Diabetes during pregnancy enhanced neuronal death in the hippocampus of rat offspring

Higher prenatal dietary glycemic index in the third trimester of pregnancy is associated with infant negative affect at 6 months

The dietary glycemic index (GI) reflects post-prandial plasma glucose generation rate, with higher-GI foods rapidly increasing blood sugar. Prenatal consumption of high-GI foods is associated with offspring risk for obesity and metabolic disorders. The impact of prenatal dietary GI exposure on infant neurodevelopment remains unclear. Maternal dietary intake, percent adiposity, and insulin resistance were prospectively assessed during the second and third trimesters in a sample of women with healthy, singleton pregnancies (N = 302). Infant negative affect was prospectively assessed at six months using observer ratings (Still Face Paradigm) and caregiver-reports (Infant-Behavior Questionnaire-Revised). Structural equation models assessed the independent effects of second and third trimester maternal dietary GI, adiposity, insulin resistance on infant negative affect, adjusted for relevant covariates. Higher third, but not second, trimester dietary GI was associated with increased observer-rated infant negative affect (β = 0.14, p = .04) and with higher caregiver-reported infant sadness (β = 0.17, p = .01), suggesting a programming effect of prenatal dietary GI on infant neurodevelopment. Targeted interventions that decrease dietary GI in later pregnancy may prove more effective for optimizing infant behavioral health compared to longer-term changes needed to alter metabolic state. Identifying modifiable early contributors to infant negative affect supports proactive strategies for mitigating future psychopathology risk.

Exposure to gestational diabetes mellitus in utero impacts hippocampal functional connectivity in response to food cues in children

OBJECTIVES

Intrauterine exposure to gestational diabetes mellitus (GDM) increases the risk of obesity in the offspring, but little is known about the underlying neural mechanisms. The hippocampus is crucial for food intake regulation and is vulnerable to the effects of obesity. The purpose of the study was to investigate whether GDM exposure affects hippocampal functional connectivity during exposure to food cues using functional magnetic resonance imaging (fMRI).

METHODS

Participants were 90 children age 7-11 years (53 females) who underwent an fMRI-based visual food cue task in the fasted state. Hippocampal functional connectivity (FC) was examined using generalized psychophysiological interaction in response to food versus non-food cues. Hippocampal FC was compared between children with and without GDM exposure, while controlling for possible confounding effects of age, sex and waist-to-hip ratio. In addition, the influence of childhood and maternal obesity were investigated using multiple regression models.

RESULTS

While viewing high caloric food cues compared to non-food cure, children with GDM exposure exhibited higher hippocampal FC to the insula and striatum (i.e., putamen, pallidum and nucleus accumbens) compared to unexposed children. With increasing BMI, children with GDM exposure had lower hippocampal FC to the somatosensory cortex (i.e., postcentral gyrus).

CONCLUSIONS

Intrauterine exposure to GDM was associated with higher food-cue induced hippocampal FC especially to reward processing regions. Future studies with longitudinal measurements are needed to clarify whether altered hippocampal FC may raise the risk of the development of metabolic diseases later in life.

Harmful Effects on the Hippocampal Morpho-Histology and on Learning and Memory in the Offspring of Rats with Streptozotocin-Induced Diabetes

Learning alterations in the child population may be linked to gestational diabetes as a causal factor, though this remains an open and highly controversial question. In that sense, it has been reported that maternal hyperglycemia generates a threatening condition that affects hippocampal development in offspring. The pyramidal cells of the CA3 subfield, a key structure in learning and memory processes, are particularly important in cognitive deficiencies. We evaluate the effect of the hyperglycemic intrauterine environment on hippocampal histomorphometry in offspring, correlating it with spatial learning and memory, as well as the morphology of dendrites and spines in 30-day-old pups (P30). The maternal hyperglycemia affected the body weight, height, and brain size of fetuses at 21 days of gestation (F21), newborn pups (P0) and P30 pups from diabetic rats, which were smaller compared to the control group. Consequently, this resulted in a decrease in hippocampal size, lower neuronal density and cytoarchitectural disorganization in the CA3 region of the hippocampus in the offspring at the three ages studied. The behavioral tests performed showed a direct relationship between morpho-histological alterations and deficiencies in learning and memory, as well as alterations in the morphology of the dendrites and spines. Therefore, knowing the harmful effects caused by gestational diabetes can be of great help to establish therapeutic and educational strategies that can help to improve learning and memory in children.

