Structural brain maturation differs between preterm and term piglets, whereas brain activity does not.

AIM: The aim of the study was to investigate whether amplitude-integrated electroencephalography (aEEG) and cerebral magnetic resonance imaging (MRI) in preterm piglets would provide measures of cerebral functional, microstructural and anatomical maturation, which might reflect the signs of functional brain immaturity, documented in preterm piglets. METHODS: During July-October 2013 at the NEOMUNE Centre, Copenhagen University, Denmark, 31 preterm (90% gestation) and 10 term piglets underwent aEEG on days 1, 2, 4 and 11, and MRI on day 25. Physical activity levels were recorded. RESULTS: Preterm showed delayed neonatal arousal and physical activity, relative to term piglets. Preterm piglets had lower growth rates and brain volume than term piglets, but aEEG patterns were similar. MRI mean diffusivity was also similar, but fractional anisotropy (FA) was lower in preterm piglets (p < 0.001). CONCLUSION: Functional brain maturation, as assessed by aEEG, was relatively advanced in preterm piglets. Conversely, the low FA in the preterm piglets suggests that the white matter microstructure remains less mature in preterm compared to term piglets at postnatal day 25. The results might be utilised to define whether and how preterm piglets may contribute to preclinical models for brain development in preterm infants.

Glucagon-like peptide 2 treatment may improve intestinal adaptation during weaning.

Transition from sow's milk to solid feed is associated with intestinal atrophy and diarrhea. We hypothesized that the intestinotrophic hormone glucagon-like peptide 2 (GLP-2) would induce a dose- and health status-dependent effect on gut adaptation. In Exp. 1, weaned pigs (average BW at weaning 4.98 ± 0.18 kg) were kept in a high-sanitary environment and injected with saline or short-acting GLP-2 (80 µg/(kg BW·12 h); n = 8). Under these conditions, there was no diarrhea and GLP-2 did not improve gastrointestinal structure or function. In Exp. 2, weaned pigs (average BW at weaning 6.68 ± 0.27 kg) were kept in a low-sanitary environment, leading to weaning diarrhea, and injected with saline or short-acting GLP-2 (200 µg/(kg BW·12 h); n = 11). Treatment with GLP-2 increased goblet cell density (P < 0.05) and reduced short chain fatty acid concentration in the colon (P < 0.01) but had limited effects on diarrhea. In Exp. 3, weaned pigs (average BW at weaning 6.90 ± 0.32 kg) were kept in a low-sanitary environment and injected with saline or a long-acting acylated GLP-2 analogue (25 µg/(kg BW·12 h); n = 8). In this experiment, GLP-2 increased intestinal weight (+22%; P < 0.01) and activity of brush border enzymes (+50-100%; P < 0.05). Circulating GLP-2 levels were in the pharmacological range in Exp. 3 (constant levels >20,000 pmol/L) and Exp. 2 (increases to 20,000 pmol/L for a few hours each day) while they were in the supraphysiological range in Exp. 1 (50-200 pmol/L). In conclusion, GLP-2 may improve gut structure and function in weanling pigs. However, the effects may be significant only under conditions of diarrhea and if GLP-2 exposure time is extended using long-acting analogues.

Invited review: the preterm pig as a model in pediatric gastroenterology.

At birth, the newborn mammal undergoes a transition from a sterile uterine environment with a constant nutrient supply, to a microbe-rich environment with intermittent oral intake of complex milk nutrients via the gastrointestinal tract (GIT). These functional challenges partly explain the relatively high morbidity and mortality of neonates. Preterm birth interrupts prenatal organ maturation, including that of the GIT, and increases disease risk. Exemplary is necrotizing enterocolitis (NEC), which is associated closely with GIT immaturity, enteral feeding, and bacterial colonization. Infants with NEC may require resection of the necrotic parts of the intestine, leading to short bowel syndrome (SBS), characterized by reduced digestive capacity, fluid loss, and dependency on parenteral nutrition. This review presents the preterm pig as a translational model in pediatric gastroenterology that has provided new insights into important pediatric diseases such as NEC and SBS. We describe protocols for delivery, care, and handling of preterm pigs, and show how the immature GIT responds to delivery method and different nutritional and therapeutic interventions. The preterm pig may also provide a sensitive model for postnatal adaptation of weak term piglets showing high mortality. Attributes of the preterm pig model include close similarities with preterm infants in body size, organ development, and many clinical features, thereby providing a translational advantage relative to rodent models of GIT immaturity. On the other hand, the need for a sow surgical facility, a piglet intensive care unit, and clinically trained personnel may limit widespread use of preterm pigs. Studies on organ adaptation in preterm pigs help to identify the physiological basis of neonatal survival for hypersensitive newborns and aid in defining the optimal diet and rearing conditions during the critical neonatal period.

