[Brain gangliosides and memory formation]

Determining the safety and efficacy of dietary supplementation with 3'-sialyllactose or 6'-sialyllactose on growth, tolerance, and brain sialic acid concentrations

Sialylated oligosaccharides, including 3'-sialyllactose (3'-SL) and 6'-sialyllactose (6'-SL), comprise a large portion of human milk and have been known to support development over the first year of life. While research has investigated the impact of early-life supplementation, longer-term supplementation remains relatively unexplored. Consequently, the following study assesses the impact of supplementation of either 3'-SL or 6'-SL on growth performance, tolerance, and brain sialic acid concentrations. Two-day-old piglets (n = 75) were randomly assigned to a commercial milk replacer ad libitum without or with 3'-SL or 6'-SL (added at 0.2673% on an as-is basis). Daily body weight and feed disappearance were recorded to assess growth performance and tolerance. Pigs were euthanized for sample collection on postnatal day 33 (n = 30) or 61 (n = 33), respectively. Across growth performance, clinical chemistry and hematology, histomorphology, and sialic acid quantification, dietary differences were largely unremarkable at either time-point. Overall, SA was well-tolerated both short-term and long-term.

Dietary Prebiotics, Milk Fat Globule Membrane, and Lactoferrin Affects Structural Neurodevelopment in the Young Piglet

INTRODUCTION

Milk fat globule membrane (MFGM) and lactoferrin have been identified as two components that have potential to affect neurodevelopment. While concentrations of some MFGM constituents in infant formulas are within human milk range, they may not be present at optimal or clinically effective levels. However, lactoferrin levels of infant formulas are consistently reported to be lower than human milk. This study sought to provide a novel combination of prebiotics, bovine-derived MFGM, and lactoferrin and assess their influence on neurodevelopment.

METHODS

Twenty-four male piglets were provided either TEST (n = 12) or CONT (n = 12) diet from 2 to 31 days of age. Piglets underwent spatial T-maze assessment starting at 17 days of age, were subjected to magnetic resonance imaging at 30 days of age, and were euthanized for tissue collection at 31 days of age.

RESULTS

Diffusion tensor imaging revealed differences in radial (P = 0.032) and mean (P = 0.028) diffusivities in the internal capsule, where CONT piglets had higher rates of diffusion compared with TEST piglets. Voxel-based morphometry indicated larger (P < 0.05) differences in cortical gray and white matter concentrations, with CONT piglets having larger tissue clusters in these regions compared with TEST piglets. In the spatial T-maze assessment, CONT piglets exhibited shorter latency to choice compared with TEST piglets on day 2 of acquisition and days 3 and 4 of reversal.

CONCLUSION

Observed differences in microstructure maturation of the internal capsule and cortical tissue concentrations suggest that piglets provided TEST diet were more advanced developmentally than piglets provided CONT diet. Therefore, supplementation of infant formula with prebiotics, MFGM, and lactoferrin may support neurodevelopment in human infants.

Sialic acid concentration of brain gangliosides: variation among eight mammalian species

Sialic acid is a vital component of brain gangliosides which play an essential role in the transmission and storage of information in the brain. The concentration of bound sialic acid in gangliosides and free sialic acid in the brain cortex of eight different mammals [human, chimpanzee (Pan troglodytes), rat (Rattus norvegicus), mouse (Mus musculus), rabbit (Oryctolagus cuniculus), sheep (Ovis aries), cow (Bos indicus) and pig (Sus scrofa)] were compared. Total sialic acid concentration (890+/-103 microg/g wet weight tissue, mean+/-SE, n = 6) was 2-4 times higher in the human brain compared with the other species studied (0.001 < p < 0.05). There was no significant difference between human males and females. The rank order of adult brain sialic acid after humans (in microg/g) was rat (493+/-23, n = 12), mouse (445+/-29, n = 16), rabbit (380+/-18, n = 6), sheep (323+/-43, n = 6), cow (304+/-14, n = 6) and pig (252+/-14, n = 6). Apart from the cow vs the sheep, the differences between species were statistically significant (p < 0.05). In the mouse, cow and sheep, total sialic acid concentration increased during maturation by 18-32% (p < 0.05). In a 2-year-old chimpanzee, the sialic acid concentration in the left lobe of the brain cortex was 25% higher than that of right lobe at 6 weeks of age (p < 0.05). Free sialic acid was higher in the human brain cortex (41+/-3 microg/g) than that of the rat and mouse (32+/-3 and 25+/-5 microg/g respectively) and absent from other species. Variation in brain sialic acid concentration among different animals has implications for the evolution of the brain and may affect learning ability in animals.

Brain gangliosides and memory formation

It is generally accepted that the process of molecular facilitation of neuronal circuits by means of stabilization of synaptic contacts represents the structural basis for memory formation. At the distinct zone of synaptic contact the following basic events occur: alterations of the electrical field strength at the outer surface of synaptic membranes, conformational changes of membrane-bound functional proteins (ion channels, ion pumps, receptors) and activation of second messenger cascade. Finally a trophic feed-back between synaptic terminals and their cell bodies through retro- and anterograde neuronal transport exists, which guarantees a stabilization of the newly formed synaptic connection. As a controlled Ca(2+)-exchange between the extracellular space (mM Ca(2+)-concentration) and the synaptoplasm (microM Ca2+) is essential for all these events, the present research concentrates on Ca(2+)-mediated primary messenger systems at the outer leaflet of synaptic membranes and on Ca(2+)-mediated modulatory mechanisms. These enable an always efficient electroresponsiveness although the environmental temperature might have changed. In this regard gangliosides being amphiphilic sialic acid containing glycosphingolipids, which are highly accumulated in complex composition in synaptic membranes play an important role. According to specific physico-chemical properties, they are assumed to fulfill the task of neuromodulators in connection with calcium, and thus contribute to the transmission and storage of information. The outcome of a series of experiments derived from neurology, ecophysiology, behavioral sciences, electron microscopy, biochemistry and physical chemistry give strong circumstantial evidence for this concept.