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PubMed1992

Alcohol and "bursts" of aggressive behavior: ethological analysis of individual differences in rats.

A quantitative ethological analysis of rodent aggression was performed in order to characterize the aggression-heightening effects of alcohol in certain individuals. In dyadic confrontations, a resident rat pursues, threatens and attacks an intruder, who reacts with defensive, flight and submissive behaviors. The behavioral data from five series of experiments conducted from 1984 through 1989 were subjected to a lag sequential analysis that identified highly predictable sequences of aggressive behavior, and to interval analysis that delineated a burst pattern of aggressive behavior. These analyses revealed a distinct behavioral sequence of pursuit----sideways threat----attack bite----aggressive posture that occurs in bursts with an inter-event interval of less than 6.6 s. In the total population, alcohol heightened attack behavior at low acute doses (0.1, 0.3, 1.0 g/kg) in 47% of the animals (n = 44), suppressed reliably attack behavior in another 25% (0.1-3.0 g/kg; n = 23) and had unreliable effects in the remaining 28% (n = 24). The peak enhancement of aggressive behavior was seen over more than a log cycle of alcohol doses (0.1, 0.3 or 1.0 g/kg) in different individuals. In an additional group of rats (n = 20), individuals were identified according to whether or not acute low alcohol doses enhanced or suppressed the frequency of attack bites. In the subgroup of five rats who doubled their attack frequency upon acute alcohol challenge, this aggression-heightening effect was confirmed on repeated occasions. The aggression-heightening effects of alcohol were seen during the high-rate interactions in the initial phase of the confrontation and particularly during the lower level of fighting later on. Regardless of alcohol dose and subgroup, the highly predictable sequence of pursuit----sideways threat----attack bite----aggressive posture remained intact as long as the individual was able to fight. The present analysis identifies those individuals in whom low alcohol doses increase the frequency of attack behavior, the number of aggressive elements in bursts and particularly the "time in burst". Alcohol produces these changes without altering the latency to initiate aggressive behavior, the rate of aggressive behavior within a burst or the number of bursts in an encounter. Alcohol may lengthen aggressive bursts by preventing termination of longer aggressive sequences rather than by altering the initiation of this behavior.

Aggression↗
PubMedDate not supplied

Expression of the startle reaction in rats genetically predisposed towards different types of defensive behavior.

The magnitudes of startle reactions, consisting of shuddering in response to acoustic signals, were studied in rats selected for predisposition to different types of defensive behavior-rats with and without passive defensive freezing reactions (catalepsy), and Norway rats selected for a lack of defensive aggression to humans or for high levels of aggression; studies were performed in an SR-Pilot apparatus. These experiments showed that expression of the startle reaction to standard sound signal in rats with a genetic predisposition to catalepsy was double that in control Wistar rats. A similar but greater difference was seen between highly aggressive and non-aggressive rats: the amplitude of the startle reaction in rats with high levels of active defensive responses was three times that in rats showing no aggression towards humans. Extinction of the reflex reaction was significantly slower in highly aggressive rats than in non-aggressive rats. A similar tendency was seen in rats with genetic predisposition to the passive defensive freezing reaction as compared with Wistar rats. It was concluded that animals with an inherited tendency to defensive behavior have higher levels of the emotional fear state, regardless of the strategy of the defensive behavior.

Agonistic Behavior↗
PubMed1991

Social experience, behavior, and stress in guinea pigs.

This study examined the effect of varying rearing and testing conditions on guinea pig aggression, courting behavior, endocrine responses and body weight. Pairs of 7-8-month-old males were placed in chronic confrontations for 6-50 days in 2 m2 enclosures. Social behavior was recorded with a total of 882 h observation time. Body weight as well as plasma glucocorticoid, testosterone and norepinephrine titers were determined for each male 20 h before, and 4, 52 and 124 h after, the onset of the chronic encounters. Three experiments were conducted: in Experiment I, 7 pairs of males, each male raised singly with one female (FRM), were confronted in the presence of an unfamiliar female, in Experiment II, 6 pairs of FRM were confronted with no female present, and in Experiment III, 7 pairs of males which were raised in different large colonies were confronted in the presence of an unfamiliar female. In Experiment II and III low levels of aggression, no distinct endocrine changes and no indications of physical injury occurred in winners or losers, whereas in Experiment I high levels of aggression and courting behavior, extreme increases in glucocorticoid titers and distinct decreases in body weights were found in both males. Losers, however, were affected to a much greater extent than winners. These findings suggest that in guinea pigs a causal relationship exists between social rearing conditions, behavior as adults and degree of social stress in chronic encounters.