Exposure to gestational diabetes mellitus in utero impacts hippocampal functional connectivity in response to food cues in children

Objectives

Intrauterine exposure to gestational diabetes mellitus (GDM) increases the risk of obesity in the offspring, but little is known about the underlying neural mechanisms. The hippocampus is crucial for food intake regulation and is vulnerable to the effects of obesity. The purpose of the study was to investigate whether GDM exposure affects hippocampal functional connectivity during exposure to food cues using functional magnetic resonance imaging.

Methods

Participants were 90 children age 7-11 years (53 females) who underwent an fMRI-based visual food cue task in the fasted state. Hippocampal functional connectivity (FC) was examined using generalized psychophysiological interaction in response to high-calorie food versus non-food cues. Food-cue induced hippocampal FC was compared between children with and without GDM exposure, while controlling for possible confounding effects of age, sex and waist-to-hip ratio.

Results

Children with GDM exposure exhibited stronger hippocampal FC to the insula and striatum (i.e., putamen, pallidum and nucleus accumbens) compared to unexposed children, while viewing high caloric food cues.

Conclusions

Intrauterine exposure to GDM was associated with higher food-cue induced hippocampal FC to reward processing regions. Future studies with longitudinal measurements are needed to clarify whether increased hippocampal FC to reward processing regions may raise the risk of the development of metabolic diseases later in life.

The effects of induced type I diabetes on developmental regulation of GDNF, NRTN, and NCAM proteins in the dentate gyrus of male rat offspring

BACKGROUND

Maternal diabetes during pregnancy can affect the neurological development of offspring. Glial cell-derived neurotrophic factor (GDNF), neurturin (NRTN), and neural cell adhesion molecules (NCAM) are three important proteins for brain development. Therefore, this study aimed to investigate the impacts of the mentioned neurotrophic factors in the hippocampal dentate gyrus (DG) of rat offspring born to diabetic mothers.

METHODS

Wistar female rats were randomly allocated into diabetic (STZ-D) [(45 mg/kg BW, STZ (Streptozotocin), i.p)], diabetic + NPH insulin (STZ-INS) [(4-6 unit/kg/day SC)], and control groups. The animals in all groups were mated by non-diabetic male rats. Two weeks after birth, male pups from each group were sacrificed and then protein contents of GDNF, NRTN, and NCAM were evaluated using immunohistochemistry.

RESULTS

The study found that the expression of GDNF and NRTN in the hippocampus of diabetic rat offspring was significantly higher compared to the diabetic+ insulin and control groups, respectively (P < 0.01, P < 0.001). Additionally, the expression of NCAM was significantly higher in the diabetic group the diabetic+ insulin and control groups (P < 0.01, P < 0.001).

CONCLUSIONS

The results of the study revealed that diabetes during pregnancy significantly impacts the distribution pattern of GDNF, NRTN, and NCAM in the hippocampus of rat neonates.

Associations among prenatal exposure to gestational diabetes mellitus, brain structure, and child adiposity markers

OBJECTIVE

The aim of this study was to investigate the mediating role of child brain structure in the relationship between prenatal gestational diabetes mellitus (GDM) exposure and child adiposity.

METHODS

This was a cross-sectional study of 9- to 10-year-old participants and siblings across the US. Data were obtained from the baseline assessment of the Adolescent Brain Cognitive Development (ABCD) Study®. Brain structure was evaluated by magnetic resonance imaging. GDM exposure was self-reported, and discordance for GDM exposure within biological siblings was identified. Mixed effects and mediation models were used to examine associations among prenatal GDM exposure, brain structure, and adiposity markers with sociodemographic covariates.

