Change of visceral sensitivity and effect of paroxetine in rats with low grade colonic mucosal inflammation

Objective To investigate the effect and mechanism of paroxetine on visceral sensitivity in rats with low grade colonic mucosal inflammation.Methods Forty-eight male SD rats were randomly divided into two groups by means of whether established low grade mucosal inflammation(LGMI),which induced by drank with dextran sulfate sodium 5 days and then drank with distilled water 7 days.Then each group was further divided into another two groups,which one was intragastric administration with paroxetine by 2 mg·kg-1·d-1 for 14 days and the other intragastric administration with distilled water.A ballonet was put into colon of every rat.The abdominal withdrawal reflex(AWR) of rats at different levels of colorectal distension(CRD) was observed.The expression of c-Fos,substance P(SP),calcitonin gene-related peptide(CGRP) in spine cord were observed by the immuno-fluorescence staining after CRD.Results The AWR scores,the expressions of c-Fos,SP and CGRP in LGMI group were significantly higher than those in noninflammatory group(P0.01).There was no significant difference in AWR scores,the expression of c-Fos,SP between LGMI group and control group after paroxetine intervention.The expression of CGRP in LGMI group was higher than that in control group(P0.05).Conclusion The results demonstrate that low grade mucosal inflammation significantly alters GI sensitivity in rats,and paroxetine can decrease the expressions of c-Fos,SP,CGRP in spine cord which may alter the visceral sensitivity.