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The Mouse Metabolic Phenotyping Center (MMPC)Live Program was established in 2023 by the National Institute for Diabetes, Digestive and Kidney Diseases (NIDDK) at the National Institutes of Health (NIH) to advance biomedical research by providing the scientific community with standardized, high quality phenotyping services for mouse models of diabetes and obesity. Emerging as the next iteration of the MMPC Program which served the biomedical research community for 20 years (2001-2021), MMPCLive is designed as an outwardly-facing consortium of service cores that collaborate to provide reduced-cost consultation and metabolic, physiologic, and behavioral phenotyping tests on live mice for U.S. biomedical researchers. Four MMPCLive Centers located at universities around the country perform complex and often unique procedures in vivo on a fee for service basis, typically on mice shipped from the client or directly from a repository or vendor. Current areas of expertise include energy balance and body composition, insulin action and secretion, whole body carbohydrate and lipid metabolism, cardiovascular and renal function, food intake and behavior, microbiome and xenometabolism, and metabolic pathway kinetics. Additionally, an opportunity arose to reduce barriers to access and expand the diversity of the biomedical research workforce by establishing the VIBRANT Program. Directed at researchers historically underrepresented in the biomedical sciences, VIBRANT-eligible investigators have access to testing services, travel and career development awards, expert advice and experimental design consultation, and short internships to learn test technologies. Data derived from experiments run by the Centers belongs to the researchers submitting mice for testing which can be made publicly available and accessible from the MMPCLive database following publication. In addition to services, MMPCLive staff provide expertise and advice to researchers, develop and refine test protocols, engage in outreach activities, publish scientific and technical papers, and conduct educational workshops and training sessions to aid researchers in unraveling the heterogeneity of diabetes and obesity.

Despite a substantial body of research, we lack fundamental understanding of the pathophysiology of COVID-19 caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) including pulmonary and cardiovascular outcomes, in part due to limitations of murine models. Most models use transgenic mice (K18) that express the human (h) angiotensin converting enzyme 2 (ACE2), ACE2 knock-in (KI) mice, or mouse-adapted strains of SARS-CoV-2. Further, many SARS-CoV-2 variants produce fatal neurologic disease in K18 mice and most murine studies focus only on acute disease in the first 14 days post inoculation (dpi). To better enable understanding of both acute (14 dpi) infection phases, we describe the development and characterization of a novel non-lethal KI mouse that expresses both the ACE2 and transmembrane serine protease 2 (TMPRSS2) genes (hACE2/hTMPRSS2). The human genes were engineered to replace the orthologous mouse gene loci but remain under control of their respective murine promoters, resulting in expression of ACE2 and TMPRSS2 instead of their murine counterparts. After intranasal inoculation with an omicron strain of SARS-CoV-2, hACE2/hTMPRSS2 KI mice transiently lost weight but recovered by 7 dpi. Infectious SARS-CoV-2 was detected in nasopharyngeal swabs 1-2 dpi and in lung tissues 2-6 dpi, peaking 4 dpi. These outcomes were similar to those in K18 mice that were inoculated in parallel. To determine the extent to which hACE2/hTMPRSS2 KI mice are suitable to model pulmonary and cardiovascular outcomes, physiological assessments measuring locomotion, behavior and reflexes, biomonitoring to measure cardiac activity and respiration, and micro computed tomography to assess lung function were conducted frequently to 6 months post inoculation. Male but not female SARS-CoV-2 inoculated hACE2/hTMPRSS2 KI mice showed a transient reduction in locomotion compared to control saline treated mice. No significant changes in respiration, oxygen saturation, heart rate variability, or conductivity were detected in SARS-CoV-2 inoculated mice of either sex. When re-inoculated 6 months after the first inoculation, hACE2/hTMPRSS2 KI became re-infected with disease signs similar to after the first inoculation. Together these data show that a newly generated hACE2/hTMPRSS2 KI mouse can be used to study mild COVID-19.

