Véronique Romé

Intestinal Development in Neonatal Calves: Effects of Glucocorticoids and Dependence on Colostrum Feeding1

The neonatal development of the gastrointestinal tract around parturition in precocious mammals is greatly affected by endocrine factors like glucocorticoids as well as by nutritional factors. We have studied the effects of glucocorticoids and colostrum supply on intestinal morphology, cell proliferation, digestive enzyme activities, and xylose absorption in neonatal calves to test the hypothesis that the intestinal development in neonatal calves is influenced by glucocorticoids, dependent on colostrum feeding. Calves designated GrFD– and GrFD+ were fed a milk-based formula, whereas those designated GrCD– and GrCD+ received colostrum. Dexamethasone (DEXA; 30 µg/kg/day) was injected at feeding times to calves of GrFD+ and GrCD+. On day 3, the D-xylose absorption was measured. The calves were euthanized on day 5 of life. Colostrum feeding increased villus sizes in jejunum and ileum, enhanced xylose absorption capacity, and increased peptidase activities in the ileum. DEXA treatment diminished sizes and cell proliferation rates of Peyer’s patches in the ileum, yet increased proliferation of crypt cells in the ileum of formula-fed calves. DEXA reduced aminopeptidase N activities in the jejunum of formula-fed calves, but increased the peptidase activities mainly of colostrum-fed calves in the ileum. Thus, DEXA effects depended on intestinal segment and on different feeding, resulting in stimulation of crypt cell proliferation in the less mature ileum (of formula-fed calves) and in stimulation of peptidase activities in the more mature ileum (of colostrum-fed calves). We conclude that the effects of DEXA were related to the developmental stage of the neonatal intestine and promoted the intestinal development, depending on the developmental stage.

Dietary sodium butyrate supplementation increases digestibility and pancreatic secretion in young milk-fed calves

The aim of this study was to test, in 8 calves fed milk formula based on soybean protein, the ability of sodium butyrate (SB) supplementation to improve nutrient digestibility and daily pancreatic secretions and to modify the kinetics of these secretions. Additionally, effects of duodenal SB infusion were evaluated. Plasma levels of gastrin, secretin, and cholecystokinin were measured. Butyrate supplementation in milk formula increased nutrient digestibility and total daily pancreatic secretions. For juice volume, this increase was most important from 12 to 17h after the morning meal. During the 3-h postprandial period, oral SB supplementation reduced the physiological decrease of postprandial pancreatic secretion (while duodenal digesta flow rate was maximal) and had a minor effect on plasma gut regulatory peptide concentrations. Compared with the diet without SB, ingestion of SB stimulated pancreatic secretion. Taken together, these results could explain the measured increase in nutrient digestibility. The data obtained after duodenal SB infusion did not indicate an effect on pancreatic secretion, apart from elevated lipase output compared with control. The mechanisms responsible for these events are not known and circulating gut regulatory peptides do not seem to be implicated. Our work brings new results regarding SB as a feed additive in young calf nutrition.

Exogenous CCK and gastrin stimulate pancreatic exocrine secretion via CCK-A but also via CCK-B/gastrin receptors in the calf

Abstract A predominance of the pancreatic cholecystokinin (CCK) receptor of the B/gastrin subtype (CCK-B/G) was reported in calves older than 1 month. Specific CCK-A and CCK-B/G receptor antagonists (SR 27897 and PD 135158, respectively) were used to identify the CCK receptor subtype involved in exogenous CCK- and gastrin-induced exocrine pancreatic responses. Conscious calves (2 months old) with catheterized pancreas, jugular vein and duodenum were used; the pancreatic juice was continuously reinfused. CCK (30 pmol kg–1 min–1, 40 min) evoked an increase in pancreatic juice flow and enzyme secretion, while the same dose of gastrin increased enzyme secretion alone. CCK-induced pancreatic secretion was abolished by SR 27897 (15 nmol kg–1 min–1, 55 min) and reduced by PD 135158 (0.15 nmol kg–1 min–1, 55 min). Gastrin-induced enzyme secretion was reduced by PD 135158 (50% to 90%) and to a lesser extent by SR 27897 (50% to 60%). These results demonstrate that CCK and gastrin in the physiological range stimulate pancreatic exocrine secretion in calves and that these effects are partly mediated by CCK-B/G receptors. Although CCK-A receptors are not predominantly expressed, they seem to play a major role in the response of pancreatic exocrine secretion to CCK.

