Behavioral Indices Of Anxiety Research Articles

Neurobiological effects of a probiotic-supplemented diet in chronically stressed male Long-Evans rats: Evidence of enhanced resilience.

Probiotics that regulate the microbiome-gut-brain axis and provide mental health benefits to the host are referred to as psychobiotics. Preclinical studies have demonstrated psychobiotic effects on early life stress-induced anxiety- and depression-related behavior in rodents; however, the specific mechanisms remain ill-defined. In the current study, we investigated the effects of probiotic supplementation on neurobiological responses to chronic stress in adult male Long-Evans rats. Twenty-four rats were randomly assigned to probiotic (PB) or vehicle control (VEH) groups, then to either chronic unpredictable stress (CUS) or no-stress control (CON) conditions within each group (n = 6/subgroup). We hypothesized that PB supplementation would reduce markers of anxiety and enhance emotional resilience, especially in the CUS animals. In the cognitive uncertainty task, a nonsignificant trend was observed indicating that the PB-supplemented animals spent more time oriented toward the food reward than VEH animals. In the open-field task, CUS-PB animals spent more time in the center of the arena than CUS-VEH animals, an effect not observed between the two CON groups. In the swim task, the PB animals, regardless of stress assignment, exhibited increased floating, suggesting a conserved response in a challenging context. Focusing on the endocrine measures, higher dehydroepiandrosterone (DHEA)-to-corticosterone fecal metabolite ratios, a correlate of emotional resilience, were observed in PB animals. Further, PB animals exhibited reduced microglia immunoreactivity in the basolateral amygdala, possibly indicating a neuroprotective effect of PB supplements in this rodent model. These results provide evidence that PB supplementation interacts with stress exposure to influence adaptive responses associated with endocrine, neural, and behavioral indices of anxiety.

Oxidative stress and neuroinflammation in a rat model of co-morbid obesity and psychogenic stress

BackgroundThere is growing recognition for a reciprocal, bidirectional link between anxiety disorders and obesity. Although the mechanisms linking obesity and anxiety remain speculative, this bidirectionality suggests shared pathophysiological processes. Neuroinflammation and oxidative damage are implicated in both pathological anxiety and obesity. This study investigates the relative contribution of comorbid diet-induced obesity and stress-induced anxiety to neuroinflammation and oxidative stress. MethodsThirty-six (36) male Lewis rats were divided into four groups based on diet type and stress exposure: 1) control diet unexposed (CDU) and 2) exposed (CDE), 3) Western-like high-saturated fat diet unexposed (WDU) and 4) exposed (WDE). Neurobehavioral tests were performed to assess anxiety-like behaviors. The catalytic concentrations of glutathione peroxidase and reductase were measured from plasma samples, and neuroinflammatory/oxidative stress biomarkers were measured from brain samples using Western blot. Correlations between behavioral phenotypes and biomarkers were assessed with Pearson's correlation procedures. ResultsWe found that WDE rats exhibited markedly increased levels of glial fibrillary acidic protein (185 %), catalase protein (215 %), and glutathione reductase (GSHR) enzymatic activity (418 %) relative to CDU rats. Interestingly, the brain protein levels of glutathione peroxidase (GPx) and catalase were positively associated with body weight and behavioral indices of anxiety. ConclusionsTogether, our results support a role for neuroinflammation and oxidative stress in heightened emotional reactivity to obesogenic environments and psychogenic stress. Uncovering adaptive responses to obesogenic environments characterized by high access to high-saturated fat/high-sugar diets and toxic stress has the potential to strongly impact how we treat psychiatric disorders in at-risk populations.

Western High-Fat Diet Consumption during Adolescence Increases Susceptibility to Traumatic Stress while Selectively Disrupting Hippocampal and Ventricular Volumes.

