KORZAN, Wayne/J; FORSTER, Gina/L; WATT, Micheal/J; �VERLI, �yvind ; SUMMERS, Cliff/H; Univ. of South Dakota; Univ. of South Dakota; Univ. of South Dakota; University of Oslo; Univ. of South Dakota: Dopaminergic activity after aggressive interactions in relation to social signals and motivation
In Anolis carolinensis, eyespot formation, i.e. darkening of postorbital skin from green to black, is stimulated by sympathetic activation of β2-adrenergic receptors. Eyespots form more rapidly in dominant males during social interaction, and aggressive behavior is reduced when animals see eyespots on an opponent. To assess the effect of eyespots on central monoamines during social interaction, males were paired by weight. They were painted postorbitally with green or black paint and allowed to interact for ten minutes, males with artificially darkened eyespots paired with males that had hidden eyespots. All males that viewed an opponent with black painted eyespots became subordinate. In these subordinate animals, dopamine and DOPAC was elevated in the medial amygdala. In contrast, males that viewed opponents with hidden eyespots and became dominant had increased dopamine in the nucleus accumbens, paleostriatum and substantia nigra/ventral tegmental area. Recent work on behavior after a novel stressor, other than aggression (such as feeding) may provide clues in predicting social rank. The role of dopamine systems in the motivation to initiate these behaviors is well established in many taxa. These results suggest ample contextual flexibility in central dopaminergic systems, sufficient for an animal to initiate behavior and establish dominance or subordination, with activity also influenced by the formation of this social hierarchy. For example, dopamine release in nucleus accumbens maybe involved in motivation to elicit the behavior required to achieve dominant status. Furthermore, social status and central dopaminergic activity was determined by a visual cue, the presence or absence of postorbital eyespots on an opponent. Supported by NIMH NRSA 1F31MH/NS64983-01 to WJK
