Objectives
Curcumin is a naturally occurring polyphenol present in the roots of the Curcuma longa plant (turmeric), which possesses antioxidant, anti-tumorigenic and anti-inflammatory properties. Here, we test whether curcumin treatment reduces high glucose-induced neural tube defects (NTDs), and if this occurs via blocking cellular stress and caspase activation.
Study Design
Embryonic day 8.5 mouse embryos were collected for use in whole embryo culture under normal glucose (100 mg/dl glucose) or high glucose (300 mg/dl glucose) conditions, with or without curcumin treatment. After 24 h in culture, protein levels of oxidative stress makers, nitrosative stress makers, endoplasmic reticulum (ER) stress makers, cleaved caspase 3 and 8 and the level of lipid peroxides (LPO) were determined in the embryos. After 36 h in culture, embryos were examined for evidence of NTD formation.
Results
Although 10 μM curcumin did not significantly reduce the rate of NTDs caused by high glucose, 20 μM curcumin significantly ameliorated high glucose-induced NTD formation. Curcumin suppressed oxidative stress in embryos cultured under high glucose conditions. Treatment reduced the levels of the lipid peroxidation marker, 4-hydroxynonenal(4-HNE), nitrotyrosine-modified protein, and LPO. Curcumin also blocked ER stress by inhibiting phosphorylated protein kinase ribonucleic acid (RNA)-like ER kinase (p-PERK), phosphorylated inositol-requiring protein-1α (p-IRE1α), phosphorylated eukaryotic initiation factor 2α (p-eIF2α), C/EBP-homologous protein (CHOP), binding immunoglobulin protein (BiP) and x-box binding protein 1 (XBP1) mRNA splicing. Additionally, curcumin abolished caspase 3 and caspase 8 cleavage in embryos cultured under high glucose conditions.
Conclusions
Curcumin reduces high glucose-induced NTD formation by blocking cellular stress and caspase activation, suggesting that curcumin supplements could reduce the negative effects of diabetes on the embryo. Further investigation will be needed to determine if the experimental findings can translate into clinical settings.