Angiotensin II Alters Mitochondrial Membrane Potential and Lipid Metabolism in Rat Colonic Epithelial Cells.

An over-active renin-angiotensin system (RAS) is characterized by elevated angiotensin II (Ang II). While Ang II can promote metabolic and mitochondrial dysfunction in tissues, little is known about its role in the gastrointestinal system (GI). Here, we treated rat primary colonic epithelial cells with Ang II (1-5000 nM) to better define their role in the GI. We hypothesized that Ang II would negatively affect mitochondrial bioenergetics as these organelles express Ang II receptors. Ang II increased cellular ATP production but reduced the mitochondrial membrane potential (MMP) of colonocytes. However, cells maintained mitochondrial oxidative phosphorylation and glycolysis with treatment, reflecting metabolic compensation with impaired MMP. To determine whether lipid dysregulation was evident, untargeted lipidomics were conducted. A total of 1949 lipids were detected in colonocytes spanning 55 distinct (sub)classes. Ang II (1 nM) altered the abundance of some sphingosines [So(d16:1)], ceramides [Cer-AP(t18:0/24:0)], and phosphatidylcholines [OxPC(16:0_20:5(2O)], while 100 nM Ang II altered some triglycerides and phosphatidylserines [PS(19:0_22:1). Ang II did not alter the relative expression of several enzymes in lipid metabolism; however, the expression of pyruvate dehydrogenase kinase 2 (PDK2) was increased, and PDK2 can be protective against dyslipidemia. This study is the first to investigate the role of Ang II in colonic epithelial cell metabolism.

Nicotine Exposure during Rodent Pregnancy Alters the Composition of Maternal Gut Microbiota and Abundance of Maternal and Amniotic Short Chain Fatty Acids.

Tobacco smoking is the leading cause of preventable death. Numerous reports link smoking in pregnancy with serious adverse outcomes, such as miscarriage, stillbirth, prematurity, low birth weight, perinatal morbidity, and infant mortality. Corollaries of consuming nicotine in pregnancy, separate from smoking, are less explored, and the mechanisms of nicotine action on maternal-fetal communication are poorly understood. This study examined alterations in the maternal gut microbiome in response to nicotine exposure during pregnancy. We report that changes in the maternal gut microbiota milieu are an important intermediary that may mediate the prenatal nicotine exposure effects, affect gene expression, and alter fetal exposure to circulating short-chain fatty acids (SCFAs) and leptin during in utero development.

Neurotoxicity assessment of QoI strobilurin fungicides azoxystrobin and trifloxystrobin in human SH-SY5Y neuroblastoma cells: Insights from lipidomics and mitochondrial bioenergetics.

Strobilurin fungicides are quinone outside inhibitors (QoI) used to treat fungal pathogens for agricultural and residential use. Here, we compared the potential for neurotoxicity of the widely used strobilurins, azoxystrobin (AZS) and trifloxystrobin (TFS), in differentiated human SH-SY5Y cells. Fungicides did not include cytotoxicity up to 200 µM but both induced loss of cell viability at 48 h, with TFS showing slightly higher toxicity that AZS. Caspase 3/7 activity was induced in SH-SY5Y cells by both fungicides at 48 h (50 µM for AZS and 25 µM for TFS). ATP levels were reduced following a 24-hour exposure to > 25 µM AZS and > 6.25 µM TFS and both fungicides rapidly impaired oxidative respiration (~12.5 µM for AZS and ~3.125 µM TFS) and decreased oligomycin-induced ATP production, maximal respiration, and mitochondrial spare capacity. AZS at 100 µM showed a continual impairment of mitochondrial membrane potential (MMP) between 4 and 48 h while TFS at > 50 µM decreased MMP at 24 h. Taken together, TFS exerted higher mitochondrial toxicity at lower concentrations compared to AZS in SH-SY5Y cells. To discern toxicity mechanisms of strobilurin fungicides, lipidomics was conducted in SH-SY5Y cells following exposure to 6.25 µM and 25 µM AZS, and a total of 1595 lipids were detected, representing 49 different lipid classes. Lipid classes with the largest proportion of lipids detected in SH-SY5Y cells included triglycerides (17%), phosphatidylethanolamines (8%), ether-linked triglycerides (8%), phosphatidylcholines (7%), ether-linked phosphatidylethanolamines (6%), and diacylglycerols (5%). Together, these 5 lipid classes accounted for over 50% of the total lipids measured in SH-SY5Y cells. Lipids that were increased by AZS included acyl carnitine, which plays a role in long chain fatty acid utilization for mitochondrial ß-oxidation, as well as non-modified, ether linked, and oxidized triacylglycerols, suggesting compensatory upregulation of triglyceride biosynthesis. The ceramide HexCer-NS, linked to neurodegenerative diseases, was decreased in abundance following AZS exposure. In summary, strobilurin fungicides rapidly inhibit mitochondrial oxidative respiration and alter the abundance of several lipids in neuronal cells, relevant for understanding environmental exposure risks related to their neurotoxicity.