Randomised controlled trial of colostrum to improve intestinal function in patients with short bowel syndrome.

BACKGROUND/OBJECTIVES: Colostrum is rich in immunoregulatory, antimicrobial and trophic components supporting intestinal development and function in newborns. We assessed whether bovine colostrum could enhance intestinal adaptation and function in adult short bowel syndrome (SBS) patients. SUBJECTS/METHODS: Twelve SBS patients in this randomised cross-over study received 4 weeks oral supplement of bovine colostrum or an iso-energetic and iso-proteinaceous control (2.4 MJ/d, 500 ml/day) separated by a 4-week washout period. Patients were admitted four times for 72-h periods of fluid, electrolyte and nutrient balance studies. Meals, faeces and urine were weighed, and energy, macronutrient and electrolyte contents were analysed to calculate net nutrient uptake. Body composition was measured by dual-energy X-ray absorptiometry scans, and functional tests of handgrip strength and lung functions were performed. Eight patients completed the study and were included in the analysis. RESULTS: Both supplements (colostrum and control) not only increased protein (0.96 ± 0.42 MJ/d, P=0.004 1.03 ± 0.44 MJ/d, P=0.003) and energy (1.46 ± 1.02 MJ/d, P=0.005, 1.76 ± 1.46 MJ/d, P=0.01) absorption but also absolute faecal wet weight excretions (231 ± 248 g/d, P=0.002, 319 ± 299 g/d, P=0.03), compared with baseline measurements. Both supplements improved handgrip strength (P=0.03) while only the control supplement increased lean body mass (1.12 ± 1.33 kg, P<0.049). Colostrum was not found to be superior to the control. CONCLUSION: Intake of high-protein milk supplements increased net nutrient absorption for adult SBS patients, but at the expense of increased diarrhoea. Despite high contents of bioactive factors, colostrum did not significantly improve intestinal absorption, body composition or functional tests compared with the control.

Prenatal gastrointestinal development in the pig and responses after preterm birth.

Despite clinical research and medical advances, care of the preterm infant remains a clinical challenge, with the immature gastrointestinal (GI) system limiting the types and amounts of nutrients that can be provided enterally to meet energy and nutrient requirements. Progress in understanding the relationship between dietary inputs and the developing GI system after preterm birth has been limited by ethical constraints of using preterm infants as experimental subjects and a lack of relevant animal models. We review development of the GI system of the pig during gestation, the similarities shared with human fetuses, and the responses to dietary stimuli. The GI systems of pigs and humans develop early in gestation, with growth and maturation accelerating during the final weeks prior to birth. As a consequence, deficits in GI digestive capacities are directly related to how early in gestation an infant or pig is delivered, thereby complicating attempts to provide adequate enteral nutrients for growth and development. Pigs differ from humans by being born with low activities of the brush border membrane carbohydrases necessary for hydrolysis of nonlactose carbohydrates. Fetuses of both species have impaired lipid digestion coinciding with lipid malabsorption after preterm birth. Protease activity, although present, may not be adequate and may limit growth potential. Undigested enteral inputs are available to the resident bacteria and the production of metabolites can influence health and nutrition. The preterm pig represents a relevant and translational animal model for understanding GI development and for identifying diet and regulatory factors that stimulate GI growth and maturation after preterm birth and thereby accelerate the transition from parenteral nutrition to full enteral nutrition.

Casein addition to a whey-based formula has limited effects on gut function in preterm pigs.

