The same stress has divergent effects on social versus asocial manifestations of anxiety-like behavior over time

Physiological and behavioral contagion/buffering effects of chronic unpredictable stress in a socially enriched environment: A preliminary study

Rodents are sensitive to the emotional state of conspecifics. While the presence of affiliative social partners mitigates the physiological response to stressors (buffering), the partners of stressed individuals show behavioral and endocrine changes indicating that stress parameters can be transmitted across the group members (contagion). In this study, we investigated the social contagion/buffering phenomena in behavior and neuroendocrine mechanisms after exposure to chronic stress, in groups of rats living in the PhenoWorld (PhW). Three groups were tested (8 stressed rats, 8 unstressed rats, and a mixed group with 4 and 4) and these were analyzed under 4 conditions: stressed (pure stress group, n = 8), unstressed (naive control group, n = 8), stressed from mixed group (stressed companion group, n = 8), unstressed from mixed group (unstressed companion group, n = 8. While naive control animals remained undisturbed, pure stress group animals were all exposed to stress. Half of the animals under the mixed-treatment condition were exposed to stress (stressed companion group) and cohabitated with their unstressed partners (unstressed companion group). We confirmed the well-established chronic unpredictable stress (CUS) effects in physiological, behavioral, and neuroendocrine endpoints; body weight gain, open arm entries and time in EPM, and oxytocin receptor expression levels in the amygdala decreased by stress exposure, whereas adrenal weight was increased by stress. Furthermore, we found that playing, rearing and solitary resting behaviors decreased, whereas huddling behavior increased by CUS. In addition, we detected significant increases (stress-buffering) in body weight gain and huddling behaviors between pure stress and stress companion animals, and significant stress contagion effects in emotional behavior and oxytocin receptor expression levels between naive control and control companion groups. Hence, we demonstrate buffering and contagion effects were evident in physiological parameters, emotional behaviors, and social home-cage behaviors of rats and we suggest a possible mediation of these effects by oxytocin neurotransmission. In conclusion, the results herein suggest that the stress status of animals living in the same housing environment influences the behavior of the group.

Microbes, oxytocin and stress: Converging players regulating eating behavior

Oxytocin is a peptide-hormone extensively studied for its multifaceted biological functions and has recently gained attention for its role in eating behavior, through its action as an anorexigenic neuropeptide. Moreover, the gut microbiota is involved in oxytocinergic signaling through the brain-gut axis, specifically in the regulation of social behavior. The gut microbiota is also implicated in appetite regulation and is postulated to play a role in central regulation of hedonic eating. In this review, we provide an overview on oxytocin and its individual links with the microbiome, the homeostatic and non-homeostatic regulation of eating behavior as well as social behavior and stress.

Home-cage behavior is impacted by stress exposure in rats

Being social animals, rats exhibit a range of social behaviors that help them build social bonds and maintain group cohesion. Behavior is influenced by multiple factors, including stress exposure, and the expression of the impact of stress on both social and non-social behaviors may also be affected by the living conditions of rats. In this study, we explored the physiological and behavioral effects of chronic unpredictable stress on group-housed rats in the PhenoWorld (PhW), a socially and physically enriched environment closer to real-life conditions. Two independent experiments were performed: one in the control condition (PhW control, n = 8) and one in the stress condition (PhW stress, n = 8). Control animals remained undisturbed except for cage cleaning and daily handling procedures. Stress group animals were all exposed to chronic unpredictable stress. Data confirm that stress exposure triggers anxiety-like behavior in the PhW. In terms of home-cage behaviors, we found that stress affects social behaviors (by decreased playing and increased huddling behaviors) and non-social behaviors (as shown by the decrease in rearing and walking behaviors). These results are of relevance to expand our knowledge on the influence of stress on social and non-social behaviors, which are of importance to understand better species-typical behaviors.

A salience hypothesis of stress in PTSD

Attention to key features of contexts and things is a necessary tool for all organisms. Detecting these salient features of cues, or simply, salience, can also be affected by exposure to traumatic stress, as has been widely reported in individuals suffering from post-traumatic stress disorder (PTSD). Interestingly, similar observations have been robustly replicated across many animal models of stress as well. By using evidence from such rodent stress paradigms, in the present review, we explore PTSD through the lens of salience processing. In this context, we propose that interaction between the neurotrophin brain-derived neurotrophic factor (BDNF) and glucocorticoids determines the long lasting cellular and behavioural consequences of stress salience. We also describe the dual effect of glucocorticoid therapy in the amelioration of PTSD symptoms. Finally, by integrating in vivo observations at multiple scales of plasticity, we propose a unifying hypothesis that pivots on a crucial role of glucocorticoid signalling in dynamically orchestrating stress salience.

