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PubMed2003

Repeated social stress and the development of agonistic behavior: individual differences in coping responses in male golden hamsters.

In male golden hamsters, repeated social subjugation during puberty accelerates the development of adult aggressive behavior and enhances its intensity in the presence of smaller individuals. The current study is focused on the characterization of the hormonal and behavioral responses to social subjugation during puberty. Subjugation consisted of daily exposure to an aggressive adult for 20-min periods from postnatal day 28 (P-28) to P-42, while controls were placed into an empty clean cage. Plasma cortisol levels were measured prior to or immediately after treatment on P-28 and P-42. On P-28, exposure to an aggressive adult or a clean and empty cage caused an increase in plasma cortisol levels. However, only social subjugation resulted in elevated cortisol levels on P-42, showing that juvenile hamsters habituate to an unfamiliar environment but not to social subjugation. In addition, we found a relationship between the frequency of submissive responses during social subjugation and the development of aggressive behavior. The transition from play fighting to adult aggression was most accelerated in the least submissive animals. These data show that behavioral response to social subjugation determines the development of aggressive behavior in golden hamsters. Our data also suggest that submissive behavior is a form of coping that attenuates the behavioral consequences of social subjugation in male golden hamsters.

Adaptation, Psychological↗
PubMed1991

[Sexual and agonistic behavior of the fishes Aphyosemion and Rivulus (Pisces: Cyprinodontes)].

Four species of Rivulus (Neotropical) and four species of Aphyosemion (Etiopical) were observed over 58.1 Hrs in acuaria. Of 37 encounters, 23 were related to sexual behaviour and fourteen to agonistic interactions. A description of the encounters is made. In the sexual encounters, the Aphyosemion male made the female oscillate more frequent intervals but for shorter periods at than Rivulus. The intensity of the aggressive interactions increased with encounter time.

Agonistic Behavior↗
PubMed1993

Agonistic behavior and its cardiovascular components elicited by microinjection of L-glutamic acid into the basal midbrain of the toad Bufo paracnemis.

Microinjection of L-glutamic acid into the basal midbrain of the toad Bufo paracnemis induced a series of responses linked to antipredator behavior such as flight, backward locomotion and defensive postures. Furthermore, alerting/orientation occurred in 20% of the animals, a behavior which is probably important for the animal to achieve the above responses. Locomotion occurred in 18% of the toads. The existence of a mesencephalic premotor control for locomotion in these animals is discussed comparatively. All responses were accompanied by changes in arterial pressure, heart rate and intrabuccal pressure. In some animals which exhibited backward locomotion responses, defensive postures and alerting/orientation, bradycardia or cardiac arrest occurred, with no appreciable changes in arterial pressure. This fact is discussed on the basis of studies which have shown the occurrence of similar alterations in situations of fear in other vertebrates. Autonomic changes without other responses occurred in 16% of the animals. Flight behavior was usually observed as a consequence of stimulation of sites located in the anterodorsal tegmental nucleus and lateral portions of the midbrain tegmentum. In contrast, locomotion was obtained by stimulating basal sites of the tegmentum located in the anteroventral nucleus and in the reticular formation lateral to it. Sites related to the remaining behaviors were located more diffusely in the basal midbrain.

Agonistic Behavior↗
PubMed1975

Chlordiazepoxide (librium)-induced changes in intraspecific attack and selected non-agonistic behaviors in male Siamese fighting fish.

Two experiments were undertaken to determine the effects of chlordiazepoxide on intraspecific attack behavior and selected non-aggressive behaviors in male Siamese fighting fish. In Exp. 1, pairs of fish fought while immersed in either 15 mug/ml or 30 mug/ml of chlordiazepoxide, or plain water. The drug groups showed significantly less attack (e.g., biting, jawlocking) than the control group, without noticeable behavioral toxicity. Also, in the drug groups alone, some variants of the copulatory clasp, seen in normal mating, occurred in many pairs. In Exp. 2, individual fish were isolated in one of the same doses or plain water for a period equivalent to that of Exp. 1. These doses produced no changes in measures of arousal, locomotion, and feeding behavior, as compared to the control condition. The drug-related appearance of the intermale mating-like behavior is discussed in terms of a theoretical formulation postulating a mutually inhibitory relationship between sex and aggression in fish.