Preterm infants are susceptible to necrotizing enterocolitis (NEC). Using preterm pigs, we determined whether a whey-casein-based formula would be superior to a formula based on whey protein alone. Twenty cesarean-derived preterm pigs (92% gestation) were given total parenteral nutrition for 36 h followed by 30 h of enteral feeding with whey [protein fraction of milk formula based on whey (WHEY); n = 11] or casein and/or whey [protein fraction of milk formula based on a combination of casein and whey (CASEIN); n = 9]-based formulas. Sugar absorptive function was investigated at 6 and 30 h after initiation of enteral feeding using bolus feedings with galactose and mannitol. Pigs were killed after the last in vivo sugar absorption test and evaluated for NEC and the mid intestine was used for ex vivo measurements of hexose absorption. Microbiota profile and short chain fatty acid (SCFA) levels were studied in gut contents. Severity of NEC lesions was similar between diet groups but galactose absorption was markedly higher in CASEIN than in WHEY (P < 0.01) although only 6 h after the start of the enteral feeding period. There were no differences in ex vivo (14)C-D-glucose uptake, digestive enzymes, microbiota profile, or SCFA concentration. Casein may transiently stimulate intestinal sugar absorption but has limited effects on gut structure, microbiota, and NEC in preterm pigs.

Escherichia coli challenge in newborn pigs.

Escherichia coli F18 is a common porcine enteric pathogen causing diarrhea and edema in weaned pigs. An essential step in the pathogenesis of this enteric colibacillosis is a fimbria-receptor interaction in the small intestine, involving the α(1,2)-fucosyltransferase gene (FUT1) enzyme for bacterial receptor binding to the epithelium. Enzyme expression is genetically determined and increases after weaning at 3 to5 wk, probably due to age- and/or diet-related intestinal maturation. We hypothesized that artificially reared piglets, deprived of sow's milk from birth, show susceptibility to F18 already in the neonatal period. First we verified the intestinal expression of FUT1 in preterm, term, and weaned pigs by quantitative real-time polymerase chain reaction. Then age-related F18 susceptibility (degree of diarrhea) was evaluated in 3-, 10-, and 20-d-old pigs after inoculation of 10(10) cfu E. coli F18 per day for 12 d. Finally, F18 susceptibility was evaluated in caesarean-delivered 0- to 7-d-old piglets inoculated daily with F18 as above. For all pigs, their sows were genotyped to ensure expression of the FUT1 enzyme. FUT1 expression was detected in the proximal and distal small intestine with no apparent differences in levels among preterm, term, and weaned pigs. No consistent F18-induced diarrhea was detected in any of the 3 groups of 3- to 20-d-old pigs. In contrast, 0- to 7-d-old caesarean-delivered pigs showed a higher score of diarrhea in pigs inoculated with F18 compared with controls (2.4 ± 0.1 vs. 1.8 ± 0.1 respectively; P < 0.001). Caesarean-delivered piglets deprived of sow milk are highly susceptible to diarrhea induced by E. coli F18. Lack of the protective effects of birth colonization and sow milk may contribute to high intestinal F18 sensitivity. The newborn pig may be a useful model to investigate factors in maternal milk that protect against F18 diarrhea.

Maternal endometrial oedema may increase perinatal mortality of cloned and transgenic piglets.

The perinatal mortality of cloned animals is a well-known problem. In the present retrospective study, we report on mortality of cloned transgenic or non-transgenic piglets produced as part of several investigations. Large White (LW) sows (n = 105) received hand-made cloned LW or minipig blastocysts and delivered either spontaneously or after prostaglandin induction followed by either Caesarean section or vaginal birth. The overall pregnancy rate was 62%, with 26% of pregnancies terminating before term. This resulted in 48 deliveries. The terminated pregnancies consisted of 12 abortions that occurred at 35 ± 2 days gestation and five sows that went to term without returning to heat and then by surgery showed the uterus without fetal content. The gestation length was for sows with LW piglets that delivered by Caesarean section or vaginally was 115.7 ± 0.3 and 117.6 ± 0.4 days, respectively. In sows with minipiglets, the gestation length for those delivered by Caesarean section or vaginally 114.4 ± 0.2 and 115.5 ± 0.3 days, respectively. Of the 34 sows that delivered vaginally, 28 gave birth after induction, whereas 6 farrowed spontaneously. Of the 14 sows that delivered after Caesarean section and in the five empty sows, the endometrium and placenta showed severe oedema. Piglet mortality following vaginal delivery was higher than after Caesarean section (31% v. 10%, respectively; P < 0.001). When vaginal delivery occurred spontaneously, the stillborn rate was greater than after induced delivery (56% v. 24%, respectively; P < 0.0001). Internal organ weights were recorded for seven cloned LW piglets and six normal piglets. The relative weight of the heart, liver, kidneys and small intestine was found to be reduced in the cloned piglets (P < 0.05). The present study demonstrates extensive endometrial oedema in sows pregnant with cloned and transgenic piglets, as well as in empty recipients, at term. The growth of certain organs in some of the cloned piglets was reduced and the rate of stillborn piglets was greater in cloned and transgenic piglets delivered vaginally, possibly because of oedema of the fetal-maternal interface.

