Visible burrow system as a model of chronic social stress: Behavoral and neuroendocrine correlates
ABSTRACT In mixed-sex rat groups maintained in visible burrow systems (VBS), consistent asymmetries in offensive and defensive behaviors of male dyads are associated with the development of dominance hierarchies. Subordinate males are characterized by particular wound patterns, severe weight loss, and a variety of behavioral changes, many of them isomorphic to target symptoms of clinical depression. In two VBS studies, subordinate males showed increased basal levels of plasma corticosterone (CORT), and increased adjusted adrenal and spleen weights compared to controls, and often, to dominants as well. Thymus weights and testosterone levels of subordinates were not reliably different in one study using highly aggressive males, but were reduced, along with testes weights, in a second study using unselected males. Glucocorticoid receptor binding levels in hippocampus, hypothalamus, and pituitary were not different, nor were aldosterone levels. When tested in a restraint stress procedure, subordinates had higher basal CORT levels, but about 40% of these animals showed a reduced, or absent, CORT response to restraint. These findings indicate that subordination may be reflected in high magnitude changes consistent with physiological indices of prolonged stress. Dominant rats of such groups may also show physiological changes suggesting stress, particularly when the groups are comprised of highly aggressive males only. The VBS colony model thus appears to enable rat groups to produce natural, stress-engendering, social interactions that constitute a particularly relevant model for investigating the behavioral, neural, and endocrine correlates of chronic stress.
- SourceAvailable from: Yasuhiko Kondo
[Show abstract] [Hide abstract]
- "In this study, we examined whether lack of social signals during adolescence increases maternal behavior in sexually naïve male mice as well as during young adulthood. Pheromone signals may be involved in these physiological and behavioral responses    ; therefore, we also examined the effect of modified social isolation that allowed male mice to smell and hear adjacent male conspecifics, but not to see or touch them. "
ABSTRACT: Maternal behavior in mice is considered to be sexually dimorphic; that is, females show maternal care for their offspring, whereas this behavior is rarely shown in males. Here, we examined how social isolation affects the interaction of adult male mice with pups. Three weeks of isolation during puberty (5-8 weeks old) induced retrieving and crouching when exposed to pups, while males with 1 week isolation (7-8 weeks old) also showed such maternal care, but were less responsive to pups. We also examined the effect of isolation during young adulthood (8-11 weeks old), and found an induction of maternal behavior comparable to that in younger male mice. This effect was blocked by exposure to chemosensory and auditory social signals derived from males in an attached compartment separated by doubled opaque barriers. These results demonstrate that social isolation in both puberty and postpuberty facilitates male maternal behavior in sexually naïve mice. The results also indicate that air-borne chemicals and/or sounds of male conspecifics, including ultrasonic vocalization and noise by their movement may be sufficient to interfere with the isolation effect on induction of maternal behavior in male mice. Copyright © 2015. Published by Elsevier Inc.Physiology & Behavior 07/2015; 151. DOI:10.1016/j.physbeh.2015.07.007 · 2.98 Impact Factor
[Show abstract] [Hide abstract]
- "Social hierarchy has also been explored in settings where dominance is established through unstaged social interactions that occur on an ongoing basis (e.g. Blanchard et al., 1995, 2001). A low position in the social (and economic/resource) hierarchy appears to be stressful across a wide range of species. "
ABSTRACT: The neurobiology of stress and the neurobiology of social behavior are deeply intertwined. The social environment interacts with stress on almost every front: social interactions can be potent stressors; they can buffer the response to an external stressor; and social behavior often changes in response to stressful life experience. This review explores mechanistic and behavioral links between stress, anxiety, resilience, and social behavior in rodents, with particular attention to different social contexts. We consider variation between several different rodent species and make connections to research on humans and non-human primates.01/2015; 1(1):116-127. DOI:10.1016/j.ynstr.2014.10.004
[Show abstract] [Hide abstract]
- "However, the difference in cortisol levels between controls and AVT treated-fish was larger in DOMs ($6-fold on average) than SUBs ($2-fold), so the experience of territory loss possibly contributed to the stress response. Alternatively, it is possible that DOMs are more sensitive to stressors than SUBs, so the same stimulus (AVT injection) would elicit a stronger response in DOMs relative to SUBs, which is supported by studies in mammals showing a reduced stress response in subordinate individuals (Blanchard et al., 1995). Interestingly, the stress axis is known to be dependent on AVT, as AVT stimulates release of adrenocorticotropic hormone (ACTH), which in turn induces the release of corticosteroid hormones such as cortisol (Antonii, 1986). "
ABSTRACT: Neuropeptides modulate many aspects of behavior and physiology in a broad range of animals. Arginine vasotocin (AVT) is implicated in mediating social behavior in teleost fish, although its specific role varies between species, sexes, life stages, and social context. To investigate whether the effects of AVT on behavior depend on social context, we used the African cichlid fish Astatotilapia burtoni, which is well-known for its remarkable behavioral plasticity. We pharmacologically manipulated the AVT system in established socially dominant and subordinate A. burtoni males, as well as in males ascending to dominance status in a socially unstable environment. Our results show that exogenous AVT causes a stress response, as evidenced by reduced behavioral activity and increased circulating levels of cortisol in established dominant and subordinate males. Administration of the AVT antagonist Manning compound, on the other hand, did not affect established subordinate or dominant males. However, AVT antagonist-treated males ascending from subordinate to dominant status exhibited reduced aggressive and increased courtship behavior compared to vehicle-treated animals. Finally, we measured circulating cortisol levels and brain gene expression levels of AVT and its behaviorally relevant V1a2 receptor in all three social phenotypes and found that plasma cortisol and mRNA levels of both genes were increased in ascending males compared to dominant and subordinate males. Our results provide a more detailed understanding of the role of the AVT system in the regulation of complex behavior in a dynamically changing social environment.General and Comparative Endocrinology 03/2014; 212. DOI:10.1016/j.ygcen.2014.03.004 · 2.47 Impact Factor