Ghrelin and feeding behaviour in preterm infants

Developmental trajectories of eating behaviors and cross-lagged associations with weight across infancy

Examining typical developmental trajectories of infant eating behaviors, correlates of those trajectories, and cross-lagged associations between eating behaviors and anthropometry, is important to understand the etiology of these behaviors and their relevance to growth early in the lifespan. Mothers (N = 276) completed the Baby Eating Behavior Questionnaire (BEBQ) and infant anthropometrics were measured at ages 1, 2, 4, 6, and 10 months. Infant and maternal characteristics were collected by maternal report. Trajectories of eating behaviors were identified using latent class growth modeling and bivariate analyses examined associations of infant eating behavior trajectory membership with infant and maternal characteristics. Cross-lagged analyses examined associations between BEBQ subscales and infant weight-for-length z-score. Infant eating behavior trajectories included: Consistently High (62%) and Consistently Moderate (38%) Enjoyment of Food; Consistently High (9%), Moderate & Decreasing (43%), and Low & Decreasing (48%) Food Responsiveness; and Consistently High (62%) and Moderate & Decreasing (38%) General Appetite. Trajectory group membership was not associated with infant sex, gestational age, birthweight, or having been exclusively fed breastmilk at 2 months. Consistently High trajectories for Enjoyment of Food, Food Responsiveness, and General Appetite were associated with maternal demographic markers of psychosocial risk (e.g., lower maternal age and educational attainment). Food Responsiveness and General Appetite tracked strongly across infancy within individuals. Cross-lagged associations of Enjoyment of Food, Food Responsiveness, and General Appetite with weight-for-length z-score across infancy were generally null. Much additional work is needed to understand eating behaviors in infancy, their development, and their etiology. Further understanding of infant eating behaviors will provide the basis for future interventions to improve life course nutrition, growth, and health.

The ghrelin system follows a precise post-natal development in mini-pigs that is not impacted by dietary medium chain fatty-acids

The ghrelin-ghrelin receptor (GHSR1) system is one of the most important mechanisms regulating food intake and energy balance. To be fully active, ghrelin is acylated with medium-chain fatty acids (MCFA) through the ghrelin-O-acetyl transferase (GOAT). Several studies reported an impact of dietary MCFA on ghrelin acylation in adults. Our study aimed at describing early post-natal development of the ghrelin system in mini-pigs as a model of human neonates and evaluating the impact of dietary MCFA. Suckled mini-pigs were sacrificed at post-natal day (PND) 0, 2, 5, and 10 or at adult stage. In parallel, other mini-pigs were fed from birth to PND10 a standard or a dairy lipid-enriched formula with increased MCFA concentration (DL-IF). Plasma ghrelin transiently peaked at PND2, with no variation of the acylated fraction except in adults where it was greater than during the neonatal period. Levels of mRNA coding pre-proghrelin (GHRL) and GOAT in the antrum did not vary during the post-natal period but dropped in adults. Levels of antral pcsk1/3 (cleaving GHRL into ghrelin) mRNA decreased significantly with age and was negatively correlated with plasma acylated, but not total, ghrelin. Hypothalamic ghsr1 mRNA did not vary in neonates but increased in adults. The DL-IF formula enriched antral tissue with MCFA but did not impact the ghrelin system. In conclusion, the ghrelin maturation enzyme PCSK1/3 gene expression exhibited post-natal modifications parallel to transient variations in circulating plasma ghrelin level in suckling piglets but dietary MCFA did not impact this post-natal development.

Influence of innate immune activation on endocrine and metabolic pathways in infancy

Prematurity is the leading cause of neonatal morbidity and mortality worldwide. Premature infants often require extended hospital stays, with increased risk of developing infection compared with term infants. A picture is emerging of wide-ranging deleterious consequences resulting from innate immune system activation in the newborn infant. Those who survive infection have been exposed to a stimulus that can impose long-lasting alterations into later life. In this review, we discuss sepsis-driven alterations in integrated neuroendocrine and metabolic pathways and highlight current knowledge gaps in respect of neonatal sepsis. We review established biomarkers for sepsis and extend the discussion to examine emerging findings from human and animal models of neonatal sepsis that propose novel biomarkers for early identification of sepsis. Future research in this area is required to establish a greater understanding of the distinct neonatal signature of early and late-stage infection, to improve diagnosis, curtail inappropriate antibiotic use, and promote precision medicine through a biomarker-guided empirical and adjunctive treatment approach for neonatal sepsis. There is an unmet clinical need to decrease sepsis-induced morbidity in neonates, to limit and prevent adverse consequences in later life and decrease mortality.