Companion animals symposium: development of the mammalian gastrointestinal tract, the resident microbiota, and the role of diet in early life.

Mammalian gastrointestinal (GI) development is guided by genetic determinants established during the evolution of mammals and matched to the natural diet and environment. Coevolution of the host GI tract (GIT) and the resident bacteria has resulted in commensal relationships that are species and even individual specific. The interactions between the host and the GI bacteria are 2-way and of particular importance during the neonatal period, when the GIT needs to adapt rapidly to the external environment, begin processing of oral foods, and acquire the ability to differentiate between and react appropriately to colonizing commensal and potentially pathogenic bacteria. During this crucial period of life, the patterns of gene expression that determine GI structural and functional development are modulated by the bacteria colonizing the previously sterile GIT of fetuses. The types and amounts of dietary inputs after birth influence GI development, species composition, and metabolic characteristics of the resident bacteria, and the interactions that occur between the bacteria and the host. This review provides overviews of the age-related changes in GIT functions, the resident bacteria, and diet, and describes how interactions among these 3 factors influence the health and nutrition of neonates and can have lifelong consequences. Necrotizing enterocolitis is a common GI inflammatory disorder in preterm infants and is provided as an example of interactions that go awry. Other enteric diseases are common in all newborn mammals, and an understanding of the above interactions will enhance efforts to support neonatal health for infants and for farm and companion animals.

The preterm piglet - a model in the study of oesophageal development in preterm neonates.

AIM: Preterm infants have difficulty in attaining independent oral feeding. This can ensue from inadequate sucking, swallowing and/or respiration. In impeding bolus transport, immature oesophageal motility may also be a cause. As studies on the development of oesophageal motility are invasive in preterm infants, the preterm piglet was investigated as a potential research model. METHODS: Oesophageal motility (EM) of term (n = 6) and preterm (n = 15) piglets were monitored by manometry for 10 min immediately following bottle feeding on days 1-2 and 3-4 of life. RESULTS: Piglets' oral feeding performance and EM were similar to those of their human counterparts. Term piglets readily completed their feeding, whereas their preterm counterparts did not. They also presented with greater peristaltic activity and propagating velocity. Peristaltic activity remained unchanged over time in preterm piglets, but an increase in synchronous and decrease in incomplete motor activity were noted. Preterm piglets that developed symptoms analogous to necrotizing enterocolitis (NEC) demonstrated uncharacteristic oesophageal activity. CONCLUSION: Immature EM may cause oral feeding difficulties. NEC-like symptoms may adversely affect EM. The piglet is a valid research model for studying human infant oral feeding and oesophageal development.

The prenatal porcine intestine has low transforming growth factor-beta ligand and receptor density and shows reduced trophic response to enteral diets.