The purpose is to examine validity and reliability for an obesity risk assessment tool developed in Spanish for immigrant families with children, 3-5 years old using an 8-week cross-sectional design with data collected over 1 year at Head Start and Special Supplemental Nutrition Program for Women, Infants and Children [WIC]. Parent/child dyads (206) provided a child obesity risk assessment, three child modified 24 h dietary recalls, three child 36+ h activity logs and one parent food behavior checklist. Main outcome measures were convergent validity with nutrients, cup equivalents, and diet quality and three assessments of reliability that included item difficulty index, item discrimination index, and coefficient of variation. Validity was demonstrated for assessment tool, named Niños Sanos. Scales were significantly related to variables in direction hypothesized [p ≤ 0.05]: Healthy Eating Index, fruit/vegetable cup equivalents, folate, dairy cup equivalents, vitamins D, β-carotene, fiber, saturated fat, sugar, time at screen/ sleep/physical activity and parent behaviors. Three measures of reliability were acceptable. The addition of nutrient values as an analytical validation approach adds strength and consistency to previously reported Niños Sanos validation results using children's blood biomarkers and body mass index. This tool can be used by health professionals as an assessment of obesity risk in several capacities: (1) screener for counseling in a clinic, (2) large survey, (3) guide for participant goal setting and tailoring interventions, and (4) evaluation.

BackgroundAccurate measurement of food-related parenting practices is necessary to inform related interventions and program evaluation. Valid tools reflect cultural attributes that affect household food environments and feeding practices. Simple, unidirectional language adaptation approaches are insufficient to capture these attributes in assessment tools. My Child at Mealtime (MCMT) is a 27-item, validated, visually enhanced self-assessment tool to measure food-related parenting practices of low-income English-speaking parents of preschoolers.ObjectivesThe aim of this study was to describe the cross-cultural adaptation of MCMT into its Spanish version Mi Niño a la Hora the Comer (Mi Niño) and to establish its face validity, factor structure, and internal consistency.MethodsMCMT was adapted into its Spanish version after an iterative process that triangulated cognitive interviews with verification of conceptual equivalence by content experts to establish face validity and semantic equivalence. The resulting tool underwent confirmatory factor analysis to determine whether internal consistency was equivalent across the 2 versions.ResultsFour rounds of cognitive interviews (n = 5, n = 6, n = 2, and n = 4, respectively) with Spanish-speaking women caregivers of children aged 3-5 y recruited from Head Start were conducted. Ten items were modified throughout the adaptation process. Modifications included improved clarity (6 items), comprehension (7 items), appropriateness (4 items), suitability (4 items), and usefulness (2 items) of text and/or accompanying visuals. Confirmatory factor analysis with a sample of Spanish-speaking caregivers (n = 243) resulted in 2 reliable factors representing "child-centered" (α = 0.82) and "parent-centered" (α = 0.87) food-related parenting practices.ConclusionsFace validity, semantic equivalence, and internal consistency of Mi Niño were established. This tool can be used in community settings to inform program content and measure changes in food-related parenting practices of Spanish-speaking parents and assist in setting food-related parenting goals. The next steps include exploring the correspondence of Mi Nino with mealtime behaviors observed through video recording.

BackgroundMicrophthalmia, anophthalmia, and coloboma (MAC) spectrum disease encompasses a group of eye malformations which play a role in childhood visual impairment. Although the predominant cause of eye malformations is known to be heritable in nature, with 80% of cases displaying loss-of-function mutations in the ocular developmental genes OTX2 or SOX2, the genetic abnormalities underlying the remaining cases of MAC are incompletely understood. This study intended to identify the novel genes and pathways required for early eye development. Additionally, pathways involved in eye formation during embryogenesis are also incompletely understood. This study aims to identify the novel genes and pathways required for early eye development through systematic forward screening of the mammalian genome.ResultsQuery of the International Mouse Phenotyping Consortium (IMPC) database (data release 17.0, August 01, 2022) identified 74 unique knockout lines (genes) with genetically associated eye defects in mouse embryos. The vast majority of eye abnormalities were small or absent eyes, findings most relevant to MAC spectrum disease in humans. A literature search showed that 27 of the 74 lines had previously published knockout mouse models, of which only 15 had ocular defects identified in the original publications. These 12 previously published gene knockouts with no reported ocular abnormalities and the 47 unpublished knockouts with ocular abnormalities identified by the IMPC represent 59 genes not previously associated with early eye development in mice. Of these 59, we identified 19 genes with a reported human eye phenotype. Overall, mining of the IMPC data yielded 40 previously unimplicated genes linked to mammalian eye development. Bioinformatic analysis showed that several of the IMPC genes colocalized to several protein anabolic and pluripotency pathways in early eye development. Of note, our analysis suggests that the serine-glycine pathway producing glycine, a mitochondrial one-carbon donator to folate one-carbon metabolism (FOCM), is essential for eye formation.ConclusionsUsing genome-wide phenotype screening of single-gene knockout mouse lines, STRING analysis, and bioinformatic methods, this study identified genes heretofore unassociated with MAC phenotypes providing models to research novel molecular and cellular mechanisms involved in eye development. These findings have the potential to hasten the diagnosis and treatment of this congenital blinding disease.

