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PubMed2007

The role of sexual scripts in sexual aggression and victimization.

Two longitudinal studies examined German adolescents' sexual scripts in relation to the normative acceptance of sexual aggression, the behavioral enactment of risk factors, and the experience of sexual aggression/victimization. Study 1 comprised a sample of 283 10th and 11th grade high school students who completed measures of sexual scripts, normative acceptance of risk elements associated with sexual aggression, behavioral risk-taking, and normative acceptance of sexual aggression in relationships twice with a nine-month interval. General and individual scripts differed significantly in terms of the prevalence of risk elements, with individual scripts containing fewer risk elements. Normative acceptance of risk elements was linked to the enactment of risky behavior in sexual interactions and also to the normative acceptance of sexual aggression, both concurrently and over time. In Study 2, 232 12th and 13th grade students completed measures of sexual scripts and of sexual aggression or sexual victimization. Higher risk scores in the individual scripts were predictive of sexual aggression among boys and sexual victimization among girls. The findings were discussed in terms of the significance of sexual scripts as guidelines for sexual behavior.

Adolescent↗
PubMed2005

Multilevel correlates of childhood physical aggression and prosocial behavior.

The study identified independent individual, family, and neighborhood correlates of children's physical aggression and prosocial behavior. Participants were 2,745 2-11-year olds nested in 1,982 families, which were themselves nested in 96 Canadian neighborhoods. Hierarchical linear modeling showed that the total variation explained by the three-level model was 28.03% for physical aggression and 17.57% for prosocial behavior. For both childhood behaviors, approximately 66% of this explained variance was between individuals and up to 30% was between families. The smallest amount of observed variation was between neighborhoods. Significant individual-level predictors common to both childhood behaviors were child's sex and maternal hostility toward the target child. Specifically, boys had more mother-reported physical aggression and less prosocial behavior. Children who experienced greater-than-average maternal hostility (compared to siblings) were more physically aggressive and less prosocial. At the family level, significant common predictors were mother depressed mood and punitive parenting. Children had higher levels of physical aggression and lower levels of prosocial behavior in families where mothers had greater depressed mood and used more punitive parenting practices. At the neighborhood level, greater perceived problems and lower poverty level were associated with higher levels of physical aggression. Results are discussed with reference to past and future studies of multilevel effects on children's socialization.

Aggression↗
PubMed2000

Impulsive aggression in borderline personality disorder.

Impulsive aggressive behaviors that include physical aggression directed towards others, self-mutilation, suicide attempts, domestic violence, substance abuse, and property destruction account for a substantial portion of the morbidity and mortality associated with personality disorders, in particular borderline personality disorder (BPD). Recent genetic, neurobiologic, and diagnostic studies suggest a dimensional approach to BPD symptomatology with impulsive aggression as one of the core dimensions for the disorder. The underlying biologic basis for impulsive aggression is centered on the serotonin hypothesis; that central 5-HT function is inversely related to aggression and suicidality. More recent research refines the theory to include associated brain regions, receptor types and neuromodulators potentially involved in the etiology of aggressivity. Treatment utilizes this information with substantial progress in well-designed placebo-controlled studies of selective serotonin reuptake inhibitors such as fluoxetine, and open-label series of atypical neuroleptics, mood stabilizers, and opioid antagonists

Aggression↗
PubMed1975

Comparative aggression in Sceloporus virgatus, S. undulatus consobrinus, and S. u. tristichus (Sauria: iguanidae).

Aggressive behaviour in both sexes of Sceloporus virgatus, S. undulatus consobrinus, and S. u. tristichus were compared by introducing a conspecific to a resident lizard in the field. Males of S. u. consobrinus exhibited high intensity aggression more commonly than did males of the other forms. Of the females, S. u. tristichus showed the greatest propensity for aggressive behaviour; S. u. consobrinus showed the least. In males, degree of aggression was correlated positively with degree of sexual dichromatism. The high degree of aggression in male S. u. consobrinus may be selectively advantageous because of (1) low density increasing space between females, (2) low density reducing selection against a relatively high frequency of violent fighting, and (3) high predation favouring lizards that do not leave their sites upon intrusion of another male. High aggression in female S. u. tristichus may be selectively advantageous because of (1) higher density leading to reduced food supply and fewer egg-laying sites, and (2) lower predation reducing selection against mobility and fighting in females.

