Effects of intraventricularly applied gangliosides and N-acetylneuraminic acid on acquisition and retention performance of a brightness discrimination task in rats

Recent advances on N-acetylneuraminic acid: Physiological roles, applications, and biosynthesis

N-Acetylneuraminic acid (Neu5Ac), the most common type of Sia, generally acts as the terminal sugar in cell surface glycans, glycoconjugates, oligosaccharides, lipo-oligosaccharides, and polysaccharides, thus exerting numerous physiological functions. The extensive applications of Neu5Ac in the food, cosmetic, and pharmaceutical industries make large-scale production of this chemical desirable. Biosynthesis which is associated with important application potential and environmental friendliness has become an indispensable approach for large-scale synthesis of Neu5Ac. In this review, the physiological roles of Neu5Ac was first summarized in detail. Second, the safety evaluation, regulatory status, and applications of Neu5Ac were discussed. Third, enzyme-catalyzed preparation, whole-cell biocatalysis, and microbial de novo synthesis of Neu5Ac were comprehensively reviewed. In addition, we discussed the main challenges of Neu5Ac de novo biosynthesis, such as screening and engineering of key enzymes, identifying exporters of intermediates and Neu5Ac, and balancing cell growth and biosynthesis. The corresponding strategies and systematic strategies were proposed to overcome these challenges and facilitate Neu5Ac industrial-scale production.

Dietary Oligofructose Alone or in Combination with 2'-Fucosyllactose Differentially Improves Recognition Memory and Hippocampal mRNA Expression

Mounting evidence suggests that dietary oligosaccharides promote brain development. This study assessed the capacity of oligofructose (OF) alone or in combination with 2'-fucosyllactose (2'-FL) to alter recognition memory, structural brain development, and hippocampal gene expression. Beginning on postnatal day (PND) 2, male pigs received one of three milk replacers formulated to contain OF, OF + 2'-FL, or no oligosaccharides (CON). Pigs were tested on the novel object recognition task using delays of 1 or 48 h at PND 22. At PND 32-33, magnetic resonance imaging (MRI) procedures were used to assess structural brain development and hippocampal tissue was collected for analysis of mRNA expression. Pigs that consumed the OF diet demonstrated increased recognition memory after a 1 h delay, whereas those consuming diets containing OF + 2'-FL displayed increased recognition memory after a 48 h delay. Pigs fed OF or OF + 2'-FL exhibited a larger relative volume of the olfactory bulbs compared with CON pigs. Provision of OF or OF + 2'-FL altered gene expression related to dopaminergic, GABAergic, cholinergic, cell adhesion, and chromatin remodeling processes. Collectively, these data indicate that dietary OF and OF + 2'-FL differentially improve cognitive performance and affect olfactory bulb structural development and hippocampal gene expression.

Sources, Production, and Clinical Treatments of Milk Fat Globule Membrane for Infant Nutrition and Well-Being

Research on milk fat globule membrane (MFGM) is gaining traction. The interest is two-fold; on the one hand, it is a unique trilayer structure with specific secretory function. On the other hand, it is the basis for ingredients with the presence of phospho- and sphingolipids and glycoproteins, which are being used as food ingredients with valuable functionality, in particular, for use as a supplement in infant nutrition. This last application is at the center of this Review, which aims to contribute to understanding MFGM's function in the proper development of immunity, cognition, and intestinal trophism, in addition to other potential effects such as prevention of diseases including cardiovascular disease, impaired bone turnover and inflammation, skin conditions, and infections as well as age-associated cognitive decline and muscle loss. The phospholipid composition of MFGM from bovine milk is quite like human milk and, although there are some differences due to dairy processing, these do not result in a chemical change. The MFGM ingredients, as used to improve the formulation in different clinical studies, have indeed increased the presence of phospholipids, sphingolipids, glycolipids, and glycoproteins with the resulting benefits of different outcomes (especially immune and cognitive outcomes) with no reported adverse effects. Nevertheless, the precise mechanism(s) of action of MFGM remain to be elucidated and further basic investigation is warranted.

