Highlights ► Agtr1a BAC transgenic mice express cells with angiotensin 1A receptors with fidelity. ► In Agtr1a BAC transgenic mice, labeled cells are prominent in brain autonomic regions. ► Labeled ...cells from these mice are suitable for anatomical and physiological studies.
Highlights • The BPH/5 preeclamptic-like mouse exhibits an overall reduction in decidual macrophages • Loss of decidual macrophages is concurrent with a decrease in the immunosuppressive cytokine ...IL-10 and increased iNOS. • Loss of immune suppression in BPH/5 decidua is associated with increases in activated T cells.
The recent miniaturization of implantable radiotelemetric devices offers the possibility of an accurate, reliable, and simple phenotyping tool for long-term, hands-off measurement of blood pressure ...in unrestrained, untethered mice; however, use has been limited because of high morbidity and mortality in all but larger-than-average mice. Also, because the device was developed for abdominal aorta implantation at the renal artery level, its use has not been feasible in studies where infrarenal blood flow is critical, i.e., in pregnant mice. We provide details of a very successful alternative approach for implanting radiotelemeters in mice, whereby thoracic aortic implantation of the pressure-sensing catheter is combined with subcutaneous placement of the transmitter body along the right flank. We used female C57/BL6 (C57) or BPH/5 mice, a strain derived from the cross of inbred hypertensive and hypotensive mouse strains. We show that this is a reliable procedure for providing high-fidelity mean arterial pressure (MAP) and heart rate (HR) recordings for 50-60 days in mice weighing 22 g on average but as small as 17 g. No morbidity or mortality was observed in either strain using this procedure. Importantly, neither strain fully recovered from anesthesia and surgery, as indicated by a return of normal circadian rhythms, until 5-7 days postsurgery. This was also reflected in significantly elevated baseline MAP and HR levels in both strains during this recovery period. Moreover, strain-related differences in relative increases in MAP during the first 5 days of recovery masked the significant elevation in BPH/5 baseline MAP (vs. C57) observed in fully recovered mice. This suggests that methods must allow at least 5-7 days recovery from surgery to provide accurate cardiovascular (CV) phenotyping in mice. Finally, we show that CV parameters can be monitored continuously before, during, and after pregnancy in mice using this alternative implantation approach. The device did not interfere with conception, gestation, delivery, or postnatal care of pups. These results demonstrate the feasibility of stress-free, long-term monitoring of CV parameters in pregnant or nonpregnant mice of typical size and offer exciting possibilities for application in CV functional genomic research.
Cardiac hypertrophy is considered a necessary compensatory response to sustained elevations of left ventricular (LV) wall stress.
To test this, we inhibited calcineurin with cyclosporine (CsA) in the ...setting of surgically induced pressure overload in mice and examined in vivo parameters of ventricular volume and function using echocardiography. Normalized heart mass increased 45% by 5 weeks after thoracic aortic banding (TAB; heart weight/body weight, 8.3+/-0.9 mg/g mean+/-SEM versus 5. 7+/-0.1 mg/g unbanded, P<0.05). Similar increases were documented in the cell-surface area of isolated LV myocytes. In mice subjected to TAB+CsA treatment, we observed complete inhibition of hypertrophy (heart weight/body weight, 5.2+/-0.3 mg/g at 5 weeks) and myocyte surface area (endocardial and epicardial fractions). The mice tolerated abolition of hypertrophy with no signs of cardiovascular compromise, and 5-week mortality was not different from that of banded mice injected with vehicle (TAB+Veh). Despite abolition of hypertrophy by CsA (LV mass by echo, 83+/-5 mg versus 83+/-2 mg unbanded), chamber size (end-diastolic volume, 33+/-6 microL versus 37+/-1 microL unbanded), and systolic ejection performance (ejection fraction, 97+/-2% versus 97+/-1% unbanded) were normal. LV mass differed significantly in TAB+Veh animals (103+/-5 mg, P<0.05), but chamber volume (end-diastolic volume, 44+/-6 microL), ejection fraction (92+/-2%), and transstenotic pressure gradients (70+/-14 mm Hg in TAB+Veh versus 77+/-11 mm Hg in TAB+CsA) were not different.
In this experimental setting, calcineurin blockade with CsA prevented LV hypertrophy due to pressure overload. TAB mice treated with CsA maintain normal LV size and systolic function.
