Synthetic α-Tocopherol, Compared with Natural α-Tocopherol, Downregulates Myelin Genes in Cerebella of Adolescent Ttpa-null Mice

Katherine M Ranard, Matthew J Kuchan, Richard S Bruno, Janice M Juraska, John W Erdman

Research output: Contribution to journalArticlepeer-review

Abstract

BACKGROUND: Vitamin E (α-tocopherol; α-T) deficiency causes spinocerebellar ataxia. α-T supplementation improves neurological symptoms, but little is known about the differential bioactivities of natural versus synthetic α-T during early life.

OBJECTIVE: We assessed the effects of dietary α-T dose and source on tissue α-T accumulation and gene expression in adolescent α-tocopherol transfer protein-null (Ttpa-/-) mice.

METHODS: Three-week-old male Ttpa-/- mice (n = 7/group) were fed 1 of 4 AIN-93G-based diets for 4 wk: vitamin E deficient (VED; below α-T limit of detection); natural α-T, 600 mg/kg diet (NAT); synthetic α-T, 816 mg/kg diet (SYN); or high synthetic α-T, 1200 mg/kg diet (HSYN). Male Ttpa+/+ littermates fed AIN-93G [75 mg synthetic α-T (CON)] served as controls (n = 7). At 7 wk of age, tissue α-T concentrations and stereoisomer profiles were measured for all groups. RNA-sequencing was performed on cerebella of Ttpa-/- groups.

RESULTS: Ttpa-/- mice fed VED had undetectable brain α-T concentrations. Cerebral cortex α-T concentrations were greater in Ttpa-/- mice fed NAT (9.1 ± 0.7 nmol/g), SYN (10.8 ± 1.0 nmol/g), and HSYN (13.9 ± 1.6 nmol/g) compared with the VED group but were significantly lower than in Ttpa+/+ mice fed CON (24.6 ± 1.2 nmol/g) (P < 0.001). RRR-α-T was the predominant stereoisomer in brains of Ttpa+/+ mice (∼40%) and Ttpa-/- mice fed NAT (∼94%). α-T stereoisomer composition was similar in brains of Ttpa-/- mice fed SYN and HSYN (2R: ∼53%; 2S: ∼47%). Very few of the 16,774 genes measured were differentially expressed. However, compared with the NAT diet, HSYN significantly downregulated 20 myelin genes, including 2 transcription factors: SRY-box transcription factor 10 (Sox10) and myelin regulatory factor (Myrf), and several downstream target genes (false discovery rate <0.05).

CONCLUSIONS: High-dose synthetic α-T compared with natural α-T alters myelin gene expression in the adolescent mouse cerebellum, which could lead to morphological and functional abnormalities later in life.

Original languageEnglish (US)
Pages (from-to)1031-1040
Number of pages10
JournalThe Journal of nutrition
Volume150
Issue number5
DOIs
StatePublished - May 1 2020

Keywords

  • Animal Feed/analysis
  • Animals
  • Body Weight
  • Carrier Proteins/genetics
  • Cerebellum/drug effects
  • Diet
  • Eating
  • Gene Expression Regulation/drug effects
  • Male
  • Mice
  • Mice, Knockout
  • Myelin Sheath/metabolism
  • alpha-Tocopherol/chemical synthesis

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