Transforming growth factor-beta (TGF-beta) plays a role in enterocyte proliferation control, cell differentiation, and immune regulation via binding to specific TGF-beta receptors (TGF-beta R) in the intestinal epithelium. Endogenous TGF-beta production is low in the intestine during the perinatal period, but some exogenous TGF-beta ligands are supplied by amniotic fluid intake in the fetus and by colostrum ingestion in the neonate. It is not clear, however, whether luminal TGF-beta receptors are present and functional at this critical time. We studied intestinal TGF-beta receptors by immunohistochemistry during the last 20% of gestation in pigs and in chronically catheterized fetuses following exposure to colostrum, milk, and amniotic fluid (control). In fetal pigs, the TGF-beta Rs were predominantly localized to the crypt epithelium, but staining intensity increased markedly just before term and shifted to the villous epithelium in newborn pigs, concurrently with marked increases in villous heights and crypt depths (+100-200%, P < 0.05). In contrast to previous observations in term newborn pigs, fetal pigs did not show any milk-induced change in TGF-beta receptor densities or localization, although a moderate increase in villous height was observed, relative to control (+25-50%, P < 0.05). We conclude that intestinal TGF-beta receptor density and localization are immature and unresponsive to TGF-beta containing milk diets in prenatal pigs. Immaturity of TGF-beta-mediated immune regulation may play a role in the increased sensitivity of preterm neonates to diet-induced intestinal inflammatory disorders.

Postnatal and diet-dependent increases in enteric glial cells and VIP-containing neurones in preterm pigs.

A mature enteric nervous system (ENS) is required to ensure a normal pattern of intestinal motility in order to regulate digestion after birth. We hypothesized that neuronal and glial components of the ENS would mature during the first postnatal days in preterm pigs that are a sensitive animal model of food intolerance and necrotizing enterocolitis (NEC). Stereological volume densities of the general neuronal population [assessed by betaIII-tubulin immunoreactivity (IR)] and subsets of neuronal (VIP-IR and nitrergic IR) and glial cells (GFAP-IR and S100-IR) were determined in the small intestine of newborn preterm piglets (93% gestation), after 3 days of receiving total parenteral nutrition (TPN) and after 3 days of TPN plus 2 days of enteral feeding with sow's colostrum or milk formula. Following TPN, VIP in the myenteric and inner submucous plexus and GFAP in the inner submucous plexus increased, while the relative volume of the total neuronal population remained constant. Introduction of enteral food induced variable degrees of food intolerance and NEC, especially after formula feeding, a diet that gave rise to a higher myenteric VIP and GFAP content in the inner submucous plexus than colostrum feeding. However, the ENS seemed unaffected by the presence of NEC-like intestinal lesions. Nevertheless, this study shows that the ENS is highly plastic during the first days after premature birth and adapts in an age- and diet-dependent manner. The observed postnatal adaptation in enteric VIP and GFAP may help to maintain intestinal homeostasis during suboptimal feeding regimens in preterm neonates.

A novel method for transuterine identification of piglets.

Implantable microchips provide a secure, permanent and unique identification of individual animals. When performing fetal intervention studies in experimental animal models easy and secure identification of fetuses is desirable, as having test and control groups within the same uterus reduces the total number of animals used in a study. The aims of this study were: (1) to establish a protocol to identify porcine fetuses in utero by microchip implantation and (2) to assess postnatally whether clinical or pathological reactions to the implant occurred. Two Danish Landrace/Danish Large White crossbred sows at day 100 of gestation were used. The sows were sedated with azaperone and induced with propofol intravenously. Anaesthesia was maintained with isoflurane and oxygen. Antibiotics were administered intramuscularly (i.m.) at induction and analgesia was given pre-, intra- and postoperatively. A laparotomy was performed and the uterus exteriorized. The rump of the first fetus was recognized through the uterine wall and the thigh muscle of the fetus was fixed between the thumb and the forefinger. The microchip was then implanted into the fetus at an angle of 45 degrees i.m. in the lateral hindleg using an insertion device with a 12G needle. The same procedure was done in every fetus. The uterus was returned to the abdomen and the abdominal wall closed. The sows gave birth to 24 liveborn piglets and one stillborn. None of the liveborn piglets were limping at the time of birth and no visible cutaneous or palpable reactions on the hindlegs were observed. Following euthanasia, the microchip was easily localized and no macroscopic reactions at the implantation site were seen. None of the piglets had more than one microchip implanted. Histology showed a chronic mild foreign body granulomatous inflammatory response with peripheral eosinophils surrounding the microchip. No inflammation was evident in the adjacent muscles. It is concluded that transuterine identification of piglets two weeks before delivery is feasible using a microchip implant as an effective, easy and reliable method for identification of individuals after birth.

