Vitamin E deficiency during embryogenesis in zebrafish causes lasting metabolic and cognitive impairments despite refeeding adequate diets

Abstract

Vitamin E (α-tocopherol; VitE) is a lipophilic antioxidant required for normal embryonic development in vertebrates, but the long-term effects of embryonic VitE deficiency, and whether they are ameliorated by feeding VitE−adequate diets, remain unknown. We addressed these questions using a zebrafish (Danio rerio) model of developmental VitE deficiency followed by dietary remediation. Adult zebrafish maintained on VitE−deficient (E−) or sufficient (E+) diets were spawned to obtained E− and E+ embryos, respectively, which we evaluated up to 12 days post-fertilization (dpf). The E− group suffered significantly increased morbidity and mortality as well as altered DNA methylation status through 5 dpf when compared to E+ larvae, but upon feeding with a VitE-adequate diet from 5–12 dpf both the E− and E+ groups survived and grew normally; the DNA methylation profile also was similar between groups by 12 dpf. However, 12 dpf E− larvae still had behavioral defects. These observations coincided with sustained VitE deficiency in the E− vs. E+ larvae (p< 0.0001), despite adequate dietary supplementation. We also found in E− vs. E+ larvae continued docosahexaenoic acid (DHA) depletion (p< 0.0001) and significantly increased lipid peroxidation. Further, targeted metabolomics analyses revealed persistent dysregulation of the cellular antioxidant network, the CDP-choline pathway, and glucose metabolism. While anaerobic processes were increased, aerobic metabolism was decreased in the E− vs. E+ larvae, indicating mitochondrial damage. Taken together, these outcomes suggest embryonic VitE deficiency causes lasting behavioral impairments due to persistent lipid peroxidation and metabolic perturbations that are not resolved via later dietary VitE supplementation.

Regulation of lipid peroxidation and ferroptosis in diverse species

“…ROS generated during embryogenesis signal cellular proliferation and tissue differentiation; however, imbalanced production of these species by endogenous metals and lack of antioxidants may lead to a risk of developmental abnormalities and cell death. During zebrafish embryogenesis, vitamin E-deficient embryos experience increased lipid peroxidation (McDougall et al 2016(McDougall et al , 2017) and a lethal dysregulation of energy metabolism (e.g., an anti-Warburg effect) (Maldonado 2017;McDougall et al 2017). These vitamin E-depleted embryos display a mitochondrial metabolic reprogramming that shunts glucose to the pentose phosphate pathway for NADPH production, ultimately increasing nonaerobic glycolysis, depleting glucose, and increasing morphological malformations (McDougall et al 2017).…”

“…During zebrafish embryogenesis, vitamin E-deficient embryos experience increased lipid peroxidation (McDougall et al 2016(McDougall et al , 2017) and a lethal dysregulation of energy metabolism (e.g., an anti-Warburg effect) (Maldonado 2017;McDougall et al 2017). These vitamin E-depleted embryos display a mitochondrial metabolic reprogramming that shunts glucose to the pentose phosphate pathway for NADPH production, ultimately increasing nonaerobic glycolysis, depleting glucose, and increasing morphological malformations (McDougall et al 2017). Thus, a metabolic switch occurs between 24 and 48 h post-fertilization (hpf), with the deficient embryo switching from high to low oxygen consumption with concomitant decreases in glutathione and NADPH (McDougall et al 2017).…”

“…These vitamin E-depleted embryos display a mitochondrial metabolic reprogramming that shunts glucose to the pentose phosphate pathway for NADPH production, ultimately increasing nonaerobic glycolysis, depleting glucose, and increasing morphological malformations (McDougall et al 2017). Thus, a metabolic switch occurs between 24 and 48 h post-fertilization (hpf), with the deficient embryo switching from high to low oxygen consumption with concomitant decreases in glutathione and NADPH (McDougall et al 2017). Furthermore, vitamin E insufficiency-linked dysmetabolism is associated with both lipid peroxidation and secondary glucose deficiency, as evidenced by partial neurological rescue with glucose injections (McDougall et al 2017).…”

Vitamin E: Regulatory role on gene and protein expression and metabolomics profiles

“…In a following vitamin E repletion trial, when the vitamin E deficient group was fed a vitamin E sufficient diet from 5 to 12 days postfertilization, vitamin E deficient embryos showed normal phenotype upon development but still had neurobehavioral impairments. The vitamin E deficiency and the metabolic perturbations in lipid, antioxidant, and energy metabolism were not resolved despite adequate vitamin E supplementation . These metabolic changes were supported by a microarray analysis of a zebrafish embryo transcriptome.…”

Lipid peroxidation biomarkers for evaluating oxidative stress in equine neuroaxonal dystrophy

“…The term vitamin E (vitE) encompasses a closely related family of 8 fat soluble naturally occurring compounds. Of these forms, α‐TOH most consistently prevents lipid peroxidation in vitro and in vivo . Biomarkers of lipid peroxidation often are assessed as indicators of oxidative damage.…”