Leonurus japonicus Houtt. modulates neuronal apoptosis in intracerebral hemorrhage: Insights from network pharmacology and molecular docking.

ETHNOPHARMACOLOGICAL RELEVANCE: Leonurus japonicus Houtt. (Labiatae), commonly known as Chinese motherwort, is a herbaceous flowering plant that is native to Asia. It is widely acknowledged in traditional medicine for its diuretic, hypoglycemic, antiepileptic properties and neuroprotection. Currently, Leonurus japonicus (Leo) is included in the Pharmacopoeia of the People's Republic of China. Traditional Chinese Medicine (TCM) recognizes Leo for its myriad pharmacological attributes, but its efficacy against ICH-induced neuronal apoptosis is unclear. AIMS OF THE STUDY: This study aimed to identify the potential targets and regulatory mechanisms of Leo in alleviating neuronal apoptosis after ICH. MATERIALS AND METHODS: The study employed network pharmacology, UPLC-Q-TOF-MS technique, molecular docking, pharmacodynamic studies, western blotting, and immunofluorescence techniques to explore its potential mechanisms. RESULTS: Leo was found to assist hematoma absorption, thus improving the neurological outlook in an ICH mouse model. Importantly, molecular docking highlighted JAK as Leo's potential therapeutic target in ICH scenarios. Further experimental evidence demonstrated that Leo adjusts JAK1 and STAT1 phosphorylation, curbing Bax while augmenting Bcl-2 expression. CONCLUSION: Leo showcases potential in mitigating neuronal apoptosis post-ICH, predominantly via the JAK/STAT mechanism.

Ginsenosides retard atherogenesis via remodelling host-microbiome metabolic homeostasis.

BACKGROUND AND PURPOSE: Panax ginseng is widely applied in the adjuvant treatment of cardiometabolic diseases in clinical practice without clear mechanisms. This study aims to clearly define the efficacy and underlying mechanism of P. ginseng and its active components in protecting against atherosclerosis. EXPERIMENTAL APPROACH: The anti-atherogenic efficacy of total ginseng saponin extract (TGS) and its components was evaluated on Ldlr-/- mice. Gut microbial structure was analysed by 16S rRNA sequencing and PCR. Bile acid profiles were revealed using targeted metabolomics with LC-MS/MS analysis. The contribution of gut microbiota to atherosclerosis was assessed by co-housing experiments. KEY RESULTS: Ginsenoside Rb1, representing protopanaxadiol (PPD)-type saponins, increased intestinal Lactobacillus abundance, resulting in enhanced bile salt hydrolase (BSH) activity to promote intestinal conjugated bile acid hydrolysis and excretion, followed by suppression of enterohepatic farnesoid X receptor (FXR)-fibroblast growth factor 15 (FGF15) signal, and thereby increased cholesterol 7α-hydroxylase (CYP7A1) transcriptional expression and facilitated metabolic elimination of cholesterol. Synergistically, protopanaxatriol (PPT)-type saponins, represented by ginsenoside Rg1, protected against atherogenesis-triggered gut leak and metabolic endotoxaemia. Ginsenoside Rg1 directly induced mucin production to nutritionally maintain Akkermansia muciniphila, which reciprocally inhibited gut permeation. Rb1/Rg1 combination, rather than a single compound, can largely mimic the holistic efficacy of TGS in protecting Ldlr-/- mice from atherogenesis. CONCLUSION AND IMPLICATIONS: Our study provides strong evidence supporting TGS and ginsenoside Rb1/Rg1 combinations as effective therapies against atherogenesis, via targeting different signal nodes by different components and may provide some elucidation of the holistic mode of herbal medicines.

The mechanism of selenium regulating the permeability of vascular endothelial cells through selenoprotein O.

