Rapid neuroendocrine responses evoked at the onset of social challenge

Abstract

At the onset of agonistic social challenge, individuals must assess the degree of threat the opponent represents in order to react appropriately. We aimed to characterize the neuroendocrine changes accompanying this period of initial social assessment using the lizard Anolis carolinensis. Conveyance of aggressive intent by male A. carolinensis is facilitated by rapid post-orbital skin darkening (eyespot), whereas eyespot presence inhibits opponent aggression. By manipulating this visual signal, we also investigated whether differing neuroendocrine changes were evoked by initial presentation of varying levels of social threat. Subjects were painted postorbitally either with black paint (high threat level), green paint (low threat level) or water (controls). Painted animals were presented with a mirror and sampled immediately upon exhibiting aggressive intent towards the reflected simulated opponent, but before producing behaviors such as motor pattern-based displays. Control animals (blank surface presented) were sampled at times derived from averaging response times of painted subjects. Brains and plasma were analyzed for monoamine activity and catecholamine levels using electrochemical HPLC. Social threat evoked increases in plasma catecholamine levels indistinguishable from those caused by brief environmental disturbance. However, brief social challenge caused distinct rapid increases in amygdala and nucleus accumbens (NAc) dopamine and serotonin levels. Amygdalar changes were associated with general social threat presence, but NAc monoamines were affected by both threat level and subject motivation to engage in confrontation. This suggests that specific rapid activity changes in key forebrain limbic nuclei differ according to the degree of social threat perceived at the start of the interaction.

Exposure to Advertisement Calls of Reproductive Competitors Activates Vocal-Acoustic and Catecholaminergic Neurons in the Plainfin Midshipman Fish, Porichthys notatus

“…Levels of the catecholamines DA and NE have been shown to increase in the brains of the lizard ( Anolis carolinensis) during presentation of an actual [85] or simulated [86] opponent. Similarly, male Lincoln’s sparrows exposed to challenging songs of other males showed increased noradrenaline metabolites in the auditory forebrain and may be involved in the modulation of a motivated behavioral response to such a challenge [87].…”

Impact of juvenile chronic stress on adult cortico-accumbal function: Implications for cognition and addiction

“…Similarly, norepinephrine from afferents arising in the locus coeruleus and nucleus of the solitary tract can increase dopamine release in the NAc shell via α 1 adrenergic receptors (Mitrano et al, 2012; Sesack & Grace, 2010). The serotonergic and adrenergic systems are highly responsive to stress-associated neuroendocrine activity (Dunn et al, 2004; Forster et al, 2006; 2008; Watt et al, 2007), offering a means by which accumbal dopamine activity and reward behavior can be modulated through perception and integration of the degree of stress associated with a particular context.…”

Behavioral plasticity in rainbow trout (Oncorhynchus mykiss) with divergent coping styles: When doves become hawks

“…On the other hand, some components of the neuroendocrine machinery are rapidly modifiable by experience (e.g. Burmeister et al, 2005;Burmeister, 2007;Watt et al, 2007) and this is likely to be reflected in plasticity in associated behavioural traits. The results presented in this paper provide an example of flexible dissociation of behavioural and physiological components of the coping strategy, using an established fish model, the rainbow trout (Onchorhynchus mykiss,…”