Fighting experiences and natural killer cell activity in male laboratory mice

There is currently much interest in the potential impact of psychological factors on immune responses. An attempt was made to assess the effects of dominant/subordinate polarity in male mice on the cytotoxic activities of their natural-killer (NK) cells. On the basis of repeated agonistic encounters, categories of subordinate and dominat animals were selected. These animals were compared with manipulated controls (introduced to a novel test cage without an opponent on each occasion) and undisturbed controls (who remained in isolation without manipulation). In terms of NK activity, immunosuppression was observed in both dominant and subordinate categories when compared to undisturbed controls. There were, however, no differences between the fighting exposed subjects and the manipulated controls, suggesting that stress accounts for any changes. © 1994 Wiley-Liss, Inc.     

Individual differences in chronically defeated male mice: behavioral, endocrine, immune, and neurotrophic changes as markers of vulnerability to the effects of stress

This study aimed to analyze different behavioral profiles in response to chronic social defeat using the sensorial contact model. We hypothesized that a passive profile, unlike an active one, would be associated with behavioral and physiological characteristics related to depression. Six-week-old OF1 male mice were subjected to defeat for 21 consecutive days. A combination of cluster and discriminant analyses of the behavior exhibited during confrontation on Day 21 established two behavioral profiles: active (n?=?22) and passive (n?=?34). Passive mice, with a high level of immobility and low non-social exploration, had higher plasma corticosterone concentrations than active mice after 21 days of defeat. Three days after the last defeat, passive mice had lower corticosterone levels than manipulated-control mice (n?=?11). Higher levels of interleukin-6 and tumor necrosis factor-α (TNF-α) in the spleen and lower hippocampal brain-derived neurotrophic factor levels were observed in passive mice in comparison with those in active mice and the manipulated controls. The only differences observed in active mice in relation to the manipulated control were higher plasma corticosterone (Day 21) and TNF-α levels. The results show that different behavioral profiles in response to chronic defeat are associated with different physiological profiles, and that the passive profile presents physiological characteristics previously associated with depression.     

Looking at the Bright Side: Forgiveness and Subjective Well-Being in Divorced Spanish Parents

Marriage dissolution might cause frustration, resentment and pain. Forgiveness is view as an adaptive reaction that has positive effects on post-divorce adjustment and coparenting; but much remains unknown about the place of forgiveness in the subjective well-being of divorced parents. The objective of the present study was to analyze in a multidimensional model the role played by forgiveness in post-divorce subjective well-being, empirically examining the relationships between time since divorce, affect (positive and negative), forgiveness and satisfaction with life in a group of Spanish divorced parents. Data were collected from 223 divorced Spanish parents (58.3 % mothers) aged 21–64 years, and who had 1–3 children. Results showed that forgiveness and time since divorce partially mediated the effect of positive affect on satisfaction with life: individuals with high levels of positive affect, over time, were more forgiving of their ex-spouses, which in turn enhanced their satisfaction with life. The present study complements the existing literature about the importance of forgiveness in post-divorce coparenting highlighting the place of forgiveness in the subjective well-being of divorced parents.     

Effects of social stress on tumor development in dominant male mice with diverse behavioral activity profiles

We examined the influence of individual psychological profile and social behavior on tumor development in dominant male mice. Male OF1 mice were subjected to an open field test (OFT) to observe their motor activity and latency. Subsequently, the animals were divided into three groups: Stress-Non-Inoculated (SNI), Stress-Inoculated (SI) and Control-Inoculated (CI). The SI and CI groups were inoculated with tumor cells and the SNI group with vehicle. SNI and SI were exposed to social stress with an anosmic intruder six (T1) and twenty one (T2) days after inoculation and their behavior was analyzed. After T2, subjects were put down and the pulmonary metastatic foci counted. SI developed greater pulmonary metastasis than CI, indicating an effect of stress despite the animal's dominant status. Active animals developed less pulmonary metastasis than their passive counterparts. No differences were found in social behavior at T1. Differences were found, however, in some behavioral categories at T2 between SI and SNI, and between active and passive animals. These differences indicate an effect of tumor development on social behavior that is more evident in passive subjects.