Hypertension induced by angiotensin II (Ang II) is associated with glutamate-dependent dysregulation of the hypothalamic paraventricular nucleus (PVN). Many forms of glutamate-dependent plasticity ...are mediated by NMDA receptor GluN1 subunit expression and the distribution of functional receptor to the plasma membrane of dendrites. Here, we use a combined ultrastructural and functional analysis to examine the relationship between PVN NMDA receptors and the blood pressure increase induced by chronic infusion of a low dose of Ang II. We report that the increase in blood pressure produced by a 2 week administration of a subpressor dose of Ang II results in an elevation in plasma membrane GluN1 in dendrites of PVN neurons in adult male mice. The functional implications of these observations are further demonstrated by the finding that GluN1 deletion in PVN neurons attenuated the Ang II-induced increases in blood pressure. These results indicate that NMDA receptor plasticity in PVN neurons significantly contributes to the elevated blood pressure mediated by Ang II.
Abstract Distal-less 3 (Dlx3)−/− mice die at E9.5 presumably due to an abnormal placental phenotype including reduced placental vasculature and secretion of placental growth factor. To examine the ...role of Dlx3 specifically within the epiblast, Dlx3 conditional knockout mice were generated using an epiblast-specific Meox2CreSor allele. Dlx3−/fl , Meox2CreSor animals were born at expected frequencies and survived to weaning providing indirect evidence that loss of Dlx3 within the trophoectoderm plays a critical role in fetal survival in the Dlx3−/− mouse. We next examined the hypothesis that loss of a single Dlx3 allele would have a negative impact on placental and fetal fitness. Dlx3+/− mice displayed reduced fetal growth beginning at E12.5 compared with Dlx3+/+ controls. Altered fetal growth trajectory occurred coincident with elevated oxidative stress and apoptosis within Dlx3+/− placentas. Oral supplementation with the superoxide dismutase mimetic, Tempol, rescued the fetal growth and placental cell death phenotypes in Dlx3+/− mice. To determine the potential mechanisms associated with elevated oxidative stress on the Dlx3+/− placentas, we next examined vascular characteristics within the feto-placental unit. Studies revealed reduced maternal spiral artery luminal area in the Dlx3+/− mice receiving water; Dlx3+/− mice receiving Tempol displayed maternal spiral artery luminal area similar to control Dlx3+/+ mice. We conclude that reduced Dlx3 gene dose results in diminished fetal fitness associated with elevated placental cell oxidative stress and apoptosis coincident with altered vascular remodeling. Administration of antioxidant therapy ameliorated this feto-placental phenotype, suggesting that Dlx3 may be required for adaptation to oxidative stresses within the intrauterine environment.
Increased angiotensin II signaling in the brain has been shown to play a critical role in the excessive sympathoexcitation and development of heart failure (HF) after myocardial infarction (MI). We ...have recently demonstrated that reactive oxygen species mediate the actions of angiotensin II in the brain. In this study, we tested the hypothesis that increased redox signaling in central cardiovascular control regions is a key mechanism in the neurocardiovascular dysregulation that follows MI. Ligation of the left coronary artery induced a large MI and subsequent HF in adult C57BL/6 mice, as demonstrated by cardiac hypertrophy, hydrothorax, and ascites. Immunohistochemical analysis of Fos, a marker of neuronal activation, revealed a significant increase in the number of Fos-positive neurons in the paraventricular nucleus and supraoptic nucleus at 2 and 4 weeks after MI compared with sham mice. Intracerebroventricular injection of an adenoviral vector encoding superoxide dismutase (Ad-Cu/ZnSOD) caused a significant decrease in the number of Fos-positive neurons in the paraventricular nucleus and supraoptic nucleus at 2 weeks after MI compared with mice receiving either saline or a control vector (Ad-LacZ). There was also a diminished role of sympathetic drive in post-MI mice treated centrally with Ad-Cu/ZnSOD, as demonstrated by significantly attenuated falls in heart rate and mean arterial pressure to the ganglionic blocker hexamethonium and decreased urinary norepinephrine levels in these mice compared with Ad-LacZ-treated MI mice. These results suggest that superoxide plays a key role in the central activation and sympathetic hyperactivity after MI in mice and that oxygen radicals in the brain may be important new targets for therapeutic treatment of heart failure.