Aggression↗
PubMed1994

Influence of the mother on development of aggressive behavior in male rats.

The present experiments investigated pre- and postnatal maternal effects on aggressive behavior in rats. Resident-intruder aggressive behavior of male rats in colonies (two males and two females) was studied in five experimental groups: 1 = WWY (n = 7) the two males of each colony were wild (biological father and mother were wild) fostered by a wild mother; 2 = WAY (n = 11) the two males were wild fostered by an albino Wistar mother; 3 = AAY (n = 11) the two males were albino (biological father and mother were Wistar) fostered by an albino mother; 4 = AWY (n = 12) the two males were albino fostered by a wild mother; and 5 = HWX+HAX (n = 9) one of the males was hybrid born and reared by a wild mother (the father was albino) and the other was also hybrid but born and reared by an albino mother (the father was wild). Each test lasted 10 min and the intruder was always a Wistar male. Aggression of wild rats was higher than the laboratory ones, independently of the mother (albino or wild) they were fostered by. However, hybrid males born and reared by a wild mother were more aggressive than those that were born and reared by an albino mother, in spite of the father being wild. In conclusion, crossfostering has little effect on territorial aggression, but prenatal maternal effects seem to play a major role on the ontogeny of aggressive behavior of male rats.

Aggression↗
PubMed1998

Asymmetric frontal brain activity, cortisol, and behavior associated with fearful temperament in rhesus monkeys.

The authors examined the hypothesis that rhesus monkeys with extreme right frontal electroencephalographic activity would have higher cortisol levels and would be more fearful compared with monkeys with extreme left frontal activity. The authors first showed that individual differences in asymmetric frontal electrical activity are a stable characteristic. Next, the authors demonstrated that relative right asymmetric frontal activity and cortisol levels are correlated in animals 1 year of age. Additionally, extreme right frontal animals had elevated cortisol concentrations and more intense defensive responses. At 3 years of age, extreme right frontal animals continued to have elevated cortisol concentrations. These findings demonstrate important relations among extreme asymmetric frontal electrical activity, cortisol levels, and trait-like fear-related behaviors in young rhesus monkeys.

Agonistic Behavior↗
PubMed2006

Differential responsiveness to fluoxetine during puberty.

In male golden hamsters (Mesocricetus auratus), attack frequency decreases during puberty. As serotonin inhibits offensive responses in adult hamsters, it is hypothesized that the serotonin system becomes upregulated in the hypothalamus during puberty. This hypothesis was tested through acute treatment with fluoxetine, a serotonin reuptake inhibitor, as well as through analysis of serotonin innervation in specific brain areas. In adults, fluoxetine treatment inhibited aggressive behavior. In juveniles, high doses of fluoxetine only reduced offensive responses (i.e., frequency and repetition of attacks), whereas low doses enhanced them. Juveniles also showed a dose-specific maturation of attack targets. In addition, the density of serotonin innervation of the hypothalamus was 20% higher in adult hamsters compared with juveniles. On the basis of these data, it is proposed that the developing serotonergic system shapes the development of offensive behaviors in male golden hamsters.

Age Factors↗
PubMed1978

Threat, attack and flight elicited by electrical stimulation of the ventromedial hypothalamus of the marmoset monkey Callithrix jacchus.

In order to elucidate whether relatively primitive primates show a similar topological organization of substrates mediating defense and flight within the ventromedial hypothalamus as has been found in other mammals, 15 marmosets (Callithrix jacchus) were chronically implanted with a total of 57 electrodes for electrical stimulation. Experiments took place in a familiar environment and under systematically altered conditions. All anatomical sites yielding vocal threat and short attacks were found to be situated in the n. ventromedialis. Flight was elicited from a region immediately lateral to this nucleus and from sites in the posterior hypothalamus. Thus, it appears that the topological organization of defense and flight behavior in cat, oppossum and marmoset are essentially similar.