Aggression↗
PubMed1989

Impulsivity, aggression, and neuroendocrine responses to serotonergic stimulation in substance abusers.

Alterations in the activity of central serotonergic systems have been implicated in impulsive and aggressive behavior. We examined the neuroendocrine and psychological responses of 24 substance users with differing levels of aggressiveness and impulsivity to the oral administration of an indirect serotonin agonist fenfluramine (60 mg) or placebo given in a double-blind crossover design. All subjects were volunteers on a closed research ward and were abstinent from drugs for a minimum of 5 days. Baseline plasma prolactin (PRL) levels were greater in the groups with higher levels of self-reported aggressiveness and impulsivity. When adjusted for the baseline, PRL and cortisol responses 180 min after fenfluramine administration were significantly elevated in subjects with higher levels of aggressiveness and impulsivity. Peak cortisol levels were correlated with impulsivity. PRL and cortisol responses to fenfluramine were more strongly correlated with impulsivity than aggressiveness. Also, the more impulsive subjects reported a decrease in subjective states of depression, hostility and anxiety after drug treatment. These data further support the hypothesis of altered serotonergic activity in aggressive and impulsive behaviors.

Adult↗
PubMed1988

Acute and chronic effects of ginseng saponins on maternal aggression in mice.

The present study investigated the acute and chronic effects of crude ginseng saponin (CGS), pure ginsenoside Rb1 (GS-Rb1) and ginsenoside Rg1 (GS-Rg1) on maternal aggression in mice. Maternal aggression was determined on postpartum days 5 and 7 in female mice that had been housed alone since the end of the 4-day mating period. Acute intraperitoneal administration of CGS (50 and 100 mg/kg) and GS-Rb1 (2.5 and 5 mg/kg) significantly suppressed maternal aggression in a dose-dependent manner, whereas GS-Rg1 was ineffective. As compared with the vehicle-treated group, chronic treatment with CGS (50 mg/kg) and GS-Rb1 (2.5 mg/kg) significantly suppressed maternal aggression without causing motor dysfunction, whereas GS-Rg1 (2.5 mg/kg) showed a tendency to facilitate maternal aggression. These findings indicate that the root of Panax ginseng contains a psychoactive ingredient, GS-Rb1, which can suppress maternal aggression.

Aggression↗
PubMed1987

Effects of testosterone manipulations on nonbreeding season territorial aggression in free-living male lizards, Sceloporus jarrovi.

Seasonal changes in testosterone levels in male mountain spiny lizards (Sceloporus jarrovi) are correlated tightly with seasonal changes in intensity of aggressive territorial defense. Testosterone levels are lowest in the winter when males aggregate, are moderately elevated during the summer when males show low-intensity territorial defense, and are highest during the fall breeding season when males show high-intensity territorial defense. In this study, we tested the hypothesis that changes in testosterone levels cause these seasonal changes in territorial behavior. We experimentally increased and decreased circulating testosterone levels in free-living males during the summer, when they display non-breeding season territoriality. Artificially increasing testosterone levels to levels equivalent to the breeding season significantly increased some, but not all, measures of territorial aggression. Levels of aggression attained, however, were still well below those typical of breeding season males. This implies that the transition to full breeding season levels of aggression is caused only partly by an increase in testosterone levels. Castration of males during the summer had no effect on several measures of territorial aggression. Thus the activation of nonbreeding season territoriality, which precedes testicular recrudescence by several months, is relatively unaffected by testosterone levels. Taken together these results suggest that the same behavior, in this case territorial aggression, may be controlled by different mechanisms in different seasons.

Aggression↗
PubMed1984

Aggression persists after ovariectomy in female rats.