PurposeDiphthamide is a post-translationally modified histidine essential for messenger RNA translation and ribosomal protein synthesis. We present evidence for DPH5 as a novel cause of embryonic lethality and profound neurodevelopmental delays (NDDs).MethodsMolecular testing was performed using exome or genome sequencing. A targeted Dph5 knockin mouse (C57BL/6Ncrl-Dph5em1Mbp/Mmucd) was created for a DPH5 p.His260Arg homozygous variant identified in 1 family. Adenosine diphosphate-ribosylation assays in DPH5-knockout human and yeast cells and in silico modeling were performed for the identified DPH5 potential pathogenic variants.ResultsDPH5 variants p.His260Arg (homozygous), p.Asn110Ser and p.Arg207Ter (heterozygous), and p.Asn174LysfsTer10 (homozygous) were identified in 3 unrelated families with distinct overlapping craniofacial features, profound NDDs, multisystem abnormalities, and miscarriages. Dph5 p.His260Arg homozygous knockin was embryonically lethal with only 1 subviable mouse exhibiting impaired growth, craniofacial dysmorphology, and multisystem dysfunction recapitulating the human phenotype. Adenosine diphosphate-ribosylation assays showed absent to decreased function in DPH5-knockout human and yeast cells. In silico modeling of the variants showed altered DPH5 structure and disruption of its interaction with eEF2.ConclusionWe provide strong clinical, biochemical, and functional evidence for DPH5 as a novel cause of embryonic lethality or profound NDDs with multisystem involvement and expand diphthamide-deficiency syndromes and ribosomopathies.

BackgroundThe diagnostic rate of Mendelian disorders in sequencing studies continues to increase, along with the pace of novel disease gene discovery. However, variant interpretation in novel genes not currently associated with disease is particularly challenging and strategies combining gene functional evidence with approaches that evaluate the phenotypic similarities between patients and model organisms have proven successful. A full spectrum of intolerance to loss-of-function variation has been previously described, providing evidence that gene essentiality should not be considered as a simple and fixed binary property.MethodsHere we further dissected this spectrum by assessing the embryonic stage at which homozygous loss-of-function results in lethality in mice from the International Mouse Phenotyping Consortium, classifying the set of lethal genes into one of three windows of lethality: early, mid, or late gestation lethal. We studied the correlation between these windows of lethality and various gene features including expression across development, paralogy and constraint metrics together with human disease phenotypes. We explored a gene similarity approach for novel gene discovery and investigated unsolved cases from the 100,000 Genomes Project.ResultsWe found that genes in the early gestation lethal category have distinct characteristics and are enriched for genes linked with recessive forms of inherited metabolic disease. We identified several genes sharing multiple features with known biallelic forms of inborn errors of the metabolism and found signs of enrichment of biallelic predicted pathogenic variants among early gestation lethal genes in patients recruited under this disease category. We highlight two novel gene candidates with phenotypic overlap between the patients and the mouse knockouts.ConclusionsInformation on the developmental period at which embryonic lethality occurs in the knockout mouse may be used for novel disease gene discovery that helps to prioritise variants in unsolved rare disease cases.

We searched a database of single-gene knockout (KO) mice produced by the International Mouse Phenotyping Consortium (IMPC) to identify candidate ciliopathy genes. We first screened for phenotypes in mouse lines with both ocular and renal or reproductive trait abnormalities. The STRING protein interaction tool was used to identify interactions between known cilia gene products and those encoded by the genes in individual knockout mouse strains in order to generate a list of "candidate ciliopathy genes." From this list, 32 genes encoded proteins predicted to interact with known ciliopathy proteins. Of these, 25 had no previously described roles in ciliary pathobiology. Histological and morphological evidence of phenotypes found in ciliopathies in knockout mouse lines are presented as examples (genes Abi2, Wdr62, Ap4e1, Dync1li1, and Prkab1). Phenotyping data and descriptions generated on IMPC mouse line are useful for mechanistic studies, target discovery, rare disease diagnosis, and preclinical therapeutic development trials. Here we demonstrate the effective use of the IMPC phenotype data to uncover genes with no previous role in ciliary biology, which may be clinically relevant for identification of novel disease genes implicated in ciliopathies.

