Fetal Piglet Research Articles

PSXIII-B-19 The Effect of Maternal Melatonin Supplementation During mid to Late Gestation on Fetal Piglet Hepatic Gene Expression

Abstract Using melatonin as a gestational therapeutic due to its antioxidant and vasodilative properties increases fetal morphometric measurements in ruminant models, however its effects on gestating swine and fetal circadian regulation remain unknown. This study evaluated the effects of dietary melatonin supplementation during gestation on fetal hepatic circadian regulatory and metabolic gene expression. Twenty-four pregnant sows were randomly assigned to either melatonin (20mg/d; MEL) or control (CON) and 0500h (AM) or 1700h (PM) harvest timepoint across fall and spring replicates. The fall replicate occurred from gestational day 38±1 to 99±1, while spring was days 41 to 106±1. At harvest small, medium, and large piglets were identified by body weight and their livers were collected. Data were analyzed using a linear mixed model by the MIXED procedure of SAS. Cry1 expression tended to increase (P=0.0575) in large fetuses compared to small during the fall, while large fetuses had the greatest expression, medium intermediary, and small least during the spring (P=0.0056). Cry2 was reduced (P< 0.001) in MEL offspring compared to CON in the fall. There was a Treatment × Class interaction (P=0.0104) for Cry2 expression during spring wherein, CON-AM was reduced compared to CON-PM, however no differences between MEL groups. A Treatment × Class interaction (P=0.0511) of Per2 expression was present in the fall, where expression of small control fetuses was reduced compared to remaining controls. Spring Per2 expression increased (P=0.0122) in large fetuses compared to other sizes, Per2 also increased (P=0.0039) in PM compared to AM. Fall IGF1 expression increased (P=0.0366) in large fetuses compared to medium and small, and spring IGF1 expression increased (P=0.0067) in large fetuses compared to small. These findings suggest that maternal melatonin supplementation during gestation modulates expression of hepatic circadian regulatory and metabolic genes which may impact growth and developmental efficiency postnatally in a seasonal manner.

Phylogenetic analysis reveals that Japanese encephalitis virus genotype III is still prevalent in swine herds in Sichuan province in China.

The genome of JEV strain SC201301, which was isolated from an aborted fetal piglet in 2013 in Sichuan province in China, was completely sequenced and phylogenetically analyzed. Sequence alignments showed that the SC201301 strain shared 97-100% sequence identity with other genotype III strains but showed less similarity to genotype I representative JEVs. Phylogenetic analysis indicated that the SC201301 strain belonged to genotype III and was most closely related to representative strains such as SA14-14-2, HW and SH0601. Our findings suggest that JEV genotype III is still prevalent in swine herds in Sichuan province in China, and thus, there is an urgent need to monitor the infection status of JEV among swine herds in China.

Histological and immunohistochemical study of the lymphoid tissue in the normal stomach of the gnotobiotic pig.

Animal models have been developed in which the role of Helicobacter pylori in the pathogenesis of different gastroduodenal diseases can be investigated. The gnotobiotic pig was one of the first animal models used. In this model, Helicobacter pylori infection causes gastritis, which shows some similarities to that in humans, such as the development of mucosa-associated lymphoid tissue (MALT). Hence, this animal model can be used to study the development of MALT in the normal stomach. The aim of our study is to see if lymphoid tissue is present or absent in the normal stomach of gnotobiotic pigs before birth and if so, to investigate its development and composition as a function of gestational age and location in the stomach. Therefore, we studied 82 foetal piglets using routine histology and immunohistochemistry. Our findings show that lymphoid tissue is present at birth. It is composed of lymphoid nodules, a diffuse mononuclear infiltrate and intra-epithelial lymphocytes. The development is a sequential process. The lymphoid tissue in the stomach at birth is composed of the immunohistochemically different immunocompetent cells normally present. In conclusion, MALT is present in normal foetal gnotobiotic pig gastric mucosa, and in this model the stomach is no exception to the rest of the gastrointestinal tract.