Aggression occurs not only in males but also in females, however, under different sex-specific stimulus and endocrine conditions. After being housed with males, female rats exhibit frequent and intense aggressive behavior toward unfamiliar rats. However, the female residents primarily attack female intruder rats, while the male residents attack males and not females. Altering the hormonal condition of the intruders can modify the behavior that they provoke from the residents. Castration of the male intruders reduces aggression from male residents, but ovariectomy of the female intruders does not alter the behavior of the female residents. Treatment of the gonadectomized intruders with gonadal steroids significantly alters the response of the male residents. Resident-intruder aggressive behavior depends on the presence of the testes in the male residents but not on the ovaries or on lactation in the female residents. Even 7 weeks after ovariectomy the female residents continue to show aggressive behavior toward female intruders. In the same time period the castrated male residents show a marked decrease in aggressive and sexual behavior.

Aggression↗
PubMed1987

Androgen levels and components of aggressive behavior in men.

Serum concentrations of testosterone (Tser), 5 alpha-dihydrotestosterone (DHT), and free testosterone (Tsal) in saliva were determined in 117 healthy young men between the ages of 20 and 30. A battery of standardized tests and projective techniques were administered simultaneously in order to measure various components of aggression, including sexual aggressiveness. All three androgens show reliable positive correlations with self-ratings of spontaneous aggression. Dominance exhibits a positive, statistically significant correlation to Tser and to DHT. In addition, DHT is negatively related to the scale restraint of aggression. These results support previous findings about Tser and point to the importance of other androgens--especially DHT--for this aspect of endocrine-affect relationships. Interest in sexual aggression yielded no significant results for Tser and DHT (Tsal shows a low positive correlation). The ratio DHT/Tser, however, correlates significantly with this component of aggression.

Adult↗
PubMed1990

Effects of prolonged estrogen-progesterone treatment and hypophysectomy on the stimulation of short-latency maternal behavior and aggression in female rats.

Two experiments were undertaken to examine the stimulation of home-cage and/or maternal aggressiveness by a hormonal treatment stimulating short-latency maternal behavior. Nonpregnant ovariectomized rats were treated with a 16-day regimen providing pregnancy levels of estrogen (E, 5-mm Silastic capsule) and progesterone (P, daily injection of 4 mg) followed by E and P withdrawal, with or without a terminal injection of estradiol benzoate (EB, 5 micrograms/kg). In Experiment 1, hormonally treated and control females were exposed continuously to pups and tested for aggression toward male intruders on the fifth day of pup exposure. Females receiving E/P/Oil and E/P/EB were highly aggressive whether or not they had yet shown maternal behavior, whereas vehicle-treated females were nonaggressive. In Experiment 2, hypophysectomized (HYPX) and Sham-HYPX females received either E/P/EB or a control treatment and were tested with male intruders (a) immediately preceding and (b) on the fifth day of continuous pup exposure. HYPX and Sham-HYPX females treated with E/P/EB were almost equally aggressive both preceding and following pup exposure (during which they initiated maternal care), whereas HYPX and Sham-HYPX vehicle-treated females were nonaggressive at both tests. In contrast, maternal behavior latencies were reduced by E/P/EB only among Sham-HYPX females. The results establish that an E/P/EB-treatment which elicits short-latency maternal responses also increases aggressiveness toward intruders. Pituitary products, although involved in the mediation of maternal responsiveness, do not contribute significantly to the stimulation of female aggressiveness by ovarian hormones.

Aggression↗
PubMed1991

Medroxyprogesterone acetate, aggression, and sexual behavior in male cynomolgus monkeys (Macaca fascicularis).