The mouse is the most commonly used model species in biomedical research. Just as human physical and mental health are influenced by the commensal gut bacteria, mouse models of disease are influenced by the fecal microbiome (FM). The source of mice represents one of the strongest influences on the FM and can influence the phenotype of disease models. The FM influences behavior in mice leading to the hypothesis that mice of the same genetic background from different vendors, will have different behavioral phenotypes. To test this hypothesis, colonies of CD-1 mice, rederived via embryo transfer into surrogate dams from four different suppliers, were subjected to phenotyping assays assessing behavior and physiological parameters. Significant differences in behavior, growth rate, metabolism, and hematological parameters were observed. Collectively, these findings show the profound influence of supplier-origin FMs on host behavior and physiology in healthy, genetically similar, wild-type mice maintained in identical environments.

PurposeWithin a medical clinic environment, pediatric obesity prevention education for families faces challenges. Existing long-term government-funded nutrition education programs have the expertise and staff to deliver. The purpose is to determine feasibility of colocating the Expanded Food and Nutrition Education Program (EFNEP) into a medical clinic setting to support pediatric obesity prevention.MethodsPhysicians from a large university teaching and research hospital (n = 73) and 4 small Medicaid-serving community clinics (n = 18) in the same geographic area in northern California were recruited and trained in the patient-referral protocol for a primary prevention intervention provided by EFNEP. The 8-week intervention deployed in the medical clinics, included general nutrition, physical activity and parenting topics anchored with guided goal setting and motivational modeling. Referral, enrollment, and attendance data were collected for 2 years. Parent and physician feasibility surveys, parent interviews and parent risk assessment tools were administered. Paired-sample t-test analysis was conducted.ResultsTwenty intervention series with parents of patients (n = 106) were conducted at 5 clinics. Physicians (n = 92) generated 686 referrals. Every 6 referrals generated 1 enrolled parent. Physicians (91%, n = 34) reported the intervention as useful to families. Parents (n = 82) reported improved child behaviors for sleep, screen time, physical activity, and food and beverage offerings (P

Children of Hispanic origin bear a high risk of obesity. Child weight gain trajectories are influenced by the family environment, including parent feeding practices. Excessive body fat can result in unhealthful metabolic and lipid profiles and increased risk of metabolic diseases. The objective was to estimate criterion validity of an obesity risk assessment tool targeting Spanish-speaking families of Mexican origin using anthropometric measures and blood values of their young children. A cross-sectional study design with five data collection sessions was conducted over an eight-week period and involved 206 parent/child dyads recruited at Head Start and the Special Supplemental Nutrition Program for Women, Infants and Children in Northern California. Main outcome measures were criterion validity of Niños Sanos, a pediatric obesity risk assessment tool, using anthropometric measures and blood biomarkers. Niños Sanos scores were inversely related to child BMI-for-age percentiles (p = 0.02), waist-for-height ratios (p = 0.05) and inversely related to blood biomarkers for the metabolic index (p = 0.03) and lipid index (p = 0.05) and positively related to anti-inflammatory index (p = 0.047). Overall, children with higher Niños Sanos scores had more healthful lipid, metabolic and inflammatory profiles, as well as lower BMI-for-age percentiles and waist-to height ratios, providing evidence for the criterion validity of the tool. Niños Sanos can be used by child obesity researchers, by counselors and medical professionals during clinic visits as a screening tool and by educators as a tool to set goals for behavior change.

This corrects the article DOI: 10.1038/nature19356.

