The effects of moderate exercise on secretory IgA production in mice depends on dietary carbohydrate intake

Abstract

Secretory immunoglobulin A (sIgA) is produced from intestinal mucosa and is essential in preventing infection. We analyzed the influence of moderate exercise on intestinal sIgA production and antioxidative function under different carbohydrate nutritional conditions. Thirty-six mice were fed an experimental diet for 10 weeks-a high-carbohydrate (HC) diet, a low-carbohydrate (LC) diet, or a control (C) diet. After 1 week on the experimental diets, mice were divided into sedentary and exercise groups (n = 6/group), where the exercise consisted of treadmill running for 30 min/day at 11 m/min for 6 days/week in 9 consecutive weeks. Intestinal sIgA levels in the exercise groups fed C or LC diets were significantly lower compared with the parallel sedentary groups, or exercise-group mice fed HC diet. Expression of the polymeric immunoglobulin receptor (pIgR) in the small intestine was significantly higher in the exercise group fed a HC diet. Superoxide dismutase activity in the small intestine was higher in the exercise group than in the sedentary group, with no effects resulting from intake carbohydrate levels. Our results indicated that moderate exercise reduced the levels of intestinal sIgA depending on decreasing of carbohydrate intake, which is connected with the expression of pIgR.

Keywords: SOD; carbohydrate intake; moderate exercise; pIgR; sIgA.

Fig. 1

Determination of total IgA and secretory (sIgA) levels in fecal extracts. The levels of total IgA (A) and sIgA (B) in fecal extract were determined by enzyme-linked immunosorbent assays (ELISAs). Fecal extracts were collected just before mice were sacrificed. Data shown are mean ± SEM. HC, high-carbohydrate diet; C, control diet; LC, low-carbohydrate diet. ^†Two-way analysis of variance results (p values) comparing the effects of various carbohydrate diets (Diet), exercise (Ex), and their interactive effects (Diet × Ex) are displayed in the upper right panel. ^‡The multiple-comparison Bonferroni’s post-hoc test was used to compare each group in cases where the interactive effect (Diet × Ex) was statistically significant.

Fig. 2

Expression of the polymeric immunoglobulin receptor (pIgR) in the small intestine. HC, high-carbohydrate diet; C, control diet; LC, low-carbohydrate diet. (A) pIgR expression in the small intestine was determined by western blot analysis. Small intestines were collected after the mice were sacrificed. pIgR bands were detected at ~80 kDa. (B) Data shown are the mean ± SEM. ^†Two-way analysis of variance results (p values) of the effects of various carbohydrate diets (Diet), exercise (Ex), and their interactive effects (Diet × Ex) are displayed in the upper right panel. ^‡The multiple-comparison Bonferroni’s post-hoc test was used to compare each group in cases where the interactive effect (Diet × Ex) was statistically significant.

Fig. 3

Antioxidant activity in the small intestine. Superoxide dismutase (SOD) activity (A) and thiobarbituric acid-reactive substance (TBARS) production (B) in the small intestine. Data shown are mean ± SEM. HC, high-carbohydrate diet; C, control diet; LC, low-carbohydrate diet. ^†Two-way ANOVA results (p values) of the effects of various carbohydrate diets (Diet), exercise (Ex), and their interactive effects (Diet × Ex) are displayed in the upper right panel. ^‡The multiple-comparison Bonferroni’s post-hoc test was used to compare each group in cases where the interactive effect (Diet × Ex) was statistically significant.