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Query: UMLS:C0848237 (acute stress)
 4,619 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Previous work has demonstrated that the brain of Anolis carolinensis is functionally split, in that the left and right eyes project predominantly to the contralateral hemisphere, and as there are minimal connections between the left and right hemispheres. Using this model, the current experiment examined the effect of mild acute stress on hemispheric regulation of territorial aggression. Thirteen adult male Anolis were paired with an antagonistic males, and eye use and behavioral responses were repeatedly measured during 3 minute behavioral trials. Trials were conducted either after exposure to mild stress, produced by handling the subject, or without stress, and they were run either in the subject's home cage or in a cage foreign to the subject. Left eye preference for aggressive movements was found during the trials run in the non-stressed conditions (p < 0.05). Conversely, stressed subjects showed a reduction in left eye/right hemisphere mediated aggressive movements relative to the non-stressed subjects but no changes in right eye/left hemisphere aggression. This effect was independent of whether or not the subject was in its home or a foreign cage. No laterality in aggressive responding was found when the subjects were placed in separate cages with visual contact. These findings suggest that territorial aggression in Anolis is preferentially initiated and processed by the left eye/right hemisphere but is subject to right-hemispheric inhibition following exposure to acute mild stress.
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PMID:Hemispheric control of territorial aggression in Anolis carolinensis: effects of mild stress. 943 69

Previous work demonstrated that the brains of many reptiles, including the American chameleon Anolis carolinensis (A. carolinensis), are functionally 'split'. Because the left eye in this species projects predominantly to the right hemisphere, and vice versa, inferences about lateralized brain functioning can be made in A. carolinensis by observation of eye use during behavioral encounters. Using this model, past work suggested that territorial aggression in Anolis is under the preferential control of the right hemisphere, and that acute stress or chronic alcohol exposure selectively reduces right hemisphere mediated territorial aggression. In addition, drugs which increase serotonin (5-HT) in the synaptic cleft inhibit aggressive responding in anoles in both hemispheres. The current experiment examined whether or not the administration of the serotonin agonists 8-hydroxy-2-(di-n-propylamine) tetralin (8-OHDPAT), quipazine, or meta-chlorophenylbiguanide (mCPBG) alter territorial aggression in Anolis. Nine adult socially isolated male A. carolinensis underwent a series of behavioral trials during which an antagonistic male was introduced into the cage. Once stable responding was initiated, all subjects were injected in a semi-randomized crossover manner with the following agents, (1) lactated Ringer's, (2) the 5-HT2 agonist quipazine (1.5 mg/kg and 3.0 mg/kg), (3) the 5-HT1 agonist 8-OHDPAT (83 mg/kg), and (4) the 5-HT3 agonist mCPBG (3.0 mg/kg and 9 mg/kg). Twenty minutes post injections, the male intruder was reintroduced into the subject's cage. Several behaviors were recorded, including: (1) the time to the first aggressive response, (2) the number of aggressive episodes mediated by the left eye or right eye, and (3) changes in skin color and posture. Aggressive responding was virtually eliminated in all subjects injected with 8-OHDPAT. On the other hand, one-way ANOVA found that both the 9 mg/kg dose of mCPBG (P=0.007), and the 3.0 mg/kg dose of quipazine (P=0.035), selectively decreased territorial aggression mediated by the left eye/right hemisphere compared to lactated Ringer's controls, but had no effect on aggression mediated by the right eye/left hemisphere. Although 8-OHDPAT inhibited aggression, injected subjects developed phenotypic displays of aggressive coloring/posturing, such as blackening of the eye spot and a raising of the neck crest. These results suggest that aggressive action can be differentiated from phenotypic displays that accompany aggression by a 5-HT1 agonist. They also indicate that there is an asymmetrical effect of 5-HT2/5-HT3 serotonin agonists on hemispheric mediation of aggression in this species.
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PMID:Effects of serotonergic drugs on lateralized aggression and aggressive displays in Anolis carolinensis. 980 42