Characterisation of Early-Life Fecal Microbiota in Susceptible and Healthy Pigs to Post-Weaning Diarrhoea.

Early-life microbial exposure is of particular importance to growth, immune system development and long-lasting health. Hence, early microbiota composition is a promising predictive biomarker for health and disease but still remains poorly characterized in regards to susceptibility to diarrhoea. In the present study, we aimed to assess if gut bacterial community diversity and composition during the suckling period were associated with differences in susceptibility of pigs to post-weaning diarrhoea. Twenty piglets from 5 sows (4 piglets / litter) were weaned in poor housing conditions to challenge their susceptibility to post-weaning diarrhoea. Two weeks after weaning, 13 pigs exhibited liquid faeces during 2 or 3 days and were defined as diarrhoeic (D) pigs. The other 7 pigs did not have diarrhea during the whole post-weaning experimental periodand were defined as healthy (H) pigs. Using a molecular characterisation of fecal microbiota with CE-SSCP fingerprint, Next Generation Sequencing and qPCR, we show that D and H pigs were mainly discriminated as early as postnatal day (PND) 7, i.e. 4 weeks before post-weaning diarrhoea occurence. At PND 7 H pigs displayed a lower evenness and a higher abundance of Prevotellaceae, Lachnospiraceae, Ruminocacaceae and Lactobacillaceae compared to D pigs. The sPLS regression method indicates that these bacterial families were strongly correlated to a higher Bacteroidetes abundance observed in PND 30 H pigs one week before diarrhoea. These results emphasize the potential of early microbiota diversity and composition as being an indicator of susceptibility to post-weaning diarrhoea. Furthermore, they support the health promoting strategies of pig herds through gut microbiota engineering.

A new role of phosphopeptides as bioactive peptides released during milk casein digestion in the young mammal: regulation of gastric secretion.

The aim of this work was to study in vivo the effect of ingestion of phosphopeptides (PP) alone or associated with caseinomacropeptide (CMP) on gastric secretion and to elucidate some possible mechanisms involved. Seven calves fitted with a gastric pouch received either a diet based on whey proteins without PP and CMP (C diet) or C diet in which PP or PP+CMP was introduced at concentrations similar to that of PP or PP+CMP in cow milk (PP diet and PP+CMP diet, respectively). Gastric juice secretion was measured during successive periods throughout the day. Twenty-four calves were fitted with a catheter introduced in one external jugular vein for blood sample collections. The daily secretion of electrolytes decreased with the presence of PP or PP+CMP in the diet. During the day, peptide supplementation in the diet resulted in (1) short term (1st-2nd postprandial h), a decrease of secreted quantities of gastric juice, enzymes and electrolytes, (2) long term (7-24h after the morning meal), a decrease of electrolyte secretions. Intervention of gastrin, CCK, somatostatin and BPP could be probable. Globally, inhibition of gastric secretions seemed more important when PP was given in association with CMP in the diet rather than alone. CMP and PP may have short and long term action respectively over the 24h day. To our knowledge, it is the first time that phosphopeptides coming from milk casein digestion are demonstrated to inhibit gastric secretion. Therapeutic uses are suggested.