Vascular diseases, a leading cause of death in human, are strongly associated with pathological damage to blood vessels. The selenoprotein (Sel) have been reported to play important roles in vascular disease. However, the role of SelO in vascular disease has not been conclusively investigated. The present experiment was to investigate the regulatory mechanism of the effect of SelO on the permeability of vascular endothelial. The H.E staining, FITC-Dextran staining, Dil-AC-LDL staining and FITC-WGA staining showed that vascular structure was damaged, and intercellular junctions were disrupted with selenium (Se)-deficient. Immunohistochemistry, qPCR and Western blot revealed decreased expression of the adhesion plaque proteins vinculin, talin and paxillin, decreased expression of the vascular connectivity effector molecules connexin, claudin-1 and E-cadherin and increased expression of JAM-A and N-cadherin, as well as decreased expression of the ZO-1 signaling pathways ZO-1, Rock, rhoGEF, cingulin and MLC-2. In a screening of 24 Sel present in mice, SelO showed the most pronounced changes in vascular tissues, and a possible association between SelO and vascular intercellular junction effectors was determined using IBM SPSS Statistics 25. Silencing of SelO, vascular endothelial intercellular junction adverse effects present. The regulatory relationship between SelO and vascular endothelial intercellular junctions was determined. The results showed that Se deficiency lead to increased vascular endothelial permeability and vascular tissue damage by decreasing SelO expression, suggesting a possible role for SelO in regulating vascular endothelial permeability.

Analysis of the Anti-Tumour Effect of Xuefu Zhuyu Decoction Based on Network Pharmacology and Experimental Verification in Drosophila.

Background: Tumours are among the most lethal diseases that heavily endanger human health globally. Xuefu Zhuyu Decoction (XFZYD) is a prescription used to treat blood-activating stasis. Although XFZYD has been shown to suppress migration and invasion of tumour cells, the active ingredients, potential targets, and underlying mechanism remain largely elusive. Purpose: To identify the prospective ingredients and major targets of XFZYD against tumours, and evaluate the efficacy and potential molecular mechanisms of XFZYD extract on tumour growth and invasion. Methods: We predicted that XFZYD might act on 80 targets through 128 active components using the network pharmacology analysis method. In addition, we prepared an XFZYD aqueous extract and employed the RasV12/lgl -/- -induced Drosophila tumour model to carry out experimental verification. Results: XFZYD did not exhibit any side effects on development, viability, and fertility. Furthermore, XFZYD significantly impeded tumour size and invasion at moderate concentrations and suppressed the increased phosphorylation of JNK but strongly enhanced the expression of Caspase 3 in the RasV12/lgl -/- model. Finally, the mRNA level of the transcription complex AP-1 component c-FOS was remarkably reduced. In contrast, the transcription of three pro-apoptotic genes was significantly increased when XFZYD was used to treat the tumour model. Conclusion: The study findings suggest that XFZYD may promote tumour cell apoptosis by activating caspase signalling to control primary growth and hinder tumour cell invasion by suppressing JNK/AP-1 signalling activity, thus providing a potential therapeutic strategy for XFZYD in the clinical treatment of cancer and other related diseases.

Octreotide-based therapies effectively protect mice from acute and chronic gastritis.

Gastritis is a common inflammation of stomach with multiple pathogenesis. This study was designed to investigate the protective effects of oral octreotide (OCT) against ethanol-induced acute gastric injury and H. pylori-induced chronic gastritis via promoting gastric mucosa restoration, reducing gastric acid secretion and inflammation. Male C57BL/6J mice were randomly divided and treated with three doses of OCT (0.5, 2.5, 10 mg/kg) alone or combined respectively with 10 mg/kg omeprazole (OME), 0.2 g/L metronidazole (MTZ)/0.1 g/L clarithromycin (CLR) in drinking water. Oxidative stress analysis, bacterial load analysis, qPCR, gastric histopathology examinations were performed in our study. Ethanol-induced acute gastric ulcer was restored by OCT alone at doses of 2.5 mg/kg, or combined with OME as indicated by markedly reducing Gastrin, Il-6 and Il1b expression through induction of Muc5ac and Occludin, significantly improving hyperacidity and gastric bleeding. As well, OCT combined with MTZ/CLR restored the integrity of gastric mucosa damaged by H. pylori via elevating the expression of Muc5ac and somatostatin receptor 2, decreasing inflammation and increasing the number of chorionic or glands. Besides, OCT is more suitable for long-term medication in the treatment of chronic gastritis than OME. In conclusion, our results proved that the newly developed oral OCT-based therapies were more effective to reverse gastric mucosa damage and inflammation in ethanol and H. pylori infection-induced gastric injury, it is of great significance for supplementing new clinical regimens for the treatment of acute and chronic gastritis.

LTM-TCM: A comprehensive database for the linking of Traditional Chinese Medicine with modern medicine at molecular and phenotypic levels.