Translating evidence into practice: Implementing culturally safe continuity of midwifery care for First Nations women in three maternity services in Victoria, Australia.

Background: Strategies to improve outcomes for Australian First Nations mothers and babies are urgently needed. Caseload midwifery, where women have midwife-led continuity throughout pregnancy, labour, birth and the early postnatal period, is associated with substantially better perinatal health outcomes, but few First Nations women receive it. We assessed the capacity of four maternity services in Victoria, Australia, to implement, embed, and sustain a culturally responsive caseload midwifery service. Methods: A prospective, non-randomised research translational study design was used. Site specific culturally responsive caseload models were developed by site working groups in partnership with their First Nations health units and the Victorian Aboriginal Community Controlled Health Organisation. The primary outcome was to increase the proportion of women having a First Nations baby proactively offered and receiving caseload midwifery as measured before and after programme implementation. The study was conducted in Melbourne, Australia. Data collection commenced at the Royal Women's Hospital on 06/03/2017, Joan Kirner Women's and Children's Hospital 01/10/2017 and Mercy Hospital for Women 16/04/2018, with data collection completed at all sites on 31/12/2020. Findings: The model was successfully implemented in three major metropolitan maternity services between 2017 and 2020. Prior to this, over a similar timeframe, only 5.8% of First Nations women (n = 34) had ever received caseload midwifery at the three sites combined. Of 844 women offered the model, 90% (n = 758) accepted it, of whom 89% (n = 663) received it. Another 40 women received standard caseload. Factors including ongoing staffing crises, prevented the fourth site, in regional Victoria, implementing the model. Interpretation: Key enablers included co-design of the study and programme implementation with First Nations people, staff cultural competency training, identification of First Nations women (and babies), and regular engagement between caseload midwives and First Nations hospital and community teams. Further work should include a focus on addressing cultural and workforce barriers to implementation of culturally responsive caseload midwifery in regional areas. Funding: Partnership Grant (# 1110640), Australian National Health and Medical Research Council and La Trobe University.

MEMRI reveals altered activity in brain regions associated with anxiety, locomotion, and cardiovascular reactivity on the elevated plus maze in the WKY vs SHR rats.

Individuals with anxiety/depression often have exaggerated cardiovascular responses to stressful stimuli and a comorbidity with hypertension. Alternatively, individuals with hypertension can be more anxious. In the present study cardiovascular changes were evaluated during behavioral testing of anxious behavior on the elevated plus maze (EPM) in the spontaneously hypertensive rat (SHR), a rodent model of neurogenic hypertension, and compared to the response of the more anxious, but normotensive, Wistar-Kyoto rat (WKY). Manganese-enhanced magnetic resonance imaging (MEMRI) was used to identify regional differences in baseline brain activity. Parallel to indicators of elevated behavioral anxiety on the EPM, WKYs had a greater increase in blood pressure but not heart rate when compared to the SHR while on the EPM. Associated with differences in anxiety-related behavior and autonomic responses, we observed increased baseline activity in the amygdala, central gray, habenula and interpeduncular nucleus with MEMRI of the WKY compared to the SHR. Conversely, elevated baseline brain activity was found in regions associated with blood pressure control and system arousal, including the hypothalamus, locus coeruleus and pedunculopontine tegmental nucleus, in the SHR vs WKY, in-line with increased resting blood pressure and increased mobility in this strain. Lastly, reduced activity in hippocampal regions was identified in the SHR compared to the WKY and may be associated with cognitive impairment previously reported in the SHR. Thus, autonomic reactivity may be a true measure of stress in rodent models of anxiety and MEMRI presents a powerful technique to uncover novel brain mechanisms of blood pressure control.