Long-term effects of footshock and social defeat on anxiety-like behaviours in rats: Relationships to pre-stressor plasma corticosterone concentration

We compared the consequences of two stressors, 'unnatural' inescapable footshocks (IFSs) and 'natural' social defeat (SD), on behaviours typically sensitive to stress [sucrose preference, open field (OF), elevated plus maze (EPM) and acoustic startle responses (ASRs)] and the association with pre-stressor plasma corticosterone concentration. After initial blood sampling, rats (n?=?20 per group) were exposed to either 10 IFSs (1?mA intensity, 5?s duration each) or to 1?h SD (defeat by an aggressive resident male rat and further exposure but separated in a small cage) or to control procedures (handling). Rats were tested once for ASR (day 19), while the other behavioural tests were applied once weekly for 3 weeks. Both stress groups showed short-lasting lowered sucrose preference, and in the EPM they showed shorter total distance moved, shorter distance moved on open arms and less time on open arms compared to controls. In the OF test, IFS rats showed shorter total distance moved up to 2 weeks after stress. The SD group showed shorter total distance moved in the OF, which was only significant 2 weeks after stress. Low pre-stressor plasma corticosterone concentration was only associated with defecation (IFS rats) and latency to enter open arms in the EPM (all low corticosterone subgroups, n?=?10 per subgroup). SD rats with high initial plasma corticosterone concentration showed enhanced ASR compared to the other subgroups with high initial plasma corticosterone concentration (n?=?9 per subgroup). The results indicate that footshock and SD, while generally leading to an increase in anxiety behaviours, represent qualitatively different stressors.     

Exploration in outbred mice covaries with general learning abilities irrespective of stress reactivity, emotionality, and physical attributes

Across multiple learning tasks (that place different sensory, motor, and information processing demands on the animals), we have found that the performance of mice is commonly regulated by a single factor ("general learning") that accounts for 30-40% of the variance across individuals and tasks. Furthermore, individuals' general learning abilities were highly correlated with their propensity to engage in exploration in an open field, a behavior that is potentially stress-inducing. This relationship between exploration in the open field and general learning abilities suggests the possibility that variations in stress sensitivity/responsivity or related emotional responses might directly influence individuals' general learning abilities. Here, the relationship of sensory/motor skills and stress sensitivity/emotionality to animals' general learning abilities were assessed. Outbred (CD-1) mice were tested in a battery of six learning tasks as well as 21 tests of exploratory behavior, sensory/motor function and fitness, emotionality, and stress reactivity. The performances of individual mice were correlated across six learning tasks, and the performance measures of all learning tasks loaded heavily on a single factor (principal component analysis), accounting for 32% of the variability between animals and tasks. Open field exploration and seven additional exploratory behaviors (including those exhibited in an elevated plus maze) also loaded heavily on this same factor, although general activity, sensory/motor responses, physical characteristics, and direct measures of fear did not. In a separate experiment, serum corticosterone levels of mice were elevated in response to a mild environmental stressor (confinement on an elevated platform). Stress-induced corticosterone levels were correlated with behavioral fear responses, but were unsystematically related to individuals' propensity for exploration. In total, these results suggest that although general learning abilities are strongly related to individuals' propensity for exploration, this relationship is not attributable to variations in sensory/motor function or the individuals' physiological or behavioral sensitivity to conditions that promote stress or fear.     

Depression: avoidance learning and physiological correlates in clinical and analog populations

The behavioral and physiological components of depression were investigated in two experiments comparing eight student and seven non-student depressed females with an equal number of students and non-student controls on avoidance tasks and electrodermal responsivity to an aversive audiotape. Avoidance behavior was assessed in both active and passive paradigms where the correct response or response suppression, respectively, function to avoid a noxious buzzer. Physiological activity and reactivity were compared using measurements of skin resistance level and SRR fluctuations during resting and aversive tape periods. It was found that the depressed groups showed inferior active and superior passive avoidance learning as compared to controls. Depressed subjects were also more emotionally responsive (showed a greater number of SRR) during presentation of the audiotape. A passive avoidance model for depression is suggested for the explanation of the phenomena observed. A distinct difference was also found between student and non-student populations. The utility of college student analogs for depression is questioned.     

