Electrophysiologic and Molecular impacts of three preeclampsia pre-clinic models on vasopressin-producing magnocellular neurons

• Grant number: 24/09501-7
• Support Opportunities: Scholarships in Brazil - Post-Doctoral
• Start date: January 01, 2025
• End date: December 31, 2027
• Field of knowledge: Health Sciences - Medicine - Maternal and Child Health
• Principal Investigator: Andre de Souza Mecawi
• Grantee: Anne Caroline Silva Barbosa
• Host Institution: Escola Paulista de Medicina (EPM). Universidade Federal de São Paulo (UNIFESP). Campus São Paulo. São Paulo , SP, Brazil
• Associated research grant: 19/27581-0 - Control of vasopressin secretion in pregnancy and its implications in pathophysiology of Preeclampsia, AP.JP

Abstract

Among the hypertensive disorders of pregnancy, pre-eclampsia (PE) is the one most associated with highmorbidity and mortality, as fetal suffering and complications occur in various organs. This fact is observedworldwide and, although it majorly affects women of advanced gestational age, young people in peripheralfinancial conditions are also vulnerable to such complications. Although PE has been known and diagnosedfor decades, the mechanism by which it is directly activated and a way to prevent its complications are stillunknown. Studies suggest that such maternal and fetal PE complications arise due to the production of thehormone arginine vasopressin (AVP), produced by the hypothalamus and released into the bloodstream bythe neurohypophysis. At the same time, PE would stimulate the production of AVP, resulting in increasinglysevere complications for both the pregnant woman and fetus. There are several animal models of PE,especially in rodents. Each model has different characteristics of the disease and there is no conclusionabout the ideal model. In this study, we hypothesize that in different animal models of pre-eclampsia, thehyperactivity of magnocellular neurons in the supraoptic nucleus culminates in intense vasopressinsecretion. Our specific aims are to 1) Validate the induction of PE in mice subjected to different animalmodels of this syndrome; 2) Compare biochemical analyzes and the expression of genes and proteinsrelated to vasopressin signaling in the kidneys, placentas and fetuses of animals subjected to PE models;3) Evaluate variations in the electrophysiological activity of vasopressin and the osmotic threshold inmagnocellular neurons of the supraoptic nucleus of these animals. Using transgenic mice that havefluorescent AVP-producing neurons, we will evaluate the impacts of three animal models of PE onelectrophysiological activity, specifically of AVP-producing magnocellular neurons. Models are based oninhibition of the enzyme nitric oxide synthase (L-NAME model), salt overload (SS, intake of 2.7% NaCl) andthe model of placental ischemia by ligation of the uterine artery (RUPP model). Blood pressure of the animalswill be measured by telemetry throughout the study and euthanasia will be carried out in three distinctperiods, in order to observe the production of AVP at the beginning, middle and end of the protocols. Bloodand urine will be collected to measure AVP and mineral markers, as well as to analyze proteinuria. At thesame time, the kidneys and placentas will be collected, weighed, and will undergo morpho functionalanalyzes that, will include RNA extraction, tissue polymerase chain reaction, protein measurement usingthe Western blot technique, and morphological analysis through hematoxylin and eosin staining. The brainswill be collected and slices containing the supraoptic nuclei will be used for electrophysiological analysis ofmagnocelular neurons to observe variations in AVP activity and gene expression changes though singlecellPCR. In collaboration with Dr. David Murphy's lab in Bristol (UK), we will also perform the RNAsequencing from the kidneys and placentas of the studied animals. The success of this proposal willguarantee advancement in knowledge about the pathophysiology of PE and in-depth knowledge of thehypothalamic neuro-pituitary system and its implications for the syndrome, which could bring hope to womenat more advanced gestational age as well as reduce maternal and infant morbidity and mortality after a PEdiagnosis.