, n = 8). Our results show that 37 genes were upregulated. while 27 genes were down-regulated in all Aggressive-P neutrophils by using RAP-PCR with 45 primer pairs. Reverse transcription-PCR analyses revealed that mRNA levels were significantly different (p<0.05) for heat shock transcription factor 4b (HSF4b) gene. Kruppel-like zinc finger transcription factor 9 (Zf9) and muskelin genes. HSF4b was greater in neutrophils from Aggressive-P compared to groups H and Chronic-P. Zf9 and muskelin genes were lower in Aggressive-P compared to the H groups, but no significant difference was noted compared to the Chronic-P group. The control genes, IL-1beta and VEGF genes, were expressed at a significantly higher level in Aggressive-P and Chronic-P than H (p<.01, p<0.05). In conclusion, the RAP-PCR technique used in this study enabled us to identify 3 Aggressive-P related genes, which had not been reported previously. Neutrophil functions in Aggressive-P patients are suggested to be altered by regulatory factors of the immune system including HSF4b (transcription factor), Zf9 (activator of TGF-beta) and muskelin (cellular adhesion).

Adult↗
PubMed1997

Relational and overt aggression in preschool.

This research was designed as an initial attempt to assess relational aggression in preschool-age children. Our goal was to develop reliable measures of relational aggression for young children and to use these instruments to address several important issues (e.g., the relation between this form of aggression and social-psychological adjustment). Results provide evidence that relationally aggressive behaviors appear in children's behavioral repertoires at relatively young ages, and that these behaviors can be reliably distinguished from overtly aggressive behaviors in preschool-age children. Further, findings indicate that preschool girls are significantly more relationally aggressive and less overtly aggressive than preschool boys. Finally, results show that relational aggression is significantly related to social-psychological maladjustment (e.g., peer rejection) for both boys and girls.

Aggression↗
PubMed2003

Physical aggression and expressive vocabulary in 19-month-old twins.

In the prevention of physical aggression, possible etiological links with language development are rarely taken into account. Indeed, little is known about when language and aggressive behavior become linked during development and which mechanisms are responsible for this association. This study investigated the association between physical aggression and language in late infancy with a genetic design that involved 562 19-month-old twins. A modest but significant correlation (r = -.20) was found between physical aggression and expressive vocabulary. Substantial heritability was found for physical aggression. Quantitative genetic modeling suggests that the correlation between expressive vocabulary and physical aggression cannot be explained by shared etiologies. However, phenotype-to-phenotype models indicate that the covariation can be entirely accounted for by a significant phenotypic path from expressive vocabulary to physical aggression. The implications of these results for early prevention of chronic physical aggression are discussed.

Aggression↗