To investigate mechanisms in the pathogenesis of cardiomyopathy associated with mutations of the dystrophin–glycoprotein complex, we analyzed genetically engineered mice deficient for either ...α-sarcoglycan (
Sgca) or δ-sarcoglycan (
Sgcd). We found that only
Sgcd null mice developed cardiomyopathy with focal areas of necrosis as the histological hallmark in cardiac and skeletal muscle. Absence of the sarcoglycan–sarcospan (SG-SSPN) complex in skeletal and cardiac membranes was observed in both animal models. Loss of vascular smooth muscle SG-SSPN complex was only detected in
Sgcd null mice and associated with irregularities of the coronary vasculature. Administration of a vascular smooth muscle relaxant prevented onset of myocardial necrosis. Our data indicate that disruption of the SG-SSPN complex in vascular smooth muscle perturbs vascular function, which initiates cardiomyopathy and exacerbates muscular dystrophy.
More than 90% of Duchenne muscular dystrophy (DMD) patients develop cardiomyopathy, and many die of cardiac failure. Despite tremendous progress in skeletal muscle gene therapy, few attempts have ...been made to treat cardiomyopathy. Microdystrophin genes are shown to correct skeletal muscle pathological lesions in the mdx mouse model for DMD. Here, we tested the therapeutic potential of adeno-associated virus (AAV)-mediated microdystrophin gene therapy in the mdx mouse heart.
AAV was delivered to the newborn mdx mouse cardiac cavity. The procedure was rapid and well tolerated. Efficient expression was achieved in the inner and the outer layers of the myocardium. The ubiquitous cytomegalovirus promoter resulted in substantially higher expression than the muscle-specific CK6 promoter. The therapeutic effects of microdystrophin were evaluated at 10 months after infection. Immunostaining demonstrated extensive microdystrophin expression and successful restoration of the dystrophin-glycoprotein complex. Importantly, AAV-mediated microdystrophin expression improved the sarcolemma integrity in the mdx heart.
We established a simple gene transfer method for efficient and persistent transduction of the mdx mouse heart. AAV-mediated microdystrophin expression restored the critical dystrophin-glycoprotein complex and improved sarcolemma integrity of the mdx heart. Our results revealed the promise of AAV-microdystrophin gene therapy for cardiomyopathy in DMD.
We have previously shown that mice transgenic for both the human renin and human angiotensinogen genes (RA+) exhibit appropriate tissue- and cell-specific expression of both transgenes, have 4-fold ...higher plasma angiotensin II (AII) levels, and are chronically hypertensive. However, the relative contribution of circulating and tissue-derived AII in causing hypertension in these animals is not known. We hypothesized that the brain renin-angiotensin system contributes to the elevated blood pressure in this model. To address this hypothesis, mean arterial pressure (MAP) and heart rate were measured in conscious, unrestrained mice after they were instrumented with intracerebroventricular cannulae and carotid arterial and jugular vein catheters. Intracerebroventricular administration of the selective AII type 1 (AT-1) receptor antagonist losartan (10 microgram, 1 microL) caused a significantly greater peak fall in MAP in RA+ mice than in nontransgenic RA- controls (-29+/-4 versus -4+/-2 mm Hg, P<0.01). To explore the mechanism of a central renin-angiotensin system-dependent hypertension in RA+ mice, we determined the relative depressor responses to intravenous administration of the ganglionic blocking agent hexamethonium (5 mg/kg) or an arginine vasopressin (AVP) V1 receptor antagonist (AVPX, 10 microgram/kg). Hexamethonium caused equal lowering of MAP in RA+ mice and controls (-46+/-3 versus -52+/-3, P>0.05), whereas AVPX caused a significantly greater fall in MAP in RA+ compared with RA- mice (-24+/-2 versus -6+/-1, P<0.01). Consistent with this was the observation that circulating AVP was 3-fold higher in RA+ mice than in control mice. These results suggest that increased activation of central AT-1 receptors, perhaps those located at sites involved in AVP release from the posterior pituitary gland, plays a role in the hypertension in RA+ mice. Furthermore, our finding that both human transgenes are expressed in brain regions of RA+ mice known to be involved in cardiovascular regulation raises the possibility that augmented local production of AII and increased activation of AT-1 receptors at these sites is involved.
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