Characterization of PGE 2 receptors in fetal and newborn ductus arteriosus in the pig

We compared the total density and the relative expression of EP receptor (EP) subtypes in ductus arteriosus (DA) of the newborn with that of the fetal piglet. Saturation binding experiments showed 3-fold less PGE2 receptors in the newborn than in the fetus because of loss of EP3 and EP4 receptors thus explaining, at least partly, the reduced responsiveness to PGE2 of the newborn DA. Displacement experiments showed that the relative proportions of EP2, EP3, and EP4 were similar in the fetal DA but only EP2 was detected in the DA of the newborn pig. Hence, PGE2 effects in the newborn DA seem to be exclusively mediated by EP2 receptors both in vitro and in vivo. These findings may help to propose more specific therapies for regulation of DA's tone in certain newborns for whom conventional therapy is contraindicated.

Immunohistochemistry in the identification of a number of new diseases in Australia

Immunohistochemistry plays an important part in the diagnosis of some viral diseases. Demonstration of viral antigen in a lesion is an important contribution to diagnosis, either at the time of investigation or retrospectively. At the CSIRO Australian Animal Health Laboratory, the most frequent use of immunohistochemistry has been in the diagnosis of the important avian diseases, highly pathogenic avian influenza and Newcastle disease. The technology took key roles in the diagnoses of Hendra virus infections, and, later, an immunoperoxidase test gave the first indication of the existence of Australian bat lyssavirus. The test can often confirm that a virus isolated in an animal is the actual virus causing disease and not a coincidental isolation. Good examples of that in some more new diseases were the association of Wallal virus with blindness in kangaroos, and of the new porcine Menangle virus in natural and experimental cerebral disease in foetal piglets.

Antibody Repertoire Development in Fetal and Neonatal Piglets. I. Four VH Genes Account for 80 Percent of VH Usage During 84 Days of Fetal Life

AbstractVDJ rearrangement and VH gene usage during fetal development in 35 outbred piglets was examined by PCR amplification of VDJs; VDJs were subsequently characterized by hybridization with VH-specific gene probes and by sequencing. VDJ rearrangement was first seen in the fetal liver on day 30 of a 114-day gestation. Four VH genes (VHA, VHB, VHC, and VHE) accounted for ~80% of all VH gene usage regardless of gestational age, choice of piglet, or lymphoid tissue tested; DHA and DHB were used in >90% of the fetal VDJs examined. Evidence of somatic hypermutation during fetal development was not found. The proportion of the four prominent fetal VH genes did not differ significantly between cDNA and DNA, suggesting the absence of selective B cell differentiation. A comparison of recombination signal sequences, flanking sequences, and framework sequences of these fetal genes with other germline VH genes of swine offered no clue as to their selective usage. N-region additions were prominent on day 40 but not on day 30, suggesting that the onset of terminal deoxynucleotidyltransferase activity occurs after 30 days of fetal development. These collective findings indicate that the preimmune, “natural Ab” repertoire of the fetal piglet is largely restricted to the use of four nonpolymorphic and nonmutated VH genes and two nonmutated DH segments. This suggests that the preimmune repertoire of swine is either highly restricted or almost entirely determined by junctional diversity in complementarity-determining region-3.

Trans fatty acids. 3. Fatty acid composition of the brain and other organs in the newborn piglet.

The effects of dietary trans fatty acids on tissue fatty acid composition were studied in newborn piglets delivered from sows fed partially hydrogenated fish oil (PHFO) (28% trans) or partially hydrogenated soybean oil (PHSBO) (36% trans) in comparison with lard (0% trans) from 3 wk of age and through gestation in Experiment 1, or fed PHFO or "fully" hydrogenated fish oil (HFO) (19% trans) in comparison with coconut oil (CF) (0% trans) with two levels, 1 and 2.7%, of dietary linoleic acid from conception through gestation in Experiment 2. The piglets were sampled immediately after delivery, without having access to mothers' milk. Incorporation of trans fatty acids into brain PE (phosphatidylethanolamine) were non-detectable or very low (less than 0.1%). The incorporation of 18:1 trans into heart-PE, liver mitochondria-PE, total plasma lipids and adipose tissue was low, and 20:1 trans was not detected. Dietary trans fatty acids had no consistent effects on the overall fatty acid composition of the different tissue lipids. It is concluded that trans fatty acids from PHFO, HFO and PHSBO have no significant effects on the fatty acid accretion in the fetal piglet.

