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At least 73 records · Page 4Linked to original sources
PubMed2000

Organization and activation of sexual and agonistic behavior in the leopard gecko, Eublepharis macularius.

Gonadal sex is determined by the temperature experienced during incubation in the leopard gecko (Eublepharis macularius). Furthermore, both factors, incubation temperature and gonadal sex, influence adult sexual and agonistic behavior in this species. Yet it is unclear whether such differences in behavior are irreversibly organized during development or are mediated by differences in hormone levels in adulthood. To address this question, we gonadectomized adult females and males generated from a female-biased (30 degrees C) and a male-biased (32.5 degrees C) incubation temperature and treated them with equivalent levels of various sex steroids. We found that 17beta-estradiol (E(2)) activated sexual receptivity in females but not males, suggesting an organized sex difference in behavioral sensitivity to E(2). There were also organized and activated sex differences in attractivity to stimulus males. Although females were more attractive than males when treated with E(2), both sexes were equally unattractive when treated with dihydrotestosterone (DHT) or testosterone (T). Likewise, sex differences in aggressive and submissive behavior were organized and activated. Attacks on stimulus males were activated by T in males but not in females. In contrast, hormones did not influence flight behavior in males but did affect female submissiveness. Overall, males also evoked more attacks by stimulus males than did females. Nevertheless, females and males treated with androgens evoked more attacks than animals of the same sex that were treated with cholesterol or E(2). Incubation temperature had some weak effects on certain behaviors and no effect on others. This suggests that temperature effects in gonadally intact geckos may be due primarily to differences in circulating levels of hormones in adulthood. We conclude that gonadal sex has both organizational and activational effects on various behaviors in the leopard gecko.

Aggression↗
PubMed1981

Carbachol-induced agonistic behavior in cats: aggressive or defensive response.

The effects of intrahypothalamic carbachol microinjections were investigated in unprovoked cats. The carbachol evoked mydriasis, attention, vocalization, and piloerection, i.e. features of a typical defense were usually concomitant in evoked response, while the clear-cut aggressive or escape patterns appeared only once. No basic differences were observed in the set of manifestations induced by low (1-2.5 micrograms) and high (20-40 micrograms) doses of carbachol, and from left and right hypothalamus as well as from medial and lateral portion of the hypothalamus. It is concluded that carbachol-induced response does not represent an aggressive pattern but corresponds to the cat’s defense and threat behavior.

Aggression↗
PubMed1998

Behavioral effects of peripheral interleukin-1 administration in adult CD-1 mice: specific inhibition of the offensive components of intermale agonistic behavior.

Peripheral administration of interleukin-1beta (IL-1beta) in rodents reduces exploratory behavior in a novel environment while decreasing social investigation of a juvenile conspecific. In this study we wanted to test the effects of peripherally administered IL-1beta on another aspect of the mouse social repertoire, namely intraspecific fighting towards an adult male intruder. In the first experiment, sickness behavior induced by IL-1beta (1 microg/mouse) in adult CD-1 mice was assessed by direct observation of behavioral changes following placement into a novel environment. Three hours after injection, subjects were individually introduced for 20 min in a cage with clean sawdust and a number of behavioral items recorded. Blood samples were collected at the end of the testing session. Body temperature was measured right before, 1 h and 3.5 h following injection. In IL-1beta treated mice, exploration (assessed by measuring duration and frequency of Wall Rearing and Rearing behaviors) was nearly totally suppressed, while duration and frequency of behaviors such as Grooming, Bar Holding, and Digging were also markedly reduced. Administration of IL-1beta significantly elevated CORT secretion above basal levels and, as previously reported for mice, induced hypothermia (about 2 degrees C). In the second experiment, we assessed mice receiving IL-1beta (0.25; 0.5 or 1 microg/mouse or saline solution) in a social context. Three hours after injection, subjects were placed into a neutral cage for 20 min with a non-injected adult male conspecific and aggressive behavior scored. Overall, IL-1beta administration affected the social repertoire of treated mice in a dose-dependent fashion. Specifically, agonistic components of aggressive behavior were nearly totally suppressed, while the defensive elements, such as Upright Defensive posture, Upright Submissive posture, Crouching, or Flee were not affected by IL-1beta. Overall these data support the notion that sickness behavior induced by IL-1beta administration represents an organized behavioral strategy and is not an aspecific response to an illness-type of condition.

Agonistic Behavior↗
PubMed1999

[Agonistic behavior: model, experiment, perspectives].

Repeated experiences of social victories or defeats in daily agonistic confrontations led to different changes of the brain neurotransmitter activities in male mice with alternative types of social behaviour. Total activation of the brain dopamine metabolism was found in winners. Chronic defeats were accompanied by specific changes in serotonin and noradrenaline metabolism in limbic areas of the brain. Between losers and winners, significant differences were found in emotionality, exploratory activity, locomotion, level of anxiety, communicative behaviour, and alcohol consumption, as well as in immune responses and susceptibility to transplanted Krebs-2 tumour growth, gonadal function, and gastric mucosa damage. A sensory contact technique is proposed for studying the neurophysiological consequences of social conflicts.

Aggression↗
PubMedDate not supplied

[The role of steroid hormones in the sexual and agonistic behaviors of male silver foxes].

