Browsing by Author "Powell, Madison"
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Item Changes in Cerebral Mitochondrial Function in Postpartum Dams Exposed to a Low-resource Environment during Weaning(2024-03-21) Jones, Kylie; Smith, Savanna; Smith, Jonna; Castillo, Angie; Powell, Madison; Cunningham, MarkBackground: Postpartum depression is a serious mental-health condition, affecting over 14% of all mothers in the U.S. Poverty, a lack of educational and economic resources, is a major determinant of adult mental health. In the U.S., poverty impacts 11% of adults, with a greater incidence in women of childbearing age (roughly 16%) and postpartum women (roughly 14%). While pregnancy and poverty separately increase risks of developing depression, few studies have combined these conditions to determine their role in the development of depression. Further, no studies have explored mechanisms contributing to depression following pregnancy and poverty. However, cerebral mitochondrial dysfunction (C-mtDys) may be one mechanism. The aim of this study is to examine C-mtDys in postpartum (PP) dams exposed to the limited-bedding-nesting (LBN) model in rats, which reduces their nesting material to simulate a low-resource environment. We hypothesize that PP dams in the LBN model will exhibit C-mtDys and elevated oxidative stress. Methods. Pregnant Sprague-Dawley rats gave birth naturally and were divided randomly into LBN (n =2) or control (n = 2) groups. LBN dams were exposed to the LBN model from PD 2 through PD 9. To validate the success of the LBN model, entropy scores, which are a measure of behavior unpredictability, were recorded for each dam. At 17 weeks PP, equivalent to 8 years PP in humans, brains were collected and used to isolate mitochondria through differential centrifugation. Mitochondrial function was evaluated via respiration (mtRes) using respiratory states. Oxidative stress in the whole brain was examined through H2O2 and total antioxidant capacity biochemical assays. Results. LBN PP dams displayed higher entropy scores (1.10 ± 0.04 v. 0.79 ± 0.04, p < 0.05), as expected based on prior literature, serving as validation of the model. At 17 weeks, PP LBN dams had reduced mtRes in all states, including the basal state (176.09 ± 5.90 v. 360.70 ± 7.73 pmol/s/mg, ns), State 2 (1044.72 ± 14.00 v. 1703.00 ± 18.10 pmol/s/mg, ns), State 3 (3843.27 ± 31.86 v. 6705.72 ± 37.54 pmol/s/mg, ns) and State 4 (776.83 ± 13.65 v. 1533.54 ± 16.46 pmol/s/mg, ns). PP LBN dams exhibited reduced total antioxidant capacity by roughly 20% (54.10 ± 1.24 v. 63.04 ± 0.99 mM Trolox) and elevated H2O2 by roughly 50% (2.12 ± 0.52 v. 1.35 ± 0.28 nM/mg, ns). Summary. In summary, preliminary data shows C-mtDys via reduced mtRes in PP dams exposed to an impoverished environment during weaning. Furthermore, this study suggests that decreased mtRes could contribute to increased oxidative stress in the brain. Elevated oxidative stress may cause damage at the cellular and circuitry levels in the brain that could facilitate the development of depression later in life. Future studies will further examine C-mtDys, oxidative stress, and depressive behaviors in PP dams exposed to LBN. This study is significant because it identifies C-mtDys as a possible mechanism causing depression after exposure to both pregnancy and poverty.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.Item A new rodent model of preeclampsia: Pregnant daughters from hypertensive placental ischemic moms have hypertension(2023) Smith, Jonna; Powell, Madison; Cromartie, Whitney; Smith, Savanna; Jones, Kylie; Castillo, Angie; Wiemann, Natalia; McCafferty, Adair; Owen, Malissa; Srivastava, Prakriti; Cunningham, MarkPurpose: Studies show that daughters from hypertensive pregnancies are twice as likely to have preeclampsia (PE), pregnancy-induced hypertension (HTN) in comparison to women born from a normal pregnancy. PE affects ~5-10% of all births in the USA and is the leading cause of intrauterine growth