RESULTS

The sample included 8521 children (7% GDM-exposed), among whom there were 28 sibling pairs discordant for GDM exposure. Across the entire study sample, prenatal exposure to GDM was associated with lower global and regional cortical gray matter volume (GMV) in the bilateral rostral middle frontal gyrus and superior temporal gyrus. GDM-exposed siblings also demonstrated lower global cortical GMV than unexposed siblings. Global cortical GMV partially mediated the associations between prenatal GDM exposure and child adiposity markers.

CONCLUSIONS

The results identify brain markers of prenatal GDM exposure and suggest that low cortical GMV may explain increased obesity risk for offspring prenatally exposed to GDM.

The impact of maternal diabetes on the future health and neurodevelopment of the offspring: a review of the evidence

Maternal health during gestational period is undoubtedly critical in shaping optimal fetal development and future health of the offspring. Gestational diabetes mellitus is a metabolic disorder occurring in pregnancy with an alarming increasing incidence worldwide during recent years. Over the years, there is a growing body of evidence that uncontrolled maternal hyperglycaemia during pregnancy can potentially have detrimental effect on the neurodevelopment of the offspring. Both human and animal data have linked maternal diabetes with motor and cognitive impairment, as well as autism spectrum disorders, attention deficit hyperactivity disorder, learning abilities and psychiatric disorders. This review presents the available data from current literature investigating the relationship between maternal diabetes and offspring neurodevelopmental impairment. Moreover, possible mechanisms accounting for the detrimental effects of maternal diabetes on fetal brain like fetal neuroinflammation, iron deficiency, epigenetic alterations, disordered lipid metabolism and structural brain abnormalities are also highlighted. On the basis of the evidence demonstrated in the literature, it is mandatory that hyperglycaemia during pregnancy will be optimally controlled and the impact of maternal diabetes on offspring neurodevelopment will be more thoroughly investigated.

Maternal Metabolic Programming of the Developing Central Nervous System: Unified Pathways to Metabolic and Psychiatric Disorders

The perinatal period presents a critical time in offspring development where environmental insults can have damaging impacts on the future health of the offspring. This can lead to sustained alterations in offspring development, metabolism, and predisposition to both metabolic and psychiatric diseases. The central nervous system is one of the most sensitive targets in response to maternal obesity and/or type 2 diabetes mellitus. While many of the effects of obesity on brain function in adults are known, we are only now beginning to understand the multitude of changes that occur in the brain during development on exposure to maternal overnutrition. Specifically, given recent links between maternal metabolic state and onset of neurodevelopmental diseases, the specific changes that are occurring in the offspring are even more relevant for the study of disease onset. It is therefore critical to understand the developmental effects of maternal obesity and/or type 2 diabetes mellitus and further to define the underlying cellular and molecular changes in the fetal brain. This review focuses on the current advancements in the study of maternal programming of brain development with particular emphasis on brain connectivity, specific regional effects, newly studied peripheral contributors, and key windows of interventions where maternal bodyweight and food intake may drive the most detrimental effects on the brain and associated metabolic and behavioral consequences.

Developmental regulation and lateralization of N-methyl-d-aspartate (NMDA) receptors in the rat hippocampus

N-methyl-d-aspartate receptors (NMDARs) are expressed abundantly in the brain and play a crucial role in the regulation of central nervous system (CNS) development, learning, and memory. During early neuronal development, NMDARs modulate neurogenesis, neuronal differentiation and migration, and synaptogenesis. The present study aimed to examine the developmental expression of NMDARs subunits, NR1 and NR2B, in the developing hippocampus of neonatal rats during the first two postnatal weeks. Fifty-four male offspring were randomly divided into three age groups, postnatal days (P) 0, 7, and 14. Real-time-PCR, western blotting, and immunohistochemistry (IHC) analyses were employed to examine and compare the hippocampal expression of the NMDA receptor subunits. The highest mRNA expression of NR1 and NR2B subunits was observed at P7, regardless of its laterality. The mRNA expression of both subunits in the right hippocampus was significantly higher than that of the left one at P0 and P7. Similarly, the highest protein level expression of NR1 and NR2B subunits was also observed at P7 in both sides hippocampi. Although the protein expression of NR1 was significantly higher on the right side in all studied days, the NR2B was significantly higher in the right hippocampus only at P7. The analysis of optical density (OD) has shown a marked increase in the distribution pattern of the NR1 and NR2B subunits at P7 in all hippocampal subregions. In conclusion, there is a marked right-left asymmetry in the expression of NR1 and NR2B subunits in the developing rat hippocampus, which might be considered as a probable mechanism for the lateral differences in the structure and function of the hippocampus in rats.