Bovine pancreatic secretion in the first week of life: potential involvement of intestinal CCK receptors

The aim of this study was to evaluate pancreatic juice secretion of calves in the first postnatal days, and determine a potential involvement of cholecystokinin (CCK) and intestinal CCK receptor in its regulation. Nine neonatal Friesian calves (five controls and four treated intraduodenally with FK480, a CCK-A receptor antagonist) were surgically fitted with a pancreatic duct catheter and a duodenal cannula before the first colostrum feeding. Collections of pancreatic juice and duodenal luminal pressure recordings were started early after recovery from anaesthesia and continued for 6 days. From day 2 or 3 of life, periodic fluctuations in pancreatic secretions were observed in concert with duodenal myoelectric motor complex (MMC) and variations in plasma pancreatic polypeptide (PP) concentrations. Intraduodenal administration of FK480 reduced pancreatic juice secretion while intravenous infusion of CCK had no effect. Immunocytochemistry indicated an association of mucosal CCK-A and -B receptors with neural components of the small intestine. In conclusion, periodic activity of the exocrine pancreas exists in neonatal calves soon after birth and local neural intestinal CCK-A receptors could be partly responsible for the modulation of neonatal calf pancreatic secretion.

A high-protein formula increases colonic peptide transporter 1 activity during neonatal life in low-birth-weight piglets and disturbs barrier function later in life.

Dietary peptides are absorbed along the intestine through peptide transporter 1 (PepT-1) which is highly responsive to dietary protein level. PepT-1 is also involved in gut homeostasis, both initiating and resolving inflammation. Low-birth-weight (LBW) neonates are routinely fed a high-protein (HP) formula to enhance growth. However, the influence of this nutritional practice on PepT-1 activity is unknown. Intestinal PepT-1 activity was compared in normal-birth-weight (NBW) and LBW piglets. The effect of HP v. normal-protein (NP) formula feeding on PepT-1 activity and gut homeostasis in LBW piglets was evaluated, during the neonatal period and in adulthood. Flux of cephalexin (CFX) across the tissue mounted in Ussing chambers was used as an indicator of PepT-1 activity. CFX flux was greater in the ileum, but not jejunum or colon, of LBW than NBW piglets during the neonatal period. When LBW piglets were formula-fed, the HP formula increased colonic CFX during the 1st week of life. Later in life, intestinal CFX fluxes and barrier function were similar whether LBW pigs had been fed NP or HP formula. However, colonic permeability of HP- but not NP-fed pigs increased when luminal pH was brought to 6·0. The formyl peptide N-formyl methionyl-leucyl-phenylalanine conferred colonic barrier protection in HP-fed piglets. Heat shock protein 27 levels in the colonic mucosa of HP-fed LBW pigs correlated with the magnitude of response to the acidic challenge. In conclusion, feeding a HP formula enhanced colonic PepT-1 activity in LBW pig neonates and increased sensitivity of the colon to luminal stress in adulthood.

Maternal 18:3n-3 favors piglet intestinal passage of LPS and promotes intestinal anti-inflammatory response to this bacterial ligand.

We recently observed that maternal 18:3n-3 increases piglet jejunal permeability. We hypothesized that this would favor intestinal lipopolysaccharide (LPS) passage and alter gut immune system education toward this bacterial ligand. Sows were fed 18:3n-3 or 18:2n-6 diets throughout gestation and lactation. In each litter, two piglets were given oral Gram-negative spectrum antibiotic from post-natal day (PND) 14 to 28. All piglets were weaned on a regular diet at PND28. 18:3n-3 piglets exhibited greater jejunal permeability to FITC-LPS at PND28. Levels of 18:3n-3 but neither 20:5n-3 nor 20:4n-6 were greater in mesenteric lymph nodes (MLN) of 18:3n-3 piglets. Jejunal explant or MLN cell cytokine responses to LPS were not influenced by the maternal diet. Antibiotic increased jejunal permeability to FITC-LPS and lowered the level of 20:5n-3 in MLN, irrespective of the maternal diet. At PND52, no long-lasting effect of the maternal diet or antibiotic treatment on jejunal permeability was noticed. 18:3n-3 and 20:4n-6 levels were greater and lower, respectively, in MLN of 18:3n-3 compared to 18:2n-6 piglets. IL-10 production by MLN cells in response to LPS was greater in the 18:3n-3 group, irrespective of the neonatal antibiotic treatment. IL-8 secretion by jejunal explants in response to LPS was lower in antibiotic-treated 18:3n-3 compared to 18:2n-6 piglets. Finally, proportion of MHC class II(+) antigen-presenting cells was greater in 18:3n-3 than 18:2n-6 MLN cells. In conclusion, maternal 18:3n-3 directs the intestinal immune response to LPS toward an anti-inflammatory profile beyond the breastfeeding period; microbiota involvement seems dependent of the immune cells considered.

