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Arguelles J, Perillan C, Beltz TG, Xue B, Badaue-Passos D, Vega JA, Johnson AK. The effects of experimental gestational hypertension on maternal blood pressure and fluid intake and pre-weanling hypothalamic neuronal activity. Appetite 2017; 116:65-74. [PMID: 28411128 DOI: 10.1016/j.appet.2017.04.008] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2016] [Revised: 04/07/2017] [Accepted: 04/08/2017] [Indexed: 12/16/2022]
Abstract
To examine the fetal programming effects of maternal hypertension, natriophilia and hyperreninemia [experimentally induced in rats by partial inter-renal aortic ligature (PAL) prior to mating] fos immunoreactivity was studied in 6-day-old offspring of PAL and control mothers. The purposes of the present set of experiments were twofold. The first was to characterize the effects of PAL on the mother's arterial blood pressure and intake of salt (1.8% NaCl solution) and water over the course of gestation. Second, was to study the pattern of neuronal activation in key brain areas of 6-day-old offspring treated with the dipsogen isoproterenol that were from PAL and control mothers. Beta-adrenergic receptor agonist-treated pups allowed the determination whether there were neuroanatomical correlates within the neural substrates controlling thirst and the enhanced water intake evidenced by the isoproterenol treated pups of PAL mothers. Hydromineral ingestive behavior along with blood pressure and heart rate of PAL (M-PAL) and control (M-sPAL) dams throughout gestation was studied. Higher salt and water intakes along with blood pressures and heart rates were found during gestation and lactation in the M-PAL group. Maternal PAL evoked significantly increased isoproterenol-elicited Fos staining in brain regions (e.g. subfornical organ, organum vasculosum of the lamina terminalis, supraoptic nucleus, hypothalamic paraventricular nucleus and median preoptic nucleus) of 6-day-old pups, which is the age of animals shown enhanced thirst responses in PAL offspring. These results indicate that PAL is compatible with pregnancy, producing a sustained increase in blood pressure and heart rate, along with increased water and salt intake. The present study demonstrates that the neural substrates involved in cardiovascular homeostasis and fluid balance in adult rats are responsive in six-day-old rats, and can be altered by fetal programming.
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Affiliation(s)
- Juan Arguelles
- Departamento de Biología Funcional, Área de Fisiología, Facultad de Medicina y Ciencias de la Salud, Universidad de Oviedo, Spain.
| | - Carmen Perillan
- Departamento de Biología Funcional, Área de Fisiología, Facultad de Medicina y Ciencias de la Salud, Universidad de Oviedo, Spain
| | - Terry G Beltz
- Department of Psychological and Brain Sciences, The University of Iowa, Iowa City, IA, 52242, USA
| | - Baojian Xue
- Department of Psychological and Brain Sciences, The University of Iowa, Iowa City, IA, 52242, USA
| | - Daniel Badaue-Passos
- Currently at Departamento de Fisiologia, Centro C. Biológicas e Saúde, Universidade Federal de Sergipe, Sau Cristovao, SE, Brazil
| | - Jose A Vega
- Departamento de Morfologia y Biologia Celular, Universidad de Oviedo, Spain; Facultad de Ciencias de la Salud, Universidad Autónoma de Chile, Santiago de Chile, Chile
| | - Alan Kim Johnson
- Department of Psychological and Brain Sciences, The University of Iowa, Iowa City, IA, 52242, USA
