Chronic Social Stress Alters Levels of Corticotropin-Releasing Factor and Arginine Vasopressin mRNA in Rat Brain

Abstract

In the visible burrow system model of chronic social stress, male rats housed in mixed-sex groups quickly form a dominance hierarchy in which the subordinates appear to be severely stressed. A subgroup of subordinates have an impaired corticosterone response after presentation of a novel restraint stressor, leading to their designation as nonresponsive subordinates. To examine the mechanism underlying the blunted corticosterone response in these animals, in situ hybridization histochemistry was used to quantify corticotropin-releasing factor (CRF) and arginine vasopressin (AVP) mRNA expression in the brain. In two separate visible burrow system experiments, the nonresponsive subordinates expressed a significantly lower average number of CRF mRNA grains per cell in the paraventricular hypothalamic nucleus compared with stress-responsive subordinates, dominants (DOM), or cage-housed control (CON) rats. The number of CRF mRNA labeled cells was also significantly lower in nonresponders than in responsive subordinates or DOM. In the central amygdala, CRF mRNA levels were increased in both groups of subordinates compared with CON rats, whereas responsive subordinates exhibited higher levels than the DOM rats as well. AVP mRNA levels did not vary with behavioral rank in any subdivision of the paraventricular hypothalamic nucleus. In the medial amygdala, the number of cells expressing AVP mRNA was significantly greater in CON rats compared with both groups of subordinates, although the average number of AVP mRNA grains per cell did not vary with rank. In addition, the number of AVP-positive cells significantly correlated with plasma testosterone level.

Protective and Damaging Effects of Stress Mediators

“…The New England Journal of Medicine hormone messenger RNA in the hypothalamus are abnormally low. 36 Human counterparts with HPA hyporesponsiveness include adults with fibromyalgia 37,38 and chronic fatigue syndrome 39,40 and children with atopic dermatitis. 41 In post-traumatic stress disorder, basal HPA activity is also low, 42,43 although reactivity to stress may not be blunted.…”

Dynamic body weight and body composition changes in response to subordination stress

“…Social stress in the VBS produces a variety of changes in neuropeptide and neurochemical systems including altered corticotrophin releasing hormone (CRH) and vasopressin expression [36] and glucocorticoid and mineralocorticoid receptor expression in hippocampus [37]. DOM and SUB also show changes in the serotonin (5-HT) [33,34,38] and dopamine systems [38,39].…”

Variation in the emission rate of sounds in a captive group of false killer whales Pseudorca crassidens during feedings: possible food anticipatory vocal activity?

“…Such signals are made in the wild as well as in captivity (Mulligan et al, 1994;Grandin, 1998;Panksepp and Burgdorf, 2000;Burgdorf and Panksepp, 2001;Manteuff el et al, 2004;Burman et al, 2007). In fact, it has been found that sound rates, type of calls, and acoustic structure within a call may vary depending on the context of behaviors such as aggression, panic, and social separation (rodents: Goldstein et al, 1996;Albeck et al, 1997;primates: Bayart et al, 1990;Champoux and Suomi, 1994;Friedman et al, 1995;Laudenslager et al, 1995;Boinski et al, 1999;farm animals: von Borell and Ladewig, 1992;Désautés et al, 1997;Weary et al, 1997). Animals living in a controlled environment with predictable daily routines, experience anticipation which is a mental state that can infl uence their behaviors including vocalizations (Krishnamurthy, 1994;Knutson et al, 1998;Burgdorf et al, 2000;Waitt and Buchanan-Smith, 2001;Ulyan et al, 2006;Düpjan et al, 2008;Gilbert-Norton et al, 2009;Polizzi di Sorrentino et al, 2010).…”