Elective cesarean delivery affects gut maturation and delays microbial colonization but does not increase necrotizing enterocolitis in preterm pigs.

Although preterm birth and formula feeding increase the risk of necrotizing enterocolitis (NEC), the influences of cesarean section (CS) and vaginal delivery (VD) are unknown. Therefore, gut characteristics and NEC incidence and severity were evaluated in preterm pigs (92% gestation) delivered by CS or VD. An initial study showed that newborn CS pigs (n = 6) had decreased gastric acid secretion, absorption of intact proteins, activity of brush-border enzymes and pancreatic hydrolases, plasma cortisol, rectal temperature, and changes in blood chemistry, indicating impaired respiratory function, compared with VD littermates (n = 6). In a second experiment, preterm CS (n = 16) and VD (n = 16) pigs were given total parenteral nutrition (36 h) then fed porcine colostrum (VD-COL, n = 6; CS-COL, n = 6) or infant milk formula (VD-FORM, n = 10; CS-FORM, n = 10) for 2 days. Across delivery, FORM pigs showed significantly higher NEC incidence, tissue proinflammatory cytokines (IFN-gamma and IL-6), Clostridium colonization, and impaired intestinal function, compared with COL pigs. NEC incidence was equal for CS (6/16) and VD (6/16) pigs, CS pigs had decreased bacterial diversity and density, higher villus heights, and increased brush-border enzyme activities (lactase, aminopeptidases) compared with VD pigs. In particular, VD-FORM pigs showed reduced mucosal proportions, reduced lactase and aminopeptidases, and increased proinflammatory cytokine IL-6 compared with CS-FORM (P < 0.06). Despite the initial improvement of intestinal and metabolic functions following VD, gut function, and inflammation were similar, or more negatively affected in VD neonates than CS neonates. Both delivery modes exhibited positive and negative influences on the preterm gut, which may explain the similar NEC incidence.

Glucagon-like peptide 2 stimulates intestinal nutrient absorption in parenterally fed newborn pigs.

OBJECTIVES: Parenteral nutrition is a critically important intervention for children with intestinal dysfunctions. However, total parenteral nutrition (TPN) with no enteral feeding is associated with small intestine atrophy and malabsorption, which complicate the transition to enteral nutrition. The objective of the present study was to evaluate the therapeutic potential of the intestinotrophic peptide glucagon-like peptide 2 (GLP-2), which reduces TPN-associated atrophy and maintains nutrient absorption in adult rats, for preventing nutrient malabsorption in neonates receiving TPN. METHODS: Term pigs obtained by cesarean delivery received from birth TPN alone (TPN; n = 7) or TPN with GLP-2 (25 nmol . kg(-1) . d(-1); GLP-2; n = 8) or were fed sow milk enterally (n = 7). The small intestine was removed on postnatal day 6 to measure morphological responses and absorption of glucose, leucine, lysine and proline by intact tissues and brush border membrane vesicles and to quantify the abundances of mRNA and protein for enterocyte glucose transporters (SGLT-1 and GLUT2). RESULTS: Relative to TPN alone, administration of GLP-2 resulted in small intestines that were larger (P < 0.01), had greater abundances of mRNA and protein for SGLT-1, but not for GLUT2, and had higher capacities to absorb nutrients (P < 0.01). Moreover, the intestines of GLP-2 pigs were comparable in size and absorptive capacities with those of pigs fed sow milk enterally. CONCLUSIONS: Providing GLP-2 to neonates receiving TPN prevents small intestine atrophy, results in small intestine absorptive capacities that are comparable to when nutrients are provided enterally and may accelerate the transition from TPN to enteral nutrition.

Cortisol increases the activities of intestinal apical membrane hydrolases and nutrient transporters before weaning in mink (Mustela vison).