restriction (IUGR). PE is associated with oxidative stress (OS) and cerebral damage. The causes of PE are unknown but is influenced by genetic and environmental conditions. Studies show that pregnancies involving placental insufficiency and HTN create an adverse environment that can affect the IUGR baby’s developmental programming and pregnancy outcomes. This study aims to characterize the pregnancy of IUGR rat offspring from hypertensive placental ischemic moms. We hypothesize female rats born from pregnant hypertensive placental ischemic moms will have elevated blood pressure (BP) and OS. Methods: Pregnant Sprague Dawley moms are divided into 2 groups: normal pregnant (NP) and the reduced uterine perfusion pressure (RUPP) hypertensive placental ischemic rats. On day 14 of pregnancy, the RUPP surgery is performed to generate PE. All dams (NP and RUPP) give birth naturally and weaned for 3 weeks. Offspring were then separated by sex and mother’s pregnancy status. ~10 weeks later, offspring were mated according to 4 groups: ♀NP x ♂NP (CON Preg, n=3), ♀NP x ♂RUPP (n=2), ♀RUPP x ♂NP (IUGR Preg, n=5), ♀RUPP x ♂RUPP (n=4). On day 19 of offspring pregnancy, BP was measured via carotid catheterization and the blood and brains were collected for analyses. Results: IUGR Preg rats have elevated BP (116 ± 4.17 vs 100.6 ± 2.54 mmHg, p<0.02) and 8-isoprostanes (439.2 ± 13.61 vs 381.3 ± 26.10 g, ns), decreased circulating antioxidant capacity (AC) (0.33 ± 0.01 vs. 0.37 ± 0.01 mM Trolox/mg protein, p<0.01), and reduced body weight (330.1 ± 5.24 vs 350.3 ± 10.82 g, ns) compared to CON Preg rats. IUGR Preg rats have larger brains, suggesting brain swelling (5.38 ± 0.10 vs 4.95 ± 0.19 g/1000g BW, p<0.04). HSP-1 (186.1 ± 28.14 vs 100.0 ± 6.36 %HSP-1/protein/CON, p<0.04) and H2O2 (25.76 ± 2.95 vs 15.81 ± 4.56 μM/mg protein, ns), markers of ROS, are increased in the brains of IUGR Preg vs. CON Preg rats. Cerebral AC was slightly reduced (260.0 ± 33.14 vs 292.3 ± 13.91 uM Trolox/mg protein) and MnSOD (antioxidant) amounts were decreased (87.96 ± 3.43 vs 100.0 ± 2.84 %MnSOD/protein/CON, p<0.63). Conclusion: IUGR Preg rats have increased systemic and cerebral OS, as well as larger brain sizes which may lead to cerebral damage. In summary, pregnant daughters from hypertensive placental ischemic moms show symptoms of a preeclamptic-like phenotype, thus creating a new model of PE. Future studies will determine the role of maternal PE status and OS in the development of HTN in pregnant IUGR offspring.Item Offspring of hypertensive placental ischemia rats have hypertension and mitochondrial dysfunction during pregnancy(2022) Powell, Madison; Cromartie, Whitney; Smith, Jonna; Cunningham, MarkPurpose: Preeclampsia is a pregnancy complication commonly observed in the third trimester of pregnancy and is often characterized by hypertension, placental ischemia, and Intrauterine growth restriction (IUGR), also referred to as fetal growth restriction. The causes of IUGR vary but are associated with maternal hypertension and placenta abnormalities. Clinical studies show that IUGR daughters of women with preeclampsia have an increased risk of developing hypertensive pregnancies, such as preeclampsia. Common factors associated with the pathophysiology of preeclampsia are systemic and tissue mitochondrial dysfunction, endothelial cell dysfunction, inflammation, and oxidative stress. Previous studies from our laboratory show that pregnant IUGR rats, derived from our reduced uterine perfusion pressure preclinical rodent model of preeclampsia (RUPP), develop hypertension during their own pregnancies along with an increase in brain size and systemic oxidative stress. However, the role of end-organ mitochondrial dysfunction has not been explored and is the focus of this study. We hypothesize that brain, heart, and kidney mitochondrial dysfunction will be present in pregnant IUGR rats. Methods: To measure mitochondrial dysfunction in the brain, heart, and kidney tissue, we will perform western