Silver fox males were tested for sexual and agonistic behaviour after introduction of a female at different stages of the reproductive cycle. The high level of aggressive interactions between male and female and no mountings were observed out of the reproductive season. During the reproductive season, the introduction of anoestrus female did not affect the aggressive behaviour but increased the number of mountings while introduction of a receptive female reduced aggressive contacts and augmented sexual behaviour in pairs independently of mating. Considerable variations in testosterone and oestradiol but not cortisol plasma levels were observed between different stages of sexual activity. At the beginning of the reproductive season, silver fox males responded to anoestrus females with significant increase in their blood levels of testosterone and oestradiol. Contents of these two hormones did not change in males during the reproductive season when they encountered a receptive female. A female did not elicit any cortisol response in a male during different periods of the reproductive cycle. The data obtained suggest that the sexual behaviour in silver fox males can be facilitated by testosterone and oestradiol while aggressive interactions between male and female occur independently of these hormones.

Agonistic Behavior↗
PubMed1985

Acute changes in plasma steroids and agonistic behavior in male Japanese quail.

A systematic analysis of the acute (minutes to hours) fluctuations of plasma steroids [androstenedione (A), 5 alpha-dihydrotestosterone (DHT), testosterone (T), corticosterone (B)] was investigated in relation to the fighting behavior displayed by experienced male Japanese quail (Coturnix coturnix) in short-term (2 min) dyadic encounters. Plasma levels of hormones measured in competitors either 1 hr before, during, or 3 min to 6 hr following a fight related poorly to either the attacking or nonattacking behavior displayed by opponents. However, transient fluctuations measured by the percentage change from prefight levels of plasma DHT, T, and B were identified in individuals following the onset of the fight. Winners demonstrated significantly greater percentage changes than did the losers at 3, 32, and 362 min for DHT and T and at 7 min for B. These differences in hormonal responses to the fight are attributed to the more aggressive behavior displayed by the victorious opponents (winners) over their defeated competitors (losers). Significance of these rapid changes is discussed in relation to the physiology and behavior of aggressive interactions.

Aggression↗
PubMed1996

Effects of the 5-HT1A antagonist (+)-WAY-100135 on murine social and agonistic behavior.

Compounds previously identified as 5-HT1A antagonists have subsequently been demonstrated to possess partial agonistic properties in models assessing somatodendritic autoreceptor function. This study examined the influences of (+)-WAY-100135, claimed to be the first selective 5-HT1A antagonist, on offensive behaviour in male mice. Employing a resident-intruder paradigm, administration of (+)-WAY-100135 (1.0-10.0 mg/kg s.c.) enhanced elements of resident offensive behaviour at 2.5 and 5.0 mg/kg but reduced such behaviour at 10.0 mg/kg. In comparison, resident defensive postures remained unchanged except for a significant increase in defensive sideways behaviour at 10.0 mg/kg. These effects were accompanied by reduced rearing behaviour across the dose range tested. Attend/approach behaviour was significantly reduced at the lowest, but increased at the highest, doses tested. Such results may reflect response competition rather than concomitant motor impairment. Given the dynamic behavioural interactions occurring in this paradigm, the increased offensive behaviour of the resident mice leads to enhanced defence and counter-attack by the intruder conspecifics. The results are discussed with reference to the current literature concerning the behavioural effects of other 5-HT1A antagonists.

Agonistic Behavior↗
PubMed1989

Temporal and sequential patterns of agonistic behavior: effects of alcohol, anxiolytics and psychomotor stimulants.

Social and agonistic interactions are composed of a range of species-typical acts, postures, displays and other communicative signals that follow characteristic patterns. Descriptive and analytic methods permit an assessment of the temporal and sequential features of highly probable patterns of agonistic interactions. Analysis of the intervals that separate consecutive attacks by a resident mouse or rat toward an intruder identifies bursts or epochs of attacks. Amphetamine (1.25, 2.5 mg/kg), but not diazepam or alcohol, alters the burst pattern of attack behavior. Higher doses of alcohol, but not diazepam, in either resident male rats or in lactating rats confronting an intruder, reduce the sequences of aggressive acts and postures with high transition probabilities as identified by lag sequential analysis. These results suggest that temporal and sequential patterning mechanisms may be differentially altered by amphetamine- and alcohol-type substances. These neural for many types of behavior.

Aggression↗
PubMed1997

Changes in the structure of the agonistic behavior of mice produced by D-amphetamine.

The effects of three acute doses of D-amphetamine (0.25, 1.5 and 3 mg/kg) were studied in a model of isolation-induced aggression in male mice. An ethopharmacological analysis of the encounters was carried out, which studied the frequency, total and mean duration of different behavioral categories, including the temporal distribution of attacks and the duration of inter-attack intervals. The results show a reduction in the total and mean duration of the Attack category and an increase in motor activity manifested by longer durations, both total and mean, of Non Social Exploration and shorter Immobility. The temporal analysis of Attack revealed an increase in the number of very short (< 15 s) inter-attack intervals and a temporal redistribution of the attacks to later in the course of the social encounters. These results confirm for a complex behavior such as aggression, that D-amphetamine, even at low doses, favors a fragmentation and repetition of motor routines with a simultaneous reduction in the influence of environmental cues on the control of behavior.

Agonistic Behavior↗