Study on the visceral sensitivity of inherent depressive rats / 中华消化杂志

ABSTRACT

Objective To explore the feasibility of inherent depressive Fawn-Hooded (FH/Wjd)rats as a comorbidity model of mental disorder and irritable bowel syndrome (IBS) by comparing visceral sensitivity of FH/Wjd rats and Sprague-Dawley (SD) rats. Methods Depression trait of FH/Wjd rats was validated through forced swimming test (FST) and sucrose preference test (SPT).Visceral sensitivity to colorectal distention (CRD) under various pressures was assessed by abdominal withdrawal reflex (AWR). The expression of 5-HT in rats' colon,c-fos expression in colon and brain areas of infralimbic cortex (IL),prelimbic cortex (PrL) and rostral anterior cingulated cortex (rACC)was tested with immunohistochemistry. Results FST indicated that the immobility time of FH/Wjd rats was significantly longer than that in SD rats (t=-8. 931,P＜0. 01). SPT showed that the ratio of sucrose water in total liquid consumed was significantly lower in FH/Wjd rats than that of SD rats(t=4. 155,P=0. 01). At each CRD pressure gradient (20,40,60 and 80 mm Hg,1 mm Hg=0. 133kPa),AWR score was all significantly higher in FH/Wjd rats than that of SD rats (t=-2. 697,-3.464,-6.822 and -3. 976,P=0. 022,0.006,0.000 and 0.003). The expression level of 5-HT in FH/Wjd rats' control group was significantly higher than that of SD rats' control group (t=-11.371,P=0. 000). Compared with their own control group,5-HT expression increased both in FH/Wjd rats dilated groups and SD rats dilated groups,and the expression level in FH/Wjd rats was higher than that of SD rats (t= -3. 364,P= 0. 007). There was no significant difference of c-fos expression in colon and prefrontal brain areas between FH/Wjd rats' control group and SD rats'control group (colont=-0. 129,P= 0. 900;ILt=-1. 316,P= 0. 218;PrLt=1. 241,P = 0. 243;rACCt=2. 151,P = 0. 057). Compared with their own control group,the expression of c-fos in colon and prefrontal brain areas significantly increased both in FH/Wjd rats dilated groups and SD rats dilated groups,and the expression level in FH/Wjd rats was higher than that of SD rats (colon t=- 5.864,P= 0.000;ILt=-2. 530,P = 0. 030;PrLt=-7. 039,P= 0. 000;rACCt=-6. 489,P=0. 000). Conclusions Inherent depressive FH/Wjd rats present visceral hypersensitivity. Meanwhile,the expression of 5-HT in colon is high,and with hyperreactivity to visceral noxious stimuli in colon and brain IL,PrL,and rACC areas. FH/Wjd rats might be a comorbidity animal model of mental disorder and IBS.