The Danger in Sexism: The Links Among Fear of Crime, Benevolent Sexism, and Well-being

In two studies utilizing undergraduate students at a large public university in the Northeastern U.S., we examined how fear of crime negatively impacts psychological well-being and gender relations. In Study 1, students (N?=?216, 105 female) who indicated higher levels of fear of crime also indicated greater endorsement of benevolent sexism (but not hostile sexism) as well as higher levels of behavioral inhibition and lower self-esteem. In Study 2, fear of crime was manipulated and participants (N?=?115, 73 female) in the crime condition indicated greater endorsement of benevolent sexism, greater behavioral inhibition and lower self-esteem, as compared to participants in a control condition. The implications of the findings for gender relations and psychological well-being are discussed.     

Interaction between catecholaminergic and opioid systems in an active avoidance task

Male NMRI mice were given intravenous injections of the noradrenergic neurotoxin DSP4 or the vehicle 24 to 72 h prior behavioral testing. Animals were given 2 days of training on a one-way active avoidance task. Naloxone was given in one of three doses prior to training on Day 1 and Day 2 or prior to training on Day 1 only (saline was given prior to training on Day 2). There was a dose-dependent impairment of acquisition by naloxone in the vehicle-pretreated groups; 10 mg/kg naloxone produced a significant impairment of acquisition. Naloxone also modulated retention (Day 2) performance of the active avoidance task. For vehicle-pretreated mice, 1 mg/kg naloxone facilitated and 10 mg/kg naloxone-impaired performance on Day 2. DSP4 alone produced an impairment of acquisition of this task but had no effect on retention; Day 2 scores were slightly higher in the DSP4-pretreated group than in the vehicle-pretreated group. Naloxone produced somewhat different effects in DSP4-pretreated animals than in vehicle-pretreated animals. Naloxone (1 mg/kg) ameliorated the DSP4-induced impairment of acquisition; 10 mg/kg naloxone did not significantly alter the acquisition performance of this group. For the DSP4-pretreated mice that received naloxone before training on both days, the dose-response characteristics for retention scores were similar to those of vehicle-pretreated mice; 1 mg/kg naloxone was the facilitatory dose. However, for DSP4-treated mice that received naloxone before training on Day 1 only, there was a shift to the right in the effective facilitatory dose of naloxone. For these animals, 10 mg/kg naloxone but not 1 mg/kg naloxone significantly enhanced retention performance. We discuss these results in the context of a possible state-dependent modulation by naloxone in the DSP4-treated animals.     

Correlation between Changes in Stress-Induced Corticosterone Secretion and GR mRNA Levels

The current study was conducted to determine the potential relationship between stress-induced corticosterone secretion and corticosteroid receptor mRNA levels after 5 days of intermittent stress. In particular, we were interested in the rate at which animals terminate a stress response, and how this termination may be altered by repeated stress. Adult male Sprague-Dawley rats were subjected to either 5 days of restraint stress or 5 days of an unpredictable stress paradigm. Restraint-stress induced corticosterone secretion was measured on Days 1 and 5 in both groups, and animals were killed on Day 6. Glucocorticoid receptor (GR), and mineralocorticoid (MR) mRNA levels were determined using in-situ hybridization techniques. Five days of restraint stress caused an habituation of the plasma corticosterone response to stress measured 60 and 90 min post-stress initiation; this pattern of corticosterone secretion was not observed in the animals subjected to unpredictable stress. Five days of either stress paradigm did not alter MR mRNA levels measured within the hippocampus or GR mRNA levels within the hippocampus or the medial parvocellular division of the paraventricular nucleus of the hypothalamus (mpPVN). However, an individual's GR mRNA levels measured within the CA1/2 region of the hippocampus and the mpPVN were significantly correlated with the degree of habituation of the corticosterone response to stress measured on Day 5. This suggests that an increase in the rate of termination of the stress response and levels of GR within the hippocampus and mpPVN may be functionally related.     

