Effects of Dominant/Subordinate Social Status on Formalin-Induced Pain and Changes in Serum Proinflammatory Cytokine Concentrations in Mice

Abstract

Current investigations regarding social stress primarily focus on the health consequences of being in stressful social hierarchies. The repetitive nature of social conflicts seems to favor an induction of hyperalgesia or hypoalgesia, both in rodents and humans. Additionally, social conflicts may affect the immune system. In order to better establish the pain and immune responses to stress, the present study implemented a sensory contact model on 32 male BALB/c mice. Subsequent to establishing a dominance/submissive social relationship, each mouse was injected with formalin (20 μl, 2%) and their pain behavior was scored and serum concentrations of proinflammatory cytokines IL-1 and IL-6, and corticosterone were also measured. Test results revealed that subordinate mice were hypoalgesic during chronic phase of formalin test compared to control and dominant mice (P<0.05). On the other hand, subordinate mice were hyperalgesic compared to dominant mice during the whole acute phase of formalin test (P<0.05). Corticosterone, IL-1 and IL-6 concentrations were much higher in serum of dominant and subordinate mice than in the control group (p<0.05). The results indicated that, although both dominant and subordinate animals displayed an increase in serum corticosterone and proinflammatory cytokines during social interactions, their response to pain perception differently was affected with the social status.

Pain threshold - measure of pain sensitivity or social behavior?

“…Nevertheless, the results of studies like this clearly show that, from the methodological point of view, one must acknowledge the potential effect of the status of the person gathering information on pain. Since pain is almost always experienced in some form of social context -even several studies conducted on rodents (Aghajani et al, 2013;Gioiosa, Chiarotti, Alleva, & Laviola, 2009;Langford et al, 2006;Langford et al, 2011) suggest that the effect of social context on pain experience goes beyond the human race -future studies are strongly advised to take social context into account.…”

A temperate endotherm trades thermoregulation for self-preservation: stress-induced changes in surface temperature as thermoregulatory trade-offs

“…Furthermore, it is also one of few to explore the presence of a trade-off under stress exposure with respect to ecologically relevant resource constraints (i.e. those induced by social hierarchies; Aghajani et al, 2013;Proctor, Freeman, & Brown, 2010).…”

Effects of Social Stresses on Immune Response in Female and Male Mice

“…Poverty and social inequality are intrinsically stressful and have deteriorating effects on health and well-being [2,3]. It is believed that both natural and laboratoryinduced stressors have profound direct and indirect influences on immune responses [4]. Such stresses along with social and psychological disturbances suppress immune responses and leave body unprotected against diseases and infections [5].…”

“…Such stresses along with social and psychological disturbances suppress immune responses and leave body unprotected against diseases and infections [5]. On the other hand, poverty may exacerbate immunopathology following prolonged activation and dysregulation of the immune system and causes altered production of proinflammatory cytokines including tumor necrosis factor-alpha (TNF-α) [4].…”