Fluprazine hydrochloride does not decrease defensive behaviors of wild and septal syndrome rats

Non-angry aggressive arousal and angriffsberietschaft: A narrative review of the phenomenology and physiology of proactive/offensive aggression motivation and escalation in people and other animals

Human aggression typologies largely correspond with those for other animals. While there may be no non-human equivalent of angry reactive aggression, we propose that human proactive aggression is similar to offense in other animals' dominance contests for territory or social status. Like predation/hunting, but unlike defense, offense and proactive aggression are positively reinforcing, involving dopamine release in accumbens. The drive these motivational states provide must suffice to overcome fear associated with initiating risky fights. We term the neural activity motivating proactive aggression "non-angry aggressive arousal", but use "angriffsberietschaft" for offense motivation in other animals to acknowledge possible differences. Temporal variation in angriffsberietschaft partitions fights into bouts; engendering reduced anti-predator vigilance, redirected aggression and motivational over-ride. Increased aggressive arousal drives threat-to-attack transitions, as in verbal-to-physical escalation and beyond that, into hyper-aggression. Proactive aggression and offense involve related neural activity states. Cingulate, insular and prefrontal cortices energize/modulate aggression through a subcortical core containing subnuclei for each aggression type. These proposals will deepen understanding of aggression across taxa, guiding prevention/intervention for human violence.

Serotonin and aggressive behavior in rodents and nonhuman primates: predispositions and plasticity

This review analyzes psychosocial and genetic determinants of aggressive behavior in rodents and nonhuman primates and the role of the serotonin (5-HT) system on aggressive behaviors in order to trace possible evolutionary common origins between psychopathological and adaptive forms of aggression. Studies in primates suggest that deficit in serotonin activity, as indicated by the levels of the cerebrospinal fluid (CSF) serotonin major metabolite 5-hydroxyindoleacetic acid (5-HIAA) correlates with impulsive and aggressive behavior. It is possible that CSF 5-HIAA reflects the prevailing serotonergic tone and may be related to an aggressive trait. Superimposed on this tone are phasic serotonin changes that may be related to the inhibition of aggressive acts. Genetic factors determine aggressive behaviors as demonstrated by classic selection and strain comparison studies. Manipulations of genes targeting 5-HT receptors, transporters and enzymes can influence aggression. Some of these genes related to the serotonin transporter (5-HTT) and the monoamine oxidase A (MAO-A) show a polymorphism that may predispose, under specific environmental conditions, certain individuals to display pathological forms of aggression.

Effects of the CRF1 antagonist SSR125543A on aggressive behaviors in hamsters

Corticotropin-releasing factor (CRF) and its receptor subtypes have been implicated in endocrine and behavioral responsivity to stress and emotion, including fear, anxiety, and aggression. SSR125543A is a new nonpeptide selective antagonist at the CRF1 receptor that has been shown to produce an anxiolytic-like effect in a number of animal models of anxiety. The present study investigated effects of an oral dose of 10, or 30 mg/kg of SSR125543A on aggressive behaviors of resident male Syrian hamsters toward male intruders. The high dose (30 mg/kg) of the CRF1 receptor antagonist produced a higher latency to bite and lower lateral attack frequencies and chase durations, indicating a reduction in aggression toward intruders in resident hamsters. The same dose of SSR125543A also enhanced frequency and duration of olfactory investigation, indicating that neither avoidance of the opponent nor deficiency in social activity is responsible for the reduction in aggression seen in these animals.

An evolutionary approach to behavioral pharmacology: using drugs to understand proximate and ultimate mechanisms of different forms of aggression in mice

Psychoactive drugs (Fluprazine and Chlordiazepoxide--CDP) were used as probes to test both differences or similarities in neurochemical substrates (proximal causations) and adaptive significance (ultimate causations) of different forms of intraspecific aggression in wild mice and laboratory Swiss CD-1 counterparts. Fluprazine (1-5 mg/kg) inhibited maternal attack on female, but not on male intruders. Thus, phenotypically different attack behaviors (offence and defence respectively) which have different functions may be modulated by different neurochemical substrates. Intrasexual attack and infanticide which are phenotypically different, but share similar functions (i.e. competition for mates and resources) were equally inhibited by Fluprazine (2 mg/kg) both in males and females of wild and laboratory mice. This indicates that the neural substrates of these behaviors are related and similarly regulated in the two sexes. Fluprazine was used to test the prediction of the evolutionary model on fighting strategies in male-male asymmetric contests as far as fighting ability and resource value (mating and cohabitation with a female) are concerned. Fluprazine inhibited the intensity of fighting (i.e. more 'defensive' behavioral phenotype of attack) only in animals without previous positive fighting experience, suggesting that different behavioral strategies are based on different neurochemical modulation. Experience of attack also influenced the effects of CDP (2.5-5 mg/kg) in both lactating females and male resident mice. The reported proaggressive effects of benzodiazepines were observed only in animals with prior fighting experience in both cases. Thus the understanding of the effects of drugs on behavior demands consideration of the biological variability (e.g. genetic, previous experience and/or interindividual differences) and the adaptive significance of behavior in the experimental context. On this background ethopharmacology can be defined as an evolutionary approach to the study of a drugs effect on neurochemical mechanisms and functions of behavior.