Aggression↗
PubMed1988

Naltrexone blocks amphetamine-induced hyperactivity, but not disruption of social and agonistic behavior in mice and squirrel monkeys.

Significant anatomical overlap of opioid and dopamine receptors as well as reciprocity of control over synthesis, metabolism, and release of opioid peptides and dopamine in brain suggests functional interactions between the two systems. In the first of two studies, the behavioral effects of amphetamine and naltrexone alone, and in combination were studied in established groups of socially interacting squirrel monkeys. Naltrexone (0.1-10.0 mg/kg, IM) increased locomotion and marking behavior in subordinate monkeys. The frequency of social initiatives directed at treated subordinate monkeys by untreated members of the group was also increased. The behavior of dominant monkeys was relatively unaffected, except at the highest dose when autonomic distress was also evident. The frequency of walking bouts by both dominant and subordinate monkeys was increased by amphetamine (0.1-0.6 mg/kg, IM), and the social behavior of dominant monkeys was disrupted by drug treatment. Naltrexone (0.1 mg/kg, IM) significantly antagonized amphetamine's effects on motor behavior, and enhanced or did not affect amphetamine's effects on social behavior. In a second study, the interaction of amphetamine (0.63-10.0 mg/kg, IP) and naltrexone (0.1-10.0 mg/kg, IP) on the behavior of resident male mice during confrontations with a male intruder was studied. Naltrexone selectively reduced the frequency of attack at the highest dose tested. Amphetamine increased locomotor activity and decreased attack and threat behavior in resident mice. A low dose of naltrexone (1.0 mg/kg, IP) blocked amphetamine's effects on locomotion and enhanced the disruption of aggressive behavior. The amphetamine-naltrexone interaction on locomotor activity in mice and monkeys is consistent with opioid receptor modulation of dopamine mediated functions.(ABSTRACT TRUNCATED AT 250 WORDS)

Aggression↗
PubMedDate not supplied

[Effect of emotionality, exploratory activity and pain sensitivity on manifestation of agonistic behavior in the mouse].

Mice of C57BL/6J line with higher exploratory and motor activities and with lower emotionality and pain threshold recorded in standard tests, as compared with the animals of CBA/Lac line, have also been found to manifest a more expressed aggression in their intermale contacts in reaction to a syngeneous partner. It is suggested that the studied physiological and behavioural parameters may determine in considerable degree the character of aggressive and submissive mice behaviour in an agonistic interaction.

Aggression↗
PubMed2004

Experimental evidence that ovary and oviducal gland extracts influence male agonistic behavior in squids.

Recent investigations of sensory and behavioral cues that initiate sexual selection processes in the squid Loligo pealeii have determined that egg capsules deposited on the substrate provide a strong visual and chemotactile stimulus to males, even in the absence of females (1, 2, 3). The visual stimulus of egg capsules attracts males to the eggs, and when the males touch the eggs, they encounter a chemical stimulus that leads to highly aggressive fighting behavior. We have recently demonstrated that egg capsule extracts implanted in artificial egg capsules elicit this aggressive behavior (4). In this communication, we present evidence that the salient chemical factor originates in the ovary and perhaps the oviducal gland of the female reproductive tract.

Agonistic Behavior↗
PubMed1996

[Agonistic behavior during stress inhibits the development of learned helplessness in rats].

Male Wistar rats were exposed to inescapable shock in individual chambers (IS), or shocked in pairs (PIS). The latter rats were fighting during the shock administration. In 48 hrs, all the rats were subjected to escape/avoidance task in a shuttle-box. Failures increased significantly in the IS rats as compared with the PIS and intact rats. Dexamethasone administration decreased the plasma corticosterone level in the latter groups, but not in the IS rats. The findings suggest that an inescapable shock induces no learned helplessness in rats having an opportunity of agonistic interaction during the shock. The findings suggest also a stress-protective effect of agonistic contacts under averse conditions.

Agonistic Behavior↗
PubMed1987

Agonistic behavior and neurochemistry in grouped Japanese quail.

Aggressive behavior and whole brain neurochemistry were measured in stable and unstable pairs of male Coturnix coturnix japonica. Aggressive pecking peaked on day 5 of the daily regrouping regime and returned to a basal level on day 14. Aggressive behavior was associated with increased brain norepinephrine (NE), dopamine (DA), and acetylcholinesterase (AChE) in unstable pairs. Habituation (12-15 days) and DA response to daily regrouping and inanition were inversely related in unstable and stable pairs respectively. Normal whole brain NE increases were attenuated in unstable pairs.