A quantitative assessment of the effects of malnutrition on behavioral development in laboratory mice

The aim of this study was to compare the effects of malnutrition on behavioral development in mice with those due to heredity obtained in a previous study. To this end behavioral development was assessed using a developmental time scale which allowed comparison of the two studies. Pregnant B6D2F1/J mice were maintained on either a protein restricted or normal protein diet from Day 7 to Day 24 postconception, at which time the low protein group was returned to the normal diet until behavioral testing at Day 32. Behavioral development in the control group replicated the values obtained in previous studies, whereas the malnourished pups were retarded by 1.4 days. This was of the same order of magnitude as that reported previously for maternal inbreeding. Measures of maternal and pup body weight at birth, Day 24 and Day 32 indicated that although the malnourished animals were initially significantly lighter in weight they had recovered by Day 32. Litter size however, declined between birth and time of behavioral testing in the malnourished group.     

Exploration and avoidance learning after ibotenic acid and radio frequency lesions in the rat amygdala

Open-field activity, avoidance behavior, and plasma corticosterone levels were studied after intraamygdala injections of 3.0 micrograms ibotenic acid (IBO) and radio-frequency (RF) lesions in the amygdala complex of male Wistar rats. The experiments were undertaken to evaluate the importance of amygdala neurons versus axons of passage in fear-motivated behavior. The IBO lesions led to increased open-field activity, but no impairments in active avoidance learning, nor changes in basal or experimental levels of plasma corticosterone. The RF lesions, on the other hand, led to an increase in experimental plasma corticosterone levels. In the one-way avoidance task the RF lesions, in contrast to the IBO lesions, led to significant impairments in the acquisition of the avoidance response. Although the long-term axon-sparing effect of IBO is questioned since cavities were detected in the affected areas 8 weeks after the injections, the differences in avoidance learning and in corticosterone levels between the RF and the IBO lesions indicate that the axons were functionally active at the time of testing (14-26 days postoperatively). The increase in open-field activity is attributed to the destruction of amygdala neurons and neurons in the overlying cortex, while an avoidance deficit seem to depend on the destruction of axons. On the basis of the behavioral results and the corticosterone data in these experiments, it is suggested that the behavioral changes are not attributable to a general reduction in the arousal of fear. However, since the IBO lesions did not affect the most medial parts of the amygdala complex including the central amygdala nucleus, the role of this nucleus in fear arousal has to be investigated further.     

Neurotoxicity of Kainate to the Hippocampus is not Accrued by Aging, Stress and Exogenous Corticosterone in Wistar Kyoto and Spontaneously Hypertensive Rats

