In the present study, supplementing the dam’s diet with 10% oligofructose during pregnancy and lactation decreased the body weight, body weight gain, length, relative weight of tissues and serum free fatty acids, which was accompanied by an increase in the serum concentration of lipopolysaccharides and lactobacillus spp. genomic DNA levels in the colon of the 21-d-old pups.
These results indicate that the supplementation of the dam’s diet with high amounts of oligofructose (10%) during pregnancy and lactation adversely affects the development and increases endotoxemia, possibly by bacterial translocation in the offspring.
The 21-d-old pups of the CF and TF groups presented lower body weights and lengths compared to the C and T groups (Figure 1), which were accompanied by a reduction in the free fatty acid serum concentration (Figure 2) and relative weights of the RET and liver (Table 2). Additionally, a lower body weight gain was also observed in the offspring of the CF group throughout the entire experimental period and in the TF group during the first and second weeks of treatment (Figure 1).
A literature review presents a limited and controversial picture of the effects of high-fibre diets during pregnancy and lactation. Corroborating our results, Carabin and Flamm reported a delay in the growth of pups from dams fed with 20% FOS diet during pregnancy and lactation . On the other hand, previous studies did not demonstrate the negative effects of FOS supplementation during pregnancy on offspring development [16, 45]. Furthermore, Pisani et al. showed that trans fatty acid intake during pregnancy and lactation did not modify the body weight of the pups during the entire period of lactation . Thus, it could be concluded that high FOS supplementation during pregnancy and lactation could harm offspring development.
In our study, the birth weights of the offspring were affected by a trans fatty acid diet and 10% OF supplementation during pregnancy and lactation (Figure 1). In this regard, Hallam and Reimer reported that dietary supplementation with 21.6% prebiotic fibres (inulin and oligofructose mixture) during pregnancy and lactation decreased the birth weight of female offspring, whereas the birth weights of male offspring did not change. In the same study, the authors also demonstrated that there were no differences in the naso-anal length within male or female pups; however, the percentage of body fat at 4 weeks of age was lower in the high-fibre offspring . Additionally, Maurer and Reimer did not observe any differences in the birth weight or body weight of the pups at postnatal days 7, 14 and 21 from dams fed a control, high-fibre (a combination of inulin and oligofructose) or high-protein diet during pregnancy and lactation . Rodenburg et al. reported no difference in the body weight gain of 8-week-old rats fed a diet containing 6% FOS for 16 days . Similarly, Parnell and Reimer showed that a high-fibre diet (10% and 20% of inulin and oligofructose) for 10 weeks did not influence the body weight and the fat mass in 8-week-old rats; however, the total liver weight decreased in the obese animals fed a diet supplemented with fibre prebiotics .
In accordance with results of corporal composition, we believe that the decrease in FFA serum concentration of the pups (Figure 2) reflects the reduction in the body weight (Figure 1) and RET-relative weight (Table 2) on the CF, T and TF groups compared to the C group. Adipose tissue is considered a major site of fatty acid storage in the body. In this regard, visceral fat depots, such as retroperitoneal adipose tissue, participate in the regulation of FFAs release to systemic circulation under several physiologic conditions . Shadid and Jensen reported that weight loss by diet and exercise is associated with a decrease in FFA flux . On the other hand, studies demonstrated that prebiotics are able to decrease the hepatic lipogenesis by a reduction in the activity and gene expression of hepatic lipogenic enzymes, such as fatty acid synthase (FAS) [18, 52]. Kok et al. showed that oligofructose supplementation (100 g/kg of diet) for 30 days decreased the activity of the FAS enzyme in male Wistar rats . In contrast, Parnell and Reimer demonstrated that high-fibre diets (10% and 20% of inulin and oligofructose, respectively) for 10 weeks increased FAS hepatic gene expression in JCR:La-cp rats . Furthermore, studies demonstrated that dietary supplementation with prebiotic fibres during pregnancy and lactation (21,6%; inulin and oligofructose mixture) does not alter FAS gene expression in the liver and brown adipose tissue and does not reduce the FFA plasma concentration in the offspring [46, 47].