blots on manganese superoxide dismutase (MnSOD), a mitochondrial specific antioxidant, and mitochondrial electron transport chain (ETC) complexes I-V in both normal pregnant (CON) and IUGR pregnant rats. Results: MnSOD protein abundance was decreased in the brain of IUGR vs CON pregnant rats (88±3 vs 100±3 % IU/Protein/CON, p= 0.05). No differences were observed in the heart and kidney of IUGR and CON pregnant rats. Brain mitochondrial complexes II (144±14 vs 100±5 % IU/Protein/CON, p< 0.05), III (119±7 vs 100±2 % IU/Protein/CON, p= 0.06), and V (125±3 vs 100±4 % IU/Protein/CON, p< 0.01) were increased in IUGR vs CON pregnant rats, and no changes were observed in the heart. However, kidney mitochondrial complexes III (84±3 vs 100±0.3 % IU/Protein/CON, p< 0.05) and V (87±2 vs 100±1 % IU/Protein/CON, p< 0.05) were decreased in IUGR vs CON pregnant rats. Conclusions: Pregnant IUGR rats have hypertension and renal mitochondrial dysfunction. The decreased amount of brain specific mitochondrial antioxidants in IUGR pregnant rats may contribute to elevated systemic and local oxidative stress. The increase in ETC mitochondrial proteins in brain may be a compensatory mechanism to increase mitochondrial function in the swelling brain. Furthermore, the increase in ETC function in the brain may also increase mitochondrial reactive oxygen species levels, which may not be able to be quenched due to the decrease in brain mitochondrial antioxidants. Nevertheless, the increase in brain mitochondrial ETC proteins warrants further investigation. In conclusion, rather or not the increase in end-organ mitochondrial dysfunction is a cause or consequence of hypertension in pregnant IUGR rats is unknown? Future studies will be designed to address this question.Item Renal Oxidative Stress May Explain Sex Differences in Blood Pressure in Adult Offspring Exposed to an Impoverished Environment(2024-03-21) Castillo, Angie; Smith, Savanna; Smith, Jonna; Jones, Kylie; Powell, MadisonNearly 40 million people experience poverty in the U.S. Poverty is linked to adverse childhood experiences (ACEs) which affects ~64% of adults in the U.S. Previous studies indicate that those who experience ACEs are at a higher risk of developing hypertension (HTN) and cardiovascular diseases (CVDs) later in life, with a greater severity and earlier onset in males. The mechanisms behind the ACEs-attributed development of sex differences in HTN later in life is unknown. One plausible mechanism for this sex difference is increased oxidative stress. One rodent model to mimic poverty as an ACE is the limited bed and nesting (LBN) model. This model simulates an impoverished and low resource environment, as observed in poverty, in which the nesting material during weaning is reduced. We hypothesize that male offspring exposed to LBN will have elevated blood pressure and oxidative stress, while females will have no change in blood pressure and reduced oxidative stress. Pregnant Sprague Dawley rats gave birth naturally and weaned their offspring for 3 weeks. During the weaning period, on Days 2-9, the dams and their respective pups were divided into 2 groups: LBN and control (CON). After LBN treatment, all rats received normal bedding. After weaning, offspring were divided by sex and experimental status: LBN male (n=5), LBN female (n=5), CON male (n=6), and CON female (n=6). At 16-17 weeks, mean arterial pressure (MAP) was measured via carotid catheterization and the kidneys, brain, heart, and plasma were collected to measure antioxidant capacity (AC) via colorimetric biochemical assays. LBN males had a significant increase (18 mmHg) in MAP compared to CON males (128.17±3.93 vs 110.72± 3.93 mmHg, P>0.001), while female LBN and CON rodents displayed no differences. In males, there were no changes in antioxidant capacity in the brain, heart, and plasma. However, there was a significant 2-fold decrease in renal antioxidant capacity (233±14.0 vs 442±12.3 mM Trolox/mg protein, p>0.0001). In females, there were no