It has been reported that a high corticosterone milieu can exacerbate various experimental insults to the nervous system, in particular to the hippocampus. However, in many of these studies the above milieu was attained by injecting corticosterone in doses (e.g. 10 mg/rat) producing supraphysiological concentrations. In the present study we have investigated whether high plasma corticosterone levels, such as those associated with aging or stress, potentiate a hippocampal excitotoxic insult. Male Wistar Kyoto (WKY) and Spontaneously Hypertensive Rats (SHR) at the age of 6, 12, 18 and 24 months (only WKY for the oldest age) were used. As in other strains, aging in these rats was marked by an increase in basal plasma corticosterone levels. Rats were infused in the dorsal hippocampus with kainic acid (0.035 μg/hippocampus) and the neuronal injury was evaluated within the areas CA3 and CA4. Results indicated that neither aging nor the hypertensive condition affected kainic acid neurotoxicity. In order to study the effect of stress, rats were stressed twice a day, with alternate types of stressors to avoid possible habituation, 3 days prior to and 3 days following the kainic acid infusion. Using this experimental paradigm the hippocampal damage in stressed rats was of the same degree as in non-stressed controls. In a complementary set of experiments, 6 month old WKY and SHR rats were injected with corticosterone (10 mg/rat s.c.). Four hours after administration plasma corticosterone levels in the range of 60-70 μg/100 ml were found. Moreover, a time-course study showed a plasma corticosterone peak in the range of 240 μg/100 ml. Daily corticosterone administration for 3 days before and 3 days after kainic acid infusion potentiated the hippocampal damage in 6 months old SHR but not in the WKY. These results demonstrate that elevation of corticosterone levels within physiological range does not exacerbate hippocampal kainate neurotoxicity and that pharmacological doses of glucocorticoid hormone, which produces plasma levels well above those observable in any physiopathological condition, might, with some strain dependency, potentiate a hippocampal neurotoxic insult.     

Internet-delivered behavioral intervention to increase physical activity in persons with multiple sclerosis: Sustainability and secondary outcomes

Physical activity is associated with many benefits, but persons with multiple sclerosis (MS) are less physically active than the general population. There is a critical need for research on methods of increasing and sustaining the physical activity levels of this population. This randomized controlled trial examined the efficacy of an Internet-delivered and theory-based behavioral intervention that was supplemented with video coaching for increasing and sustaining physical activity over time in persons with MS. Physically inactive, ambulatory persons with MS (N?=?45) were randomly assigned to intervention (n?=?22) or control (n?=?23) conditions and completed a battery of questionnaires before, after, and three months after a 12-week intervention period. Data analyses were conducted in PASW 18.0. Partial eta squared ([Formula: see text]) effect size indicated that there was a large, statistically significant condition-by-time interaction on physical activity ([Formula: see text]). Cohen's d effect sizes indicated that the intervention group had a large increase in physical activity after the 12-week trial (d?=?.98) that was sustained over a three-month follow-up (d?=?.79). The current study supports the efficacy of a behavioral intervention for increasing and sustaining physical activity in a sample of persons with MS.     

Behavioral and physiological responses of young horses to different weaning protocols: a pilot study

In this study, effects of weaning on behavioral and physiological stress parameters in young horses (foals) were determined. Foals were weaned either simultaneously without the presence of adult horses (group A, n?=?6), or in the presence of two adult females familiar but unrelated to the foals (group B, n?=?5), or weaned consecutively by removing two mother horses per day (group C, n?=?6). Behavior, locomotion, salivary cortisol concentration, beat-to-beat (RR) interval, heart rate variability (HRV) and weight were determined. Group A foals lost weight for 2 days (mean?±?SEM) -?8.3?±?1.6?kg, p?相似文献   

Dominance-popularity status, behavior, and the emergence of sexual activity in young adolescents

In this paper, we investigated the sexual activity levels of several subtypes of middle adolescents (age 14-15 years). The subtype profiles were based on dominance-popularity status and a range of behaviors associated with dominance and popularity. In addition, gender differences in behavioral profiles were examined among dominant-popular, sexually active young adolescents. Results showed that socially dominant and popular young adolescent boys who exhibited a highly aggressive profile were more sexually active than their low-status and non-aggressive male peers; dominant-popular girls who were very attractive and gossips were more sexually active than their female peers. The results are discussed from an evolutionary psychological framework.     