Acetylcholinesterase↗
PubMed1975

Effects of olfactory bulb ablation and androgen on marking and agonistic behavior in male Mongolian gerbils (Meriones unguiculatus).

Male Mongolian gerbils, selected for high marking frequency, were paired with male opponents, and marking and fighting behavior were recorded. Animals then underwent castration, bilateral bulbectomy, unilateral bulbectomy, the combined operations, or a sham operation; and their behavior was again observed. All operated animals showed drastic reduction in both marking and aggressive encounters. Injections of testosterone propionate (TP) produced complete restoration of marking in castrates, but not in bilaterally or unilaterally bulbectomized animals or combined operates. The exhibition of aggression after injections of TP, however, was enhanced to supernormal levels in bulbectomized or bulbectomized-castrated animals. The results suggest the following: that removal of the olfactory bulbs may eliminate a critical neural input necessary for the normal expression of marking and agonistic; that although marking and fighting are influences by olfactory input and gonadal steroids, their regulatory mechanisms may not be identical; and that removal of the bulbs may sensitize a neural mechanism controlling aggression, thus potentiating its elicitation following administration of exogenous androgen.

Aggression↗
PubMed1985

Olfactory cues and pig agonistic behavior: evidence for a submissive pheromone.

One hundred and two prepubertal pigs were used in two experiments to determine if adrenocorticotropin hormone (ACTH)-induced increase in submissive behavior could be mediated by odorous signals. In experiment one, urine was collected from pigs treated with either 0, 1 or 10 IU/kg ACTH. Urine from pigs given 1.0 IU/kg ACTH caused a trend for a rise in submissive behavior. Level of plasma cortisol from donor pigs correlated well (r = .92) with duration of submissive behavior in the tested pigs. In experiment two, urine from ACTH-treated pigs increased submissive behavior when sprayed in the air during late fight. Thus, ACTH-induced submissiveness may be mediated by a pheromone. These results fit the hypothesis that, in addition to visual cues, an olfactory cue (perhaps adrenal in origin) is released towards the end of a fight to signal submission. Aerosolizing urine from ACTH-treated pigs may have interfered with this pheromonal signal.

Adrenocorticotropic Hormone↗
PubMed2005

Does individual variation in stress responses and agonistic behavior reflect divergent stress coping strategies in juvenile rainbow trout?

Individual rainbow trout were transferred to visual isolation in experimental aquaria. As a measure of the speed of acclimation, individual food intake was quantified during the first 6 d following transfer. Following acclimation, aggression was quantified by subjecting the fish to three resident-intruder tests, with 30 d of recovery between the tests. Moreover, between the resident-intruder tests (i.e., two times) the fish were exposed to an unfamiliar environment and their cortisol response was measured. The results of this study show that individuals of juvenile rainbow trout differ distinctly in their response to changes in their environment, and that this diversity in behavior is reflected by consistent behavioral traits displayed by individual fish. These traits have proven to be consistent not only over time but also across situations, revealing two distinct behavioral profiles, in the same manner as shown in studies on proactive and reactive mammals. Our results also show that the reactivity of the hypothalamic-pituitary-interrenal (HPI) axis, when exposed to a stressor, is a consistent physiological trait in juvenile rainbow trout. We found that difference in HPI axis reactivity is linked to the different behavioral profiles. However, HPI axis reactivity could not be linked directly to the singular behavioral traits measured. In other words, we did not find that the consistent behavioral traits shown by the fish were associated with a difference in HPI axis reactivity in the same manner as the reactivity of the hypothalamic-pituitary-adrenocortical axis does in mammals. Taken together, our results show that stress coping strategies akin to what has been described as reactive and proactive stress coping in mammals appear to exist in juvenile rainbow trout.

Adaptation, Psychological↗
PubMed1975

An approach to the interpretation of the communicative meaning of visual signals in agonistic behavior of squirrel monkeys.

The repertoire of the visually recognizable agonistice signals of the squirrel monkey can be divided up into classes in such a manner that elements of the same class have a similar, and elements of different classes a different communicative meaning. The differences between these classes are described using quantitative values. An attempt is made to derive clues from these differences for an interpretation of the communicative meaning of the individual classes. The admissibility of the criteria used and the question of the general validity of the quantitative values are discussed.