Benefiting from the development of network pharmacology, Traditional Chinese Medicine (TCM) shows great potential in modern drug discovery. Recently, more and more TCM-related databases have been established for both academic and industry research, but they are still insufficient in data standardization, integrity, and precision. To better accelerate the TCM research and overcome these shortcomings, we construct a web-based TCM platform, LTM-TCM, which is currently the most comprehensive TCM database that includes the following advantages: (1) High-quality data integration from fourteen TCM authoritative databases, especially with additional manual collected 41,025 clinical treatment records and 213 ancient Chinese medical books. (2) Accurate correction of multi-source TCM interactions (between symptoms, prescriptions, herbs, ingredients and targets) through in-house Biomedical Natural Language Processing (BioNLP) approaches in more than 30 million articles. (3) Diverse cross-field pipelines (e.g., bioactive ingredients screening, targets prediction, and mechanism prediction, etc.) help integrating traditional medicine with modern science in common aspects at both the molecular and phenotypic levels. In summary, LTM-TCM contains 1928 symptoms, 48,126 prescriptions, 9122 plants, 34,967 ingredients, 13,109 targets and 1170,133 interactions among all TCM related components. LTM-TCM has both Chinese and English interfaces, and it is accessible at http://cloud.tasly.com/#/tcm/home.

Ginsenosides regulation of lysophosphatidylcholine profiles underlies the mechanism of Shengmai Yin in attenuating atherosclerosis.

ETHNOPHARMACOLOGICAL RELEVANCE: The traditional Chinese medicine (TCM) preparation, Shengmai Yin (SMY), is widely applied in cardiovascular disease treatments. However, the pharmacological mechanism of its therapeutic effects has not been fully clarified. AIM OF THIS STUDY: This study aimed to clearly define the efficacy and underlying mechanism of SMY and its active components in protecting against atherosclerosis. MATERIALS AND METHODS: The pharmacological effects of SMY and its components were evaluated upon a mouse hypercholesteremia model induced by a high cholesterol diet (HCD) for 12 weeks and Apoe-/- mice, a mouse atherosclerosis model. Pathological indicators including serum cholesterol levels, cytokines and histological changes in aortic root plaques were assessed. Untargeted metabolomic, untargeted lipidomic and targeted lipidomic changing profiles were investigated to clarify pharmacological mechanisms. RESULTS: SMY and red ginseng crude extracts (GE) significantly decreased the serum cholesterol levels in hypercholesteremia mice and reduced the aortic root plaque areas and exerted antiatherogenic efficacy in Apoe-/- mice. Moreover, total red ginseng saponin extracts (TGS) showed the most apparent improvement on maintaining lipid homeostasis, representing the effects of red ginseng in SMY on atherosclerosis treatment. Mechanically, TGS inhibited serum secreted phospholipase A2 (sPLA2) activity and lowered the serum levels of lysophosphatidylcholine (lysoPC), which is a risk factor for atherosclerosis. CONCLUSIONS: Our findings revealed that ginsenosides from SMY exerted therapeutic effects on atherosclerosis by maintaining lipid homeostasis including cholesterol and lysoPCs.

Effect of Baduanjin exercise on the cognitive function of middle-aged and older adults: A systematic review and meta-analysis.

BACKGROUND: Age-related cognitive decline is a pervasive problem in the ageing population. Baduanjin training is a mind-body exercise with the characteristics of traditional Chinese medicine, and increasing numbers of studies have reported its usefulness in modulating the cognitive performance of various populations. However, no systematic review has evaluated the effect of Baduanjin training on cognition in middle-aged and older adults. OBJECTIVE: To systematically evaluate the effects of Baduanjin on the global cognitive function and specific cognitive domains of middle-aged and elderly people. METHODS: Four literature databases (PubMed, Cochrane library, EMBASE, and Web of Science) and four Chinese databases (Wanfang, China National Knowledge Infrastructure, Chinese Science and Technology Periodical and China Biology Medicine) were searched from inception through May 2020. Randomized controlled trials (RCTs) examining the effect of Baduanjin exercise on the cognitive function of middle-aged and elderly people were included. Assessment of the risk of bias for the included studies and data synthesis were conducted using the software Review Manager 5.3 based on the methods given in the Cochrane Handbook. RESULTS: Baduanjin training showed significant benefit for global cognitive function and parts of specific domains of cognition, including general memory and its sub-domains (i.e., immediate memory and delayed memory), executive function, and processing speed, but no significant difference was found in attention function, visual-spatial ability or long-term memory (a sub-domain of memory). No related adverse events were reported in the included studies. CONCLUSIONS: The findings of this review suggest that Baduanjin is safe and effective in enhancing global cognitive function and memory in middle-aged and older adults and potentially beneficial to parts of the other specific domains of cognition, including executive function and processing speed. However, additional trials with larger sample sizes and a more rigorous design are needed before more definitive conclusions can be drawn.