Maternal diabetes-induced alterations in the expression of brain-derived neurotrophic factor in the developing rat hippocampus

Maternal diabetes during pregnancy affects the development of hippocampus in the offspring. Brain-derived neurotrophic factor (BDNF) has received increasing attention for its role in regulating the survival and differentiation of neuronal cells in developing and adult brain. In the current study, we evaluated the effects of maternal diabetes and insulin treatment on expression and distribution pattern of BDNF in the hippocampus of neonatal rats at the first two postnatal weeks. We found no differences in hippocampal expression of BDNF between diabetics with normal control or insulin treated neonatal rats at postnatal day (P0) (P > 0.05 each). Nevertheless, there was a marked BDNF downregulation in both sides' hippocampi of male/female diabetic group in two-week-old offspring (P ≤ 0.05 each). Furthermore, the numerical density of BDNF+ cells was significantly reduced in the right/left dentate gyrus (DG) of male and female newborns born to diabetic animals at all studied postnatal days (P ≤ 0.05 each). In addition, a lower number of reactive cells have shown in the all hippocampal subareas in the diabetic pups at P14 (P ≤ 0.05 each). Our results have demonstrated that the insulin-treatment improves some of the negative impacts of diabetes on the expression of hippocampal BDNF in the newborns. We conclude that diabetes in pregnancy bilaterally disrupts the expression of BDNF in the hippocampus of the both male and female newborns at early postnatal days. In addition, good glycemic control by insulin in the most cases is sufficient to prevent the alterations in expression of BDNF protein in developing hippocampus.

Selective morphological and volumetric alterations in the hippocampus of children exposed in utero to gestational diabetes mellitus

Prior epidemiological studies have found that in utero exposure to gestational diabetes mellitus (GDM) is associated with increased risk for neurodevelopmental disorders. However, brain alterations associated with GDM are not known. The hippocampus is pivotal for cognition and emotional regulation. Therefore, we assessed relationships between in utero exposure to GDM and hippocampal morphology and subfield structure during childhood. One hundred seventeen children aged 7–11 years (57% girls, 57% exposed to GDM), born at Kaiser Permanente Southern California, participated in the BrainChild Study. Maternal GDM status was determined from electronic medical records. Children underwent brain magnetic resonance imaging. Freesurfer 6.0 was used to measure hippocampal and individual hippocampal subfield gray matter volume (mm³). Morphological analyses on the hippocampal surface were carried out using shape analysis. GDM‐exposed children exhibited reduced radial thickness in a small, spatially‐restricted portion of the left inferior body of the hippocampus that corresponds to the CA1 subfield. There was a significant interaction between GDM‐exposure and sex on the right hippocampal CA1 subfield. GDM‐exposed boys had reduced right CA1 volume compared to unexposed boys, but this association was no longer significant after controlling for age. No significant group differences were observed in girls. Our results suggest that GDM‐exposure impacts shape of the left hippocampal CA1 subfield in both boys and girls and may reduce volume of right hippocampal CA1 only in boys. These in‐depth findings illuminate the unique properties of the hippocampus impacted by prenatal GDM‐exposure and could have important implications for hippocampal‐related functions.

