Obesity predisposes humans to a range of life-threatening comorbidities, including type 2 diabetes and cardiovascular disease. Obesity also aggravates neural pathologies, such as Alzheimer's disease, but this class of comorbidity is less understood. When Drosophila melanogaster (flies) are exposed to high fat diet (HFD) by supplementing a standard medium with coconut oil, they adopt an obese phenotype of decreased lifespan, increased triglyceride storage, and hindered climbing ability. The latter development has been previously regarded as a potential indicator of neurological decline in fly models of neurodegenerative disease. Our objective was to establish the obesity phenotype in Drosophila and identify a potential correlation, if any, between obesity and neurological decline through behavioral assays and expression microarray. We found that mated female w 1118 flies exposed to HFD maintained an obese phenotype throughout adult life starting at seven days, evidenced by increased triglyceride stores, diminished life span, and impeded climbing ability. While climbing ability worsened between seven and fourteen days of exposure to HFD, there was no corresponding alteration in triglyceride content. Microarray analysis of the mated female w 1118 fly head revealed HFD-induced changes in expression of genes with functions in memory, metabolism, olfaction, mitosis, cell signaling, and motor function. Meanwhile, an Aversive Phototaxis Suppression assay in mated female flies indicated reduced ability to recall an entrained memory six hours after training. Overall, our results support the suitability of mated female flies for examining connections between diet-induced obesity and nervous or neurobehavioral pathology, and provide many directions for further investigation.

Embryonic hyperglycemia negatively impacts retinal development, leading to abnormal visual behavior, altered timing of retinal progenitor differentiation, decreased numbers of retinal ganglion cells and Müller glia, and vascular leakage. Because synaptic disorganization is a prominent feature of many neurological diseases, the goal of the current work was to study the potential impact of hyperglycemia on retinal ribbon synapses during embryonic development. Our approach utilized reverse transcription quantitative PCR (RT-qPCR) and immunofluorescence labeling to compare the transcription of synaptic proteins and their localization in hyperglycemic zebrafish embryos, respectively. Our data revealed that the maturity of synaptic ribbons was compromised in hyperglycemic zebrafish larvae, where altered ribeye expression coincided with the delay in establishing retinal ribbon synapses and an increase in the immature synaptic ribbons. Our results suggested that embryonic hyperglycemia disrupts retinal synapses by altering the development of the synaptic ribbon, which can lead to visual defects. Future studies using zebrafish models of hyperglycemia will allow us to study the underlying mechanisms of retinal synapse development.

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Background and Aim One in ten pregnancies in the US, suffers from Gestational Diabetes Mellitus (GDM). Offspring born to mothers who have GDM have a higher risk of developing Obesity, Type 2 diabetes and Non‐alcoholic fatty liver disease later in life. Although in utero glucose exposure provides evidence for developmental programming leading to metabolic disorders in adults, the molecular mechanisms are still unclear. We aim to understand the mechanisms implicated in developmental programming and their associated adult outcomes in a well‐established zebrafish model of fetal hyperglycemia that mimics the metabolic disorders in human GDM. Methods We developed a zebrafish model of fetal hyperglycemia by exposing embryos to high glucose (4.5% w/v) during the last day of embryogenesis from 96 to 120 hours post fertilization. Glucose level was detected in embryos and larvae homogenates and in adult serum by glucometer. Body composition was determined in adults by EchoMRI, gene expression of glycolytic, lipogenic (Acetyl‐CoA Carboxylase (acca) and mitochondria biogenesis (Peroxisome proliferator‐activated receptor‐gamma coactivator [PGC‐1α/β) markers were quantified by RT‐qPCR and acca by western blot. Lipid accumulation was detected by Oil‐Red‐O staining (ORO) and quantified by spectrophotometry. Triglyceride and cholesterol levels (ELISA), adiposity (Nile red staining) and mitochondrion number (mitotracker staining) were also evaluated. We also assessed if co‐administration of metformin or ND646 (known inhibitors of acca) with glucose can attenuate fetal hyperglycemia‐mediated metabolic outcomes. Results Zebrafish embryos exposed to high glucose for 24 hrs are transiently hyperglycemic while normoglycemia is restored after glucose exposure. Larvae and adults with embryonic glucose exposure are normoglycemic. Embryos showed an upregulation of hexokinase and pyruvate Kinase expression when assessed at 120 hpf, but no change in expression was detected in larvae. Embryos exposed to glucose showed increased lipid accumulation by ORO staining (0.22 ±0.01 Vs 0.17±0.01) while larvae showed a 5‐fold increase in adiposity. Adult fish develop obesity characterized by increased BMI (0.83±26.34 Vs. 0.60± 33.89) kg/m2 and fat mass (12.07± 2.92 Vs 3.4± 0.4) g. Embryos showed increase in both acca mRNA expression (3‐folds) and activation (decreased phosphorylation). Interestingly, acca expression remained increased in larvae while glycemia was normal. Moreover, there was a significant increase in cholesterol (57.92± 0.7 Vs 34.8±1.01 µM) and triglyceride levels in glucose exposed embryos compared to controls (4.1± 0.75 Vs 0.98±0.27 µM). Our data in embryos revealed an increase in mitochondria number validated by an increase in the expression of PGC‐1α/β. Finally, ORO staining showed that embryonic lipid accumulation was decreased to normal levels, by metformin or ND646 exposure when co‐administered with glucose. Conclusion and significance Together our results show that embryonic glucose exposure alters developmental programming, incl...