Medroxyprogesterone acetate (MPA) is used clinically to treat male sex offenders, but there are conflicting reports about its effects on aggression. To investigate these matters in a nonhuman primate, four intact male cynomolgus monkeys were studied in a testing paradigm that involved the presence of a caged, aggression-arousing stimulus male either immediately before or during a pair-test with an ovariectomized, untreated female partner. After two 4-week periods of pretreatment baseline, males received weekly injections of 40 mg MPA either alone (two 4-week treatment periods) or in combination with testosterone replacement with sc implants (one period) and additional daily injections of 2 mg testosterone propionate (two periods). MPA was then withdrawn while testosterone replacement continued (three periods). The testing paradigm was effective in maintaining aggression, especially male-male aggression, for many months. Male-male aggression increased with MPA treatment, and increased further with testosterone replacement, whereas male-female aggression tended to change in the opposite direction. As in earlier studies, MPA decreased both plasma testosterone and male sexual activity, but restoring plasma testosterone levels in treated males failed to restore their sexual activity. MPA therefore has behavioral effects that are not mediated primarily by its suppression of circulating androgens.

Aggression↗
PubMed1987

Imidazole modification of aggressive behaviour in rats and mice.

Imidazole (IMID) strongly affected aggressive behaviour in rodents, the type of influence varying according to the experimental model considered. In morphine-dependent rats, during naloxone-induced abstinence syndrome, signs of irritability and mild aggressiveness were observed after treatment with IMID. Moreover, IMID enhanced aggressive posturing elicited by the dopaminergic (DA) agonist lisuride, whether rats were affected by morphine-withdrawal symptoms or not. In isolation test in mice, on the other hand, IMID inhibited aggression. Imidazoleacetic acid, one of the metabolites of histamine, comparatively investigated in the same behavioural tests, never potentiated lisuride-induced aggressiveness in rats; moreover, it was more effective than IMID in inhibiting aggression in isolated mice.

Aggression↗
PubMed1984

Episodic excitation and changes in aggressive behavior induced by apomorphine in rats subjected to REM sleep deprivation.

Behavioral changes induced by apomorphine in normal, pseudodeprived (control) and REM sleep-deprived AM-2/TOR inbred rats were investigated. Deprived rats exhibited aggressive behavior for nearly 30 min in the absence of administration of drug, this effect not being observed in normal or control rats. The administration of apomorphine (1, 2 and 5 mg/kg) 5 min before the test elicited short periods of aggressive behavior in normal and control rats, but decreased the total duration of aggressive behavior in deprived rats. However, the deprived rats exhibited a more intense aggressive behavior, since the frequency of real fighting events was enhanced. The administration of apomorphine to deprived rats elicited stereotyped behavior. Enhancement of stereotyped behavior by increasing the dose was correlated with a reduction in the duration of aggressive behavior. Apomorphine also induced short episodes of intense excitability, manifested by increased locomotor activity, jumping and vocalization. This behavioral response was termed "episodic excitation". Deprived rats were significantly more sensitive to apomorphine-induced episodic excitation than normal and control rats. The episodic excitation, stereotyped and aggressive behavior displayed by deprived rats, injected with apomorphine, alternated with time. The results demonstrate increased responsiveness to apomorphine after deprivation of REM sleep. The possible mechanism for such interaction is discussed.

Aggression↗
PubMed1986

Effect of chronic administration of alprazolam and adinazolam on clonidine- or apomorphine-induced aggression in laboratory rodents.

The activity of chronic (3 weeks) treatment with the triazolobenzodiazepines, alprazolam and adinazolam, on clonidine- and apomorphine-induced aggression were studied. Adinazolam, like desipramine, potentiated aggression induced by clonidine while diazepam and alprazolam completely abolished it. In the apomorphine-induced aggression, adinazolam suppressed both aggressivity and stereotypy, while diazepam slightly potentiated it. Alprazolam did not modify the effect of aggression induced by apomorphine. On the whole, while adinazolam seemed to develop an activity closer to that of a classical antidepressant like desipramine, alprazolam appeared to be more similar to the benzodiazepines on clonidine-induced aggression in mice. Compared to desipramine and diazepam, adinazolam left these two effects induced by apomorphine almost unchanged. The experiments performed showed differences between the profiles of action of the two triazolobenzodiazepines studied.

