Browsing by Author "Hart, Savannah"
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Item Early Life Sex Differences and Alterations in Mitochondrial Function in IUGR Offspring after Weaning may Contribute to Adult Sex Differences in Cerebrovascular Dysfunction and Hypertension in Rodents(2024-03-21) Hart, Savannah; Smith, Savanna; Smith, Jonna; Jones, Kylie; Castillo, Angie; Davis, Zandria; Springfield, Alex; Rollings, Alyssa; Narra, Sreeram; Cunningham, MarkBackground: Preeclampsia is a hypertensive pregnancy disorder that usually occurs in the third trimester. Preeclampsia, due to placental ischemia, decreases nutrient and oxygen delivery to the fetus, causing intrauterine growth restriction (IUGR). IUGR increases the risk for chronic conditions such as cerebrovascular dysfunction (CVD) and hypertension (HTN). Human and animal studies show sex differences in CVD and HTN development in IUGR offspring, with males exhibiting a higher prevalence of both. Preliminary data from our lab showed that 17-week-old IUGR male rodents developed CVD, HTN and mitochondrial dysfunction (mtDYS), while IUGR female rodents only developed CVD. The reason for these sex differences is unknown but may be attributed to mtDYS. Although mitochondrial differences appear at 17 weeks, earlier mitochondrial function is unknown. This study investigates changes in mitochondrial function in IUGR offspring after weaning. We hypothesize that mtDYS is elevated in3-week-old IUGR rodent offspring, with greater dysfunction in IUGR males. Methods: Pregnant Sprague Dawley rats were divided into two groups: normal pregnant (NP) and preeclamptic pregnant rats, which underwent reduced uterine perfusion pressure (RUPP) surgery on gestational day 14. RUPP dams gave birth to IUGR offspring, and NP dams gave birth to control (CON) offspring. After 3 weeks of weaning, offspring were separated by sex and dam pregnancy status. Brains were collected from the following groups: IUGR males (n=6), IUGR females (n=6), CON males (n=4), and CON females (n=6) to measure mitochondrial function via respiration, electron transport chain (ETC) protein amounts, and mitochondrial dynamics of fission (DRP-1) and fusion (MFN-1) proteins. Mitochondrial respiration was assessed using the Oroboros Oxygraph O2K. Protein amounts of ETC complexes (I-V), DRP-1, and MFN-1 were quantified using Western blots. Results: 3-week-oldIUGR females had increased cerebral mitochondrial respiration suggested by State 3 (490.41 ± 49.85 vs 257.32 ± 69.76pmol O2/sec/mg; p=0.02) and increased protein amounts of ETC Complex I (135.91 ± 9.27 vs 107.77 ± 4.23IU/Protein/CON%; p=0.02) and Complex III (141.76 ± 13.99 vs 110.43 ± 7.73IU/Protein/CON%; p=0.07). MFN-1 protein amounts (133.42 ± 18.75 vs 84.67 ± 6.89IU/Protein/CON%; p=0.03) and DRP-1 protein amounts (111.31 ± 1.89 vs 95.24 ± 2.14IU/Protein/CON%; p<0.0003) were increased in IUGR compared to CON females. Conversely, 3-week-old IUGR males showed decreased cerebral mitochondrial respiration in Basal state (21.48±5.49 vs 55.79 ± 6.96pmol O2/sec/mg; p=0.03) and State 2 (146.22 ± 25.55 vs 224.70 ± 23.13pmol O2/sec/mg; p=0.13). DRP-1 protein amounts were decreased in IUGR males (85.72 ± 3.07 vs 110.18 ± 1.82IU/Protein/CON%; p=0.02), with no changes in mitochondrial ETC complexes or MFN-1 protein amounts compared to CON males. Conclusion: Early on, IUGR females show mitochondrial function, while IUGR males display mtDYS. Furthermore, the mtDYS in IUGR males at 3 weeks may contribute to HTN development observed in IUGR males and not IUGR females at 17 weeks of age. Future studies are warranted to investigate mtDYS and HTN development in IUGR males and possible protective mechanisms in IUGR females. This