Male rhesus monkeys unfamiliar with each other were paired in a cage, and blood samples were collected before and a few hours after pair formation. Adrenocorticotrophic hormone (ACTH) and cortisol levels in each blood sample were measured. Dominant-subordinate status was ascertained through two rank tests, the food competition test and the agonistic behavior test, which were performed immediately after pair formation. As a result, the dominance relationship was determined in seven pairs formed from five animals, and the differences in ACTH and cortisol values between the dominant and subordinate animal in these pairs were compared statistically. The day after the first encounter, a second encounter was conducted in randomly selected pairs of monkeys. In the first encounters, higher levels of both ACTH and cortisol were detected in dominant animals in comparison to subordinate animals. Changing the animal's partner altered the stress responses whenever the animal's dominant-subordinate status changed. The elevated levels of ACTH and cortisol in dominant animals disappeared on the day after the first encounter. In dominant animals, the pituitary-adrenocortical stress response reacts sharply to situational demands, whereas subordinate animals have a weaker response. This acute stress response is different from a chronic stress response. When the subordinate animal cannot escape, its hypothalamic-pituitary-adrenocortical axis appears to be suppressed.
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PMID:Pituitary-adrenocortical responses to the first dyadic encounters in male rhesus monkeys: effect of dominance relationship. 1076 49

Although final brain size and the number of available neurons and axons appear to be established early in infancy, plasticity of the brain continues during adolescence through an integrated process of overproduction and elimination of synapses and receptors. In addition, hormonal levels change dramatically during this period, as a result of the onset of puberty. This age-specific condition has been suggested to serve as a permissive factor for the emergence of a number of early-onset neuropsychiatric disorders, including schizophrenia, attention-deficit hyperactivity disorder (ADHD), and perhaps substance abuse. However, relatively few investigations have focused on animal models of this developmental phase. The periadolescent rodent (similar30-45-day-old), has been proposed as a useful model. Periadolescent rats and mice are generally associated with a peculiar behavioral profile, consisting of basal hyperactivity, high attraction towards novel stimuli and a marked involvement in affiliative and playful behaviors. Moreover, a unique profile of psychopharmacological responsivity characterizes rodents around this age. Recent experiments by our group investigated age-related discontinuities in the response of the hypothalamic-pituitary-adrenal axis (HPA) to both stress and psychostimulants. The latter are often administered as therapeutic drugs to children with ADHD, which have been also associated with an impaired response to stress and abnormalities in HPA axis function. Indeed, an altered functioning of the HPA axis has been proposed as a possible risk factor and a potential marker for such a behavioral vulnerability. Animals were studied at adulthood (> pnd 70) or during periadolescence. Experiment I characterized basal corticosterone (CORT) levels in naive mice kept undisturbed in standard social conditions from weaning to sacrifice. Periadolescent male mice showed higher basal CORT levels than adult subjects, suggesting that the set up of the HPA axis is physiologically elevated during adolescence. In experiment II, we investigated age-related differences in the response to both acute and chronic stress conditions. Periadolescent and adult mice were housed either in a standard (three animals per cage) or in a crowding condition (nine animals per cage). The latter has been indeed reported to potentiate the subsequent reaction to acute stress in adult rodents. At the end of this period and following 24 h individual housing, mice were injected with either saline (SAL) or a standard amphetamine (AMPH) dose (2 mg/kg), and faced with a mild acute psychological stress, namely removal of sawdust from the home cage. Important sex differences emerged in animals of the two ages. Periadolescent females showed a reduced CORT response to acute stress. Within the adult male group, the chronic crowding condition produced a prominent potentiation of CORT response to the acute stress challenge. Conversely, this profile was not evidenced in periadolescents. These results indicate a strong role for gender and social variables in the response of periadolescent subjects to the various aspects of stress. As for AMPH effects, in the absence of significant changes in adult subjects, the drug produced a marked CORT release in periadolescent mice. A better understanding of neuroendocrine-related AMPH effects as a function of social and environmental risk factors during adolescence, might deepen our knowledge on the neurobiological bases of genetically determined neuropsichiatric disorders and possibly improve the therapeutical efficacy of psychostimulant drugs.
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PMID:Peculiar response of adolescent mice to acute and chronic stress and to amphetamine: evidence of sex differences. 1186 27

Social isolation and lack of social support have deleterious effects on health, thus being regarded as one of the most relevant causes of diseases in human and other mammalian species. However, only few are the studies aimed at evaluating the psychoneuroimmunological functions of individually housed subjects. The present study was designed to understand how the behavior and the physiology of male house mice might be affected by individual housing. We first analyzed whether individual housing of different duration (1-42 days) would result in immuno-endocrine dysfunction (experiment 1). Then we investigated whether housing conditions would affect the reaction to an acute mild psychological stress (experiments 2 and 3). There were three main findings: first, individually housing mice for increasing time periods did not induce any major immuno-endocrine effects compared to a stable sibling group housing. Therefore, prolonged isolation does not seem to dramatically impair mice immuno-endocrine functions. Second, when exposed to a mild acute stress, i.e. forced exposure to a novel environment, isolated mice showed higher basal corticosterone and lower type 1 (IL-2) and type 2 (IL-4) cytokines as well as splenocytes proliferation compared to group housed male mice. Finally, when faced with a free choice between a novel environment and their home cage, individually housed mice showed reduced neophobic responses resulting in increased exploration of the novel environment, thus suggesting a low anxiety profile. Altogether, our findings suggest that individual housing in itself does not change immunocompetence and corticosterone level, but does affect reactivity to a stressor. In fact, individually housed mice showed high behavioral arousal, as well as altered immuno-endocrine parameters, when challenged with mild psychological novelty-stress.
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PMID:Individual housing induces altered immuno-endocrine responses to psychological stress in male mice. 1268 11