Dietary Sialyllactose Does Not Influence Measures of Recognition Memory or Diurnal Activity in the Young Pig

Sialic acid (SA) is an integral component of gangliosides and signaling molecules in the brain and its dietary intake may support cognitive development. We previously reported that feeding sialyllactose, a milk oligosaccharide that contains SA, alters SA content and diffusivity in the pig brain. The present research sought to expand upon such results and describe the effects of feeding sialyllactose on recognition memory and sleep/wake activity using a translational pig model. Pigs were provided ad libitum access to a customized milk replacer containing 0 g/L or 380 g/L of sialyllactose from postnatal day (PND) 2-22. Beginning on PND 15, pigs were fitted with accelerometers to track home-cage activity and testing on the novel object recognition task began at PND 17. There were no significant effects of diet on average daily body weight gain, average daily milk intake, or the gain-to-feed ratio during the study (all p ≥ 0.11). Pigs on both diets were able to display recognition memory on the novel object recognition task (p < 0.01), but performance and exploratory behavior did not differ between groups (all p ≥ 0.11). Total activity and percent time spent sleeping were equivalent between groups during both day and night cycles (all p ≥ 0.56). Dietary sialyllactose did not alter growth performance of young pigs, and there was no evidence that providing SA via sialyllactose benefits the development of recognition memory or gross sleep-related behaviors.

The role of gangliosides in brain development and the potential benefits of perinatal supplementation

The maternal diet provides critical nutrients that can influence fetal and infant brain development and function. This review highlights the potential benefits of maternal dietary ganglioside supplementation on fetal and infant brain development. English-language systematic reviews, preclinical studies, and clinical studies were obtained through searches on PubMed. Reports were selected if they included benefits and harms of maternal ganglioside supplementation during pregnancy or ganglioside-supplemented formula after pregnancy. The potential benefits of ganglioside supplementation were explored by investigating the following: (1) their role in neural development, (2) their therapeutic use in neural injury and disease, (3) their presence in human breast milk, and (4) their use as a dietary supplement during or after pregnancy. Preclinical studies indicate that ganglioside supplementation at high doses (1% of total dietary intake) can significantly increase cognitive development and body weight when given prenatally. However, lower ganglioside supplementation doses have no beneficial cognitive effects, even when given throughout pregnancy and lactation. In human clinical trials, infants given formula supplemented with gangliosides showed increased cognitive development and an increase in ganglioside content. Ganglioside supplementation may promote brain development and function in offspring when administered at the optimum dosage. We propose that prenatal maternal dietary supplementation with gangliosides throughout pregnancy may promote greater long-term effects on brain development and function. Before this concept can be encouraged in preconception clinics, future research and clinical trials are needed to confirm the ability of dietary gangliosides to improve cognitive development, but available results already encourage this area of research.

Sialic acid is an essential nutrient for brain development and cognition

The rapid growth of infant brains places an exceptionally high demand on the supply of nutrients from the diet, particularly for preterm infants. Sialic acid (Sia) is an essential component of brain gangliosides and the polysialic acid (polySia) chains that modify neural cell adhesion molecules (NCAM). Sia levels are high in human breast milk, predominately as N-acetylneuraminic acid (Neu5Ac). In contrast, infant formulas contain a low level of Sia consisting of both Neu5Ac and N-glycolylneuraminic acid (Neu5Gc). Neu5Gc is implicated in some human inflammatory diseases. Brain gangliosides and polysialylated NCAM play crucial roles in cell-to-cell interactions, neuronal outgrowth, modifying synaptic connectivity, and memory formation. In piglets, a diet rich in Sia increases the level of brain Sia and the expression of two learning-related genes and enhances learning and memory. The purpose of this review is to summarize the evidence showing the importance of dietary Sia as an essential nutrient for brain development and cognition.