Comparing different forms of male and female aggression in wild and laboratory mice: an ethopharmacological study

The purpose of this study was to compare the effects of 2 mg/kg fluprazine (a serotonergic psychoactive drug with antiaggressive properties) on intrasexual attack, infanticide, and predation (on an insect larva) in males and females of wild and Swiss mice. The results showed that, in both stocks of mice, fluprazine significantly inhibited intrasexual and infanticidal attack in both sexes, but predatory attack was not altered by the drug treatment. Motivational and neural substrates underlying intrasexual attack and infanticide appear, thus, to be related to each other, and similarly modulated in both males and females. Conversely, predatory attack seems to be under a different neurohumoral control. The similar regulation of proximal mechanisms of aggressive behavior observed in wild and Swiss mice suggests a common neurobiology of aggression. For this reason, the outbred laboratory Swiss mice appear to be a reliable model for studies on causal and functional mechanisms of aggression.

Adipsic, but not anorectic, effect of fluprazine hydrochloride in rats

The present experiment explored the anorectic and adipsic effects of fluprazine hydrochloride, a phenylpiperazine compound. Thirty-eight albino rats were randomly assigned either to a control saline group (six rats) or to groups (eight subjects each) receiving an IP dose of fluprazine in saline (1.25, 2.5, 5 or 10 mg/kg). No anorectic effect of the drug doses was observed 30, 60, 90, 120, 180 and 240 min, and 24 h after drug injection. However, water drinking was significantly decreased 30 min after drug administration, with 5 and 10 mg/kg, compared to saline.

Fluprazine inhibits intermale attack and infanticide, but not predation, in male mice

The effects of fluprazine (1, 2, and 5 mg/kg) on intermale attack, infanticide and predation (insect larvae) by male mice were assessed. Fluprazine dose-dependently inhibited attacks by males on conspecific intruders and genetically unrelated mouse pups. However, predatory attack on insect larvae was unaltered by any dose of the compound. Thus the neurohumoral substrates underlying intraspecific attack and pup killing may be similar to each other, but different from those modulating predatory attack and prey killing. These data support the hypothesis that male infanticide is a form of intraspecific aggression and not an expression of intraspecific predation (cannibalism). Drug-induced stimulation of paternal behavior in some previously infanticidal males suggests that serotonergic substrates may also be involved in the natural mechanisms which mediate the inhibition of infanticide and promote parental care.

Serenics fluprazine (DU 27716) and eltoprazine (DU 28853) enhance neophobic and emotional behaviour in mice

Two tests designed to elicit responses to novelty and to aversive stimuli were used to study the effects of the serenics fluprazine and eltoprazine on the behaviour of male Swiss mice: a free exploratory test (fluprazine; 2.5, 5 and 10 mg/kg; eltoprazine: 2.5, 5, 10 and 15 mg/kg) and a two-box choice procedure (fluprazine: 1.25, 2.5, 5 and 7.5 mg/kg; eltoprazine: 2.5, 5, 7.5 and 10 mg/kg). Both drugs increased the neophobic reaction, as well as the avoidance of a brightly illuminated box. These effects closely resemble those of psychostimulant drugs such as methamphetamine and caffeine. It is hypothesized that the behavioural changes induced by these drugs may be due to a nonspecific increase of the emotional reactivity of animals.