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Hai PV, Schonewille JT, Van Tien D, Everts H, Hendriks WH. Improved acceptance of Chromonaela odorata by goat kids after weaning is caused by in utero exposure during late but not early pregnancy. Appl Anim Behav Sci 2014. [DOI: 10.1016/j.applanim.2014.07.004] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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Mao C, Liu R, Bo L, Chen N, Li S, Xia S, Chen J, Li D, Zhang L, Xu Z. High-salt diets during pregnancy affected fetal and offspring renal renin-angiotensin system. J Endocrinol 2013; 218:61-73. [PMID: 23620529 PMCID: PMC4406098 DOI: 10.1530/joe-13-0139] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Intrauterine environments are related to fetal renal development and postnatal health. Influence of salty diets during pregnancy on renal functions and renin-angiotensin system (RAS) was determined in the ovine fetuses and offspring. Pregnant ewes were fed high-salt diet (HSD) or normal-salt diet (NSD) for 2 months during middle-to-late gestation. Fetal renal functions, plasma hormones, and mRNA and protein expressions of the key elements of renal RAS were measured in the fetuses and offspring. Fetal renal excretion of sodium was increased while urine volume decreased in the HSD group. Fetal blood urea nitrogen was increased, while kidney weight:body weight ratio decreased in the HSD group. The altered ratio was also observed in the offspring aged 15 and 90 days. Maternal and fetal plasma antidiuretic hormone was elevated without changes in plasma renin activity and Ang I levels, while plasma Ang II was decreased. The key elements of local renal RAS, including angiotensinogen, angiotensin converting enzyme (ACE), ACE2, AT1, and AT2 receptor expression in both mRNA and protein, except renin, were altered following maternal high salt intake. The results suggest that high intake of salt during pregnancy affected fetal renal development associated with an altered expression of the renal key elements of RAS, some alterations of fetal origins remained after birth as possible risks in developing renal or cardiovascular diseases.
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Affiliation(s)
- Caiping Mao
- Institute for Fetology and Reproductive Medicine Center, First Hospital of Soochow University, Suzhou 215006, People's Republic of China.
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Shi L, Fan Y, Xu Z. Development of oxytocin- and vasopressin-network in the supraoptic and paraventricular nuclei of fetal sheep. Physiol Res 2012; 61:277-86. [PMID: 22480425 DOI: 10.33549/physiolres.932257] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
The hypothalamic supraoptic and paraventricular nuclei consist of oxytocin and arginine vasopressin synthesizing neurons that send projections to the neurohypophysis. A growing body of evidence in adult animals and young animals at near term confirmed the structure and function in the vasopressinergic and oxytocinergic network. However, whether those distinctive neural networks are formed before near term is largely unknown. This study determined the special patterns in location and distribution of oxytocin- and vasopressin-neurons in the paraventricular and supraoptic nuclei from preterm to term in the ovine fetuses. The results showed that oxytocin- and vasopressin-neurons were present in both nuclei at the three gestational time periods (preterm, near term, and term). In the paraventricular nuclei, vasopressin-cells concentrated mainly in the core of the middle magnocellular paraventricular nuclei, and oxytocin-cells were scattered surrounding the core. In the supraoptic nuclei, vasopressin-cells mostly located in the ventral part, and oxytocin-cells in the dorsal part. The data demonstrated that the special distributed patterns of vasopressin- and oxytocin-neuron network have formed in those two nuclei at least from preterm. Intracerebroventricular injection of angiotensin II significantly increased fetal plasma oxytocin and vasopressin levels at preterm, which was associated with an increase of oxytocin- and vasopressin-neuron activity marked with c-fos expression. The data provided new evidence for the structural and functional development of the oxytocin- and vasopressin-network before birth.
