Continuous social defeat induces an increase of endogenous opioids in discrete brain areas of the mongolian gerbil.
Dyads of a victor and a loser of mongolian gerbils (Meriones unguiculatus) coexisted for seven days; isolated animals served as a further experimental group. beta-Endorphin, Met-enkephalin and dynorphin were measured in several brain areas and in the anterior and neurointermediate pituitary. beta-Endorphin and Met-enkephalin were increased in the amygdala of defeated as compared to victorious animals. Met-enkephalin in the hypothalamus and in the striatum were lower in isolated than in coexisting gerbils. Coexistence decreased beta-endorphin in the amygdala and in the hypothalamus as compared to isolation. The results provide biochemical evidence for the role of central endogenous opioid-peptide systems in the physiology of victory and defeat. Dynorphin showed no variation with social conflict and social status.
Raab
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A
Seizinger
B R
BR
Herz
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A
D000311:Adrenal Glands / Q000033:anatomy & histology / Q000201:enzymology; D000818:Animals; D001921:Brain / Q000378:metabolism*; D004399:Dynorphins / Q000378:metabolism; D004723:Endorphins / Q000378:metabolism*; D004744:Enkephalin, Methionine / Q000378:metabolism; D005849:Gerbillinae / Q000502:physiology*; D008297:Male; D009929:Organ Size; D012930:Social Dominance / Q000502:physiology*; D013315:Stress, Psychological / Q000502:physiology; D013737:Testis / Q000033:anatomy & histology; D014446:Tyrosine 3-Monooxygenase / Q000378:metabolism; D001615:beta-Endorphin
D004723:Endorphins; D004744:Enkephalin, Methionine; D001615:beta-Endorphin; D004399:Dynorphins; D014446:Tyrosine 3-Monooxygenase