Fetal Hyperglycemia (FH) plays a critical role in adult obesity. FH occurs upon fetal exposure to high maternal glucose during Gestational Diabetes, resulting in hyperinsulinemia and increased fetal fat deposition. At birth, these infants are larger than normal babies, hypoglycemic and hyperinsulinemic and have a higher risk of adult-onset metabolic disorders such as obesity, Type 2 Diabetes and non-alcoholic fatty liver disease (NAFLD). Although in utero glucose exposure provides evidence in the above-mentioned conditions the molecular mechanisms remain unclear. Using a Zebrafish model of FH, we aim to test the hypothesis that FH increases hepatic de novo lipogenesis causing obesity later in life. Methods: We developed a novel Zebrafish model of FH by exposing embryos to high glucose (4.5% w/v) at day 4 post fertilization (4 dpf) during the last day of embryogenesis. At 5 dpf the glucose media was replaced by regular media with or without the Acetyl-CoA Carboxylase (acca) inhibitor ND646 for additional 24 hrs followed by embryo collection. Adult fish were raised from glucose-exposed embryos on a normal diet. Fat mass was assessed by Echo-MRI and glucose levels by glucometer. The substrate of de novo lipogenesis, malonyl CoA level was quantified by ELISA and triglycerides by colorimetry. Insulin expression (visualized by whole mount in-situ hybridization), lipogenic (acca), beta oxidation [(Carnitine palmitoyltransferase, (cpt1/2)] and gluconeogenic [(Glucagon (gcga), Glucose-6-Phosphatase (G6Pase), Phosphoenolpyruvate carboxykinase (pck1)] markers were quantified by RT-qPCR. Oil-Red-O staining (ORO) was used to detect lipid accumulation and quantified using spectrophotometry, while Nile red staining was used to detect adipocyte accumulation. Results: Zebrafish embryos become transiently hyperglycemic and hyperinsulinemic after 24 hrs of glucose exposure at 5 dpf. Surprisingly, despite being normoglycemic glucose-exposed embryos at 6 dpf showed significantly higher levels of hepatic lipid accumulation (48%) and de novo lipogenesis (acca and malonyl CoA) as well as markers of gluconeogenesis (gcga, G6Pase, pck1) and beta oxidation (cpt1/2), compared to controls. Interestingly, adult fish (3 months) become obese (fat mass, 2.5±0.2 vs 3.7±0.2) and develop epicardial fat deposition, despite being normoglycemic. At the molecular level, adult fish have increased fasting hepatic de novo lipogenesis, as indicated by elevated acca expression and malonyl CoA levels which was associated with higher hepatic triglyceride levels (1.5-fold) compared to adult fish raised from unexposed embryos. ND 646 administration reduced lipid accumulation in embryos. The effect of ND 646 on adult fish is under evaluation. Conclusion: Together our results show that FH induces persistent increase in whole embryonic and adult hepatic de novo lipogenesis and its pharmacological inhibition could be promising therapeutic intervention to rescue FH-induced adulthood obesity. National Institute of Health grant (P20 GM104357) This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.