Social defeat stress activates medial amygdala cells that express type 2 corticotropin-releasing factor receptor mRNA.
Defeat is a social stressor involving subordination by a threatening conspecific. Type 2 corticotropin-releasing factor receptors (CRF(2)) are abundant in brain regions implicated in defeat responses and are putative stress-related molecules. The present study sought to determine whether neuroactivation and CRF(2) expression co-occurred at brain region or cellular levels following acute defeat. Male "intruder" Wistar rats were placed into the cage of an aggressive "resident" Long-Evans rat (n=6). Upon defeat, intruders (n=6) were placed in a wire-mesh chamber and were returned to the resident's cage for an additional 75 min. Controls (n=6) were handled and returned to their home cage for the same duration. Coronal brain sections were stained for an immediate early gene product, Fos, as a neuronal activation marker. Combined immunohistochemistry with in situ hybridization was performed on a subset of brain sections from defeated intruders to visualize Fos immunoreactivity and CRF(2) mRNA jointly. Defeated rats had fivefold, sevenfold, and 10-fold more Fos-positive cells than controls in the arcuate, ventromedial nucleus of the hypothalamus, and medial amygdala post-defeat. Significant colocalization of CRF(2) mRNA and Fos-positive cells was observed in the posterior medial amygdala but not in the arcuate nucleus or ventromedial hypothalamus. The results indicate CRF(2) receptor-positive neurons in the posterior medial amygdala are involved in the neural response to social defeat.
Fekete
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EM
Committee on the Neurobiology of Addictive Disorders, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037, USA.
Zhao
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Y
Li
C
C
Sabino
V
V
Vale
W W
WW
Zorrilla
E P
EP
D000679:Amygdala / Q000378:metabolism*; D000818:Animals; D001111:Arcuate Nucleus of Hypothalamus / Q000378:metabolism; D004291:Dominance-Subordination; D007150:Immunohistochemistry; D017403:In Situ Hybridization; D008297:Male; D009474:Neurons / Q000378:metabolism*; D016548:Prosencephalon / Q000378:metabolism; D016760:Proto-Oncogene Proteins c-fos / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D020318:Rats, Long-Evans; D017208:Rats, Wistar; D018019:Receptors, Corticotropin-Releasing Hormone / Q000378:metabolism*; D013315:Stress, Psychological / Q000378:metabolism*; D014697:Ventromedial Hypothalamic Nucleus / Q000378:metabolism
C101531:CRF receptor type 2; D016760:Proto-Oncogene Proteins c-fos; D012333:RNA, Messenger; D018019:Receptors, Corticotropin-Releasing Hormone