Glucocorticoids from endogenous and exogenous sources accelerate maturation of brush-border membrane (BBM) hydrolases in omnivorous laboratory rodents and pigs. Less is known for carnivores, and whether the route of administration (oral or systemic) has an influence. The present study examined the influence of administering cortisol (hydrocortisone succinate, 5 mg/kg-day) to mink during postnatal week 4, just prior to weaning, on small intestine glucose and amino acid (aspartate, leucine, lysine, methionine, proline) absorption and on the activities of BBM disaccharidases and peptidases. Kits treated with cortisol were smaller (P<0.05), but had small intestines that were proportionally larger (P<0.05 for length and mass per kg body weight, but not for mucosal mass) than control kits with higher rates of absorption for most nutrients, except leucine, and increased activities of most BBM hydrolases, except lactase. As a consequence, cortisol increased hydrolytic and absorptive capacities of the entire small intestine, with the responses more pronounced when the cortisol was given orally. These findings indicate administration of cortisol stimulates growth of the developing mink small intestine, but does not accelerate the postnatal declines in nutrient transport, and may be a dam-to-kit signal that prepares suckling mink to digest and absorb the adult diet.

The intestinal trophic response to enteral food is reduced in parenterally fed preterm pigs and is associated with more nitrergic neurons.

In term neonates, total parenteral nutrition (TPN) induces mucosal atrophy, whereas the first intake of milk is followed by intestinal growth. This may be explained in part by an NO-mediated increased blood flow. We hypothesized that the immature gut has an altered response to TPN and enteral nutrition. In Expt. 1, preterm caesarean-delivered pigs were administered elemental nutrients for 3 d, infused parenterally (TPN, n = 7) or enterally (TENT, n = 7). In Expt. 2, preterm pigs were fed sow's colostrum, cow's colostrum, or infant formula for 2 d after a 3-d TPN period (TPN-SOW, TPN-COW, TPN-FORM, n = 8-11). Intestinal morphology and the number of enteric neurons containing nitric oxide synthase-1 (NOS-1) were quantified. Both the TPN and TENT groups had increases in intestinal mass, circumference, and mucosal mass, volume, and surface density, relative to values at birth (+30-50%, P < 0.05). In Expt. 2, the magnitudes of the intestinal trophic responses to feeding were similar to those in Expt. 1, but were also associated with an increased number of nitrergic myenteric neurons and some mucosal damage, most frequently observed for the formula group. We conclude that 1) a short period of TPN does not induce mucosal atrophy in preterm pigs, whereas elemental nutrients infused luminally do not mimic the trophic response seen with milk diets, 2) enteral feeding of preterm pigs after a short period of TPN is associated with a modest, diet-dependent trophic response that may be related in part to the actions of an increased population of enteric NOS-1 neurons.

Short-term fasting induces intra-hepatic lipid accumulation and decreases intestinal mass without reduced brush-border enzyme activity in mink (Mustela vison) small intestine.

For many mammalian species short-term fasting is associated with intestinal atrophy and decreased digestive capacity. Under natural conditions, strictly carnivorous animals often experience prey scarcity during winter, and they may therefore be particularly well adapted to short-term food deprivation. To examine how the carnivorous gastrointestinal tract is affected by fasting, small-intestinal structure, brush-border enzyme activities and hepatic structure and function were examined in fed mink (controls) and mink that had been fasted for 1-10 days. During the first 1-2 days of fasting, intestinal mass decreased more rapidly than total body mass and villus heights were reduced 25-40%. In contrast, tissue-specific activity of the brush-border enzymes sucrase, maltase, lactase, aminopeptidase A and dipeptidylpeptidase IV increased 0.5- to 1.5-fold at this time, but returned to prefasting levels after 6 days of fasting. After 6-10 days of fasting there was a marked increase in the activity of hepatic enzymes and accumulation of intra-hepatic lipid vacuoles. Thus, mink may be a useful model for studying fasting-induced intestinal atrophy and adaptation as well as mechanisms involved in accumulation of intra-hepatic lipids following food deprivation in strictly carnivorous domestic mammals, such as cats and ferrets.

Combined ACTH and glucocorticoid treatment improves survival and organ maturation in premature newborn calves.