Incidence and risk factors of suicide in patients with lung cancer: a scoping review

PURPOSE

To explore the high-risk period of the occupation of suicide after diagnosis; and clarify the risk factors of suicidal behaviors (suicidal ideation, suicide attempt, and suicidal death) behind the lung cancer patients during the cancer cure process.

METHODS

This scoping review was conducted through the whole month of April 2021. We extracted data of the suicide mortality after diagnosis and latent risk factors of suicidal behaviors among lung cancer patients where we used to study from the two online databases which are PubMed and Web of Science. Two online databases were searched and written in English without age restriction. To note that the standardized mortality ratio (SMR), person-years, and odds ratio (OR) associated with lung cancer were documented.

RESULTS

Out of 570 records, 23 studies mentioned suicidal behaviors and lung cancer met the included criteria. Eleven (n = 47.8%) of the selected publications reported changes in suicide mortality. None of them reported suicidal ideation or suicide attempt after diagnosis. The individuals with lung cancer have significantly higher rates of suicidal death (SMR, 2.04-13.4) during the first years after diagnosis and decrease over subsequent years (SMR, 0.66-3.17). The median time from cancer diagnosis to suicide death was around 7 months. Across all studies with the 22 studies that examined factors, we extracted the data of the suicidal ideation (n = 3), suicide attempt (n = 1), and suicidal death (n = 18) in individuals. For patients with suicidal ideation, there was a significantly higher incidence in males than in females. Among patients who attempted suicide, the incidence of mental illness is greater than the incidence of physical illness. Factors for suicidal death, including gender (male, 56.3-100%), prognosis tumors (poor, 25.8-66.3%), marital status (widowhood or unmarried, 19-75.7%), and age of patients (> 70 years, 24.5-47%) with lung cancer, play a vital role. Treatment of lung cancer is expected to affect a patient in his/her mental state.

CONCLUSION

Overall, our finding indicates that lung cancer patients have been presented with a higher incidence of suicide death in a specific period, especially the early years after diagnosis. Discovering risk factors for suicide helps prevent potential suicide. It is essential to screen lung cancer patients for suicidal ideation, especially those with high-risk factors. Future prospective studies are necessary to confirm these findings to support care.

Sex differences in the delayed impact of acute stress on the amygdala

There is accumulating evidence that stress triggers specific temporal patterns of morphological plasticity in the amygdala, a brain area that plays a pivotal role in the debilitating emotional symptoms of stress-related psychiatric disorders. Acute immobilization stress is known to cause a delayed increase in the density of dendritic spines on principal neurons in the basolateral amygdala (BLA) of rats. These neuronal changes are also accompanied by a delayed enhancement in anxiety-like behavior. However, these earlier studies used male rats, and the delayed behavioral and synaptic effects of acute stress on the BLA of female rats remain unexplored. Here, using whole-cell recordings in rat brain slices, we find that a single exposure to 2-h immobilization stress leads to an increase, 10 days later, in the frequency of miniature excitatory postsynaptic currents (mEPSCs) recorded from lateral amygdala (LA) principal neurons in male rats. Further, acute stress also causes a reduction in the frequency of miniature inhibitory postsynaptic currents (mIPSCs) in LA neurons 10 days after acute stress. In striking contrast, excitatory and inhibitory synaptic transmission in the LA of female rats does not exhibit any delayed change despite exposure to the same acute stress. Finally, we examined the functional impact of these contrasting synaptic changes at the behavioral level. Male rats exhibit a delayed increase in anxiety-like behavior on the elevated plus-maze 10 days after acute stress. However, the same stress does not lead to a delayed anxiogenic effect in female rats. Together, these results demonstrate that the delayed modulation of the balance of synaptic excitation and inhibition in the amygdala, as well as anxiety-like behavior, differ between males and females. These findings provide a framework, across biological scales, for analyzing how affective symptoms of stress disorders vary between the sexes.