Optimal exercise parameters of tai chi for balance performance in older adults: A meta-analysis.

BACKGROUND: Tai chi is considered a safe and low-cost treatment for improving balance ability among an older population. However, there is no existing evidence on the optimal exercise parameters of tai chi for improving balance in older adults. OBJECTIVES: To investigate the optimal parameters of a tai chi intervention to improve balance performance of older adults. DESIGN: Systematic review and meta-analysis of randomized controlled trials (RCTs). SETTING: PubMed, Embase, Cochrane Library, Web of Science, Scopus, China National Knowledge Infrastructure, Wanfang, Chinese Science and Technology Periodical and China Biology Medicine were searched from inception until November 30, 2020. PARTICIPANTS: Adults aged 60 years and over. MEASUREMENTS: Two reviewers independently extracted the data and assessed the quality of the included studies according to the Physiotherapy Evidence Database (PEDro) scale. Subgroup analyses and meta-regressions were conducted to elucidate the impact of tai chi training programs on balance measures. RESULTS: Twenty-six eligible RCTs were included in the meta-analysis. Pooled results showed that tai chi has moderate effects for improving proactive balance (weighted mean standardized mean differences [SMDwm ] = 0.61, 95% CI 0.33-0.89) and static steady-state balance (SMDwm  = 0.62, 95% CI 0.30-0.95) and small effects for improving dynamic steady-state balance (SMDwm  = 0.38, 95% CI 0.03-0.73) and balance test batteries (SMDwm  = 0.47, 95% CI 0.13-0.81) in adults over 60 years of age. The practice frequency could predict the effects of tai chi on static steady-state balance, and the 24-form simplified Yang style tai chi (45-60 min/session, more than four sessions per week and at least 8 weeks) was the most optimal. CONCLUSIONS: Tai chi is effective at improving the balance ability of adults over 60 years of age. A medium duration and high frequency of 24-form tai chi may be the optimal program for improving balance, but this evidence should be recommended with caution due to limitations of the methodology and small sample sizes.

The omics based study for the role of superoxide dismutase 2 (SOD2) in keratinocytes: RNA sequencing, antibody-chip array and bioinformatics approaches.

In this study, we aimed to identify critical factors associated with superoxide dismutase 2 (SOD2) in human keratinocytes through gene and protein expression profiling approaches. After recombinant SOD2 was exogenously added to culture media, we conducted serial OMICS studies, which included RNA sequencing analysis, integrated antibody-chip arrays, and the implementation of bioinformatics algorithms, in order to reveal genes and proteins that are possibly associated with SOD2 in keratinocytes. These approaches identified several novel genes and proteins in keratinocytes that are associated with exogenous SOD2. These novel genes included DCT, which was up-regulated, and CD38, GPR151, HCK, KIT, and AFP, which were down-regulated. Among them, CD38 and KIT were also predicted as hub proteins in PPI mappings. By integrating the datasets obtained from these complementary high-throughput OMICS studies and utilizing the strengths of each method, we obtained new insights into the functional role of externally added SOD2 in skin cells and into several critical genes that are thought to play important roles in SOD2-associated skin function. The approach used here could help contribute to our clinical understanding of SOD2-associated applications and may be broadly applicable to a wider range of diseases. AbbreviationsSOD2superoxide dismutase 2DAVIDthe database for annotation, visualization and integrated discoveryKEGGKyoto Encyclopedia of Genes and GenomesPPIprotein-protein interactionsHTSHigh-throughput screeningCommunicated by Ramaswamy H. Sarma.

Protective Effects of Magnesium Glycyrrhizinate on Methotrexate-Induced Hepatotoxicity and Intestinal Toxicity May Be by Reducing COX-2.