Glucocorticoids play an important role in prenatal organ maturation in many species. In humans, maternal treatment with synthetic glucocorticoids improves neonatal adaptation of prematurely born infants. In cows, pre-term calf survival is improved following a single maternal glucocorticoid administration. We hypothesized that stimulation of endogenous cortisol secretion by adrenocorticotropin (ACTH) treatment combined with maternal dexamethasone treatment, would be even more efficient in stimulating organ maturation in the prematurely delivered calf. Three groups of premature calves were delivered by caesarian section at 90% of gestation length from dams which were either untreated or injected with dexamethasone before delivery, combined with either prenatal or postnatal ACTH treatment to the calf. During the first 24h after birth, thermoregulation, blood chemistry, liver values and organ weights were recorded. In the untreated calves, survival was significantly correlated with blood oxygenation, sodium and calcium levels at the moment of birth. There were marked maturational effects of the treatments on body temperature regulation, blood acid-base status, oxygenation, glucose, insulin, IGF-1 levels, weight of the heart, liver, gastrointestinal tract and thymus weight. For many of the measured metabolic, endocrine and organ weight parameters, the intrauterine ACTH treatment was associated with improved values relative to the postnatal ACTH treatment, which appeared to have no immediate effect on calf viability. In conclusion, the premature calf delivered by caesarian section at 90% of gestation length showed blood chemistry, metabolic, endocrine and organ growth characteristics that indicated severe prematurity. However, the maturation of organ function in newborn premature calves following maternal glucocorticoid injections was further enhanced if is was preceded by intra-fetal injections of ACTH.

A method to reduce the invasiveness of fetal catheterization in the cow.

Surgical intervention in general anesthesia (GA) of the cow in late gestation is a stressful condition for both mother and fetus, potentially leading to premature delivery or fetal death. The present study hypothesized that fetal catheterization at days 246-253 (90% of gestation) is done with less physical and metabolic stress for the mother and fetus, when the surgery is performed on a standing cow and local anesthesia (LA) rather than on a recumbent cow in general anesthesia. Fetal and uterine maternal intra-vascular catheters were implanted during general anesthesia (GA, n=24) or local analgesia (LA, n=7). Blood gases and metabolite levels in the fetal calves and their mothers were measured during surgery and for 5 days post-operatively. During surgery, venous blood pH was higher (7.44 +/- 0.01 versus 7.39 +/- 0.01, P<0.05) and hemoglobin and oxygen contents lower in LA cows compared with GA cows (9.3 +/- 0.3 mg/dl versus 11.8 +/- 0.2 mg/dl, P<0.001 and 10.0 +/- 0.3 ml/dl versus 12.6 +/- 0.6 ml/dl, P<0.05). The differences between the two groups of fetuses reflected those of their dams in that LA fetuses showed lower arterial oxygen pressure (18.3 +/- 1.4 mmHg versus 24.8 +/- 1.4 mmHg, P<0.05) and hemoglobin (7.81 +/- 0.30 mg/dl versus 9.22 +/- 0.21 mg/dl P<0.01) and furthermore, they also showed higher blood glucose (2.4 +/- 0.2 mM versus 1.4 +/- 0.1 mM, P<0.01). During the 5 days post-surgery, 10 GA fetuses (42%) and 1 LA fetus (14%) died in utero. Bacterial contamination was implicated in six of the GA deaths and in the one LA death. In the dams with surviving calves, differences in hemoglobin (9.49 +/- 0.21 mg/dl versus 11.17 +/- 0.23 mg/dl P<0.001) and O2ct (10.9 +/- 0.3 ml/dl versus 12.5 +/- 0.5 ml/dl, P<0.05) were still present, and in addition, blood glucose was higher in LA versus GA cows (4.3 +/- 0.2 mM versus 3.8 +/- 0.1 mM, P<0.05). The choice of surgical method did not affect post-surgery blood chemistry in the surviving fetuses, except that the higher blood glucose in the LA fetuses at surgery tended to be maintained also post-operatively (2.0 +/- 0.2 mM versus 1.5 +/- 0.1 mM, P=0.07). The observed differences in blood chemistry parameters between the two methods of surgery and possibly in the fetal death may be explained by differences in catheterization method and the associated differences in physical and metabolic stress during and after surgery. Thus, surgery upon a standing cow in local anesthesia should be considered as an alternative to surgery in universal anesthesia for fetal catheterization in the cow in late gestation.