Aggression↗
PubMed2000

Substantia nigra glutamate antagonists produce contralateral turning and basal ganglia Fos expression: interactions with D1 and D2 dopamine receptor agonists.

Experiments measuring behavior and immediate-early gene expression in the basal ganglia can reveal interactions between dopamine (DA) and glutamate neurotransmission. Nigrostriatal DA projections influence two striatal efferent pathways that, in turn, directly and indirectly influence the activity of the substantia nigra pars reticulata (SNr). This report tests the interactions between striatal DA receptors and nigral glutamate receptors on basal ganglia function by examining both contralateral turning and Fos immunoreactivity in striatum and pallidum following unilateral intranigral microinfusions of glutamate antagonists given to intact and 6-OHDA-lesioned rats. The NMDA antagonist AP5 (1 microg), or the AMPA/kainate antagonist DNQX (0.015-1.5 microg), injected into the SNr (0.5 microl) elicited contralateral turning as well as both striatal and pallidal Fos expression. Moreover, intranigral DNQX elicited more turning and greater numbers of Fos-positive striatal neurons in 6-OHDA-lesioned animals than in unlesioned controls, suggesting that the 6-OHDA injection induces functional changes in nigral glutamate transmission. In 6-OHDA-lesioned rats, systemic injections of the DA D1 receptor agonist SKF38393 (0.5 mg/kg, i.p.) increased striatal Fos expression due to intranigral DNQX. In contrast, the D2 agonist quinpirole (0.1 mg/kg, i.p.) decreased striatal Fos expression but increased the pallidal Fos arising from intranigral AP5. In additional experiments, both intact and 6-OHDA-lesioned rats were given simultaneous intranigral and intrastriatal infusions and turning and pallidal Fos expression were measured. 6-OHDA-lesioned rats given 5 microg of intrastriatal quinpirole exhibited both turning and pallidal Fos that was significantly increased by intranigral AP5. These results indicate that the opposing influences of D2 agonists and endogenous nigral glutamate transmission are mediated by striatal D2 receptors. Finally, the behavioral effects of intranigral glutamate antagonism can be dissociated from the effects on striatal or pallidal immediate-early gene expression.

Animals↗
PubMed1993

5-HT1A and 5-HT1C/1D receptor agonists produce reciprocal effects on male sexual behavior of rhesus monkeys.

Research has indicated that serotonin (5-HT) is involved in regulating male sexual behavior in rodent, as well as primate species. The present study was designed to further characterize 5-HT influences on male sexual behavior of rhesus monkeys. Experiment 1 examined the effects of 5-HT1A and 5-HT1C/1D receptor stimulation on penile erections and yawning behavior. Administration of the 5-HT1C/1D receptor agonist, m-chlorophenylpiperazine (m-CPP, 0.8 and 3.0 mg/kg), facilitated the occurrence of penile erection, and at doses greater than 0.2 mg/kg stimulated yawning. By contrast, the 5-HT1A receptor agonist, 8-hydroxy-2-(di-n-propylamino)tetralin (8-OH-DPAT, 0.01-0.2 mg/kg) did not significantly influence penile erections or yawning behavior. Experiment 2 evaluated the effects of m-CPP and 8-OH-DPAT on the behavior of male monkeys in the presence of a sexually receptive female monkey which the males could see, hear and smell, but not physically contact. Administration of m-CPP along with presentation of a receptive female stimulated penile erections to a greater extent than they were stimulated by either one of these manipulations alone. Administration of 8-OH-DPAT (0.1 and 0.2 mg/kg) produced a decrease in the percent of monkeys exhibiting penile erections in the presence of the female. In this experiment, yawning was affected in opposite directions, with m-CPP stimulating and 8-OH-DPAT decreasing the frequency of yawning. Experiment 3 assessed the effects of m-CPP on male copulatory behavior of rhesus monkeys. Administration of m-CPP (0.8-3.0 mg/kg) produced a dose-dependent decline in the percent of males initiating copulation and achieving ejaculation.(ABSTRACT TRUNCATED AT 250 WORDS)

8-Hydroxy-2-(di-n-propylamino)tetralin↗
PubMed1991

A comparative study of the behavioral effects of d-amphetamine and apomorphine in the rat.