Light-dark variation and changes across the lactational period in the behaviors of undisturbed mother and infant guinea pigs (Cavia porcellus)

Lactating guinea pigs (Cavia porcellus) and their litters were observed by videophotography across the light/dark cycle at 1, 11, 21, and 31 days postpartum. The highest level of behavioral activity was seen in the dark, particularly in the hour after light offset. This circadian pattern was evident from Day 1 in mothers and from Day 11 in pups. Contact between mothers and pups was inversely related to activity, occurring more frequently during light. Maternal grooming of pups occurred on Day 1 and then declined: self-grooming by pups increased across days. Intake of solid food and water by pups occurred on Day 1 and increased thereafter. A nearly complete transition from nursing to independent ingestion was observed between 21-31 days of age. Overall, we document several ontogenetic changes in young guinea pigs and demonstrate that under laboratory conditions mother and infant guinea pigs exhibit a nocturnal activity pattern.     

Negative life events and substance use moderate cognitive behavioral adolescent depression prevention intervention

Investigate factors that amplify or mitigate the effects of an indicated cognitive behavioral (CB) depression prevention program for adolescents with elevated depressive symptoms. Using data from a randomized trial (Registration No. NCT00183417; n?=?173) in which adolescents (M age =?15.5, SD =?1.2) were assigned to a brief cognitive behavioral prevention program or an educational brochure control condition, we tested whether elevated motivation to reduce depression and initial depressive symptom severity amplified intervention effects and whether negative life events, social support deficits, and substance use attenuated intervention effects. Hierarchical linear modeling (HLM) indicated differential intervention effects for two of the five examined variables: negative life events and substance use. For adolescents at low and medium levels of substance use or negative life events, the CB intervention produced declines in depressive symptoms relative to controls. However, at high levels of substance use or negative life events, the CB intervention did not significantly reduce depressive symptoms in comparison to controls. Results imply that high-risk adolescents with either high rates of major life stress or initial substance use may require specialized depression prevention efforts.     

The role of defeat and entrapment in depression, anxiety, and suicide

Defeat and entrapment are psychological constructs that have played a central role in evolutionary accounts of depression. These concepts have since been implicated in theoretical accounts of anxiety disorders and suicidality. The current article reports on a systematic review of the existing research investigating the links among defeat, entrapment, and psychopathology in the domains of depression, suicidality, posttraumatic stress disorder (PTSD), and other anxiety syndromes. Fifty-one original research articles were identified and critically reviewed. There was strong convergent evidence for a link with depressive symptoms, across a variety of clinical and nonclinical samples. Preliminary support for an association with suicidality was also observed, with effects not readily explainable in terms of comorbid depression. There was strong evidence for an association between defeat and PTSD, although this may have been partly accounted for by comorbid depression. The findings for other anxiety disorders were less consistent. There was, however, evidence that social anxiety in individuals with psychosis may be related to perceptions of entrapment. Overall, there was evidence that perceptions of defeat and entrapment were closely associated with various forms of human psychopathology. These effects were often in the moderate to large range and superseded the impact of other environmental and psychological stressors on psychopathology. We provide a unified theoretical model of how defeat and entrapment may contribute to these different psychopathological conditions. Clinical implications and avenues for future research are discussed.     

Internet-delivered physical activity intervention for college students with mental health disorders: a randomized pilot trial

The prevalence of mental health disorders among college students is rising and the increasing rates of anxiety and depression have important societal implications. Physical activity has been proposed as an adjuvant to traditional treatment approaches (i.e. psychotherapy or pharmacotherapy), and the internet is a potentially useful means of delivering physical activity information to the college-aged population. This randomized pilot trial examined the effects of an internet-based physical activity intervention on physical activity, self-efficacy, depression, and anxiety in college students (n?=?47) receiving mental health counseling. Physical activity, depression, anxiety, exercise self-efficacy, and barriers self-efficacy were assessed at baseline and post-intervention. There was a significant time effect for physical activity, with both groups increasing their physical activity levels across the 10-week intervention but with a larger increase in the intervention condition (d?=?0.68) than the control condition (d?=?0.05). Exercise and barriers self-efficacy declined across the intervention, but more so in the control than intervention condition. Effects on depression and anxiety were nonsignificant. Finally, correlation analyses showed increases in physical activity were associated with increases in exercise self-efficacy (r?=?0.62) and barriers self-efficacy (r?=?0.63) and decreases in depression (r?=?-0.44) in the intervention condition, but not in the control condition. These results suggest that an internet-delivered physical activity intervention may be a promising approach to promoting physical activity among college students undergoing mental health counseling.     