The effect of gestational diabetes on identification of key genes and pathways in human umbilical vein endothelial cell by integrated bioinformatics analysis

Maternal diabetes may lead to long-term risks for the offspring. The study aims at identifying the potential crucial genes and pathways associated with foetal metabolism and malformation of gestational diabetes mellitus (GDM). Gene Expression Series 49524 and 87295 were downloaded from Gene Expression Omnibus database, including eight from GDM and eight from non-GDM. A total of 35 differentially expressed genes were identified. Gene ontology functional annotation and signalling pathway analyses were performed. Four hub genes were identified by protein-protein interaction network: SHH, E2F1, STAT1, and HOXA9. The four hub genes were assessed by western blot and real-time quantitative PCR in clinical samples. The results of this data mining and integration help to reveal the pathophysiologic and molecular mechanism imprinted in primary umbilical cord-derived cells from GDM offspring. These genes and pathways identified are potential stratification biomarkers and provide further insight for developing therapeutic intervention for the offspring of diabetic mothers.Impact statementWhat is already known on this subject? Maternal diabetes may lead to long-term risks for the offspring. A high glucose environment might change the umbilical cord expression of genes implicated in foetal metabolism and development. However, underlying molecular mechanisms have not been investigated thoroughly.What do the results of this study add? GO functional annotation showed that the biological functions of differentially expressed genes mainly involved in metanephros development, salivary gland morphogenesis, fat cell differentiation, vasculogenesis, muscle cell proliferation, heart morphogenesis and Wnt signalling pathway. Signalling pathway analyses found that these differentially expressed genes mainly implicated in the apoptosis, cell cycle, Hedgehog, P53, and NOTCH signalling pathway. Four hub genes were identified by protein-protein interaction network: SHH, E2F1, STAT1 and HOXA9.What are the implications of these findings for clinical practice and/or further research? The genes and pathways identified in the present study are potential stratification biomarkers and provide further insight for developing therapeutic intervention for the offspring of diabetic mothers.

Dietary Fructose Intake and Hippocampal Structure and Connectivity during Childhood

In rodent literature, there is evidence that excessive fructose consumption during development has a detrimental impact on hippocampal structure and function. In this study of 103 children ages 7–11 years old, we investigated whether dietary fructose intake was related to alterations in hippocampal volume and connectivity in humans. To examine if these associations were specific to fructose or were related to dietary sugars intake in general, we explored relationships between dietary intake of added sugars and the monosaccharide, glucose, on the same brain measures. We found that increased dietary intake of fructose, measured as a percentage of total calories, was associated with both an increase in the volume of the CA2/3 subfield of the right hippocampus and increased axial, radial, and mean diffusivity in the prefrontal connections of the right cingulum. These findings are consistent with the idea that increased fructose consumption during childhood may be associated with an inflammatory process, and/or decreases or delays in myelination and/or pruning. Increased habitual consumption of glucose or added sugar in general were associated with an increased volume of right CA2/3, but not with any changes in the connectivity of the hippocampus. These findings support animal data suggesting that higher dietary intake of added sugars, particularly fructose, are associated with alterations in hippocampal structure and connectivity during childhood.

Sex differences in the association between prenatal exposure to maternal obesity and hippocampal volume in children

INTRODUCTION

Animal studies have shown that male but not female offspring exposed to maternal obesity have abnormal hippocampal development. Similar sex differences were observed in animal models of developmental programming by prenatal stress or maternal diabetes. We aimed to translate this work into humans by examining sex-specific effects of exposure to maternal obesity on hippocampal volume in children.

METHODS

Eighty-eight children (37 boys and 51 girls) aged 7-11 years completed the study. Maternal prepregnancy body mass index (BMI) was obtained from electronic medical records. A high-resolution anatomical scan was performed using a 3-Tesla magnetic resonance imaging (MRI) scanner. Total hippocampal volume and hippocampal subfield volumes were analyzed using FreeSurfer 6.0. Linear regression was used to investigate sex differences in relationships between maternal prepregnancy BMI and child hippocampal volume.

