Search results for "Agonistic behaviour"
showing 10 items of 36 documents
Knee-clicks and visual traits indicate fighting ability in eland antelopes: multiple messages and back-up signals
2008
Abstract Background Given the costs of signalling, why do males often advertise their fighting ability to rivals using several signals rather than just one? Multiple signalling theories have developed largely in studies of sexual signals, and less is known about their applicability to intra-sexual communication. We here investigate the evolutionary basis for the intricate agonistic signalling system in eland antelopes, paying particular attention to the evolutionary phenomenon of loud knee-clicking. Results A principal components analysis separated seven male traits into three groups. The dominant frequency of the knee-clicking sound honestly indicated body size, a main determinant of fight…
Haloperidol does not antagonize the effects of stress on aggressive behaviour in mice.
1990
The possibility that antipsychotic drugs antagonize the behavioural effects of stress on agonistic behaviour has been explored. Male mice of the OF.1 strain were subjected to the following treatments: 1) Immobilization stress (ten or twenty minutes in duration), 2) haloperidol (three doses) and 3) immobilization stress (ten minutes) plus haloperidol. Individually housed experimental animals confronted standard opponents (anosmic animals) in ten-minute encounters in a neutral cage. Encounters were videotaped and behaviour evaluated, assigning times allocated by subjects to eleven broad behavioural categories. The data show that stress markedly decreases attack behaviour, but haloperidol does…
Acute social defeat stress increases the conditioned rewarding effects of cocaine in adult but not in adolescent mice.
2015
Stressful experiences modify activity in areas of the brain involved in the rewarding effects of psychostimulants. In the present study we evaluated the influence of acute social defeat (ASD) on the conditioned rewarding effects of cocaine in adolescent (PND 29-32) and adult (PND 50-53) male mice in the conditioned place preference (CPP) paradigm. Experimental mice were exposed to social defeat in an agonistic encounter before each session of conditioning with 1mg/kg or 25mg/kg of cocaine. The effects of social defeat on corticosterone levels were also evaluated. Adult mice exposed to ASD showed an increase in the conditioned reinforcing effects of cocaine. Only these mice developed cocaine…
Changes in the structure of the agonistic behavior of mice produced by D-amphetamine.
1997
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…
Studies on effects of tamoxifen (ICI 46474) on agonistic encounters between pairs of intact mice.
1988
The anti-estrogen tamoxifen (Tam), which has been shown to dramatically suppress offensive behavior in male rats without markedly influencing other aspects of the social encounter, was tested for its effectiveness in mice. TO strain albino mice were given control injections or 50 or 100 micrograms of Tam for 4 or 8 days. Subsequently, mice were tested in pairs (for a particular dose and treatment duration) in which both animals received Tam, one animal received Tam and one saline, or both animals received saline control injections. Ten-minute videotaped encounters were analyzed in terms of total times allocated to nonsocial investigation, social investigation, offense, defense, sexual activ…
Ethopharmacological studies on the effects of antihormones on rodent agonistic behavior with especial emphasis on progesterone.
1991
The effects of a range of antiandrogens and antiestrogens on conflict behaviors in laboratory rats and mice are reassessed in the light of recent studies applying ethophamacological analyses (recording the full spectrum of behaviors) to such investigations. It is argued that any antihostility properties of the antiandrogen cyproterone acetate are largely a consequence of indirect actions on odor communication, whereas antiestrogens (e.g., tamoxifen and CI 680) seem to have more fundamental motivational effects in addition to communicatory actions. A detailed example of the approach is provided in which progesterone (which can be antiandrogenic) is given to rats paired in different ways. The…
Social behavioural profile of cocaine in isolated and grouped male mice
2003
Studies concerning the relationship between cocaine and aggression in humans as well as in animals have discrepant outcomes. Increases, decreases, or no changes, have been reported after single or chronic cocaine administration in animal models. To clarify, at least in part, the complex behavioural actions of cocaine, the present study evaluated cocaine effects on social behaviours of mice exposed to different situations (isolated or group housed) using confrontations between two male mice in a neutral area. Different doses of cocaine (6, 25 and 50 mg/kg) were administered in a single or binge pattern (three doses in 24 h) and the behavioural test was performed 20 min after the last injecti…
Changes in behavioural response of Mediterranean Seabass (Dicenthratus labrax L.) under different feeding distributions
2009
Captive-induced behavioural deviations may involve many aspects of fish behaviour such as swimming activity and enhancement of individual aggressiveness. We studied seabass (Dicentrarchus labrax) behaviour as a function of manual and automatic feeding distribution modes. Under manual mode, the food is distributed over an extended area for a longer period, and its precise location is not always predictable, while with pneumatic automatic feeders, fish receive the same amount of resource, which is concentrated in the same surface area over a shorter period. We compared seabass behaviour under automatic and manual conditions collecting video image recordings before, during, and after feeding d…
Behavioral roles of the sexually dimorphic structures in the male harvestman, Phalangium opilio (Opiliones, Phalangiidae)
2006
Abstract: In various animal species, male sexual dimorphic characters may be used during intrasexual contests as ornaments to attract females, or to hold them before, during, or after copulation. In the well-known harvestman, Phalangium opilio L., 1758, the behavioral functions of these male sexually dimorphic structures have never been studied in detail. Therefore, in addition to a morphometric study, 21 male contests and 43 sexual interactions were analyzed. Our observations revealed that during contests, the male cheliceral horns form a surface by which the contestants use to push each other face-to-face while rapidly tapping their long pedipalps against the pedipalps of the opponent, oc…
Honesty of agonistic signalling and effects of size and motivation asymmetry in contests
1999
Game theoretical models predict that the main function of fighting behaviour is to assess the relative fighting ability of opponents. The sequential assessment game has often been used to investigate contests, while honest signalling theory has received much less attention. With the wolf spider Hygrolycosa rubrofasciata we investigated whether male agonistic signalling can reveal honest information about fighting ability, and how size and motivation asymmetries affect male fighting behaviour. We also determined whether male–male competition affects the courtship behaviour of the males. We found that agonistic drumming activity is an honest indicator of male fighting ability, and that relati…