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Affiliation(s)
- L Shi
- Beijing Sport University, Beijing China
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Shi L, Mao C, Zeng F, Zhang L, Xu Z. Central angiotensin I increases swallowing activity and oxytocin release in the near-term ovine fetus. Neuroendocrinology 2012; 95:248-56. [PMID: 22086358 PMCID: PMC3701448 DOI: 10.1159/000332736] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/10/2011] [Accepted: 06/28/2011] [Indexed: 11/19/2022]
Abstract
The brain renin-angiotensin system (RAS) plays an important role in hydromineral and neuroendocrine balance. Although previous studies showed that exogenous angiotensin (Ang) II increased dipsogenic and vasopressin responses in near-term fetuses, little is known about the functional development of fetal endogenous brain RAS in the regulation of body fluid homeostasis. To determine the functional development of the central angiotensin-converting enzyme (ACE) in utero, we investigated the electrocortical (ECoG) activity, swallowing activity, oxytocin (OT) release, and c-fos expression in response to intracerebroventricular Ang I administration in the near-term fetal lamb. Ang I did not change fetal low-voltage (LV) and high-voltage (HV) ECoG temporal distributions, but increased fetal swallowing activity during LV ECoG (1.0±0.1 to 3.5±0.4 swallows/min). Additionally, Ang I evoked an increase in c-fos-immunoreactivity in putative dipsogenic centers, including the supraoptic and paraventricular nuclei of the hypothalamus, accompanied by an increase in fetal plasma OT levels. The expression of c-fos was demonstrated in OT neurons in the hypothalamus. The Ang I-mediated increase in fetal swallowing and plasma OT was inhibited by captopril. These results demonstrate the functional development of the fetal brain ACE system in the last trimester of gestation, which plays an important role in the RAS-mediated dipsogenic response and OT release in the regulation of body fluid homeostasis.
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Affiliation(s)
- Lijun Shi
- Beijing Sport University, Beijing, The First Hospital of Soochow University, Suzhou, PR China
| | - Caiping Mao
- Beijing Sport University, Beijing, The First Hospital of Soochow University, Suzhou, PR China
| | - Fanxing Zeng
- Beijing Sport University, Beijing, The First Hospital of Soochow University, Suzhou, PR China
| | - Lubo Zhang
- Beijing Sport University, Beijing, The First Hospital of Soochow University, Suzhou, PR China
- Center for Perinatal Biology, Loma Linda University School of Medicine, Loma Linda, Calif., USA
| | - Zhice Xu
- Beijing Sport University, Beijing, The First Hospital of Soochow University, Suzhou, PR China
- Center for Perinatal Biology, Loma Linda University School of Medicine, Loma Linda, Calif., USA
- *Zhice Xu, Institute for Fetal-Origin Diseases, The First Hospital of Soochow University, 188 Shizhi Rd., Suzhou 215007 (PR China), Tel. +86 512 6185 9998, E-Mail
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Geng C, Mao C, Wu L, Cheng Y, Liu R, Chen B, Chen L, Zhang L, Xu Z. Cholinergic signal activated renin angiotensin system associated with cardiovascular changes in the ovine fetus. J Perinat Med 2010; 38:71-6. [PMID: 19921993 PMCID: PMC3009554 DOI: 10.1515/jpm.2010.009] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
AIM Cholinergic regulation is important in the control of cardiovascular and endocrine responses. The mechanisms behind cardiovascular responses induced by cholinergic activation are explored by studying hormonal systems, including renin-angiotensin and vasopressin (VP). RESULTS In chronically prepared fetal sheep, intravenous infusion of the cholinergic agonist carbachol increased fetal systolic, diastolic, and mean arterial pressure accompanied with bradycardia at near-term. Although intravenous administration of carbachol had no effect on plasma VP concentrations, this agonist increased angiotensin I and angiotensin II levels in fetal plasma. Fetal blood values, including sodium, osmolality, nitric oxide, hemoglobin, and hematocrit were unchanged by intravenous carbachol. CONCLUSION Cholinergic activation by carbachol controls fetal blood pressure and heart rate in utero. An over-activated fetal renin-angiotensin-system (RAS) is associated with changes in vascular pressure following intravenous administration of carbachol, indicating that the cholinergic stimulation-mediated hormonal mechanism in the fetus might play a critical role in the regulation of cardiovascular homeostasis.
