A short-term ingestion of fructo-oligosaccharides increases immunoglobulin A and mucin concentrations in the rat cecum, but the effects are attenuated with the prolonged ingestion

Figures & data

Table 1. Food intake, body weight gain, cecal variables including weights of tissue and contents, and pH in rats fed the control diet or a diet containing FOS at 60 g/kg diet for 1, 2, 4, or 8 wk (experiment 1).^a

	1 wk		2 wk		4 wk		8 wk		Split plot ANOVA P
	Control	FOS	Control	FOS	Control	FOS	Control	FOS	Diet	Time	D × T
Food intake, g	107 ± 5	88 ± 5*	208 ± 5	204 ± 6	438 ± 7	403 ± 11	849 ± 14	846 ± 15	0.16	<0.0001	0.61
Body weight gain, g	40 ± 2	34 ± 3	75 ± 4	72 ± 3	133 ± 2	119 ± 5*	196 ± 5	187 ± 7	<0.0001	<0.0001	0.60
Cecum
Tissue, wet g	0.5 ± 0.0	1.0 ± 0.0*	0.5 ± 0.0	1.1 ± 0.1^#	0.6 ± 0.1	1.3 ± 0.1^#	0.6 ± 0.0	1.2 ± 0.1*	<0.0001	0.21	0.69
Contents, g	1.8 ± 0.1	5.1 ± 0.5^#	1.7 ± 0.1	4.5 ± 0.4*	2.3 ± 0.1	6.2 ± 0.3*	2.4 ± 0.2	4.7 ± 0.3*	<0.0001	0.40	0.20
pH	7.7 ± 0.1	5.8 ± 0.1*	7.5 ± 0.1	5.9 ± 0.2^#	7.7 ± 0.1	6.4 ± 0.2^#	7.8 ± 0.1	6.6 ± 0.2*	<0.0001	0.20	<0.01

^a Data are expressed as the mean ± SE, n = 6. Split plot design ANOVA was used to assess the effects of diet, time of exposure, and interactions between diet and time.

^# Individual means at each time point were compared by Welch’s-t test (p < 0.05) to assess the effects of diet.

* Individual means at each time point were compared by Student-t test (p < 0.05) to assess the effects of diet.

Table 2. Cecal organic acids and cecal numbers of lactobacilli and bifidobacteria in rats fed the control diet or a diet containing FOS at 60 g/kg diet for 1, 2, 4, or 8 wk (experiment 1).^a

	1 wk		2 wk		4 wk		8 wk		SPLIT PLOT ANOVA P
	Control	FOS	Control	FOS	Control	FOS	Control	FOS	Diet	Time	D × T
Organic acid, μmol/g wet contents
Acetate	43.5 ± 3.1	17.2 ± 1.9*	47.9 ± 1.9	35.5 ± 6.8	43.8 ± 2.9	48.0 ± 8.2	42.0 ± 1.6	82.1 ± 3.5*	0.72	<0.05	<0.0001
Propionate	18.1 ± 1.2	8.9 ± 1.0*	14.9 ± 0.6	19.2 ± 3.9	17.1 ± 0.6	13.4 ± 1.3*	17.5 ± 0.5	14.1 ± 1.4	<0.05	0.39	0.86
n-Butyrate	2.7 ± 0.1	1.6 ± 0.5	4.0 ± 0.3	9.7 ± 4.0	2.0 ± 0.3	14.4 ± 5.1*	1.9 ± 0.2	27.7 ± 3.9*	<0.0001	0.10	<0.0001
Lactate	0	16.0 ± 3.5^#	0	24.5 ± 10.0^#	0.1 ± 0.1	4.7 ± 4.7	0	0	<0.01	0.26	<0.05
Succinate	1.6 ± 0.3	10.8 ± 3.1*	1.4 ± 0.4	10.4 ± 5.1	2.7 ± 1.0	12.8 ± 2.0*	1.4 ± 0.2	16.7 ± 8.0*	<0.0001	0.68	0.32
SCFA^b	64.3 ± 4.2	27.7 ± 3.2*	66.9 ± 2.1	64.4 ± 9.1	63.0 ± 3.3	75.8 ± 10.2	61.4 ± 2.1	123.9 ± 5.5*	0.13	<0.05	<0.0001
Lactobacilli, copies×10^8/g	7.1 ± 2.1	66.6 ± 11.5*	9.6 ± 3.3	14.2 ± 3.7	3.6 ± 0.9	6.4 ± 2.0	1.3 ± 0.5	0.9 ± 0.4	<0.0001	0.09	<0.001
Bifidobacteria, copies×10^7/g	ND^c	216 ± 87 (n = 5)	28.5 ± 12.5 (n = 3)	84.2 ± 25.0	ND	ND	0.6 ± 0.1 (n = 5)	133 ± 116 (n = 3)

^a Data are expressed as the mean ± SE, n = 6, unless otherwise noted. Split plot design ANOVA was used to assess the effects of diet, time of exposure, and interactions between diet and time.