Preferential oxygen supply to the brain and upper body in the fetal pig.

In the fetal pig over 50% of the oxgenated umbilical venous blood bypasses the liver via vascular channels of over 100mu diameter which appear to act as a ductus venosus (DV). In the present experiments the oxygen levels (pO2, SO2 and O2 content) in the fetal carotid (CA) and femoral (FA) arteries were measured to determine whether preferential streaming of the oxygenated blood is maintained from the bypass to the foramen ovale and thence through the left heart to the upper body, as in other species. The results were obtained from 12 piglets catheterized and maintained in utero under sodium pentobarbitone anaesthesia. Significant CA-FA differences in pO2, SO2 and O2 content were observed in these fetuses during both normoxaemia and hypoxaemia showing that a higher level of oxygen can be maintained to the fetal head and brain over a wide range of oxygenation. These results confirm that the hepatic channels in the fetal piglet act as a fully functional DV.

The Neonatal Piglet as a Model for Human Neonatal Carnitine Metabolism

Investigations concerning carnitine metabolism and possible requirements for exogenous carnitine in human preterm neonates are limited by ethical considerations. The neonatal piglet is a potential animal model for these investigations. Tissue carnitine concentrations were determined in fetuses from cross-bred domestic gilts at stages of gestation corresponding to those of neonates found in neonatal intensive care units. Fetal piglet plasma and red blood cell carnitine levels decreased from approximately 90 d to term. Skeletal muscle carnitine increased from 60 d to term. Temporal changes in fetal carnitine concentrations in plasma, red blood cells and skeletal muscle throughout gestation are similar to the pattern reported by our laboratory for the human neonate. Cardiac muscle carnitine increased earlier than skeletal muscle but also continued to increase to term. Carnitine concentrations in fetal liver, kidney and intestine were maximal at 90 d and decreased until term. Similarities in physiology, metabolism and profiles of tissue carnitine concentration between the newborn piglet and the human neonate indicate that the neonatal piglet is an appropriate animal model for investigations concerning neonatal carnitine metabolism.

Heart-rate changes and gasping during intra-partum asphyxiation of a piglet. A case report

Fetal heart rate and gasping were monitored in a chronically-catheterized fetal piglet which became asphyxiated during delivery. This piglet was the fourth to be delivered in a litter of seven. Prior to delivery of the second piglet in the litter (which was next to the affected piglet in the uterine horn), blood pH and pO 2 values were within normal limits and heart rate changes were restricted to acceleration during uterine contractions. After expulsion of the second piglet in the litter, fetal heart rate became very irregular and fetal gasping became pronounced. Terminally, periods of severe bradycardia (with gasping) which occurred late in or after uterine contractions were observed between periods when the fetal heart rate was increased. These late decelerations followed a pattern similar to those seen in asphyxiated human infants.

Effects of Maternal Starvation on Some Blood Metabolites, Liver Glycogen, Birth Weight and Survival of Piglets

Pregnant crossbred sows were assigned to three treatments during the third trimester of gestation for an evaluation of the effects of maternal starvation on fetal development and piglet survival. Two groups of sows were taken off feed (water and trace mineralized salt only) on days 93 and 107 of gestation, respectively; the third group was fed 1.82 kg of complete sow diet/day and served as the control. Litter size, gestation length and pig birth weight in the 7-day and 21-day starvation groups were not different from those in the control group (P less than .05). Liver weight was depressed (P greater than .05) among the 7-day and 21-day progeny. However, liver glycogen concentrations and total liver glycogen were unaffected. Maternal blood glucose decreased to a fasting but steady level, while free fatty acid (FFA) increased in the two starved groups. Blood glucose and FFA at birth were similar for all treatment groups; however, FFA increased in the progeny of sows in the 7-day (P greater than .05) and 21-day (P greater than .01) starvation groups at 48 hr of age. Blood glucose at 48 hr did not vary (P less than .05), but the control progeny showed a faster glucose utilization, suggesting a greater dependence on carbohydrate metabolism than in the progeny of starved dams. Survival rate at 72 hr of age was higher among 21-day (43.8%) and 7-day (37.5%) progeny than among control progeny (8.5%). The increased plasma FFA level observed with fasting in the progeny of starved dams might indicate a shift toward lipid metabolism, which would account for the improved survival observed among the progeny of treated dams.

