Resveratrol Improves Brain-Gut Axis by Regulation of 5-HT-Dependent Signaling in the Rat Model of Irritable Bowel Syndrome

Abstract

Irritable bowel syndrome (IBS) is at high risk of co-morbid depression and anxiety, which reduces patients' quality of life and increases the burden of health care costs. However, the pathophysiological mechanisms responsible for IBS still remain unknown. This study investigated the effects of resveratrol on stress-related depression, anxiety, intestinal and visceral dysfunction in rat model of IBS. Rats received chronic acute combining stress (CACS) for 22 days exhibited depression/anxiety-like behavior, visceral hypersensitivity and altered intestinal motility, as measured by the forced swimming, marble bury, abdominal withdrawal reflex (AWR) and intestinal tract motility (ITM) tests. These abnormalities were accompanied by reduced 5-hydroxytryptamine (5-HT) level in the hippocampus and increased 5-HT expression in the gut (ileum and colon) after CACS. Chronic treatment of IBS rats with resveratrol dose-dependently normalized CACS-induced both central nervous and peripheral dysfunction, which were consistent with its differentially regulating 5-HT contents in the brain and intestine. Pretreatment with the 5-HT_1A receptor antagonist NAN-190 hydrobromide (NAN-190) prevented such effects. While sub-threshold of 5-HT_1A receptor agonist 8-OH-DPAT potentiated the effects of low dose of resveratrol (10 mg/kg) on CACS-related behavioral abnormalities. Furthermore, resveratrol markedly increased PKA, p-cAMP-response element binding protein (p-CREB) and brain derived neurotrophic factor (BDNF) expression in the hippocampus of IBS rats, while decreased PKA, pCREB and BDNF levels were found in the ileum and colon. These effects were prevented by NAN-190, which were consistent with the behavioral changes. The present results suggested that resveratrol improved anti-IBS-like effects on depression, anxiety, visceral hypersensitivity and intestinal motility abnormality through regulating 5-HT_1A-dependent PKA-CREB-BDNF signaling in the brain-gut axis.

Keywords: 5-HT; BDNF; chronic acute combining stress; irritable bowel syndrome; pCREB.

Figure 1

A schematic presentation about the link between brain and gut axis (A) and drug treatment and behavioral tests procedure (B). Animals were treated with resveratrol, fluoxetine or diazepam, 1 h or 30 min before chronic acute combining stress (CACS) for 22 days. The behavioral tests were started from day 23 to 26. MBT, marble-burying task; FST, forced swimming test; ITM, intestinal tract motility; AWR, abdominal withdrawal reflex test.

Figure 2

The effects of resveratrol on central nervous and peripheral systems in the forced swimming (A), marble burying (B), the number of fecal outputs in 1-h restraint period (C) and AWR score (D). Values are expressed as mean ± SEM (n = 6–8, per group), **P < 0.01, ***P < 0.001 vs. vehicle-treated control group (“Veh + Ctrl” group); ^#P < 0.05, ^##P < 0.01, ^###P < 0.001 vs. vehicle-treated CACS group (“Veh + CACS” group).

Figure 3

The antidepressant- (A,C) and anxiolytic-like (B,D) effects of resveratrol in irritable bowel syndrome (IBS) rats were involved in 5-HT_1A receptor. Values are expressed as mean ± SEM (n = 6–8, per group), ***P < 0.001 vs. vehicle-treated control group (“Veh + Ctrl” group); ^###P < 0.001 vs. vehicle-treated CACS group (“Veh + CACS” group); ^$P < 0.05, ^$$$P < 0.001 vs. 10 mg/kg resveratrol-treated CACS group (“RES 10 + CACS” group); ^&P < 0.05, ^&&P < 0.01 vs. 40 mg/kg resveratrol-treated CACS group (“RES 40 + CACS” group).

Figure 4

The effects of resveratrol on CACS-induced intestinal motility disorder (A,C) and visceral hypersensitivity (B,D) were involved in regulation of 5-HT_1A receptor function. Values are expressed as mean ± SEM (n = 6–8, per group), ***P < 0.001 vs. “Veh + Ctrl” group; ^#P < 0.05, ^##P < 0.01, ^###P < 0.001 vs. “Veh + CACS” group; ^$$P < 0.01, ^$$$P < 0.001 vs. “RES 10 + CACS” group; ^&P < 0.05, ^&&&P < 0.001 vs. “RES 40 + CACS” group.