A wide range of doses of d-amphetamine and apomorphine were injected into rats, in order to better characterize and compare dopaminergic agonist-induced behavioral effects. The study was carried out using a computerized technique for the quantification and analysis of various behavioral elements. Although both drugs increased motor activity and provided dose-dependent stereotyped responses, the whole pattern of behavior in the open field showed a different structure. d-Amphetamine in doses that did not produce stereotyped responses induced a wide range of varied behavioral elements with increased frequency but decreased mean duration, while apomorphine induced a more restricted behavioral profile. Furthermore, a higher frequency of freezing reaction was observed after d-amphetamine treatment in low doses but not after apomorphine treatment. Both drugs in high doses elicited a similar stereotyped syndrome characterized by repetitive movements of great duration, but at low doses the behavioral pattern was completely different. The apomorphine-induced syndrome was characterized mainly by moving and sniffing, interrupted by rearing, while the amphetamine-induced syndrome by sniffing and moving, interrupted by standing and freezing.

Animals↗
PubMed1990

Selective unilateral inactivation of striatal D1 and D2 dopamine receptor subtypes by EEDQ: turning behavior elicited by D2 dopamine receptor agonists.

The unilateral intrastriatal injection of the irreversible dopamine (DA) receptor blocker N-ethoxycarbonyl-2-ethoxy-1,2-dihydroquinoline (EEDQ) induces a marked decrease in the density of D1 (-48%) and D2 (-51%) DA receptors available for binding to [3H]SCH 23390 and [3H]raclopride, respectively. A challenge dose of the D2 agonist LY 171555 (1 mg/kg, i.p., 24 h after EEDQ) causes intensive ipsiversive circling behavior, whereas the selective D1 agonist SKF 38393 (20 mg/kg, i.p., 24 h after EEDQ) is unable to induce rotations. The density of D1 and D2 DA receptors returns to basal levels by 7 days after the intrastriatal infusion of EEDQ. This biochemical recovery is associated with a progressive decrease in the number of rotations elicited by a challenge dose of LY 171555, suggesting that EEDQ does not cause any relevant neuronal damage. A selective inactivation of striatal D1 or D2 DA receptors can be obtained by injecting EEDQ 30 min after the administration of the D2 antagonist raclopride (20 mg/kg, i.p.) or of the D1 antagonist SCH 23390 (2 mg/kg, s.c.), respectively. The intensity of the circling behavior induced by LY 171555 24 h after EEDQ in animals with a selective inactivation of D2 DA receptors is similar to that found in rats in which both D1 and D2 DA receptors have been inactivated. In contrast, LY 171555 does not cause rotations when the density of D1 DA receptors is selectively decreased by EEDQ in rats pretreated with raclopride.(ABSTRACT TRUNCATED AT 250 WORDS)

2,3,4,5-Tetrahydro-7,8-dihydroxy-1-phenyl-1H-3-ben↗
PubMedDate not supplied

5-HT1A agonists modulate mouse antipredator defensive behavior differently from the 5-HT2A antagonist pirenperone.

The mouse defense test battery (MDTB) has been designed to investigate defensive reactions in Swiss-Webster mice to situations associated with a natural predator, the rat, such as flight, avoidance, defensive threat, defensive attack, and risk assessment activities. The present study evaluated the ability of 8-OH-DPAT (0.05-10 mg/kg, SC, 5) and gepirone (2.5-10 mg/kg, IP, 30), a full- and a partial agonist at 5-HT1A sites, as well as pirenperone (0.25-1 mg/kg, IP, 30), a preferential 5-HT2A receptor antagonist, to exert an anxiolytic-like action in the MDTB. The most consistent effect of both 5-HT1A receptor agonists across tests was a marked reduction in predator assessment activity and defensive attack behavior. In contrast, neither of the two ligands was able to reduce flight responses to the approaching predator, and both failed to reduce in a specific manner contextual defense behaviors after the predator was removed. The 5-HT2A receptor antagonist pirenperone did not provide significant indication of an anxiolytic effect on predator assessment activity and postpredator potentiation of contextual defense responses, and had negligible influence on antipredator defensive behavior. The most interesting exception to this profile was a dose-related reduction in flight-related measures. In view of previous results indicating that the panic-promoting drug yohimbine increases flight/escape reactions and that the panicolytic compound alprazolam reduces these responses, we tentatively suggest that the preferential 5-HT2A receptor antagonist pirenperone may have some efficacy in improving panic attacks. In addition, the lack of effect of the 5-HT1A receptor agonists on these flight responses is consistent with clinical findings indicating that these agents are of limited use in the treatment of panic disorder. These findings suggest that the MDTB provides behavioural measures capable of differentiating between various classes of antianxiety drugs.