Carbohydrate metabolism in the fetal pig during late gestation.

In acute experiments on pregnant sows under sodium pentobarbitone anaesthesia, acid base balance, oxygenation and plasma metabolite concentrations were well maintained in the dam and all fetuses which remained undisturbed in utero, irrespective of the duration of the experiment. Fetal liver glycogen concentrations were also unaffected by the time of removal of the fetus. By contrast, intravascular catheterization and withdrawal of blood led to fetal hyperglycaemia and depletion of hepatic glycogen although blood gas and pH values were not changed by these procedures. In the 1 1/2--2 h sampling period following catheterization the normal positive umbilical venous-arterial differences in plasma glucose and lactate generally became reversed. These changes were prevented by the administration of hexamethonium (10--15 mg . kg-1 i.v.) but the drug did not block the fall in hepatic glycogen in catheterized fetuses. Both adrenaline and noradrenaline, which were each infused intravenously at 2.7--3.9 or 0.6--0.9 microgram . kg-1 . min-1, resulted in fetal hyperglycaemia and lacticacidemia together with a fall in arterial blood pH; hepatic glycogen concentrations in these fetuses were also reduced. The apparent sensitivity of the glycogenolytic mechanism to surgical trauma and haemorrhage in the fetal piglet is discussed in relation to findings in other species.

The polyunsaturated fatty acid status of foetal and neonatal ruminants.

1. Information on the fatty acid composition of tissues of foetal calves, neonatal lambs, deer and piglets reported by Payne (1978) has been quantified by the use of an internal standard during analysis, to give concentrations of total polyunsaturated fatty acids (PUFA) derived from linoleic acid (ω6) and linolenic acid (ω3) expressed on a per kg tissue basis. The total concentration of both acids (ω6+ω3) was similar in all tissues examined except brain. Because muscle, the main constituent of the soft tissues of young animals, contains about 40–50 % of the total body content of these acids, it is considered that muscle concentrations are a reflection of total body status of these acids.2. Concentrations in muscle of both ω6 derivatives and total PUFA were significantly lower in the neonatal lamb and foetal calf than in the mature animal whereas in pigs and deer the concentrations in the young animal were similar to those in the mature animal. Concentrations of ω6 derivatives and total PUFA in lambs were significantly lower than those in calves; the presence of ω3 derivatives reduced the level of significance for total PUFA. Again, total PUFA content did not differ significantly between the piglet and the young ruminants.3. There was a substantial placental transfer, with apparently a preferential transfer of ω3 derivatives.4. In brain the levels of ω3 acids were as high in the foetal and neonatal animals as in mature animals. The levels of ω6 acids were lower in young animals.5. Calculations of ω6 intake from milk showed that the total deficit of ω6 could be made up within a few days.6. It was concluded that the extent of deficiency of ω6 in young ruminants raised in a grazing situation, as in New Zealand, is marginal and any feeding to overcome this is unlikely to be of any benefit.

Isolation of Porcine parvovirus from aborted piglets

Summary The isolation of three strains of porcine parvovirus from aborted foetal piglets is recorded and the role of this virus as a cause of reproductive failure in pigs is discussed.

Ontogeny of the phytohemagglutinin response of fetal piglet thymic and splenic lymphocytes.

Lymphocytes derived from 72- to 90-day-old fetal piglet thymuses respond in vitro to phytohemagglutinin quantitatively greater than do spleen cell lymphocytes.