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Affiliation(s)
- Chunsong Geng
- Perinatal Biology Center, Soochow University School of Medicine, Suzhou, China
| | - Caiping Mao
- Perinatal Biology Center, Soochow University School of Medicine, Suzhou, China
| | - Lei Wu
- Perinatal Biology Center, Soochow University School of Medicine, Suzhou, China
| | - Yu Cheng
- Perinatal Biology Center, Soochow University School of Medicine, Suzhou, China
| | - Rulu Liu
- Perinatal Biology Center, Soochow University School of Medicine, Suzhou, China
| | - Bingxin Chen
- Perinatal Biology Center, Soochow University School of Medicine, Suzhou, China
| | - Ling Chen
- Perinatal Biology Center, Soochow University School of Medicine, Suzhou, China
| | | | - Zhice Xu
- Perinatal Biology Center, Soochow University School of Medicine, Suzhou, China
- Center for Prenatal Biology, Loma Linda University School of Medicine, CA 92350, USA
- Corresponding author: Zhice Xu, PhD, Director, Perinatal Biology Center, Soochow University School of Medicine, China, ;
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Zhang Y, Can R, Mao C, Zhang Y, Zhu L, Shao H, Wang L, Wang A, Xu Z. The effect of tanshinone IIA on renal and liver functions in ovine fetusesin utero. Drug Chem Toxicol 2009; 32:362-71. [DOI: 10.1080/01480540903176594] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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Jianli Zheng, Weili Yang, Li Cao, Shigang Li, Yuying Zhang, Zhen Wan, Caiping Mao. Muscarinic effects and foetal cardiovascular and hormonal responses in utero. J Renin Angiotensin Aldosterone Syst 2009; 10:138-46. [DOI: 10.1177/1470320309104866] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Introduction. Cholinergic mechanisms play an important role in the control of hormonal and vascular regulation. However, in utero development of cholinergic regulation in the foetal hormonal systems is not clearly understood.This study investigated foetal hormonal and cardiovascular responses following application of the muscarinic antagonist atropine. Materials and methods. Chronically prepared near-term ovine foetuses (control and experimental: n=5, each group) were used.After 4—5 days’ surgical recovery, conscious ewes and their foetuses were tested in vivo. Results. In response to intravenous atropine, foetal systolic, diastolic, and mean arterial pressure, as well as heart rate, increased immediately. Inhibition of muscarinic systems in the circulation caused a reduction of plasma angiotensin II levels, while angiotensin I in the circulation remained unchanged in the foetus. In addition, foetal plasma aldosterone levels were significantly increased following blockade of the cholinergic receptor, while other hormones, including arginine vasopressin, adrenocorticotrophic hormone, and atrial natriuretic peptide, were not changed in foetal blood under the same condition. Conclusions. The results suggest that foetal automatic systems, not those hormonal factors tested, play a major role in cholinergic mechanisms mediating cardiovascular control. Furthermore, the data provide new information on how muscarinic inhibition affects renin-angiotensin system and adrenal cortex functions. Key words: aldosterone, angiotensin-converting enzyme, autonomic regulation, foetus
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Affiliation(s)
- Jianli Zheng
- Perinatal Biology Centre, Soochow University School of Medicine, Suzhou 215123, People's Republic of China
| | - Weili Yang
- Perinatal Biology Centre, Soochow University School of Medicine, Suzhou 215123, People's Republic of China
| | - Li Cao
- Perinatal Biology Centre, Soochow University School of Medicine, Suzhou 215123, People's Republic of China
| | - Shigang Li
- Perinatal Biology Centre, Soochow University School of Medicine, Suzhou 215123, People's Republic of China
| | - Yuying Zhang
- Perinatal Biology Centre, Soochow University School of Medicine, Suzhou 215123, People's Republic of China
| | - Zhen Wan
- Perinatal Biology Centre, Soochow University School of Medicine, Suzhou 215123, People's Republic of China
| | - Caiping Mao
- Perinatal Biology Centre, Soochow University School of Medicine, Suzhou 215123, People's Republic of China,
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Mao C, Shi L, Xu F, Zhang L, Xu Z. Development of fetal brain renin-angiotensin system and hypertension programmed in fetal origins. Prog Neurobiol 2009; 87:252-63. [PMID: 19428956 DOI: 10.1016/j.pneurobio.2008.12.001] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2008] [Revised: 10/27/2008] [Accepted: 12/16/2008] [Indexed: 11/30/2022]
Abstract
Since the concept of fetal origins of adult diseases was introduced in 1980s, the development of the renin-angiotensin system (RAS) in normal and abnormal patterns has attracted attention. Recent studies have shown the importance of the fetal RAS in both prenatal and postnatal development. This review focuses on the functional development of the fetal brain RAS, and ontogeny of local brain RAS components in utero. The central RAS plays an important role in the control of fetal cardiovascular responses, body fluid balance, and neuroendocrine regulation. Recent progress has been made in demonstrating that altered fetal RAS development as a consequence of environmental insults may impact on "programming" of hypertension later in life. Given that the central RAS is of equal importance to the peripheral RAS in cardiovascular regulation, studies on the fetal brain RAS development in normal and abnormal patterns could shed light on "programming" mechanisms of adult cardiovascular diseases in fetal origins.
