Effects of nociceptin/orphanin FQ on rats with cathartic colon.
OBJECTIVE
To demonstrate the change and effect of nociceptin/orphanin FQ in the colon of rats with cathartic colon.


METHODS
The cathartic colon model was established by feeding rats rhubarb for 3 mo, the changes of colonic electromyography were investigated by both suspension muscle strips test and serosal recordings of colonic myoelectrical activity. Immunohistochemical staining (S-P methods) and image analysis were used to determine the changes of nociceptin/orphanin FQ in the proximal colon and distal colon of rats with cathartic colon.


RESULTS
Suspension muscle strips test in vitro showed OFQ (10(-9)-10(-6) mol/L) concentration dependently caused an immediate tonic contraction in the isolated colon. But the increase of tension in cathartic colon was less than control groups (P < 0.01). Intravenous administration of OFQ (1 microg/kg) caused phasic contractions in the proximal colon, while the amplitude of phasic contractions caused by OFQ in cathartic colon was much lower than that in the control groups (2.58 +/- 0.41 vs 4.16 +/- 0.53, t = -2.6, P = 0.012). OFQ was highly expressed in the myenteric plexus of the rat colon but not in the muscle cells. The immunoreactivity of OFQ in the proximal colon in cathartic colon rats decreased significantly compared with the control group (P = 0.001).


CONCLUSIONS
Colonic smooth muscle of cathartic colon showed low sensitivity to the stimulation of OFQ, suggesting that it might be caused by the abnormal distribution of OFQ or the abnormalities of receptors, leading to the disorganization of dynamic and incoordinated contractions.
Li
Hai-Yan
HY
Department of Geriatrics, 1st Affiliated Hospital of Lanzhou University, Lanzhou 730000, Gansu Province, China. lihaiyan99@tom.com
Yan
Xiang
X
Xue
Quan-Lai
QL
Zhou
Yong-Ning
YN
Gao
Yan
Y
Wang
Rui
R
Liu
Yong-Ming
YM
Ran
Jun-Tao
JT
D000818:Animals; D002400:Cathartics / Q000494:pharmacology*; D003106:Colon / Q000187:drug effects* / Q000294:innervation / Q000473:pathology / Q000503:physiopathology*; D003109:Colonic Diseases, Functional / Q000188:drug therapy / Q000473:pathology / Q000503:physiopathology; D004195:Disease Models, Animal; D004576:Electromyography; D017615:Enteric Nervous System / Q000503:physiopathology; D005260:Female; D005769:Gastrointestinal Motility / Q000187:drug effects* / Q000502:physiology; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects / Q000502:physiology; D009130:Muscle, Smooth / Q000187:drug effects / Q000503:physiopathology; D018847:Opioid Peptides / Q000494:pharmacology*; D010528:Peristalsis / Q000187:drug effects / Q000502:physiology; D051381:Rats; D017208:Rats, Wistar; D000097629:Nociceptin
D002400:Cathartics; D018847:Opioid Peptides; D000097629:Nociceptin