Kiitiro Sitizyo

Characteristic transport of lactoferrin from the intestinal lumen into the bile via the blood in piglets

Lactoferrin is a major iron-binding protein in milk from several species, such as humans, monkeys, mice and sows. Using neonatal and weaner piglets, the characteristic transfer of lactoferrin from intestinal lumen into bile via the circulation was investigated. Bovine lactoferrin (1 or 3 g/kg body weight) was infused into the stomach through a polyethylene tube or into the duodenum through a duodenal catheter over 5 min. Peripheral blood and bile samples were collected after the infusion. Lactoferrin absorbed into plasma and bile were assayed quantitatively by double-antibody enzyme-linked immunosorbent assay, and homogeneity of bovine lactoferrin in plasma and bile was identified by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and immunoblotting methods. Morphological investigation was carried out according to the peroxidase anti-peroxidase method. Following oral administration in neonatal pigs, bovine lactoferrin appeared in the blood circulation and reached a peak level after 2 h. It was confirmed immunohistochemically that lactoferrin was transported by endocytosis via the epithelial cells. Lactoferrin absorbed into the blood was also detected in the bile and reached a peak value 12 h after oral administration. Transportation of lactoferrin from the intestinal lumen into the bile via the bloodstream was also observed in weaner piglets. Lactoferrin transported into plasma and bile was confirmed to be the same substance as administrated lactoferrin by electrophoresis and immunoblotting methods. Lactoferrin transported into bile was re-absorbed into the blood in neonatal pigs. These results demonstrate that lactoferrin contained in milk is transported into the circulation from the intestinal lumen and excreted into the bile, suggesting the possibility of entero-hepatic circulation of lactoferrin in neonatal pigs.

Characteristic Transfer of Colostral Components into Cerebrospinal Fluid via Serum in Neonatal Pigs

In order to evaluate the possibility of modification of brain function by colostral suckling, the characteristic transfer of colostral components into serum and cerebrospinal fluid (CSF) has been studied by SDS electrophoresis, immunoblot and ELISA methods in nonsuckling pigs. Total protein concentrations in the serum increased immediately after oral administration of bovine colostrum, reaching a peak value (7.0 ± 0.7 g/dl) at 24 h after administration, corresponding to a 3-fold increase compared to preinfusion levels. IgG and other macromolecular components (MW 19,000–58,000) were recognized in serum by electrophoretic and ELISA analysis. Total protein concentrations in the CSF collected from the cisterna magna also increased steeply after colostral administration, reaching a maximal value (54.1 ± 5.0 mg/dl) at 4 h, corresponding to a 4-fold increase compared to preinfusion levels. Two colostral components (MW 19,000 and 31,000) in serum were confirmed to be present in the CSF by electrophoresis. The component of MW 19,000 was identified by immunoblot as β-lactoglobulin. IgG in serum transferred from colostrum could not be detected in the CSF by ELISA. Lactoferrin administered into the intestine was also detected in the CSF via serum. These results indicate that some components of colostrum can be transported into the CSF via the serum, suggesting the possibility of modification of immature brain functions by colostral suckling in neonatal pigs.

Postnatal development of EEG patterns, catecholamine contents and myelination, and effect of hyperthyroidism in Suncus brain

The postnatal development of the central nervous system (CNS) in house musk shrew in the early stage of maturation was studied. The electroencephalogram (EEG) and visual evoked potential (VEP) in association with catecholamine contents and myelin basic protein (MBP) immunoreactivity were carried out from the 1st to the 20th day of postnatal age. Different EEG patterns which were specific to behavioral states (awake and drowsy) were first recorded on the 5th day, and the total power which was obtained by power spectrum analysis increased after this stage. The latencies of all peaks in VEP markedly shortened between the 5th and the 7th day. Noradrenalin (NA) content of the brain showed a slight increase after the 3rd day, and reached maximum levels on the 7th day, which was delayed a few days compared to dopamine (DA). In hyperthyroidism, the peak latency of VEP was shortened and biosynthesis of NA in cerebral cortex and DA in hippocampus was accelerated. The most obvious change in MBP-immunoreactivity of the telencephalon occurred from the 7th to the 10th day. These morphological changes in the brain advanced at the identical time-course to those in the electrophysiological development and increment of DA and NA contents.