Behavioural pharmacology of the serenic, eltoprazine

In this paper the effects of serenics (eltoprazine and fluprazine) are described in several animal models for offensive agonistic, defensive agonistic and predatory behaviour. They are compared with the effects of a number of other putative anti-aggressive compounds or drugs used clinically in order to ameliorate aggressive behaviour of psychiatric patients. In isolation-induced offensive aggression in mice, eltoprazine has a marked and potent anti-aggressive activity, although numerous other psychoactive drugs also exert anti-aggressive effects. The behavioural specificity of this anti-aggressive profile was investigated using an ethologically derived animal model, social interaction in male mice. In this model, eltoprazine has a very specific anti-aggressive (serenic) profile, inhibiting aggression while social interaction and exploration are not decreased but even enhanced; inactivity, a measure for sedation, is not affected. Such a profile contrasts sharply with that of neuroleptics (chlorpromazine, haloperidol), psychostimulants (d-amphetamine) or benzodiazepines (chlordiazepoxide), which exert severe sedation (neuroleptics) or even aggression-enhancing effects (BDZ). After subchronic treatment no tolerance for the anti-aggressive effects of eltoprazine occurred. The specific anti-aggressive effects of eltoprazine were also found in rat models of offensive agonistic behaviour. In one such model - resident-intruder aggression - eltoprazine reduced offensive behaviour specifically, leaving social interactions and exploration intact, and did not induce sedation or other unwanted side-effects. The neuroleptic haloperidol was very sedative in this model, as was the 5-HT1A-agonist buspirone. Benzodiazepines (chlordiazepoxide) have a biphasic effect in this paradigm, enhancing offence at low doses and decreasing it at higher doses, due to muscle relaxation. In another offensive model, colony-aggression, in which a dominant and subordinate male in a colony are confronted with a male intruder, eltoprazine reduced offensive behaviour of both the dominant and the subordinate against the intruder. In contrast, chlordiazepoxide enhanced aggression, at least at lower doses, whereas alcohol had, up to very high doses, no effect on the offensive behaviour. In a brain-stimulation induced offensive model--hypothalamically-induced aggression in rats--eltoprazine specifically reduces offence. Locomotion, a measure for sedation, was either unaffected or even somewhat enhanced, indicating the absence of any sedatory activity of this serenic compound. In contrast, haloperidol heavily sedated animals, making them incapable of aggression.(ABSTRACT TRUNCATED AT 400 WORDS)

The inhibitory effects of fluprazine on parental aggression in female mice are dependent upon intruder sex

Lactating resident mice respond differently to male and female intruder conspecifics, showing defensive attack towards the former and offensive attack towards the latter. The effects of fluprazine (1-5 mg/kg) on this differential response pattern have been assessed. Although fluprazine increased the latencies of attack on male intruders, a very much more potent inhibitory effect was observed on attacks directed towards female intruders. Fluprazine also modestly reduced social investigation of female intruders and increased nest-oriented behaviour irrespective of the intruder's sex. As the pattern of attack on intruders, exploration, fear responses and maintenance behaviour all remained largely intact under drug treatment, it seems unlikely that the drug's inhibitory action on attack involves fear potentiation and/or olfactory impairment. It is suggested that the greater sensitivity of offensive attack to the inhibitory actions of fluprazine may reflect the relative degree of threat to resident parental investment posed by male and female conspecific intruders.

Effects of septal-forebrain lesions on maternal aggression and maternal care

Septal-forebrain lesions significantly increased the defensive reactions of lactating Long-Evans rats (n = 13) relative to nonlesioned control females. The lesions greatly enhanced defensive behaviors on a number of standard tests (e.g., responsiveness to humans and anesthetized conspecifics) while abolishing aggression toward intruding male conspecifics. The lesions also produced a striking disruption in maternal behavior as evidenced by absence of nest building, reduced litter weights, failure to retrieve, lick, or nurse pups, and increased cannibalization. While these results cannot be interpreted as indicating that maternal aggression is equivalent to offense, they are congruent with such a view. Certainly they are not supportive of a view that maternal aggression is primarily defensive. The lesion-induced abolition of maternal attack may have resulted from an inhibition of offensive tendencies by heightened defensiveness and/or reduced pup stimulation. There was no evidence that the lesion-induced impairment in maternal behavior resulted from a failure to sequence the individual behavioral acts comprising maternal behavior. Rather, all features of maternal care seemed to be greatly attenuated.

Effects of fluprazine hydrochloride on conspecific odor preferences in rats

The effect of Fluprazine Hydrochloride (DU 27716) on preference for conspecific male, estrous female and food odors was examined in male rats utilizing a two-compartment choice apparatus. Treatment with 8.0 mg/kg Fluprazine enhanced the preference of males for male odors but had no effect on preference for either estrous female or food odors. The drug-induced enhancement of male odor preference is consistent with the suggestion that Fluprazine interferes in some way with the processing of olfactory stimuli which normally precede offensive attack. The failure of the drug to alter the preference of males for estrous female odors suggests that the increased sniffing of estrous females noted during social testing may be secondary to other sources of conspecific stimulation or may reflect a highly transitory effect on olfactory processes. These results suggest that the suppressive effects of Fluprazine on intermale aggression and copulation are mediated by somewhat distinct mechanisms.

Maternal aggression in rats: lack of interaction between chlordiazepoxide and fluprazine

In a paradigm of female aggression, maternal aggression, low doses of chlordiazepoxide (CDP) enhanced aggression, whereas the serenic drug fluprazine dose-dependently decreased aggression. In this study one selected dose of CDP (5 mg/kg PO) clearly enhanced aggression of female lactating rats against a naive male intruder. This dose of CDP however, was not able to antagonize the dose-dependent decrease observed after fluprazine treatment (5, 10, 20 mg/kg IP). These data suggest that fluprazine and CDP do not simply have opposite effects at the same site of action. It is suggested that fluprazine decreased the offensive motivation of animals, whereas CDP increased attacks indirectly by reduction of the approach-avoidance conflict in a social context.