Figure 5

The effects of resveratrol on PKA, pCREB/CREB and brain derived neurotrophic factor (BDNF) levels in the hippocampus. (A) Photomicrographs of representative immune-blotting bands. Lane 1: “Veh + Ctrl” group, lane 2: “Veh + CACS” group, lane 3: “RES 10 + CACS” group, lane 4: “RES 20 + CACS” group, lane 5: “RES 40 + CACS” group and lane 6: “FLU 10 + CACS” group. (B–D) PKA, the ratio of pCREB to CREB and BDNF expression in the hippocampus. (E) Photomicrographs of representative immune-blotting bands. Lane 1: “Veh + Ctrl” group, lane 2: “Veh + CACS” group, lane 3: “NAN-190 + CACS” group, lane 4: “RES 40 + CACS” group and lane 5: “RES 40 + NAN-190 + CACS” group. (F–H) PKA, the ratio of pCREB to CREB and BDNF expression in the hippocampus. Values are expressed as mean ± SEM (n = 6–8, per group), **P < 0.01, ***P < 0.001 vs. “Veh + Ctrl” group; ^#P < 0.05, ^##P < 0.01, ^###P < 0.001 vs. “Veh + CACS” group; ^&P < 0.05, ^&&P < 0.01 vs. “RES 40 + CACS” group.

Figure 6

The effects of resveratrol on PKA, pCREB/CREB and BDNF expression in the ileum. (A) Photomicrographs of representative immune-blotting bands. Lane 1: “Veh + Ctrl” group, lane 2: “Veh + CACS” group, lane 3: “RES 10 + CACS” group, lane 4: “RES 20 + CACS” group, lane 5: “RES 40 + CACS” group and lane 6: “FLU 10 + CACS” group. (B–D) PKA, the ratio of pCREB to CREB and BDNF expression in the ileum. (E) Photomicrographs of representative immune-blotting bands. Lane 1: “Veh + Ctrl” group, lane 2: “Veh + CACS” group, lane 3: “NAN-190 + CACS” group, lane 4: “RES 10 + CACS” group and lane 5: “RES 10 + NAN-190 + CACS” group. (F–H) PKA, the ratio of pCREB to CREB and BDNF expression in the ileum. Values are expressed as mean ± SEM (n = 6–8, per group), *P < 0.05, **P < 0.01, ***P < 0.001 vs. “Veh + Ctrl” group; ^#P < 0.05, ^##P < 0.01, ^###P < 0.001 vs. “Veh + CACS” group; ^&P < 0.05, ^&&P < 0.01 vs. “RES 10 + CACS” group.

Figure 7

The effects of resveratrol on PKA, pCREB/CREB and BDNF expression in the colon. (A) Photomicrographs of representative immune-blotting bands. Lane 1: “Veh + Ctrl” group, lane 2: “Veh + CACS” group, lane 3: “RES 10 + CACS” group, lane 4: “RES 20 + CACS” group, lane 5: “RES 40 + CACS” group and lane 6: “FLU 10 + CACS” group. (B–D) PKA, the ratio of pCREB to CREB and BDNF expression in the colon. (E) Photomicrographs of representative immune-blotting bands. Lane 1: “Veh + Ctrl” group, lane 2: “Veh + CACS” group, lane 3: “NAN-190 + CACS” group, lanes 4: “RES 10 + CACS” group and lane 5: “RES 10 + NAN-190 + CACS” group. (F–H) PKA, the ratio of pCREB to CREB and BDNF expression in the colon. Values are expressed as mean ± SEM (n = 6–8, per group), *P < 0.05, **P < 0.01, ***P < 0.001 vs. “Veh + Ctrl” group; ^#P < 0.05, ^##P < 0.01, ^###P < 0.001 vs. “Veh + CACS” group; ^&P < 0.05, ^&&P < 0.01 vs. “RES 10 + CACS” group.