Despite a substantial body of research, we lack fundamental understanding of the pathophysiology of COVID-19 caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) including pulmonary and cardiovascular outcomes, in part due to limitations of murine models. Most models use transgenic mice (K18) that express the human (h) angiotensin converting enzyme 2 (ACE2), ACE2 knock-in (KI) mice, or mouse-adapted strains of SARS-CoV-2. Further, many SARS-CoV-2 variants produce fatal neurologic disease in K18 mice and most murine studies focus only on acute disease in the first 14 days post inoculation (dpi). To better enable understanding of both acute (<14 dpi) and post-acute (>14 dpi) infection phases, we describe the development and characterization of a novel non-lethal KI mouse that expresses both the ACE2 and transmembrane serine protease 2 (TMPRSS2) genes (hACE2/hTMPRSS2). The human genes were engineered to replace the orthologous mouse gene loci but remain under control of their respective murine promoters, resulting in expression of ACE2 and TMPRSS2 instead of their murine counterparts. After intranasal inoculation with an omicron strain of SARS-CoV-2, hACE2/hTMPRSS2 KI mice transiently lost weight but recovered by 7 dpi. Infectious SARS-CoV-2 was detected in nasopharyngeal swabs 1-2 dpi and in lung tissues 2-6 dpi, peaking 4 dpi. These outcomes were similar to those in K18 mice that were inoculated in parallel. To determine the extent to which hACE2/hTMPRSS2 KI mice are suitable to model pulmonary and cardiovascular outcomes, physiological assessments measuring locomotion, behavior and reflexes, biomonitoring to measure cardiac activity and respiration, and micro computed tomography to assess lung function were conducted frequently to 6 months post inoculation. Male but not female SARSCoV-2 inoculated hACE2/hTMPRSS2 KI mice showed a transient reduction in locomotion compared to control saline treated mice. No significant changes in respiration, oxygen saturation, heart rate variability, or conductivity were detected in SARS-CoV-2 inoculated mice of either sex. When re-inoculated 6 months after the first inoculation, hACE2/hTMPRSS2 KI became re-infected with disease signs similar to after the first inoculation. Together these data show that a newly generated hACE2/hTMPRSS2 KI mouse can be used to study mild COVID-19. [ABSTRACT FROM AUTHOR]

Approximately one-third of all mammalian genes are essential for life. Phenotypes resulting from knockouts of these genes in mice have provided tremendous insight into gene function and congenital disorders. As part of the International Mouse Phenotyping Consortium effort to generate and phenotypically characterize 5,000 knockout mouse lines, here we identify 410 lethal genes during the production of the first 1,751 unique gene knockouts. Using a standardized phenotyping platform that incorporates high-resolution 3D imaging, we identify phenotypes at multiple time points for previously uncharacterized genes and additional phenotypes for genes with previously reported mutant phenotypes. Unexpectedly, our analysis reveals that incomplete penetrance and variable expressivity are common even on a defined genetic background. In addition, we show that human disease genes are enriched for essential genes, thus providing a dataset that facilitates the prioritization and validation of mutations identified in clinical sequencing efforts.

Previous research suggests obesity is negatively related to cognitive functioning and academic outcomes in addition to physical health. However, not much is known about this association in early childhood or potential physiological underpinnings. Biomarkers related to obesity have been associated with cognition, in particular the adipokine leptin, and pro-inflammatory cytokines including interleukin-6 (IL-6), tumor necrosis factor-alpha (TNF-alpha) and C-reactive protein (CRP). These associations may be further exacerbated for children who experience early life stress. With a sample of low-income preschoolers, the current study examined associations between obesity-related biomarkers and aspects of behavioral and cognitive school readiness. Partial correlations controlling for child age show hypothesized negative associations between pro-inflammatory cytokines and school readiness, while leptin was positively associated with cognitive school readiness and body mass index (BMI) z-score. Findings suggest connections between obesity, physiology, and school readiness need further examination, but may have implications for early childhood education and health interventions.