It has been hypothesized that in avian social groups subordinate individuals should maintain more energy reserves than dominants, as an insurance against increased perceived risk of starvation. Subordinates might also have elevated baseline corticosterone levels because corticosterone is known to facilitate fattening in birds. Recent experiments showed that moderately elevated corticosterone levels resulting from unpredictable food supply are correlated with enhanced cache retrieval efficiency and more accurate performance on a spatial memory task. Given the correlation between corticosterone and memory, a further prediction is that subordinates might be more efficient at cache retrieval and show more accurate performance on spatial memory tasks. We tested these predictions in dominant-subordinate pairs of mountain chickadees (Poecile gambeli). Each pair was housed in the same cage but caching behavior was tested individually in an adjacent aviary to avoid the confounding effects of small spaces in which birds could unnaturally and directly influence each other's behavior. In sharp contrast to our hypothesis, we found that subordinate chickadees cached less food, showed less efficient cache retrieval, and performed significantly worse on the spatial memory task than dominants. Although the behavioral differences could have resulted from social stress of subordination, and dominant birds reached significantly higher levels of corticosterone during their response to acute stress compared to subordinates, there were no significant differences between dominants and subordinates in baseline levels or in the pattern of adrenocortical stress response. We find no evidence, therefore, to support the hypothesis that subordinate mountain chickadees maintain elevated baseline corticosterone levels whereas lower caching rates and inferior cache retrieval efficiency might contribute to reduced survival of subordinates commonly found in food-caching parids.
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PMID:The relationship between dominance, corticosterone, memory, and food caching in mountain chickadees (Poecile gambeli). 1312 80

The role of vasopressin, cosecreted with corticotropin-releasing hormone (CRH), in stress is debated, because both normal as well as reduced adrenocorticotropin hormone (ACTH) rise to an acute challenge has been reported in Brattleboro rats genetically lacking vasopressin (di/di). Because di/di pups could be born either from di/+ (heterozygous) or from di/di mothers, and maternal influence is known to modify adult responsiveness, we investigated whether the influence of maternal genotype could explain the variability. Adult rats from mothers with different genotypes were stressed with 60 min restraint and trunk blood was collected for measuring hormone content by radioimmunoassay at the end of stress. All offspring of di/+ mothers had similar ACTH responses to restraint, while the di/di rats born to, and raised by di/di mothers showed reduced ACTH reactivity to restraint. The di/di rats showed elevated water turnover and required a daily cage cleaning every day, which meant frequent handling. To offset the role of handling, all rats had daily cage cleaning in the next series, but the results were the same as in the first series. To investigate whether lactation, the behaviour of the mother or some other factor during the pregnancy is responsible for the differences, pups from di/+ dams were raised by di/di foster mothers and vice versa. We found that the genotype of parental mother is more important than that of the foster mother. The corticosterone and prolactin elevation normally seen after acute stress was unchanged by family history, maternal or personal genotype. Furthermore, in studies with mutant animals, the rearing conditions should be controlled by the experimenter. In experiments with Brattleboro rats, the use of homozygous and heterozygous rats from the same litters of di/+ dams and di/di males is recommended. Our results suggest that vasopressin is not indispensable for ACTH release, and that the di/di genotype of the parental mother can decrease the stress reactivity of the di/di Brattleboro rats.
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PMID:Maternal genotype influences stress reactivity of vasopressin-deficient brattleboro rats. 1463 71