Moreover, the changes in a pup’s body weight evolution and length of the CF and TF groups compared to the C and T groups (Figure 1) accompanied by a reduction in the liver relative weight of the TF group compared to the T group (Table 2) are consistent with the hypothesis that the 10% oligofructose supplementation during pregnancy and lactation contributes to offspring malnutrition, most likely as a consequence of impaired somatic and morphologic development. Taken together, these results suggest that the amount and type of the ingested prebiotic as well as the treatment period and physiological conditions could influence the development of the animal.
Finally, our results established that the 21-d-old offspring of the CF group had a higher lipopolysaccharide serum concentration (Figure 2), accompanied by a 2.23-fold increase in lactobacillus spp. genomic DNA levels in the faecal content of the colon (Figure 3) compared to the C group.
The inulin-type fructans are known to selectively stimulate the growth and the activity of the lactobacillus present in the colonic microbiota, thereby modulating the intestinal environment through changes in intestinal permeability, bacterial composition and SCFA production and contributing to the reduction in the LPS serum concentration, which benefits the host’s health [32, 54, 55]. In fact, Parnell and Reimer reported an increase in the lactobacillus spp. levels of 8-week-old obese rats fed a high-fibre diet (20% of inulin and oligofructose) for 10 weeks . Mangell et al. demonstrated that Lactobacillus plantarum 299v can reduce Escherichia coli-induced intestinal permeability . Additionally, the authors showed a reduction in the bacterial translocation to the liver and mesenteric lymph node of the rats pretreated with Lactobacillus plantarum 229v for one week before intra-peritoneal injection of LPS . Rodes et al. demonstrated that the administration of Lactobacillus rhamnosus and Lactobacillus reuteri in an in vitro human colonic microbiota model decreased LPS concentrations in a time-dependent manner .
On the other hand, in accordance with our data, Ten Bruggencate et al. showed that a low calcium diet supplemented with FOS (60 g/kg of diet) for two weeks stimulated the growth of lactobacilli on cecal and colonic mucosa, accompanied by an increase in the intestinal permeability and translocation of Salmonella enteritidis in 8-wk-old Wistar rats . Similarly, Ten Bruggencate et al. also demonstrated that the daily FOS consumption (20 g/day) associated with lower calcium intake during two weeks by healthy men increased the number of faecal lactobacillus, faecal mucin excretion and total faecal lactic acid excretion. The authors suggested that the mucin secretion induced by rapid production of organic acids (lactate and SCFA), in response to excessive prebiotic fermentation, is related to the irritation and impairment of the intestinal barrier function .
Another study demonstrated a dose-dependent increase in the colonisation and translocation of Salmonella enteritidis, accompanied by a higher lactic acid concentration in cecal contents in the FOS supplemented group (6% and 3%) in 8-wk-old Wistar rats; however, no changes were reported in the number of faecal lactobacilli . Likewise, Rodenburg et al. observed an increase in the intestinal permeability and in the mitochondrial gene expression in 8-week-old rats submitted to a 16-day diet, low in calcium and supplemented with FOS (6%). In this study, the authors proposed that the rapid FOS fermentation by the colonic microbiota, resulting in acid lactic accumulation, excessive organic acids production and decreased luminal pH, leads to acidification of the cellular cytoplasm and indirectly induces ATP-depletion, which consequently increases the expression of colonic mitochondrial genes that may be involved in the maintenance of the intestinal barrier because disrupted energy metabolism leads to increases in intestinal permeability .
Accordingly, we observed that 10% FOS supplementation triggered diarrhoea in dams during the treatment (data not shown), which may be associated with the calcium loss. Additionally, it is possible that the oligosaccharides present in maternal milk [39, 40] and the maternal intestinal bacteria transferred to the offspring through the breast milk  may lead to excessive production and luminal accumulation of organic acids in the pup’s gut, altering intestinal permeability and bacterial composition in the 21-d-old offspring [48, 60–62]. Thus, changes in the composition of the microbiota and increases in intestinal permeability, along with damage to the intestinal barrier integrity, can cause an increase in bacterial translocation and LPS serum concentration, resulting in TLR4-mediated inflammatory responses in the offspring .
In fact, we previously showed that 10% oligofructose supplementation during pregnancy and lactation increased the TNF-α content in the liver of pups in the CF group and IL-6 and TNF-α contents in RET of pups in the TF group, accompanied by a reduction in the serum adiponectin concentrations of the offspring in the CF, T and TF groups .