Magnesium isoglycyrrhizinate (MgIG), which has been widely employed to treat chronic hepatitis, is synthesized from 18-ß glycyrrhizic acid, a main component of traditional Chinese medicine Glycyrrhiza uralensis Fisch. Although the protective effects of MgIG on methotrexate (MTX)-induced liver toxicity have been well-documented, the underlying mechanism remains elusive. MTX was initially used to treat pediatric acute leukemia, and has been widely applied to psoriasis therapy. However, its clinical applications are limited due to hepatotoxicity and intestinal toxicity. Herein, prophylactic administration of MgIG (9 and 18 mg/kg/day) significantly reduced the levels of aspartate aminotransferase and alanine aminotransferase in the serum of rats receiving intravenous injection of MTX (20 mg/kg body weight). MgIG also attenuated MTX-induced hepatic fibrosis. Moreover, it better protected against MTX-induced hepatocyte apoptosis and decreased the serum level of malondialdehyde than reduced glutathione (80 mg/kg/day) did. Interestingly, MTX-induced cyclooxygenase-2 (COX-2) expression, intestinal permeability and inflammation were attenuated after MgIG administration. In addition, MgIG (9 and 18 mg/kg) reduced MTX-induced colocalization of zonula occludens-1 (ZO-1) and connexin 43 (Cx43) in intestinal villi. In conclusion, MgIG exerted beneficial effects on MTX-induced hepatotoxicity and intestinal damage, as a potentially eligible drug for alleviating the hepatic and intestinal side effects of MTX during chemotherapy.

Zhile Capsule Exerts Antidepressant-Like Effects through Upregulation of the BDNF Signaling Pathway and Neuroprotection.

Major depressive disorder is now becoming a common disease in daily life, and most patients do not have satisfactory treatment outcomes. We herein evaluated the therapeutic effects of Zhile capsule and clarified the molecular mechanism. A rat model of chronic unpredictable mild stress-induced depression was established to assess the antidepressant-like effects of Zhile by using the sucrose preference test, open field test, forced swim test, tail suspension test and HPLC. Systems pharmacology was then performed to unravel the underlying mechanism which was confirmed by western blot, enzyme-linked immunosorbent assay, and qPCR. Zhile alleviated depression-like behaviors by upregulating the cAMP-CREB-BDNF (brain-derived neurotrophic factor) axis to exert neuroprotective effects. It may be beneficial to depressive patients in clinical practice.

Combined host-guest complex with coffee-ring effect for constructing ultrasensitive SERS substrate for phenformin hydrochloride detection in healthcare products.

Phenformin hydrochloride (PHE), once used as a traditional anti-diabetic drug, has now been banned due to significant side effects. However, the phenomenon of the illegal addition of PHE to hypoglycemic healthcare products is still rampant. Thus, the detection of illegally added PHE is urgently needed. Surface-enhanced Raman scattering (SERS) is a promising candidate for this purpose, but the weak affinity between PHE and bare metal (Au or Ag) limits direct SERS detection of PHE. In this paper, we prepared Ag nanoparticles coated with ß-cyclodextrin (AgNP@ß-CD), which display the coffee-ring effect, that can be used for PHE sensing. ß-CD-functionalized nanoparticles could capture the analyte and fix the molecular orientation in the hydrophobic cavity. The coffee-ring effect could improve the SERS effect through a higher concentration of the analyte, higher density of nanoparticles, and more hot spots. The SERS performance of the AgNP@ß-CD substrate was characterized by using o-phenylenediamine dihydrochloride as a probe molecule. The excitation wavelength and pH value were optimized. A linear response for PHE detection is in the 7.0 × 10-8-1.0 × 10-6 mol L-1 concentration range, and the limit of detection is as low as 8.0 × 10-9 mol L-1. This AgNP@ß-CD coffee-ring effect substrate was applied to the detection of PHE in healthcare products, with recoveries between 95.3 and 105.0% and relative standard deviations of less than 5.16%. It is anticipated that the AgNP@ß-CD substrate will also have great potential for the monitoring of other aromatic drugs in healthcare products.

Relationship between Ulcerative Colitis and Lung Injuries.