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Affiliation(s)
- Caiping Mao
- Perinatal Biology Center, Soochow University School of Medicine, Suzhou 215007, China
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Shi L, Mao C, Zeng F, Zhu L, Xu Z. Central cholinergic mechanisms mediate swallowing, renal excretion, and c-fos expression in the ovine fetus near term. Am J Physiol Regul Integr Comp Physiol 2008; 296:R318-25. [PMID: 19005017 DOI: 10.1152/ajpregu.90632.2008] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Fetal swallowing and renal metabolism contribute importantly to amniotic and body fluid homeostasis. To determine central cholinergic modulation of swallowing activity and renal excretion associated with neural activity, we examined the effects of intracerebroventricular injection of carbachol, a cholinergic agonist, in ovine fetuses at 0.9 gestation. Fetuses were chronically prepared with thyrohyoid, nuchal and thoracic esophagus, and diaphragm electromyogram electrodes, as well as lateral ventricle and vascular catheters. Electrodes were also implanted on the parietal dura for determination of fetal electrocorticogram (ECoG). After 5 days of recovery, fetal swallowing, ECoG, and urine output were monitored during basal period and the experimental period following intracerebroventricular injection of 0.9% NaCl as the control (n = 5) or carbachol (3 microg/kg, n = 5). Central carbachol did not significantly change fetal low voltage (LV) and high voltage (HV) ECoG temporal distributions. However, swallowing activity during LV ECoG was elevated significantly after intracerebroventricular carbachol. Associated with the swallowing activation, c-fos immunoreactivity in the putative dipsogenic center, subfornical organ, was enhanced significantly. The fetal urine flow rate and renal Na+, K+, and Cl(-) excretion were markedly increased following intracerebroventricular carbachol and sustained at the high level for at least 2 h. The results indicate that the central cholinergic mechanism is established and functional in regulation of fetal behavior and renal excretion at least at 0.9 gestation, which plays an important role in maintenance of fetal body fluid homeostasis.
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Affiliation(s)
- Lijun Shi
- Department of Human Sport Science, Beijing Sport University, Beijing, China
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Shi L, Mao C, Zeng F, Zhang Y, Xu Z. Central cholinergic signal-mediated neuroendocrine regulation of vasopressin and oxytocin in ovine fetuses. BMC DEVELOPMENTAL BIOLOGY 2008; 8:95. [PMID: 18828925 PMCID: PMC2570685 DOI: 10.1186/1471-213x-8-95] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/30/2008] [Accepted: 10/02/2008] [Indexed: 11/10/2022]
Abstract
BACKGROUND The hypothalamic-neurohypophysial system plays a fundamental role in the maintenance of body fluid homeostasis by secreting arginine vasopressin (AVP) and oxytocin (OT) in response to a variety of signals, including osmotic and nonosmotic stimuli. It is well established that central cholinergic mechanisms are critical in the regulation of cardiovascular responses and maintenance of body fluid homeostasis in adults. Our recent study demonstrated that intracerebroventricular (i.c.v.) injection of carbachol elicited an increase of blood pressure in the near-term ovine fetuses. However, in utero development of brain cholinergic mechanisms in the regulation of the hypothalamic neuropeptides is largely unknown. This study investigated AVP and OT neural activation in the fetal hypothalamus induced by central carbachol. RESULTS Chronically prepared near-term ovine fetuses (0.9 gestation) received an i.c.v. carbachol (3 microg/kg). Fetal blood samples were collected for AVP and OT assay, and brains were used for c-fos mapping studies. I.c.v. carbachol significantly increased fetal plasma AVP and OT concentrations. Intense FOS immunoreactivity (FOS-ir) was observed in the fetal supraoptic nuclei (SON) and paraventricular nuclei (PVN) in the hypothalamus. Double labeling demonstrated that a number of AVP- and OT-containing neurons in the fetal SON and PVN were expressing c-fos in response to central carbachol. CONCLUSION The results indicate that the central cholinergic mechanism is established and functional in the regulation of the hypothalamic neuropeptides during the final trimester of pregnancy. This provides evidence for a functional link between the development of central cholinergic mechanisms and hypothalamic neuropeptide systems in the fetus.
