Effect of inherent depression on chronic visceral hypersensitivity induced by colon acetate stimulation in neonatal rats

To explore the effect of inherent depression on chronic visceral hypersensitivity. The differences of visceral sensitivity, colitis, and brain activation between Fawn-Hooded (FH/Wjd) and Sprague-Dawley(SD) rats were identified after neonatal colon acetate stimulation.The specific pathogen free Fawn-Hooded (FH/Wjd) and Sprague-Dawley(SD) rats were used to establish irritable bowel syndrome (IBS) model. The visceral sensitivity was measured by colorectal distension (CRD). The expression of 5-hydroxytryptamine (5-HT), mast cell (MC), indoleamine 2,3-dioxygenase (IDO) in colon and IDO in specific cerebral regions were detected through immunohistochemistry.Abdominal withdrawal reflex (AWR) scores showed that visceral sensitivity of acetate-enema groups was significantly higher than that of saline-enema groups (FH/Wjd:2.44 ± 0.04 vs.1.96 ± 0.07, P < 0.05; SD: 1.75 ± 0.13 vs.1.32 ± 0.05, P < 0.05). Furthermore, FH/Wjd rats of IBS group scored significantly higher than SD rats of IBS group (2.44 ± 0.04 vs.1.75 ± 0.13, P < 0.05). The MC amounts of both SD and FH/Wjd IBS group rats were significantly more than those of their control groups (FH/Wjd:43.24 ± 1.72 vs. 24.92 ± 1.38, P < 0.01. SD: 23.80 ± 1.28 vs. 14.24 ± 0.92, P < 0.01). Besides, the MC amounts of control and IBS group of FH/Wjd rats were significantly more than that of SD IBS group rats (P < 0.01). The IDO and 5-HT positive cells in colonic mucosa of IBS group of both SD and FH/Wjd rats were significantly more than those of their control groups, respectively(P < 0.01). The IDO, 5-HT positive cells in colonic mucosa of both control and IBS group of FH/Wjd rats were significantly more than those of both control and IBS group of SD rats (control:IDO,24.64 ± 2.22 vs. 15.52 ± 1.39;5-HT,21.32 ± 1.26 vs. 12.72 ± 1.12. IBS: IDO,44.92 ± 2.31 vs. 20.85 ± 1.72; 5-HT, 31.84 ± 1.57 vs. 19.65 ± 1.09.P <0.01). The expression of IDO in prelimbic cortex (PrL) areas of FH/Wjd IBS rats was significantly higher than that of IBS group of SD rats (49.60 ± 4.31 vs. 35.60 ± 2.42, P <0.01), and the expression of IDO in rostral anterior cingulate cortex (rACC) areas of FH/Wjd IBS rats was significantly more than that of FH/Wjd control rats (45.44 ± 1.16 vs. 34.08 ± 2.76, P <0.01).Inherent depressive FH/Wjd rats were more sensitive to neonatal colon acetate stimulation, presenting as visceral hypersensitivity which maybe associated with increased MC amounts and over-expression of 5-HT and IDO in colon, suggesting that depression disorder may aggravate functional disturbance of gastrointestinal tract by regulating the response to inflammatory stimulation.PubMed02289-944