Neonatal maternal separation elevates thalamic corticotrophin releasing factor type 1 receptor expression response to colonic distension in rat.
OBJECTIVE
Early life psychological stress is an essential factor contributing to the development of irritable bowel syndrome (IBS), with corticotrophin releasing factor (CRF) having been implicated in this common gastrointestinal disorder. The aim of our study is to examine the effect of neonatal maternal separation (NMS), an early life stress model, on the brain CRF expression following visceral pain induced by colorectal distension (CRD) stimuli in male rats.


METHODS
Male neonatal Sprague-Dawley rats were subjected to 3-hr daily maternal separation on postnatal day 2-21, with unseparated normal (N) rats serving as controls. Electromyogram signals (EMG) in response to phasic CRD were measured. The results demonstrated an increased pain response and EMG magnitudes in NMS rats as compared to N rats in response to CRD stimulation. The mRNA and protein expressions of CRF in hippocampus, cortex and thalamus of NMS and N group following the CRD stress were determined by real-time quantitative PCR and western-blotting studies respectively.


RESULTS
There was an increased mRNA and protein level of CRF in thalamus of NMS rats but no apparent change in CRF expression in hippocampus and cortex of both groups. Furthermore, an increased expression of CRF type 1 receptor (CRF-R1) was observed in the thalamus of NMS rats.


CONCLUSIONS
These results suggested an up-regulation of thalamus CRF-R1 is associated with visceral hyperalgesia in the rat model of NMS.
Tjong
Yung Wui
YW
School of Chinese Medicine, The Chinese University of Hong Kong, Shatin, NT, China.
Ip
Siu Po
SP
Lao
Lixing
L
Wu
Justin
J
Fong
Harry H S
HH
Sung
Joseph J Y
JJ
Berman
Brian
B
Che
Chun Tao
CT
D015746:Abdominal Pain / Q000378:metabolism* / Q000503:physiopathology / Q000523:psychology; D000818:Animals; D000831:Animals, Newborn / Q000378:metabolism / Q000523:psychology; D002540:Cerebral Cortex / Q000378:metabolism; D003106:Colon / Q000503:physiopathology; D004108:Dilatation, Pathologic / Q000503:physiopathology; D004576:Electromyography; D006624:Hippocampus / Q000378:metabolism; D006930:Hyperalgesia / Q000378:metabolism* / Q000503:physiopathology / Q000523:psychology; D008297:Male; D008426:Maternal Deprivation; D017288:Pain Threshold / Q000523:psychology; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D018019:Receptors, Corticotropin-Releasing Hormone / Q000235:genetics / Q000378:metabolism*; D012007:Rectum / Q000503:physiopathology; D013315:Stress, Psychological / Q000378:metabolism*; D013788:Thalamus / Q000378:metabolism*; D015854:Up-Regulation / Q000235:genetics; D000099052:CRF Receptor, Type 1
D012333:RNA, Messenger; D018019:Receptors, Corticotropin-Releasing Hormone; D000099052:CRF Receptor, Type 1