Psychosocial stressors contribute to the pathophysiology of affective disorders and variations of cytokine functioning have been implicated in this process. The present investigation demonstrated, in mice, the impact of stressful aggressive encounters on activity levels, plasma corticosterone and cytokine concentrations, and on cytokine mRNA expression within the prefrontal cortex (PFC) and hip...

Recent findings from our laboratory and others indicate that exposure to stress can increase expression of the pro-inflammatory cytokine interleukin-1 (IL-1). In a series of studies examining this response, we observed pronounced differences in baseline levels of hypothalamic IL-1 of pair-housed rats. We hypothesized that these pair-wise differences might be a result of prolonged social stress ...

Background: Chronic social stress triggers the development of major depression in humans and depression-like behavior in animal models. Hyperexcitability of the hypothalamic-pituitary-adrenal (HPA) axis has been implicated in the pathophysiology of depression. The HPA axis is tightly controlled by GABAergic inhibition at the level of corticotrophin-releasing hormone (CRH) neurons in the paraven...

Behaviors, such as those that establish dominant and subordinate social status, are thought to be driven by various neuromodulators and hormones. In crustaceans, the level of serotonin (5-HT) in the hemolymph is correlated with degree of aggressiveness. The crustacean heart is neurogenic and is modulated by neural secretion of 5-HT in the hemolymph, which bathes the cardiac tissue. We discuss a...

We measured the metabolic rates as a direct estimate of energy expenditure of individual Neolamprologus pulcher, a cooperatively breeding cichlid ®sh, when resting and when performing agonistic, submissive or digging behaviours in a respirometer. Standard and routine metabolic rates increased linearly with body mass (range 0.9±8.4 g) when plotted on a doubly logarithmic scale (linear regression...

Electric fishes modulate their electric organ discharges with a remarkable variability. Some patterns can be easily identified, such as pulse rate changes, offs and chirps, which are often associated with important behavioral contexts, including aggression, hiding and mating. However, these behaviors are only observed when at least two fish are freely interacting. Although their electrical puls...

Social animals adjust their behavior according to social relationships and momentary circumstances. Dominant-submissive relationships modulate, but do not completely determine, their competitive behaviors. For example, a submissive monkey's decision to retrieve food depends not only on the presence of dominant partners but also on their observed behavior. Thus, behavioral expression requires a ...