Is there adaptation of the exocrine pancreas in wild animal? The case of the Roe Deer

BackgroundPhysiology of the exocrine pancreas has been well studied in domestic and in laboratory animals as well as in humans. However, it remains quite unknown in wildlife mammals. Roe deer and cattle (including calf) belong to different families but have a common ancestor. This work aimed to evaluate in the Roe deer, the adaptation to diet of the exocrine pancreatic functions and regulations related to animal evolution and domestication.ResultsForty bovine were distributed into 2 groups of animals either fed exclusively with a milk formula (monogastric) or fed a dry feed which allowed for rumen function to develop, they were slaughtered at 150 days of age. The 35 Roe deer were wild animals living in the temperate broadleaf and mixed forests, shot during the hunting season and classified in two groups adult and young. Immediately after death, the pancreas was removed for tissue sample collection and then analyzed. When expressed in relation to body weight, pancreas, pancreatic protein weights and enzyme activities measured were higher in Roe deer than in calf. The 1st original feature is that in Roe deer, the very high content in pancreatic enzymes seems to be related to specific digestive products observed (proline-rich proteins largely secreted in saliva) which bind tannins, reducing their deleterious effects on protein digestion. The high chymotrypsin and elastase II quantities could allow recycling of proline-rich proteins. In contrast, domestication and rearing cattle resulted in simplified diet with well digestible components. The 2nd feature is that in wild animal, both receptor subtypes of the CCK/gastrin family peptides were present in the pancreas as in calf, although CCK-2 receptor subtype was previously identified in higher mammals.ConclusionsBovine species could have lost some digestive capabilities (no ingestion of great amounts of tannin-rich plants, capabilities to secrete high amounts of proline-rich proteins) compared with Roe deer species. CCK and gastrin could play an important role in the regulation of pancreatic secretion in Roe deer as in calf. This work, to the best of our knowledge is the first study which compared the Roe deer adaptation to diet with a domesticated animal largely studied.

Phaseolin from Phaseolus vulgaris bean modulates gut mucin flow and gene expression in rats

Dietary protein might modulate mucin flow and intestinal mucin gene expression. Since unheated phaseolin from Phaseolus vulgaris bean is resistant to digestion and increases gut endogenous protein losses, we hypothesised that unheated phaseolin influences mucin flow and gene expression, and that phaseolin heat treatment reverses these effects. The hypothesis was tested using a control diet containing casein as the sole protein source and three other diets with casein being replaced by 33 and 67 % of unheated and 67 % of heated phaseolin. The rats were fed for 6 d and euthanised. Digesta and faeces were collected for determining digestibility and mucin flow. Gut tissues were collected for mucin (Muc1, Muc2, Muc3 and Muc4) and Trefoil factor 3 (Tff3) gene expressions. Colonic mucin flow decreased linearly with increasing the dietary level of unheated phaseolin (P < 0·05). Unheated phaseolin increased N flow in ileum, colon and faeces (P < 0·05), and reduced apparent N digestibility linearly (P < 0·01). Heat treatment reversed all these changes (P < 0·05 to < 0·001), except mucin flow. The expressions of Muc mRNA in gut tissues were influenced by dietary phaseolin level (ileum and colon: Muc3 and Muc4) and thermal treatment (ileum: Muc2; colon: Muc2, Muc3, Muc4 and Tff3) (P < 0·05 to 0·001). In conclusion, phaseolin modulates mucin flow and Muc gene expression along the intestines differentially.