Associations of coping and appraisal styles with emotion regulation during preadolescence

We investigated the associations of appraisal and coping styles with emotion regulation in a community sample of preadolescents (N = 196, 9-12 years of age), with appraisal, coping styles, and emotion regulation measured at a single time point. In a previous study, we identified five frustration and four anxiety emotion regulation profiles based on children’s physiological, behavioral, and self-reported reactions to emotion-eliciting tasks. In this study, preadolescents’ self-reported appraisal and coping styles were associated with those emotion regulation profiles. Overall, findings revealed that children who were more effective at regulating their emotions during the emotion-eliciting tasks had higher levels of positive appraisal and active coping when dealing with their own problems. Conversely, children who regulated their emotions less effectively had higher levels of threat appraisal and avoidant coping.     

从进化观点看应激对健康的影响

从进化的观点解释了不同生物体应对应激的不同行为策略及其生理基础,和由此引起的对不同应激性疾病易感性的差异。行为策略和生理基础的差异使得一定环境条件下引发的应激反应对不同个体产生了不同的非稳态获益和代价（非稳态负荷)。非稳态的获益和代价影响了健康和疾病间的平衡：攻击性个体由于非稳态调质失调,更可能出现冲动控制障碍、高血压、自身免疫性疾病、慢性疲劳状态等;反之,非攻击性个体由于非稳调质过度释放,更易发生焦虑障碍、抑郁症、代谢综合症等     

Subordinate male mice show long-lasting differences in spatial learning that persist when housed alone

In the wild, house mice live in social groups, whereas in the laboratory male mice are often singly housed. Environmental enrichment such as that provided by social housing has been argued to improve the cognitive performance of laboratory animals in experimental tests. The aim of the present study was to test the cost of aggressive social interactions on learning in male CD-1 mice. We found that subordinate mice from more aggressive dyads showed spatial learning impairment, measured as alternation on a T-maze. Learning impairments in subordinates have hitherto been presumed attributable to the animals' exposure to, and relative standing within, the social group. By contrast, the impairment we observed could not have been the result of recent social defeat because it persisted weeks later when the mice were housed alone. Elevated urinary corticosterone predicted later subordination, though paradoxically these abnormally high levels were reduced by pair housing.     

Neuropharmacological aspects of adaptive pain inhibition in murine “victims” of aggression

This review outlines recent research on a subset of physiological responses in murine “victims” or aggression. In a typical resident-intruder paradigm, the detailed study of intruders has revealed that exposure to conspecific attack (and related stimuli) is associated with two forms of analgesia which appear to be integral components of the murine defensive repertoire. In response to intense/enduring attack, intruder mice display a profound, long-lasting and opioid-mediated analgesia. This reaction is highly correlated with defensive immobility and may function to reduce involuntary cues to further attack. In contrast, the inhibition of pain reactivity in mice tested immediately upon the display of defeat is less intense, shorter-lasting, non-opioid in nature and may function to facilitate active defenses such as escape. As this form of pain inhibition is also evident in intruders exposed to the scent of an aggressive male conspecific, a possible anticipatory defensive function linked to mechanisms of anxiety has been proposed. This hypothesis is supported by 1) the prevention of defeat analgesia by a range of antianxiety drugs (benzodiazepines, 5-hydroxytryptamine_1A [5-HT_1A] receptor agonists, and 5-HT₃ receptor antagonists) and 2) the effects of social defeat on behavior in the elevated plusmaze model of anxiety. These findings are discussed in relation to coping mechanisms in murine “victims” of aggression. © 1995 Wiley-Liss, Inc.