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Affiliation(s)
- Lijun Shi
- Perinatal Biology Center, Soochow University School of Medicine, Suzhou 215007, PR China.
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Guan J, Mao C, Feng X, Zhang H, Xu F, Geng C, Zhu L, Wang A, Xu Z. Fetal development of regulatory mechanisms for body fluid homeostasis. Braz J Med Biol Res 2008; 41:446-54. [DOI: 10.1590/s0100-879x2008005000025] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2008] [Accepted: 04/14/2008] [Indexed: 11/22/2022] Open
Affiliation(s)
- J. Guan
- Soochow University School of Medicine, China; Bengbu Medical College, China
| | - C. Mao
- Soochow University School of Medicine, China
| | - X. Feng
- Soochow University School of Medicine, China
| | - H. Zhang
- Soochow University School of Medicine, China
| | - F. Xu
- Soochow University School of Medicine, China
| | - C. Geng
- Soochow University School of Medicine, China
| | - L. Zhu
- Soochow University School of Medicine, China
| | - A. Wang
- Soochow University School of Medicine, China
| | - Z. Xu
- Soochow University School of Medicine, China; Loma Linda University School of Medicine, USA
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Xu Z, Shi L, Yao J. Central angiotensin II-induced pressor responses and neural activity in utero and hypothalamic angiotensin receptors in preterm ovine fetus. Am J Physiol Heart Circ Physiol 2003; 286:H1507-14. [PMID: 14684369 DOI: 10.1152/ajpheart.00764.2003] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The central renin-angiotensin system is important in the control of blood pressure in the adult. However, few data exist about the in utero development of central angiotensin-mediated pressor responses. Our recent studies have shown that the application of ANG II into the fetal brain can increase blood pressure at near term. The present study determined fetal blood pressure and heart rate in response to a central application of ANG II in the chronically prepared preterm ovine fetus, determined the action sites marked by c-Fos expression in the fetal central pathways after intracerebroventricular injection of ANG II in utero, and determined angiotensin subtype 1 receptors in the fetal hypothalamus. Central injection of ANG II significantly increased fetal mean arterial pressure (MAP). Adjusted fetal MAP against amniotic pressure was also increased by ANG II. Fetal heart rate was subsequently decreased after the central administration of ANG II and/or the increase of blood pressure. ANG II induced c-Fos expression in the central putative cardiovascular area, the paraventricular nuclei in the brain sympathetic pathway. Application of ANG II also caused intense Fos immunoreactivity in the tractus solitarius nuclei in the hindbrain. In addition, intense angiotensin subtype 1 receptors were expressed in the hypothalamus at preterm. These data demonstrate that central ANG II-related pressor centers start to function as early as at preterm and suggest that the central angiotensin-related sympathetic pathway is likely intact in the control of blood pressure in utero.
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Affiliation(s)
- Zhice Xu
- Harbor-University of California Los Angeles Medical Center, (UCLA), Harbor-UCLA Medical Center, Torrance, CA 90502, USA.