Background: Accurate measurement of food-related parenting practices is necessary to inform related interventions and program evaluation. Valid tools reflect cultural attributes that affect household food environments and feeding practices. Simple, unidirectional language adaptation approaches are insufficient to capture these attributes in assessment tools. My Child at Mealtime (MCMT) is a 27-item, validated, visually enhanced self-assessment tool to measure food-related parenting practices of low-income English-speaking parents of preschoolers. Objectives: The aim of this study was to describe the cross-cultural adaptation of MCMT into its Spanish version Mi Niño a la Hora the Comer (Mi Niño) and to establish its face validity, factor structure, and internal consistency. Methods: MCMT was adapted into its Spanish version after an iterative process that triangulated cognitive interviews with verification of conceptual equivalence by content experts to establish face validity and semantic equivalence. The resulting tool underwent confirmatory factor analysis to determine whether internal consistency was equivalent across the 2 versions. Results: Four rounds of cognitive interviews (n = 5, n = 6, n = 2, and n = 4, respectively) with Spanish-speaking women caregivers of children aged 3-5 y recruited from Head Start were conducted. Ten items were modified throughout the adaptation process. Modifications included improved clarity (6 items), comprehension (7 items), appropriateness (4 items), suitability (4 items), and usefulness (2 items) of text and/or accompanying visuals. Confirmatory factor analysis with a sample of Spanish-speaking caregivers (n = 243) resulted in 2 reliable factors representing "child-centered" (α = 0.82) and "parent-centered" (α = 0.87) food-related parenting practices. Conclusions: Face validity, semantic equivalence, and internal consistency of Mi Niño were established. This tool can be used in community settings to inform program content and measure changes in food-related parenting practices of Spanish-speaking parents and assist in setting food-related parenting goals. The next steps include exploring the correspondence of Mi Nino with mealtime behaviors observed through video recording. [ABSTRACT FROM AUTHOR]

Numerous studies support the concept that a major cause of pregnancy complications can be suboptimal embryonic and fetal nutrition. Although the negative effects of diets low in energy on pregnancy outcome are well documented, less clear are the effects of diets that are low in one or more essential micronutrients. However, several observational and intervention studies suggest that diets low in essential vitamins and minerals can pose a significant reproductive risk in diverse human populations. Although maternal nutritional deficiencies typically occur as a result of low dietary intakes of essential nutrients, nutritional deficiencies at the level of the conceptus can arise through multiple mechanisms. Evidence from experimental animals supports the concept that in addition to primary deficiencies, secondary embryonic and fetal nutritional deficiencies can be caused by diverse factors including genetics, maternal disease, toxicant insults and physiological stressors that can trigger a maternal acute phase response. These secondary responses may be significant contributors to the occurrence of birth defects. An implication of the above is that the frequency and severity of pregnancy complications may be reduced through an improvement in the micronutrient status of the mother. KEY WORDS: * zinc * copper * pregnancy * nutrition * malformations

Approximately 3% of infants born have at least one serious congenital malformation. In the U.S., an average of 10 infants per thousand die before 1 y of life; about half of these deaths can be attributed to birth defects, low birth weight or prematurity. Although the causes of developmental abnormalities are clearly multifactorial in nature, we suggest that a common factor contributing to the occurrence of developmental abnormalities is suboptimal mineral nutrition during embryonic and fetal development. Using zinc and copper as examples, evidence is presented that nutritional deficiencies can rapidly affect the developing conceptus and result in gross structural abnormalities. Deficits of zinc or copper can result in rapid changes in cellular redox balance, tissue oxidative stress, inappropriate patterns of cell death, alterations in the migration of neural crest cells and changes in the expression of key patterning genes. In addition to well-recognized malformations, mineral deficiencies during perinatal development can result in behavioral, immunological and biochemical abnormalities that persist into adulthood. Although these persistent defects can in part be attributed to subtle morphological abnormalities, in other cases they may be secondary to epigenetic or developmental changes in DNA methylation patterns. Epigenetic defects combined with subtle morphological abnormalities can influence an individual's risk for certain chronic diseases and thus influence his or her risk for morbidity and mortality later in life. KEY WORDS: * zinc * copper * pregnancy * embryo * epigenetics

Because glucose is an important metabolic fuel during perinatal development, the effect of restriction of maternal dietary glucose on the developmental profile of neonatal glucoregulatory pathways was investigated. Pregnant rats were fed isoenergetic diets (0, 12, 24 or 60% glucose) and offspring were killed at seven postpartum time periods: 0-2, 4-6, 12-16 and 24 h, and 3, 6 and 15 d. Failure of the most restricted pups (0%) to survive 24 h was explained by persistent hypoglycemia resulting from the following: 1) insufficient tissue glycogen reserves at birth; 2) lower liver glycogen mobilization; 3) delayed phosphorylase a induction; and 4) low phosphoenolpyruvate carboxykinase (PEPCK) gene expression, all of which occurred despite the lower insulin:glucagon ratio. Differences in liver glycogen stores, which had been exhausted in all dietary groups by 16 h, could not account for the high d 1 pup mortality in the moderately restricted (12 and 24% glucose) groups. However, a certain metabolic distress was suggested because these moderately restricted neonates had significantly higher liver PEPCK gene expression at 12-16 h but significantly lower plasma glucose at 24 h. The high d 3 mortality, confirmed by analysis of deviance, was not supported by significant differences in any of the measured glucoregulatory indices. We conclude that dietary glucose during pregnancy is required for neonatal survival; its restriction not only lowers tissue glycogen reserves, but can disrupt the normal gene expression of liver PEPCK and the neonatal profile of phosphorylase a activity. Importantly, these observations show that the development of neonatal glucoregulatory mechanisms is modified by the availability of maternal dietary glucose. KEY WORDS: glycogen; phosphorylase; synthase; phosphoenolpyruvate carboxykinase (PEPCK); neonatal rats

