Hypothalamic insulin receptor expression and DNA promoter methylation are sex-specifically altered in adult offspring of high-fat diet (HFD)-overfed mother rats.

Maternal overnutrition around reproduction has been shown to increase the offspring's risk for "diabesity," mediated by altered hypothalamic neuropeptide expression. In this report, a possible contribution of altered hypothalamic sensing capacity for the peripheral satiety signals glucose, insulin and leptin will be addressed, taking into account potential sex differences. Specifically, we evaluated the effects a maternal high-fat diet (HFD) overfeeding has in rats pre- and during pregnancy and lactation on the hypothalamic gene expression patterns of insulin and leptin receptors (InsR, ObRb) and glucose transporter 3 (Glut3) as well as DNA methylation in the offspring at adult age (day 200 of life). Maternal HFD consumption resulted in a metabolic syndrome phenotype, i.e., obesity, hyperleptinemia, hyperinsulinemia, impaired glucose tolerance and increased homeostatic model assessment of insulin resistance. Interestingly, in turn, insulin resistance was more pronounced in male offspring, accompanied by decreased hypothalamic InsR-mRNA. This was linked with hypermethylation of an activating transcription factor binding site within the hypothalamic InsR promoter. The degree of methylation correlated inversely with respective InsR expression, while InsR expression itself was inversely related to phenotypic "diabesity." Expression of ObRb and Glut3 mRNA was not significantly changed. In conclusion, sex-specific alterations of hypothalamic InsR expression and DNA promoter methylation in adult offspring of HFD-overfed dams may lead to hypothalamic insulin resistance and "diabesity," with males predisposed to this epigenetic malprogramming.

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