Effect of Scutellariae Radix extract on experimental dextran-sulfate sodium-induced colitis in rats

Abstract

Aim: To investigate the effect of Scutellariae Radix extract (SRE) on ulcerative colitis (UC) in rats induced by dextran-sulfate sodium (DSS).

Methods: Colitis was induced in male Sprague-Dawley (SD) rats (170-180 g) by 4% dextran sulfate sodium (DSS, wt/v; MW 54000) in drinking water for 8 d. The treated rats received 4% DSS and SRE orally (100 mg/kg per day). Control rats received either tap water or SRE only. Macroscopic assessment which included body weight changes, fecal occult blood and stool consistency were determined daily. At the appointed time, the rats were sacrificed and the entire colons were removed. The colon length and the myeloperoxidase (MPO) activity were measured. The severity of colitis was graded by morphological and histological assessments. The ion transport activity of the colonic mucosa was assessed by electrophysiological technique.

Results: Rats treated with oral administration of 4% DSS regularly developed clinical and macroscopic signs of colitis. Treatment with SRE relieved the symptoms, including the reduction in body weight, shortening and ulceration of the colon. Administration of SRE also significantly reduced the histological damage induced by DSS. Moreover, the I(SC) responses of the colonic mucosa to forskolin were suppressed after the induction of colitis. The stimulated ion transport activity of DSS-rats treated with SRE displayed significant improvement in the secretory responsiveness.

Conclusion: SRE was effective in treating acute DSS-induced ulcerative colitis, as gauged by reduced clinical disease, improved macroscopic and histological damage scores, and enhanced recovery of normal colonic secretory function.

Figure 1

Figure showing the weight gain percentage (%) in different groups of rat from d 0 to d 7. Body weight was assessed daily and expressed as percentage increase of basal body weight. Values are expressed as the means ± SE, (n = 8), ^aP < 0.05 vs Ctr group, ^bP < 0.05 vs DSS group, one-way ANOVA followed by Tukey multiple comparison test.

Figure 2

Ameliorative effect of SRE treatment on the time-course changes in the macroscopic score over the 8-d experimental period. The macroscopic score of Ctr and Ctr + SRE groups is 0 (data not shown). ^aP < 0.05 vs DSS group. Non-parametric data are expressed as the means ± SE, Kruskal-Wallis One Way Analysis using Student-Newman-Keuls method (n = 6-8).

Figure 3

Macroscopic view of the colon showing the changes in colon length in different groups of rat on d 7. Not much difference was observed between the colon of the Ctr (A) and Ctr + SRE group (B), but significant difference could be found in the DSS group (C) which displayed extensive hyperemia and edema. In the DSS + SRE group, the shortening of colon was less severe (D) when compared with the control (A).

Figure 4

Histological sections from different groups of rats on d 7. A: DSS group showing extensive ulceration with a severe inflammatory cell infiltrate; B: DSS + SRE group showing recovery in the inflammatory cell infiltration with less severe ulceration; C: Non-colitic Ctr group showing the normal histology of the colon; D: Ctr + SRE group showing the normal morphology of the colon. (HE staining; original magnifications, x 100).

Figure 5

Ameliorative effect of SRE treatment on the time-course changes in the microscopic score from d 3 to d 7. The microscopic score of Ctr and Ctr + SRE groups is 0 (data not shown). ^aP < 0.05 vs DSS group. Non-parametric data are expressed as the means ± SE, Kruskal-Wallis One Way Analysis using Student-Newman-Keuls method (n = 4-5).

Figure 6

Representative tracings showing the change in I_SC evoked by forskolin in different groups of rat on d 7. All four groups showed an increase in ISC but with different magnitudes (A-D). The I_SC response was greatly reduced in the DSS group (C) when compared with the control (A). On the other hand, the reduction in secretory response appears to be ameliorated in the DSS + SRE group (D). The transient current pulses were the results of intermittently clamping the potential at 1 mV. The horizontal lines represent zero I_SC. The record is representative of at least six experiments.