Supplementation with a mixture of complex lipids derived from milk to growing rats results in improvements in parameters related to growth and cognition

Alterations in nutritional factors during early development can exert long-term effects on growth, neural function, and associated behaviors. The lipid component of milk provides a critical nutritional source for generating both energy and essential nutrients for the growth of the newborn. The present study, therefore, investigated the hypothesis that nutritional supplementation with a complex milk lipid (CML) preparation, derived from the milk fat globule membrane rich in phospholipids and gangliosides from young rats, has beneficial effects on learning behavior and postnatal growth and development. Male Wistar rat offspring from normal pregnancies were treated from neonatal day 10 until postnatal day 80 with either vehicle or CML at a dose of 0.2% (low) and 1.0% (high) based on total food intake (n = 16 per group). Neonatal dosing was via daily oral gavage, while postweaning dosing was via gel supplementation to a standard chow diet. Animals underwent behavioral tasks related to spatial memory, learning, and cognitive function. Complex milk lipid supplementation significantly increased linear growth rate (P < .05), and the improved growth trajectory was not related to changes in body composition as quantified by dual-energy x-ray absorptiometry scanning or altered plasma lipid profiles. Moreover, this effect was not dose dependent and not attributable to the contribution to total energy intake of the CML composition. Supplementation of the CML to growing rats resulted in statistically significant improvements in parameters related to novelty recognition (P < .02) and spatial memory (P < .05) using standard behavioral techniques, but operant testing showed no significant differences between treatment groups. Supplementation with a CML containing gangliosides had positive growth and learning behavioral effects in young normal growing rats.

Postnatal dietary supplementation with either gangliosides or choline: effects on spatial short-term memory in artificially-reared rats

This study addressed the hypothesis that dietary supplementation with either gangliosides or choline during the brain growth spurt would enhance short-term spatial memory. Male Long-Evans rats were reared artificially from postnatal days (PD) 5-18 and were fed diets containing either (i) choline chloride 1250 mg/l (CHL), (ii) choline chloride 250 mg/l and GD3 24 mg/l (GNG) or (iii) choline chloride 250 mg/l (STD). A fourth group (SCK) was reared normally. Rats were weaned onto AIN 93G diet and on PD 35 were trained on a cued delayed- matching-to-place version of the Morris water maze. All groups learned to swim to the beacon that indicated the platform position on the first trial; similarly, on the second un-cued trial, the distance swam to reach the platform decreased to the same extent in all groups over the five days of training. The groups also responded in the same way to an increase in delay between the first and second trial from 1 min to 1 h, showing an increase in the distance swam, accompanied by a decrease in the number of direct swims to the platform. Thus, all rats were equally proficient at using spatial short-term memory, regardless of the choline or ganglioside content of the preweaning diet.

Ganglioside or sialic acid attenuates ethanol-induced decrements in locomotion, nose-poke exploration, and anxiety, but not body temperature

1. This laboratory has previously reported that pretreatment with ganglioside, or even with its constituent, sialic acid (SA), can attenuate certain intoxicating effects of ethanol. It was important to see if these findings could be replicated, particularly by using other measures of ethanol effects. Herein we report that pretreatment with either gangliosides or SA attenuated ethanol-induced decrements in locomotion, nose-poke exploration, and anxiety, but not body temperature. 2. An ethanol dose of 4 gm/kg caused a temperature drop of about 3 degrees C, which was unaffected by any pretreatment. The onset to sleep, however, was delayed an average of 18 or 36 secs in mice pretreated with ganglioside or SA, respectively. Ethanol-only (4 gm/kg) depressed mean cumulative locomotor activity to 31% of normal, whereas the depression was 83% of normal with beef brain ganglioside pretreatment. At 2 gm/kg ethanol alone decreased nose poking in a hole-board test to 29% of normal, but the depression was only 55-63% of normal with SA or ganglioside pretreatment. In a staircase climbing anxiety test, this dose of ethanol had no effect by itself, but both ganglioside and SA pre-treatment increased climbing by 22%. Ethanol did depress rearing to only 11% of normal, whereas rearing was 51 and 99% of normal with SA and ganglioside pretreatment, respectively. In a dark-preference test, ethanol-only caused mice to spend 64% of the time in the light, compared to 31% for controls. Time in the light was only 39 and 46% with ganglioside and SA pretreatment, respectively. 3. Blood levels of ethanol were not significantly affected by pretreatment. 4. When given alone, gangliosides significantly stimulated locomotion and staircase climbing. SA significantly decreased rearing in the staircase test. Both gangliosides and SA tended to increase nose poking, number of crossings in the dark-preference test, and time in a lighted compartment. Thus, it is possible that some of the attenuation of intoxication is attributable to non-specific stimulant properties of gangliosides and SA.