Behavioral, neurochemical, and neuroimmune changes associated with social buffering and stress contagion

Abstract

Social buffering can provide protective effects on stress responses and their subsequent negative health outcomes. Although social buffering is beneficial for the recipient, it can also have anxiogenic effects on the provider of the social buffering – a phenomena referred to as stress contagion. Social buffering and stress contagion usually occur together, but they have traditionally been studied independently, thus limiting our understanding of this dyadic social interaction. In the present study, we examined the effects of preventative social buffering and stress contagion in socially monogamous prairie voles ( Microtus ochrogaster ). We tested the hypothesis that this dynamic social interaction is associated with coordinated alterations in behaviors, neurochemical activation, and neuroimmune responses. To do so, adult male prairie voles were stressed via an acute immobilization restraint tube (IMO) either alone (Alone) or with their previously pair-bonded female partner (Partner) in the cage for 1 h. In contrast, females were placed in a cage containing either an empty IMO tube (Empty) or one that contained their pair-bonded male (Partner). Anxiety-like behavior was tested on the elevated plus maze (EPM) following the 60-mins test and brain sections were processed for neurochemical/neuroimmune marker labeling for all subjects. Our data indicate that females in the Partner group were in contact with and sniffed the IMO tube more, showed fewer anxiety-like behaviors, and had a higher level of oxytocin expression in the paraventricular nucleus of the hypothalamus (PVN) compared to the Empty group females. Males in the Partner group had lower levels of anxiety-like behavior during the EPM test, greater activation of corticotropin-releasing hormone expressing neurons in the PVN, lower activation of serotonin neurons in the dorsal raphe, and lower levels of microgliosis in the nucleus accumbens. Taken together, these data suggest brain region- and neurochemical-specific alterations as well as neuroinflammatory changes that may be involved in the regulation of social buffering and stress contagion behaviors.

Evidence for the existence of facilitatory interactions between the dopamine D2 receptor and the oxytocin receptor in the amygdala of the rat. Relevance for anxiolytic actions

“…Oxytocin, on its side, has been widely demonstrated to be a critical modulator of fear and anxiety (Jurek and Neumann, 2018), which in the vast majority of cases, elicits anxiolytic effects (see Jang et al (2021); Chun et al (2022)). Thus, in agreement with this, results from our laboratory (de la Mora et al, 2016) showed that oxytocin infusion (above 25 ng/side) into the CeA triggered anxiolytic effects in rats when using the shock-probe burying test.…”

Toll-like receptor 4 in the interface between neuroimmune response and behavioral alterations caused by stress

“…In animal studies, these effects often depend on specific individual characteristics of the subjects [46]. It is beyond the scope of the present review to address all these pathways; there are excellent reviews about this topic (for example, [53]).…”