Environmental factors in early life are clearly established risk factors for cardiovascular disease in later life. Most studies have focused on nutritional programming and analysed basal cardiovascular parameters rather than responses. In the present study we have investigated whether prenatal stress has long-term effects on cardiovascular responses in adult offspring. Female pregnant Sprague-Dawley rats were subjected to stress three times daily from day 15 to day 21 of gestation. Litters from stressed and control females were cross-fostered at birth to control for mothering effects. When the offspring were 6 months old, blood pressure was measured in the conscious rats through implanted catheters at rest, during restraint stress and during recovery. Basal haemodynamic parameters were similar in the different groups but the pattern of cardiovascular responses during stress and recovery differed markedly between prenatally stressed (PS) and control animals. PS rats had higher and longer-lasting systolic arterial pressure elevations to restraint stress than control animals. They also showed elevated systolic and diastolic blood pressure values during the recovery phase. PS rats demonstrated a greater increase in blood pressure variability compared with control animals during exposure to restraint stress, and showed more prolonged heart rate responses to acute stress and delayed recovery than controls. There was no effect of prenatal stress on baroreflex regulation of heart rate. PS females showed a greater increase in systolic arterial pressure and blood pressure variability and delayed heart rate recovery following return to the home cage then did PS males. These findings demonstrate for the first time that prenatal stress can induce long-term, sex-related changes in the sensitivity of the cardiovascular system to subsequent stress.
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PMID:Prenatal stress alters cardiovascular responses in adult rats. 1503 22

Studies of behavior, endocrinology and physiology have described experiments in which animals housed in groups or in isolation were normally tested individually. The isolation of the animal from its group for testing is perhaps the most common situation used today in experimental procedures, i.e., there is no consideration of the acute stress which occurs when the animal is submitted to a situation different from that it is normally accustomed to, i.e., group living. In the present study, we used 90 male 120-day-old rats (Rattus norvegicus) divided into 5 groups of 18 animals, which were housed 3 per cage, in a total of 6 cages. The animals were tested individually or with their groups for exploratory behavior. Hormones were determined by radioimmunoassay using specific kits. The results showed statistically significant differences between testing conditions in terms of behavior and of adrenocorticotrophic hormone (ACTH: from 116.8 +/- 15.27 to 88.77 +/- 18.74 when in group and to 159.6 +/- 11.53 pg/ml when isolated), corticosterone (from 561.01 +/- 77.04 to 1036.47 +/- 79.81 when in group and to 784.71 +/- 55.88 ng/ml when isolated), luteinizing hormone (from 0.84 +/- 0.09 to 0.58 +/- 0.05 when in group and to 0.52 +/- 0.06 ng/ml when isolated) and prolactin (from 5.18 +/- 0.33 to 9.37 +/- 0.96 when in group and to 10.18 +/- 1.23 ng/ml when isolated) secretion, but not in terms of follicle-stimulating hormone or testosterone secretion. The most important feature observed was that in each cage there was one animal with higher ACTH levels than the other two; furthermore, the exploratory behavior of this animal was different, indicating the occurrence of almost constant higher vigilance in this animal (latency to leave the den in group: 99.17 +/- 34.95 and isolated: 675.3 +/- 145.3 s). The data indicate that in each group there is an animal in a peculiar situation and its behavior can be detected by ACTH determination in addition to behavioral performance.
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PMID:Social condition affects hormone secretion and exploratory behavior in rats. 1526 26

The present study investigated whether the 'psychological threat' induced by sensory contact with an aggressive conspecific would be a sufficient factor in inducing behavioural and physiological disturbances. Repeated sensory contact with an aggressive mouse (social threat) in a partitioned cage was compared with repeated exposure to a novel partitioned cage in male NMRI mice. We first examined parameters of stress responsiveness (body weight, plasma corticosterone levels, frequency of self-grooming and defecation). The temperature and physical activity responses to stress were also recorded during and after the 4 weeks of stress using radiotelemetry. Finally, cognitivo-emotional performance was assessed after acute stress and 2 and 4 weeks of stress by measuring decision making, sequential alternation performance and behaviour in the elevated T-maze. Social threat had a greater impact than novel cage exposure on most parameters of stress responsiveness, although mice did not habituate to either stressor. Social threat rapidly led to an anticipatory rise in core body temperature and physical activity before the scheduled stress sessions. Such anticipation developed within the first week and persisted for 9 days after ending the stress procedure. Some memory impairment in the sequential alternation test was found in stressed mice, independent of the stressor. After 4 weeks of stress, inhibitory avoidance in the elevated T-maze was enhanced in socially stressed mice and reduced in novel cage mice. The sustained anticipation of stress in the social threat group preceded aversive responding. It remains to be established whether anticipation contributes to the development of aversive responses.
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PMID:Repeated sensory contact with aggressive mice rapidly leads to an anticipatory increase in core body temperature and physical activity that precedes the onset of aversive responding. 1530 72


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