Rodents exposed to placental ischemia in utero display sex differences in brain miRNA expression, mitochondrial function, and blood pressure in adulthood

Placental ischemia (PI), a prenatal stressor, affects ∼1 in 10 human pregnancies worldwide and is associated with several pregnancy complications such as preeclampsia, placental abruption, and intrauterine growth restriction (IUGR). Both human and animal IUGR fetuses have an increased risk of developing hypertension (HTN) in adulthood, with males having a higher risk. Furthermore, multiple studies suggest that changes in brain function and molecular markers may contribute to HTN development. However, the alterations in brain mitochondrial dysfunction (MtDys), oxidative stress (OS), and epigenetic changes (miRNAs) in forebrain and midbrain collectively have not been investigated. Thus, we hypothesize that the sex difference in high blood pressure (HBP) is due to changes in miRNAs, brain MtDys, and increased OS in IUGR males (M) but not IUGR females (F). To test this hypothesis, IUGR and control (CON) M and F Sprague Dawley rats were evaluated at 16-18 wk (adulthood). IUGR adults were generated from PI dams, and CON adults from normal pregnant dams. Results identified 11 differentially expressed miRNAs in IUGR versus CON, with let-7d-3p miRNA being upregulated in IUGR M. IUGR M also displayed HBP, MtDys [decreased adenosine triphosphate (ATP)], and OS (∼50% increase in hydrogen peroxide). Conversely, mitochondrial G protein elongation factor (GFM-1), a protein regulated by let-7d-3p, and electron transport chain (ETC) proteins were increased with no changes in ATP production in IUGR F. In summary, our data suggest that increases in let-7d-3p will inhibit the compensatory increase in GFM-1 and ETC proteins needed to prevent HBP and cerebral OS in IUGR M. However, unchanged let-7d-3p may increase GFM-1 and ETC proteins in IUGR F to inhibit brain MtDys, OS, and HBP. Findings from this study provide insights into the mechanisms linking epigenetic changes to brain MtDys and OS along with HTN in adults born IUGR.<b>NEW & NOTEWORTHY</b> Adult IUGR male rodent offspring exposed to placental ischemia in utero have elevated mean arterial blood pressure with increased brain miRNA let-7d-3p expression, mitochondrial dysfunction, and oxidative stress, while adult IUGR females do not. Moreover, our results suggest that brain epigenetic changes may contribute to mitochondrial dysfunction and oxidative stress, eventually leading to hypertension. In conclusion, lifetime health begins in utero, and patients and healthcare providers should be aware of the consequences that prenatal stressors have on long-term health.