Aggression↗
PubMed1991

Ethopharmacological studies on the effects of antihormones on rodent agonistic behavior with especial emphasis on progesterone.

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 type of pairing has a very substantial effect on the actions seen after treatment, and the ethopharmacological approach generates a better picture of antihormone effect than traditional psychopharmacological tests.

Agonistic Behavior↗
PubMed2003

Bimodal signal requisite for agonistic behavior in a dart-poison frog, Epipedobates femoralis.

Animal acoustic signals play seminal roles in mate attraction and regulation of male spacing, maintenance of pairbonds, localization of hosts by parasites, and feeding behavior. Among vertebrate signals, it is becoming clear that no single stereotyped signal feature reliably elicits species-specific behavior, but rather, that a suite of characters is involved. Within the largely nocturnal clade of anuran amphibians, the dart-poison frog, Epipedobates femoralis, is a diurnal species that physically and vigorously defends its calling territory against conspecific intruders. Here we report that physical attacks by a territorial male are provoked only in response to dynamic bimodal stimuli in which the acoustic playback of vocalizations is coupled with vocal sac pulsations, but not by either unimodal cues presented in isolation or static bimodal stimuli. These results suggest that integration of dynamic bimodal cues is necessary to elicit aggression in this species.

Agonistic Behavior↗
PubMed1996

Pavlovian conditioning of agonistic behavior in male threespine stickleback (Gasterosteus aculeatus).

The red coloration of male stickleback (Gasterosteus aculeatus) possesses signal value in male-male interactions. Therefore, it was predicted that males would learn to associate a red signal more readily than a green signal with a conspecific rival in a Pavlovian conditioning experiment. Males were presented red and green signal lights where one signal was always paired with presentation of a rival (excitatory conditioned stimulus, CS+) and one signal was never paired with presentation of a rival (nonreinforced stimulus, CS-). Males learned the task rapidly, showing conditioned approach and zigzag responses, but CS+ vs. CS- differentiation persisted, even after a prolonged extinction period. In addition, there were no differences in learning rates between fish trained to the red signal as the CS+ and fish trained to the green signal as the CS+. The results suggest that, although males may rapidly learn about rivals, they are not predisposed to associated red (over green) with the appearance of a rival under the conditions of this experiment. Because males must establish and maintain territories in order to nest and mate, learning about neighboring rivals may be an adaptive mechanism by which males more effectively defend their territories and thereby increase their reproductive fitness.

Agonistic Behavior↗
PubMed1994

Vasopressin and serotonin interactions in the control of agonistic behavior.

In hamsters, dominant/subordinate relationships are initially determined by overt aggression, but subsequently communicated by flank marking, an arginine vasopressin (AVP)-dependent behavior. Once a relationship is established, dominant males will flank mark at a higher frequency than their subordinate partners. Flank marking displayed during social encounters can be turned "on or off" by microinjection of AVP or AVP-receptor antagonist within the anterior hypothalamus (AH). For instance, microinjecting dominant hamsters with AVP-receptor antagonist blocks their flank marking and provokes an immediate induction of flank marking by subordinate animals. The central effects of AVP have been extended to include a role in offensive aggression. Microinjection of AVP-receptor antagonist into the AH inhibits the aggression of a resident hamster toward an intruder and diminishes aggression between hamsters placed into a neutral arena. Microinjection of AVP into the ventrolateral hypothalamus (VLH) facilitates offensive aggression of a resident toward an intruder. As AVP receptors in the VLH are testosterone-dependent, it is possible that the reduction of aggression observed in castrated hamsters is due to a loss of AVP responsiveness in the VLH. Recent work has focused on the notion that serotonin (5-HT) antagonizes AVP activity in the CNS. The AH and VLH have a high density of 5-HT terminals and binding sites. Indeed, there appear to be 5-HT synapses on AVP neurons in the AH. Microinjection of 5-HT into the AH inhibits AVP-induced flank marking while IP injection of fluoxetine a serotonin reuptake inhibitor inhibits AVP-induced offensive aggression in the VLH. It is possible that serotonin interacts with AVP to modulate offensive aggression.

Aggression↗