Serum ghrelin is associated with early feeding readiness but not growth in premature infants

BACKGROUND

Feeding tolerance among premature infants is unpredictable using clinical parameters. Ghrelin, a peptide hormone, acts on the hypothalamus to increase hunger and gut motility. It is present in fetal tissues, promotes intestinal maturation, and is secreted in milk. We hypothesized that higher serum ghrelin levels on days 0-7 are associated with improved feeding tolerance and growth in premature infants.

METHODS

Infants (<  1500 g birth weight, n = 36) were recruited on day (D) 0-7. Serum ghrelin was measured by ELISA on D 0-7, D 10-14, and D 24-32, and milk ghrelin in a feeding concurrent with each serum sample. Feeding tolerance was assessed as days to first and full enteral feeds. Growth was quantified as both weight and adipose and muscle deposition by ultrasound.

RESULTS

Mean serum ghrelin levels decreased from D 0-7 to D 24-32. Higher ghrelin levels on D 0-7 were correlated with shorter time to first enteral feeding, but not with time to full enteral feeds, rate of weight gain, or rate of accretion of muscle or adipose tissue. Milk ghrelin was not related to serum ghrelin or growth. Abdominal and suprascapular muscle and adipose increased during the first month, but weight gain correlated only with the rate of accretion of abdominal adipose.

CONCLUSIONS

Elevated serum ghrelin in the first days of life may contribute to gut motility and readiness to feed. Weight gain in premature infants may primarily indicate abdominal fat accumulation, suggesting that ultrasound measurement of muscle accretion is a better marker for lean body growth.

Response of metabolic hormones and blood metabolites to realimentation in rehabilitated harbor seal (Phoca vitulina) pups

Mammals with increased requirements for adipose tissue stores, such as marine mammals, have altered nutrient allocation priorities compared to many terrestrial mammals and thus the physiological response to undernutrition (low nutritional status) and realimentation (refeeding) may differ. Key regulators of nutrient allocation and tissue specific growth include metabolic hormones of the somatotropic axis, growth hormone (GH) and insulin-like growth factor (IGF)-I, as well as satiety and adipose promoting ghrelin and the stress hormone cortisol. Longitudinal measurements of metabolic hormones, blood metabolites, and morphometrics were collected over a 10-week period in twelve (male n = 3, female n = 9) harbor seal pups (< 6 weeks of age). Blood metabolites were used to indicate metabolic response during realimentation while morphometrics estimated tissue specific growth priorities. Harbor seal pups undergoing refeeding after nutritional deprivation show a preference for protein sparing despite severe malnutrition. Both BUN and total protein were negatively associated with GH and positively associated with IGF-I and ghrelin highlighting the importance of these metabolic hormones in the regulation of protein metabolism. While the response of the somatotropic axis to realimentation was typical of the mammalian pattern, the surprising increase of ghrelin across the study period suggests the priority of adipose accretion in addition to a possible mechanism regulating compensatory growth of vital adipose stores in a species, which prioritizes adipose accretion for survival.

Preterm Birth Has Effects on Gut Colonization in Piglets Within the First 4 Weeks of Life

OBJECTIVES

Preterm neonates have an immature gastrointestinal tract and show an altered bacterial colonization of the gut. However, it is not clear if such immature gut microbiota (GM) colonization is induced by specific delivery, diet, environment, and/or host factors related to preterm birth. Using piglets as models for infants, we hypothesized that both shortened gestational age (GA) and start of enteral feeding affect GM composition after caesarean delivery and rearing in identical environments.

METHODS

Caesarean-delivered preterm and term pigs were reared in incubators and fed total parenteral nutrition (TPN) or gradually increasing early enteral feeding (EEF) for 5 days, followed by full enteral feeding with bovine milk until day 26. GM composition was determined by 16S rRNA gene-amplicon sequencing and luminal short-chain fatty acids (SCFAs) by GC-MS.