RESULTS

Maternal prepregnancy BMI ranged from 19.0 to 50.4 kg/m2 . We observed a significant interaction between maternal prepregnancy BMI and sex on total hippocampal volume (p < .001) such that boys (r = -.39, p = .018) but not girls (r = .11, p = .45) had a significant negative relationship between maternal prepregnancy BMI and total hippocampal volume. This relationship in boys remained significant after adjusting for child and maternal covariates (β = -126.98, p = .012). The sex interactions with prepregnancy BMI were consistently observed in hippocampal subfields CA1 (p = .008), CA2/3 (p = .016), CA4 (p = .002), dentate gyrus (p < .001), and subiculum (p < .001).

CONCLUSIONS

Our results support findings in animal models and suggest that boys may be more vulnerable to the adverse effects of exposure to maternal obesity on hippocampal development than girls.

Severe Uncontrolled Maternal Hyperglycemia Induces Microsomia and Neurodevelopment Delay Accompanied by Apoptosis, Cellular Survival, and Neuroinflammatory Deregulation in Rat Offspring Hippocampus

Maternal diabetes constitutes an unfavorable intrauterine environment for offspring development. Although it is known that diabetes can cause brain alterations and increased risk for neurologic disorders, the relationship between neuroimmune activation, brain changes, and neurodevelopment deficits in the offspring remains unclear. In order to elucidate the short- and long-term biological basis of the developmental outcomes caused by the severe uncontrolled maternal hyperglycemia, we studied apoptosis, neurogenesis, and neuroinflammation pathways in the hippocampus of neonates and young rats born to diabetic dams. Diabetes was induced on gestational day 5 by an injection of streptozotocin. Evaluations of milestones, body growth, and inhibitory avoidance were performed to monitor the offspring development and behavior. Hippocampal modifications were studied through cellular survival by BrdU in the dentate gyrus, expression of apoptosis-regulatory proteins (procaspase 3, caspase 3, and Bcl-2), BDNF, and neuroinflammatory modulation by interleukins, MHC-I, MHC-II, Iba-1, and GFAP proteins. Severe maternal diabetes caused microsomia and neurodevelopmental delay in pups and decrease of Bcl-2, procaspase 3, and caspase 3 in the hippocampus. Moreover, in a later stage of development, it was found an increase of TNF-α and a decrease of procaspase 3, caspase 3, MHC-I, IL-1β, and BDNF in the hippocampus, as well as impairment in cellular survival in the dentate gyrus. This study showed significant short- and long-term commitments on the development, apoptosis, cell survival, and neuroinflammation in the offspring hippocampus induced by severe uncontrolled maternal hyperglycemia. The data reinforce the need for treatment of maternal hyperglycemic states during pregnancy and breast-feeding.

Expression of apoptosis-regulatory genes in the hippocampus of rat neonates born to mothers with diabetes

Diabetes during pregnancy impairs the development of the central nervous system (CNS) and causes cognitive and behavioral abnormalities in offspring. However, the exact mechanism by which the maternal diabetes affects the development of the brain remains to be elucidated. The aim of the present study was to investigate the effects of maternal diabetes in pregnancy on the expression of Bcl-2 and Bax genes and the numerical density of degenerating dark neurons (DNs) in the hippocampus of offspring at the first postnatal two weeks. Wistar female rats were maintained diabetic from a week before pregnancy through parturition and male offspring was sacrificed at P0, P7, and P14. Our findings demonstrated a significant down-regulation in the hippocampal expression of Bcl-2 in the diabetic group newborns (P < 0.05). In contrast, the mRNA expression of Bax was markedly up-regulated in the offspring born to diabetic dams at all of studied time-points (P < 0.05). Moreover, we found a striking increase in the numerical density of DNs in the various subfields of hippocampus of diabetic group pups (P < 0.05). The results of the present study revealed that maternal hyperglycemia during gestational period may result in disturbances in the expression of Bcl-2 and Bax genes as two important genes in neuronal apoptosis regulation and induces the production of DNs in the developing hippocampus of neonatal rats. These disturbances may be a reason for the cognitive, structural, and behavioral anomalies observed in offspring born to diabetic mothers. Furthermore, the control of maternal glycaemia by insulin administration in most cases normalized these negative impacts.