Psychological trauma and obesity co-occur frequently and have been identified as major risk factors for psychiatric disorders. Surprisingly, preclinical studies examining how obesity disrupts the ability of the brain to cope with psychological trauma are lacking. The objective of this study was to determine whether an obesogenic Western-like high-fat diet (WD) predisposes rats to post-traumatic stress responsivity. Adolescent Lewis rats (postnatal day 28) were fed ad libitum for 8 weeks with either the experimental WD diet (41.4% kcal from fat) or the control diet (16.5% kcal from fat). We modeled psychological trauma by exposing young adult rats to a cat odor threat. The elevated plus maze and the open field test revealed increased psychological trauma-induced anxiety-like behaviors in the rats that consumed the WD when compared with control animals 1 week after undergoing traumatic stress (p < 0.05). Magnetic resonance imaging showed significant hippocampal atrophy (20% reduction) and lateral ventricular enlargement (50% increase) in the animals fed the WD when compared with controls. These volumetric abnormalities were associated with behavioral indices of anxiety, increased leptin and FK506-binding protein 51 (FKBP51) levels, and reduced hippocampal blood vessel density. We found asymmetric structural vulnerabilities to the WD, particularly the ventral and left hippocampus and lateral ventricle. This study highlights how WD consumption during adolescence impacts key substrates implicated in post-traumatic stress disorder. Understanding how consumption of a WD affects the developmental trajectories of the stress neurocircuitry is critical, as stress susceptibility imposes a marked vulnerability to neuropsychiatric disorders.

Visitor effects on anxiety in two captive groups of western lowland gorillas

There is growing interest in examining the effects that visitors have on the welfare of zoo primates. Most recently, the importance of evaluating the combined impacts of visitors and management practices on anxiety levels of these animals has been highlighted. Studies that take such an approach have the potential not only to highlight how visitors affect the welfare of zoo primates, but also how these impacts may be mediated by management interventions, such as enrichment. The aim of this study was to explore the potential impact of visitor numbers on behavioural indices of anxiety among western lowland gorillas in two UK zoos, Port Lympne and Chessington, and to determine whether feeding enrichment mediates any such visitor effects. During fifteen minute focal watches, visitor numbers were assessed and all occurrence data collected on two behavioural indices of anxiety: self-scratching and visual monitoring of visitors. Data collected at each site were divided according to whether they were taken during periods of feeding enrichment, or during periods when no such enrichment was being given. Analyses revealed no evidence for a visitor effect at Chessington, with durations of self-scratching and visual monitoring unrelated to visitor number, either during periods of enrichment or outside of such times. At Port Lympne, durations of both self-scratching and visual monitoring were positively associated with visitor number when no feeding enrichment was taking place; no such relationships were seen, however, during periods of feeding enrichment. Potential reasons for the difference between sites in the occurrence of visitor effects, and for the absence of visitor effects during feeding enrichment at Port Lympne are discussed. The results of this study highlight the importance of assessing visitor effects on the same species at multiple sites, and also suggest that such effects may be reduced by positive management approaches.

The Contributions of Eye Movements to the Efficacy of Brief Exposure Treatment for Reducing Fear of Public Speaking

The present study was designed to isolate the effects of the eye-movement component of the Eye Movement Desensitization and Reprocessing (EMDR) procedure in the treatment of fear of public speaking. Seventy-one undergraduate psychology students who responded in a fearful manner on the Fear Survey Schedule II and on a standardized, self-report measure of public speaking anxiety (Personal Report of Confidence as a Speaker; PRCS) were randomly assigned to one of four groups in a 2 × 2 factorial design. The two independent variables assessed were treatment condition (imagery plus eye movements vs. imagery alone) and type of imagery (fear-relevant vs. relaxing). Dependent variables assessed were self-reported and physiological anxiety during exposure and behavioral indices of anxiety while giving a speech. Although process measures indicated exposure to fear-relevant imagery increased anxiety during the procedure, no significant differences among groups were found on any of the outcome measures, except that participants who received eye movements were less likely to give a speech posttreatment than participants who did not receive eye movements. Addition of the eye movements to the experimental procedure did not result in enhancement of fear reduction. It was concluded, consistent with the results of past research, that previously reported positive effects of the EMDR procedure may be largely due to exposure to conditioned stimuli.

Influence of coping style and precolonoscopy information on pain and anxiety of colonoscopy

Background: This study assessed the relationship between patient coping style, precolonoscopy information, and anxiety and pain associated with colonoscopy. Methods: Eighty consecutive adult patients undergoing initial colonoscopy were classified into two groups on the basis of coping style: information seekers or information avoiders. All were given standardized information about colonoscopy. Half of each group was randomly assigned to receive additional sensory information describing what they could expect to feel. Self-report, physiologic, and behavioral indices of anxiety and pain were measured. Results: Patients given information congruent with coping style experienced significantly less self-report anxiety immediately after the information intervention and spent less time in recovery. In contrast, patients given information not congruent with coping style maintained their pre-intervention anxiety level. Patients given information congruent with coping style scored lower on behavioral indices of pain, but there were no differences with respect to patient perception of pain or the dosage of sedative drugs. Most patients reported that the bowel preparation was the most distressing part of the colonoscopy. Conclusions: Assessment of coping style and provision of congruent information reduces anxiety, recovery time, and observed behavioral indices of pain of colonoscopy but has no effect on sedation dose or patient perception of pain. (Gastrointest Endosc 1998;48:119-27.)