^b Short-chain fatty acids; the sum of acetate, propionate, and n-butyrate.

^c Not detected (detection limit × 104).

# Individual means at each time point were compared by Welch’s-t test (^#p < 0.05) to assess the effects of diet.

* Individual means at each time point were compared by Student-t test (^*p < 0.05) to assess the effects of diet.

Fig. 1. PCR-DGGE analysis of cecal microbiota based on 16S rRNA gene sequences in rats fed the control diet or a diet containing FOS at 60 g/kg diet for 1, 2, 4, or 8 wk (expt 1).

Notes: (A) 1 and 2 wk, (B) 4 and 8 wk. Similarities among DGGE band profiles of cecal bacteria were calculated based on the position and intensity of bands, and the dendrogram of DGGE band profiles was constructed by the unweighted pair-group method with arithmetic mean (UPGMA) clustering method. Distances are measured in arbitrary units. C1–C8, samples from rats fed the control diet for 1, 2, 4, or 8 wk. F1–F8, samples from rats fed the FOS diet for 1, 2, 4, or 8 wk.

Fig. 2. Cecal immunoglobulin A (IgA) concentrations (per g wet cecal contents) (A), the percentage of IgA plasma cells (B), and cecal mucin concentrations (per g wet cecal contents) (C) in rats fed the control diet or a diet containing FOS at 60 g/kg diet for 1, 2, 4, or 8 wk (expt 1).

Notes: Data are expressed as the mean ± SE, n = 6. Split plot design ANOVA was used to assess the effects of diet, time of exposure, and interactions between diet and time. Individual means at each time point were compared by Student-t test (^*p < 0.05) or Welch’s-t test (^#p < 0.05) to assess the effects of diet.

Table 3. Food intake, body weight gain, cecal variables including weights of tissue and contents, and ph in rats fed the control diet or a diet containing FOS at 60 g/kg Diet for 1, 2, 4, or 8 wk (experiment 2).^a

	1 wk		2 wk		8 wk		SPLIT PLOT ANOVA P
	Control	FOS	Control	FOS	Control	FOS	Diet	Time	Diet x time
Food intake, g	104 ± 2	84 ± 2*	209 ± 3	184 ± 4*	869 ± 15	845 ± 14	<0.01	<0.0001	0.84
Body weight gain, g	37 ± 2	26 ± 1*	72 ± 2	63 ± 2*	185 ± 4	182 ± 6	<0.05	<0.0001	0.27
Cecum
Tissue, g	0.5 ± 0.0	1.1 ± 0.0*	0.5 ± 0.0	1.4 ± 0.1*	0.6 ± 0.0	1.0 ± 0.0*	<0.0001	0.27	<0.01
Contents, wet g	2.0 ± 0.1	3.6 ± 0.3^#	2.1 ± 0.1	4.41 ± 0.3*	1.9 ± 0.1	4.3 ± 0.3*	<0.0001	0.52	0.09
pH	7.9 ± 0.1	5.9 ± 0.1*	7.7 ± 0.1	5.8 ± 0.1*	7.9 ± 0.1	6.4 ± 0.1*	<0.0001	<0.0001	<0.01

^a Data are expressed as the mean ± SE, n = 12. Split plot design ANOVA was used to assess the effects of diet, time of exposure, and interactions between diet and time.

^# Individual means at each time point were compared by Welch’s-t test (^#p < 0.05) to assess the effects of diet.

* Individual means at each time point were compared by Student-t test (^*p < 0.05) to assess the effects of diet.

Fig. 3. Cecal immunoglobulin A (IgA) concentrations (per g wet cecal contents) (A), the percentage of IgA plasma cells (B), and the gene expression of pIgR (relative value) (C) in rats fed the control diet or a diet containing FOS at 60 g/kg diet for 1, 2, or 8 wk (expt 2).

Notes: Data are expressed as the mean ± SE, n = 6. Split plot design ANOVA was used to assess the effects of diet, time of exposure, and interactions between diet and time. Individual means at each time point were compared by Student-t test (^*p < 0.05) or Welch’s-t test (^#p < 0.05) to assess the effects of diet.

Fig. 4. Changes in immunoglobulin A (IgA) concentrations during the incubation of cecal contents (expt 2).

Notes: Cecal contents were incubated under nitrogen gas at 37 °C for up to 6 h. After incubation, IgA concentrations were determined and compared with values of 0 time incubation as 100%. Each point represented the mean ± SE, n = 6.

Fig. 5. Cecal mucin concentrations (per g wet cecal contents) (A), the gene expression of Muc 2 (relative value) (B), and mucinase activities (per min per mg nitrogen) (C) in rats fed the control diet or a diet containing FOS at 60 g/kg diet for 1, 2, or 8 wk (expt 2).

Notes: Data are expressed as the mean ± SE, n = 6 except for those of mucinase activities (n = 12). Split plot design ANOVA was used to assess the effects of diet, time of exposure, and interactions between diet and time. Individual means at each time point were compared by Student-t test (^*p < 0.05) to assess the effects of diet.