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Shi L, Hu F, Morrissey P, Yao J, Xu Z. Intravenous angiotensin induces brain c-fos expression and vasopressin release in the near-term ovine fetus. Am J Physiol Endocrinol Metab 2003; 285:E1216-22. [PMID: 12933353 DOI: 10.1152/ajpendo.00289.2003] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The effect of intravenous angiotensin II (ANG II) on fetal brain c-fos expression and arginine vasopressin (AVP) release was studied in the near-term ovine fetus. Fetuses with chronically implanted catheters received an intravenous infusion of ANG II or saline. Fetal plasma AVP concentrations were significantly increased after the peripheral administration of ANG II, with peak levels (3-fold) at 30 min after the intravenous infusion. There was no change in fetal plasma osmolality, sodium, and hematocrit levels between the control and experimental groups or between the periods before and after the infusion of ANG II. Intravenous ANG II administration induced Fos immunoreactivity (Fos-IR) in the circumventricular organs and the median preoptic nucleus of the fetal brain. Fos-IR was also demonstrated in the fetal supraoptic nuclei (SON). Double labeling demonstrated that the AVP-containing neurons in the SON were expressing c-fos in response to intravenous ANG II. These results indicate that the peripheral ANG II in the fetus may play a significant role in stimulating the central hypothalamic-neurohypophysial system during late gestation. It supports the hypothesis that circulating ANG II may act at the fetal AVP neurons in the hypothalamus in body fluid balance via the circumventricular organs, which are situated outside the blood-brain barrier, and the central neural pathway between these two brain structures has been relatively established in utero, at least at near-term.
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Affiliation(s)
- Lijun Shi
- Department of Obstetrics and Gynecology, Harbor-UCLA Medical Center and Research and Education Institute, Torrance, California 90502, USA
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Caston-Balderrama A, Nijland MJ, McDonald TJ, Ross MG. Intact osmoregulatory centers in the preterm ovine fetus: Fos induction after an osmotic challenge. Am J Physiol Heart Circ Physiol 2001; 281:H2626-35. [PMID: 11709432 DOI: 10.1152/ajpheart.2001.281.6.h2626] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We previously demonstrated a functional systemic dipsogenic response in the near-term fetal sheep (128-130 days; 145 days = full-term) with swallowing activity stimulated in response to central and systemic hypertonic saline. Preterm fetal sheep (110-115 days) do not consistently demonstrate swallowing in response to hypertonic stimuli, and it is unclear whether this is due to immaturity of osmoreceptor mechanisms or neuronal pathways activating swallowing motor neurons. To determine whether osmoreceptive regions in the preterm fetus are activated by changes in plasma tonicity, we examined Fos expression with immunostaining in these neurons in response to an osmotic challenge. Nine preterm fetal sheep [five hypertonic saline-treated fetuses (Hyp) and four isotonic saline-treated fetuses (Iso)] were prepared with vascular and intraperitoneal catheters. Seventy-five minutes before tissue collection, hypertonic (1.5 M) or isotonic saline was infused (12 ml/kg) via an intraperitoneal catheter to fetuses. Brains were examined for patterns of neuronal activation (demonstrated by Fos protein expression). Hyp demonstrated increases in plasma osmolality (~10 mosmol/kg H(2)O) and Na concentrations (5 meq/l). Increased Fos expression was detected in Hyp in the organum vasculosum of the lamina terminalis (OVLT), subfornical organ (SFO), median preoptic nucleus (MnPO), supraoptic (SON), and paraventricular nuclei (PVN) compared with Iso animals. Neuronal activation within the OVLT, SFO, and MnPO indicates intact osmoregulatory mechanisms, whereas activation of the SON and PVN suggests intact fetal neural pathways to arginine vasopressin neurons. These results suggest that preterm fetal swallowing insensitivity to osmotic stimuli may be due to immaturity of integrated motor neuron pathways.
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Affiliation(s)
- A Caston-Balderrama
- Perinatal Research Laboratory, Department of Obstetrics and Gynecology, Harbor-University of California Los Angeles Medical Center, Torrance, California 90502, USA
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