Aggression↗
PubMed1975

Light-dark rhythms in aggressive behavior of the male golden hamster.

A nocturnal rhythm in aggressive behavior in the male golden hamster is described. The peak frequency of aggression occurs shortly after the time of dark onset (Experiments 1 and 3). Results suggest that the rhythm is likely to be independent from similar rhythms in non-hostile social behavior and locomotor activity. The aggression rhythm is not dependent on the illumination conditions during the 10 min testing period, but is instead a function of the time of testing relative to the LD 12:12 cycle (Experiment 2). The rhythm persists for over a week in continuous illumination and requires between 2 and 4 weeks to reentrain to a 12 hr phase shift (Experiment 4). These results support the hypothesis that the aggression rhythm is endogenous to the animal. The functional significance of the aggression rhythm and its implications for future research in aggression are also discussed.

Aggression↗
PubMed1975

Effects of adrenalectomy on rhythmic and non-rhythmic aggressive behavior in the male golden hamster.

Male golden hamsters, adrenalectomized and maintained by subcutaneous implants od deoxycorticosterone-acetate (adx-DOCA), show a loss of the nocturnal rhythm in aggression seen in sham operated (sham-op) animals. A similar loss of the nocturnal aggression rhythm is evident in hamsters adrenalectomized and implanted with separate pellets of DOCA and cortisol-acetate (adx-DOCA-cortisol). However, while Adx-DOCA animals do not differ from sham-op animals in the level of aggression summed over all tests (overall aggression), the overall aggression levels of the adx-DOCA-cortisol animals are significantly higher than the levels of either the adx-DOCA or sham-op animals. Nocturnal rhythms in locomotor activity persist in all three groups. It is suggested that circadian rhythms of the pituitary-adrenocoritcal axis are important for the expression of the aggression rhythm. A possible mechanism of action is discussed.

Adrenal Glands↗
PubMed1979

Influence of PCPA, shock level, and home-cage conditions on shock-induced aggression.

In a series of experiments, the effect of parachlorophenylalanine (PCPA) on shock-induced fighting was assessed rats raised and maintained under either a 12-hr alternating light-dark cycle (LD) or constant light conditions (LL). PCPA increased shock-induced aggression only in LL groups when testing was accomplished using a 2 mA shock; PCPA resulted in increased aggression in groups from the LD condition only when testing was done at 1 mA. A procedure that used castrated and intact cagemates to manipulate home-cage social experience provided evidence for a role for social experience in determining differences between LL and LD reared rats in shock-induced aggression. However, these data also suggested that home-cage social experience was not a factor in the lighting condition influence on the effect of PCPA on shock-induced aggression. Finally, a separate experiment demonstrated that diurnal rhythms in shock-induced aggression were disrupted by handling and vehicle injection in the control procedures, so the possible role of serotonin in diurnal rhythms of aggression behavior could not be assessed.

Aggression↗
PubMed1982

Differential effects of medial, central and basolateral amygdaloid lesions on four models of experimentally-induced aggression in rats.

To clarify whether various nuclei of the amygdaloid complex play different roles in aggressive behavior including muricide, 4 types of aggression were experimentally induced in rats. These include olfactory bulbectomy (OB rats), midbrain raphe lesions (Raphe rats), administration of delta 9-tetrahydrocannabinol (THC rats) and long-term isolation (Iso rats). Rats which exhibited muricide following these treatments were subjected to bilateral lesions of either the medial (AME), central (ACE) or basolateral (ABL) amygdaloid nuclei. Both muricide and hyperemotionality in the OB rat were markedly inhibited by AME lesions. Those of the Iso and THC rats were moderately inhibited. However, in the Raphe rat, aggressive behavior was not inhibited by AME lesions. Furthermore, ACE or ABL lesions caused no significant changes in all 4 models of aggression. These results suggest that the AME plays a facilitatory role in aggression of OB, Iso and THC rats, but aggression in Raphe rat is independent of amygdaloid activity.

Aggression↗