Cafeteria Diet Consumption during Lactation in Rats, Rather than Obesity Per Se, alters miR-222, miR-200a, and miR-26a Levels in Milk

SCOPE: The aim of the present study is to investigate in nursing rats the impact of cafeteria-diet feeding during lactation (cafeteria dams) on specific miRNA levels in breast milk and to discern them from the effects of maternal adiposity per se (postcafeteria dams). METHODS AND RESULTS: Milk samples are collected from control, cafeteria, and postcafeteria dams at three time points of lactation (days 5, 10, and 15) and levels of selected miRNAs (miR-222, miR-203, miR-200a, miR-103, miR-27a, and miR-26a) were determined. Levels in milk of miR-222 rise while miR-103 and miR-27 fall throughout lactation. Moreover, at day 15 of lactation, cafeteria dams present higher miR-222 and lower miR-200a and miR-26a levels in milk than controls. No differences are found in postcafeteria dams compared with controls. At weaning, the offspring of cafeteria dams, but not the offspring of postcafeteria dams, displays lower expression levels of Cdkn1c (a validated target gene of miR-222) in liver than controls. CONCLUSION: Cafeteria diet intake in nursing rats, rather than obesity per se, leads to alterations in specific miRNA levels, which, through the milk supply, may alter expression of target genes and potentially affect offspring phenotype.