To examine the effects of chronic restriction of maternal dietary glucose on lactational performance, pregnant dams were fed one of four isoenergetic diets containing graded levels of glucose (0, 12, 24 and 60%) from d 2 of pregnancy to d 15 of lactation. Dams fed the 0% glucose diet produced colostrum with higher protein and lower lactose and fat concentrations than normal, but all pups born to these dams failed to survive more than 24 h postpartum. Dams fed glucose-restricted diets (12 and 24%) had significantly lower d 15 milk fat concentration than dams fed the control diet, but there were no differences in milk protein, lactose and glucose concentrations. On d 15, pups suckling dams fed the 12% glucose diet had significantly lower body weights than pups of dams fed 24 and 60% glucose diets. Restriction of dietary glucose to 12% resulted in significantly smaller mammary gland cell size but failed to produce any significant differences in mammary gland composition (protein, fat and glycogen). The results indicate that the level of glucose in the maternal diet is an important determinant of milk composition and that >24% glucose is needed for optimal milk fat concentration, whereas 12% dietary glucose is sufficient to sustain normal milk lactose concentration. The altered lactational performance in response to dietary glucose restriction was not mediated through changes in mammary gland composition, but in part by the reduced mammary gland size.

In spite of evidence that dietary carbohydrate can increase brain tryptophan and 5-hydroxytryptamine in adult rats, the possible influence of maternal dietary carbohydrate on fetal brain indoles has received little attention. We studied the effect of graded levels (0, 4, 12 and 60%) of maternal dietary fructose or glucose fed throughout pregnancy on fetal brain glycogen and indoles. The diets were isoenergetic and met the NRC energy requirements for pregnant rats. The results demonstrated that low maternal dietary carbohydrate, with adequate energy intake, reduced fetal brain weight and concentrations of glycogen, tryptophan, 5-hydroxytryptamine and 5-hydroxyindoleacetic acid. There were no significant differences between glucose and fructose feeding at any dietary carbohydrate level for any fetal brain measurements, showing that it was the level and not the type of dietary carbohydrate that was important. Significant correlations between fetal brain 5-hydroxytryptamine and brain glycogen, and between fetal brain 5-hydroxytryptamine and brain weight, suggested that lowered brain 5-hydroxytryptamine was only one symptom of disrupted and brain development in fetuses of dams fed low levels of carbohydrate. The results show that dietary carbohydrate restriction during pregnancy can have adverse effects on fetal brain development, glycogen levels, and neurotransmitter synthesis even when maternal dietary protein and energy intake are adequate. J. Nutr. 123: 42-51, 1993.

In this study we investigated whether placental glycogen reserves and protein and DNA content could be manipulated by altering the level of glucose in the maternal diet. Pregnant rat dams were fed isocaloric diets containing graded levels of glucose (0, 12, 24 and 60%), and placentas were analyzed for glycogen, protein and DNA content on gestational days 18.5 to 21.5. Regardless of the level of glucose in the maternal diet, there was a significant increase in placental size with advancing age, which was characterized by protein accretion but not by an increase in cell number or glycogen content. Restriction of glucose in the diets of pregnant dams failed to produce statistically significant reductions in placental protein, DNA and glycogen and did not retard placental growth, even though intrauterine growth retardation was observed. Fetal weight, plasma glucose, and liver and heart glycogen were positively correlated with placental weight and inversely correlated with placental glycogen and DNA concentrations; by contrast, no significant correlations were calculated between maternal and placental variables. Our study indicates that the placenta is not affected by a specific dietary glucose restriction and that changes in placental weight or glycogen content do not account for the growth retardation observed in fetuses of dams fed glucose-restricted diets. J. Nutr. 122: 2374-2382, 1992.