8-Hydroxy-2-(di-n-propylamino)tetralin↗
PubMed1988

Social organization in caged layers: the peck order revisited.

The dominance hierarchy that exists among free ranging chickens is a peck order. Several researchers have attempted to correlate various production parameters of caged layers with dominance rank, with mixed results. Animal welfare groups have expressed increasing concern over the effects of battery cage housing on the behavior of layers, even though several researchers have shown that the incidence of aggressive pecks decreases in these cages. The studies presented here demonstrate that agonistic interactions occur among most pairs of hens housed in pens but do not occur among most pairs of hens housed in cages. Therefore, peck orders could be constructed for hens housed in pens but not for hens housed in cages. Incidence of agonistic interactions is highest in cage-housed hens immediately following housing of the hens; this peak is matched when group membership is mixed. These results suggest that a social system does form among caged hens even if a peck order does not. A single dominant hen in each cage was involved in and won a large majority of the agonistic encounters in the cages. The lack of evidence of dominance relationships between pairs of hens in cages, other than those between a single dominant hen and its cage mates, supports the hypothesis that despotism, not a peck order, was the prevailing social organization among hens housed in high-density cages.

Aggression↗
PubMed1976

Behavioral effects of amphetamine in a group of rhesus monkeys with lesions of dorsolateral frontal cortex.

Four macaques with lesions of dorsolateral frontal cortex and 4 normal monkeys were injected with 1 mg/kg d-amphetamine. Observations of social behaviors and motor activity were conducted over a 1-month period. The results of this experiment show a partial dissociation of effects of amphetamines on behavior of normal and frontally lesioned animals. The frontal monkeys showed a dramatic increase in hyperactivity while normal monkeys showed a variable motor response to the drug. Conspecific social interactions were disrupted by amphetamine in normal as well as lesioned animals. A functional system featuring the caudate nucleus and dorsolateral frontal cortex is presented. In addition, the possible influence of these areas on the balance of behavior modulated by limbic structures is explored. Changes in catecholamine levels are also hypothesized.

Agonistic Behavior↗
PubMed1991

Timing of neonatal testosterone exposure in the differentiation of estrogenic regulatory systems for aggression.

Neonatal female CF-1 mice were exposed to testosterone (T) or oil vehicle on Days 1-3, 4-6, or 7-9 postpartum and were tested for the display of male-like aggressive behavior in response to diethylstilbestrol (DES) after ovariectomy during adulthood. The results showed that only the Day 1-3 T treatment established the capacity to exhibit fighting behavior following estrogen administration. These data suggest that sexual differentiation of an estrogen-responsive regulatory system for aggressive behavior occurs during a highly restricted period early in life.

Aggression↗
PubMed1983

Ethological analysis of drug action on aggression and defense.

Psychopharmacological research on aggression pursues divergent objectives: From a pharmacological perspectives, animal aggression tests are employed in order to differentiate classes of psychotherapeutic drugs and to screen for specific agents. Psychiatric interests in animal aggression research attempt to model pathological aggressive behavior in humans. These efforts have yielded disappointing results because they are based neither on a detailed understanding of the behavioral characteristics of aggression nor of the relevant neural processes. The ethological approach to aggression research focuses on biologically relevant situations and behavior patterns. Quantitative methods describe drug action on the interactive and episodic nature of aggressive behavior. An analysis of the temporal pattern of aggressive behavior indicates how, for example, amphetamine and alcohol modulate sequences of aggressive interactions.

Aggression↗