changes in the kidneys, heart, and brain antioxidant capacity. Conversely, LBN females showed a trending increase in plasma antioxidant capacity compared to CON (3.33±0.16 vs 2.53±0.35 mM Trolox/mg protein, p=0.053). Males exposed to an impoverished environment during weaning have elevated blood pressure, while females do not. This difference in blood pressure may be explained by decreases in renal AC in males only. On the other hand, females may be protected from elevated blood pressure because they experience a slight increase in systemic AC. Future studies will examine the role of antioxidants in blood pressure regulation in the kidneys. This is clinically relevant because ACEs affect a large percentage of the American population with ~17% of adults experiencing 4 or more ACEs, with minorities at a greater risk. Understanding the mechanisms on how ACEs contribute to HTN may alleviate some of the racial and ethnic disparities for people with HTN and CVDs. Perhaps, organ and sex-specific antioxidant therapies may prevent or reduce the development of HTN in adults that were exposed to ACEs, like poverty during childhood.Item Sex differences in cerebrovascular dysfunction and hypertension in offspring of hypertensive pregnant rats(2022) Smith, Jonna; Powell, Madison; Cromartie, Whitney; Cunningham, Mark; Duncan, JeremyPURPOSE: Offspring from preeclamptic women have a greater risk of hypertension and cerebrovascular dysfunction later in life. One of the major contributors of cerebrovascular dysfunction is impaired cerebral blood flow (CBF) autoregulation. In the USA, 1 in 25 pregnancies are preeclamptic. Preeclampsia, as defined as new-onset hypertension during pregnancy, is an inflammatory condition characterized by elevated interleukin 17 (IL-17), mitochondrial reactive oxygen species (mtROS), mitochondrial dysfunction (mt-Dys), and intrauterine growth restriction (IUGR). Preliminary work from our laboratory demonstrates that offspring from preeclamptic rats have sex differences. Males have hypertension and a greater impairment of CBF autoregulation, while females have no change in blood pressure with impaired CBF autoregulation. The exact mechanisms for the sex differences in cerebrovascular dysfunction and hypertension is unknown and is the focus of this study. We hypothesize that changes in cerebral mt-dys, cerebral mtROS, and circulating IL-17 contributes to the sex differences in hypertension and cerebrovascular dysfunction in male and female offspring from preeclamptic rats. METHODS: In this study, we compared male and female offspring from normal pregnant and preeclamptic Sprague Dawley rats. All offspring were divided into controls (CON) and IUGR by sex. Hypertensive male and non-hypertensive female offspring's with impaired CBF autoregulation were examined at 17 weeks of age for changes in cerebral mitochondrial electron transport chain (ETC) protein complexes, cerebral manganese superoxide dismutase (MnSOD), and circulating IL-17. RESULTS: Female CON (151±5% IU/Protein/male CON) and IUGR (149±8 %IU/Protein/male CON) offspring have increased MnSOD compared to CON (100±7 %IU/Protein/male CON) and IUGR (122±4 %IU/Protein/male CON) males (p< 0.05). No changes in female ETC protein complexes between IUGR and CON. Male IUGR have a decrease in complex II (71±5 vs. 100±8 %IU/Protein/male CON, p< 0.05) and V (57±2 vs. 100±10 %IU/Protein/male CON, p< 0.05) ETC proteins, and elevated IL-17 (944±370 vs. 412±115 pg/mL, ns) compared to CON males. CONCLUSION: Male IUGR offspring have mt-Dys and elevated IL-17, which may contribute to hypertension and a greater impairment in CBF autoregulation. Female IUGR offspring may be protected due to an increase in mitochondrial antioxidants. In summary, studying the dimorphic sex differences in the mechanisms of hypertension and cerebrovascular dysfunction in offspring of preeclamptic women, may improve the offspring's risk of hypertension, cardiovascular disease, stroke, and cognitive dysfunction later in life.