RESULTS

Both GA and EEF feeding affected GM composition on day 5, but only the GA effect persisted until day 26. On day 5, Enterobacteriaceae were dominant, with Lachnospiraceae members also being abundant. Enterobacteriaceae still dominated the GM at day 26 but with higher Akkermansia relative abundance in term pigs. Colonic concentrations of acetate and propionate were higher, and formate lower in term pigs, relative to preterm pigs on day 26.

CONCLUSIONS

Preterm and term piglets, born and reared in similar ways, show differences in GM colonization during the first 4 weeks of life, which may play a role for early and later gut dysfunction resulting from preterm birth.

Breastfeeding Initiation Associated With Reduced Incidence of Diabetes in Mothers and Offspring

OBJECTIVE

To examine associations between breastfeeding initiation and subsequent diabetes among First Nations (indigenous people in Canada who are not Métis or Inuit) and non-First Nations mothers and their offspring with and without gestational diabetes mellitus (GDM).

METHODS

This retrospective database study included 334,553 deliveries (1987-2011) in Manitoba with up to 24 years of follow-up for diabetes using population-based databases. Information of breastfeeding initiation before hospital discharge was obtained from hospital abstracts recorded by nurses in postpartum wards. Cox proportional hazard models were applied to examine the association between breastfeeding initiation and risk of diabetes in mothers and their offspring.

RESULTS

Breastfeeding initiation was recorded in 83% of non-First Nations mothers and 56% of First Nations mothers (P<.001). Breastfeeding initiation was associated with a reduced risk of incident (later developed) diabetes in non-First Nations mothers without GDM (hazard ratio [HR] 0.73 [or -27% of risk], 95% confidence interval [CI] 0.68-0.79), non-First Nations mothers with GDM (HR 0.78 or -22% of risk, CI 0.69-0.89), First Nations mothers without GDM (HR 0.89 or -11% of risk, CI 0.81-0.98), and First Nations mothers with GDM (HR 0.82 or -18% of risk, CI 0.73-0.92) with 24 years of follow-up or less. With 24 years of follow-up or less, breastfeeding initiation was associated with a 17% lower risk of youth-onset type 2 diabetes in offspring (HR 0.83, CI 0.69-0.99, P=.038). The association between breastfeeding initiation and subsequent diabetes in mothers and offspring was independent of family income, rural residence, First Nations status, GDM, parity, gestational hypertension, and age of the mother.

CONCLUSION

Breastfeeding initiation is associated with a reduced risk of diabetes among women and their offspring in Manitoba. The results suggest that breastfeeding might be a potentially modifiable factor to reduce the risk of diabetes in both First Nations and non-First Nations women and children.

Rapid gut growth but persistent delay in digestive function in the postnatal period of preterm pigs

Preterm infants often tolerate full enteral nutrition a few weeks after birth but it is not known how this is related to gut maturation. Using pigs as models, we hypothesized that intestinal structure and digestive function are similar in preterm and term individuals at 3-4 wk after birth and that early enteral nutrition promotes maturation. Preterm or term cesarean-delivered pigs were fed total parenteral nutrition, or partial enteral nutrition [Enteral (Ent), 16-64 ml·kg(-1)·day(-1) of bovine colostrum] for 5 days, followed by full enteral milk feeding until day 26 The intestine was collected for histological and biochemical analyses at days 0, 5, and 26 (n = 8-12 in each of 10 treatment groups). Intestinal weight (relative to body weight) was reduced in preterm pigs at 0-5 days but ENT feeding stimulated the mucosal volume and peptidase activities. Relative to term pigs, mucosal volume remained reduced in preterm pigs until 26 days although plasma glucagon-like peptide 2 (GLP-2) and glucose-dependent insulin-trophic peptide (GIP) levels were increased. Preterm pigs also showed reduced hexose absorptive capacity and brush-border enzyme (sucrase, maltase) activities at 26 days, relative to term pigs. Intestinal structure shows a remarkable growth adaptation in the first week after preterm birth, especially with enteral nutrition, whereas some digestive functions remain immature until at least 3-4 wk. It is important to identify feeding regimens that stimulate intestinal maturation in the postnatal period of preterm infants because some intestinal functions may show long-term developmental delay.