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.
Committee on the Neurobiology of Addictive Disorders, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037, USA.
E M
EM
Fekete
Y
Y
Zhao
C
C
Li
V
V
Sabino
W W
WW
Vale
E P
EP
Zorrilla
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