study highlights sex differences in cerebral mitochondrial function in prepubescent IUGR offspring, offering insight into the pathophysiology of HTN and CVD development in adulthood, along with suggestions for novel therapeutic targets to prevent HTN and CVD in adult IUGR offspring.Item Elevated Renal Oxidative Stress and Na+ Transporters are Associated with Hypertension in Postpartum Preeclamptic Rats(2024-03-21) Smith, Savanna; Castillo, Angie; Jones, Kylie; Smith, Jonna; Hart, Savannah; Powell, Madison; Cunningham, MarkApproximately 5-10% of US pregnancies result in preeclampsia (PE). PE is characterized by new onset hypertension (HTN) during pregnancy and is usually accompanied by end-organ damage, especially in the kidneys. Postpartum (PP) women and dams that had PE have an increased risk of developing HTN and chronic kidney disease (CKD) later in life. However, mechanisms linking PE to the long-term development of HTN and CKD are unknown. One aspect that may contribute to renal injury in PP PE women and dams is oxidative stress. Elevated concentrations of oxidative stress have been shown to augment the abundance and activity of renal transporters to increase sodium (Na+) reabsorption and blood volume. These alterations in renal transporters can consequently facilitate HTN. We hypothesize that at 6 weeks PP (~3 human years), PE dams will display oxidative stress, renal Na+ transporter abundance, and elevated blood pressure (BP). Pregnant Sprague Dawley rats were assigned to two groups: normal (CON) and PE dams. On gestational day 14, the reduced uterine perfusion pressure surgery was performed to generate a model of PE. Dams gave birth naturally and weaned for 3 weeks. After 6 weeks PP, BP was measured via carotid catheterization, and kidneys were removed and sectioned. Western blots were used to quantify renal Na+ transporters: Na+ K+ 2Cl-transporter (NKCC2) in the kidney medulla (KM) and epithelial Na+ channel (ENaC) in both the kidney cortex (KC) and KM. Oxidative stress was evaluated by heat shock protein 1 (HSP-1), copper zinc superoxide dismutase (CuZnSOD), and manganese superoxide dismutase (MnSOD) via Western blots. Hydrogen peroxide (H2O2) and antioxidant capacity concentrations were assessed via colorimetric assays. PP PE dams had increased BP (126.3±6.18vs105.7±3.74 mmHg, p<0.05) at 6 weeks after birth. KC HSP- 1, H2O2, MnSOD, and antioxidant capacity were unchanged between groups. However, KC CuZnSOD protein abundance was decreased in PP PE dams (69.51±11.64vs100±5.73 IU/Protein/Control%, p<0.05). In the KM, HSP-1 abundance (113.7±3.3vs100±5.07 IU/Protein/Control%, p=0.06) and H2O2 concentrations (1.97±0.11vs1.31± 0.38 nM H2O2/mg Protein, p=0.08) were elevated in PP PE dams. MnSOD, CuZnSOD, and antioxidant capacity were unchanged between groups in the KM. No changes occurred in KC and KM ENaC protein abundance. However, NKCC2 protein abundance was elevated by ~50% in PP PE dams (151.71±22.17vs100±5.59 IU/Protein/Control%, p=0.06). In summary, BP, oxidative stress, and NKCC2 were elevated in PP PE dams at 6 weeks. The presence of oxidative stress in the KM may lead to increased NKCC2 abundance. However, more studies are warranted to make this conclusion. NKCC2 elevation may result in increased Na+ and water reabsorption, leading to an increase in BP. Future studies will assess renal oxidative stress regulation of Na+ transporters in PP PE dams and determine the timeline PP in which changes in oxidative stress, Na+ transporters, and BP occur. This study is clinically relevant, because it indicates oxidative stress and NKCC2 in the KM, separately or together, may have a formative role in the pathogenesis of HTN and CKD in PP PE women later in life.