OBJECTIVE: To explore the relationship between ulcerative colitis (UC) and lung injuries by assessing their clinical manifestations and characteristics. METHODS: From July 2009 to April 2012, 91 UC patients presenting to Longhua Hospital who met the established inclusion and exclusion criteria were enrolled in this retrospective study. According to the scores of disease activity index, the patients were divided into the mild, moderate, and severe groups. Meanwhile, the records of pulmonary symptoms, chest X-ray image, and pulmonary function were reviewed. RESULTS: Sixty-eight (74.7%) patients had at least 1 pulmonary symptom, such as cough (38.5%), shortness of breath (27.5%), and expectoration (17.6%). And 77 (84.6%) had at least 1 ventilation abnormality. Vital capacity value was significantly lower in the severe group than that in the mild group (91.82%±10.38% vs. 98.92%±12.12%, P<0.05). CONCLUSIONS: Lung injury is a common extraintestinal complication of UC. According to the theory in Traditional Chinese Medicine that the lung and large intestine are related, both the lungs and large intestine should be treated simultaneously.

Effects of i.c.v. losartan on the angiotensin II-mediated vasopressin release and hypothalamic fos expression in near-term ovine fetuses.

Our previous studies have shown that central administration of angiotensin (ANG II) causes arginine vasopressin (AVP) release in the fetus at 70-90% gestation. This is evidence that the hypothalamic-neurohypophysial system is relatively mature before birth. However, few data exist regarding central ANG receptor mechanisms-mediated AVP response during fetal life. To determine roles of brain ANG receptor subtypes in this response, AT1 and AT2 receptor antagonists, losartan and PD123319, were investigated in the brain in chronically prepared ovine fetuses at the last third of gestation. Application of losartan intracerebroventricularly (i.c.v.) at 0.5 mg/kg suppressed central ANG II-stimulated plasma AVP release. Losartan at 5 mg/kg (i.c.v.) demonstrated a significant enhancement of AVP increase to i.c.v. ANG II. Associated with the increase of plasma vasopressin levels, c-fos expression in the hypothalamic neurons was significantly different between the low and high doses of losartan. The low dose losartan markedly reduced the dual immunoreactivity for FOS and AVP in the supraoptic nuclei and paraventricular nuclei after i.c.v. ANG II, whereas the high dose losartan together with ANG II, significantly increased the co-localization of positive FOS in the AVP-containing neurons than that induced by i.c.v. ANG II alone. Central ANG II induced fetal plasma vasopressin increase was not altered by PD123319. The data suggest that losartan in the fetal brain has remarkably different effects based on the doses administrated on central ANG II-related neuroendocrine effects at the late gestation, and that the AT1 mechanism is critical in the regulation of fetal body fluid homeostasis related to plasma AVP levels.

Effects of intracerebroventricular losartan on angiotensin II-mediated pressor responses and c-fos expression in near-term ovine fetus.

The renin-angiotensin system plays an important role in cardiovascular control. Intracerebroventricular (i.c.v.) angiotensin (ANG) II causes a reliable pressor response in the fetus at 90% gestation. To determine the roles of brain AT1 and AT2 receptors in this response, the effects of the central AT1 and AT2 receptor antagonists losartan and PD123319 were investigated in chronically prepared near-term ovine fetuses. Losartan at 0.5 mg/kg (i.c.v.) abolished central ANG II-induced pressor responses. High-dose losartan (5 mg/kg, i.c.v.) showed a potentiation of the pressor response to i.c.v. ANG II, accompanied by bradycardia. Associated with the pressor responses, c-fos expression in the cardiovascular controlling areas was significantly different between the low and high doses of losartan. These areas included the subfornical organ, median preoptic nucleus, organum vasculosum of the lamina terminalis, and paraventricular nuclei in the forebrain, and the tractus solitarius nuclei, lateral parabrachial nuclei in the hindbrain. Low-dose losartan markedly reduced c-fos in these areas after i.c.v. ANG II, while the high-dose losartan together with ANG II elicited a much stronger FOS-immunoreactivity in these areas than that induced by i.c.v. ANG II alone. This is a novel finding, that c-fos expression in the brain can be both activated and inhibited under the same condition. Central ANG II-induced fetal pressor responses were not altered by PD123319 (0.8 mg/kg). These results indicate that i.c.v. losartan at a high and a low dose has strikingly different effects on central ANG II-induced pressor responses in fetuses at late gestation, and that the AT1 mechanism plays an important role in fetal cardiovascular regulation.