Lesion of the habenular efferent pathway produces anxiety and locomotor hyperactivity in rats: a comparison of the effects of neonatal and adult lesions

Recent studies have implicated the habenula in modulating states of arousal and chronic responses to stress. We examined whether lesion of the habenula efferent pathway, the fasciculus retroflexus (FR), at either 3 (P3) or 70 (P70) days of age affects stress-related anxiety (elevated plus-maze test) and activity levels (open-field test) in rats tested as adults. Both P3- and P70-lesioned rats showed chronically elevated plasma levels of corticosterone. Rats receiving FR lesions as neonates (P3) exhibited greater open arm avoidance on the elevated plus-maze than controls 2 months postoperatively, suggesting a heightened state of anxiety. In contrast, P70-lesioned rats behaved similarly to controls on the plus-maze, but showed increased locomotion and increased grooming in the open field, effects not observed in P3-lesioned rats. When an additional stressful condition was imposed (5 days of social isolation plus 24 h food deprivation) before testing, both FR-lesion groups showed an attenuation of the normal behavioral responses (decreased open-arm entries/time in open arms, increased freezing). The effects of FR lesions on activity and behavioral indices of anxiety may be due to disruption of lateral habenular projections to dopaminergic neurons in the ventral tegmentum and/or projections to regions containing high concentrations of benzodiazepine receptors, the median and dorsal raphe and dorsal periaqueductal gray. Behavioral differences observed as a function of lesion age suggest differential capabilities of P3- and P70-lesioned rats to utilize compensatory mechanisms to correct FR lesion-induced deficits.

Effects of the estrous cycle and ovarian hormones on behavioral indices of anxiety in female rats.

The influence of the estrous cycle and the effects of exogenous administration of estradiol and progesterone on level of anxiety were studied in intact and ovariectomized rats. Intact Sprague-Dawley female rats were classified according to the stages of estrous cycle. Another group of rats was ovariectomized bilaterally and, 14 days after surgery, they received estradiol benzoate (10 micrograms/kg, s.c.) and/or progesterone (25 mg/kg, s.c.) or corn oil (1 ml/kg). The behavioral tests began 3 h after estradiol or 6 h after progesterone and consisted of: (1) exploration of an elevated plus-maze; and (2) retention of a passive avoidance response. Open-arm exploration of the plus-maze varied according to light intensity and the stages of the estrous cycle. There was a slight increase in open-arm exploration by rats in metestrus, under high light intensity. Low light intensity increased the exploration of the open arms by rats in proestrus and estrus, compared to the other phases of the cycle. Retention of the passive avoidance response was inhibited during proestrus and estrus. Progesterone increased open-arm exploration of the plus-maze under high light conditions, whereas estradiol antagonized this effect. Retention of passive avoidance was inhibited after estradiol or progesterone injection. These results suggest that the behavioral indices of anxiety can vary across the estrous cycle, that low light intensities have anxiolytic-like effects, and that the sensitivity to this effect is higher during proestrus and estrus. This could be explained through modulatory effects of ovarian hormones upon behavioral indices of anxiety.

Coping with a stressful medical procedure: further investigation with volunteer blood donors.

The coping strategies used by volunteer blood donors were studied in an attempt to replicate and extend the findings of Kaloupek et al. [(1984). J. Behav. Med. 7:35-60]. Specifically, coping was assessed by process, state, and trait measures that were then examined in terms of their relationships with subjective, physiological, and behavioral indices of anxiety. Ratings of anxiety made by the donors themselves and by attending nurses generally replicated the previous finding of lower distress associated with avoidant coping (e.g., distraction). Problem-focused coping was also associated with lower distress, including a lower heart rate for first-time donors. Other evidence suggests that for some individuals the expression of distress may be part of a coping strategy that is associated with reduced physiological responding. Discussion concerns links between coping and anxiety which may have relevance to stressful medical situations, including the possible need for anxiety reduction to allow successful application of avoidant coping.

Behavioral indices of anxiety and locus of control.

Behavioral indices of anxiety and locus of control.