Biomedical subjects

Robert M Weiss

Publications and source records attributed to Robert M Weiss.

At least 19 recordsLinked to original sources

PubMed2006

Calcific aortic valve stenosis in old hypercholesterolemic mice.

BACKGROUND: Hypercholesterolemia and old age are clinical risk factors for development of aortic valve stenosis, and hypercholesterolemia is a putative therapeutic target. We tested the hypothesis that calcification and aortic valve stenosis would develop in genetically hypercholesterolemic old mice. METHODS AND RESULTS: Twenty-four low-density lipoprotein receptor-deficient apolipoprotein B-100-only (LDLr(-/-)ApoB(100/100)) mice were fed normal chow from weaning until age 20.1+/-0.5 months (mean+/-SE; range 17 to 22 months). Twenty-one age-matched (20.8+/-0.9 months, range 17 to 25 months) C57Bl/6 mice served as controls. Echocardiographic imaging was used to assess morphology and function of the aortic valve and left ventricle. A subset of 12 mice underwent invasive hemodynamic assessment of aortic valve function. Functionally significant aortic stenosis, with >75% reduction in valve area, occurred in 8 of 24 LDLr(-/-)ApoB(100/100) mice and in 0 of 21 controls (P=0.01). In the subset that underwent catheterization, mice with echocardiographic evidence of aortic stenosis had a systolic transvalvular gradient of 57+/-6 mm Hg. In the group of all LDLr(-/-)ApoB(100/100) mice with aortic stenosis, left ventricular mass was increased by 67% (P=0.001) and ejection fraction was decreased by 30% (P=0.004) compared with LDLr(-/-)ApoB(100/100) without aortic stenosis. Von Kossa staining of the aortic valve demonstrated abundant mineralization in LDLr(-/-)ApoB(100/100) mice but not in control mice. Superoxide (oxyethidium fluorescence) was present in valve tissue from all 3 groups of mice and was more abundant in mice with aortic stenosis. CONCLUSIONS: Hypercholesterolemic LDLr(-/-)ApoB(100/100) mice are prone to develop calcification and oxidative stress in the aortic valve, with functional valvular heart disease, mimicking the clinical syndrome. This discovery holds promise for elucidation of the pathophysiology of aortic valve disease mechanisms and for the design of effective nonsurgical treatment.

Aging↗

PubMed2006

Novel effect of mineralocorticoid receptor antagonism to reduce proinflammatory cytokines and hypothalamic activation in rats with ischemia-induced heart failure.

Blocking brain mineralocorticoid receptors (MRs) reduces the high circulating levels of tumor necrosis factor (TNF)-alpha in heart failure (HF) rats. TNF-alpha and other proinflammatory cytokines activate neurons in the paraventricular nucleus (PVN) of hypothalamus, including corticotropin-releasing hormone (CRH) neurons, by inducing cyclooxygenase (COX)-2 activity and synthesis of prostaglandin E2 by perivascular cells of the cerebral vasculature. We tested the hypothesis that systemic treatment with a MR antagonist would reduce hypothalamic COX-2 expression and PVN neuronal activation in HF rats. Rats underwent coronary ligation to induce HF, confirmed by echocardiography, or sham surgery, followed by 6 weeks treatment with eplerenone (30 mg/kg per day, orally) or vehicle (drinking water). Eplerenone-treated HF rats had lower plasma TNF-alpha, interleukin (IL)-1beta and IL-6, less COX-2 staining of small blood vessels penetrating PVN, fewer PVN neurons expressing Fra-like activity (indicating chronic neuronal activation), and fewer PVN neurons staining for TNF-alpha, IL-1beta, and CRH than vehicle-treated HF rats. COX-2 and CRH protein expression in hypothalamus were 1.7- and 1.9-fold higher, respectively, in HF+vehicle versus sham+vehicle rats; these increases were attenuated (26% and 25%, respectively) in HF+eplerenone rats. Eplerenone-treated HF rats had less prostaglandin E2 in cerebrospinal fluid, lower plasma norepinephrine levels, lower left ventricular end-diastolic pressure, and lower right ventricle/body weight and lung/body weight ratios, but no improvement in left ventricular function. Treatment of HF rats with anticytokine agents, etanercept or pentoxifylline, produced very similar results. This study reveals a previously unrecognized effect of MR antagonism to minimize cytokine-induced central neural excitation in rats with HF.

Animals↗

PubMed2006

Severe feto-placental abnormalities precede the onset of hypertension and proteinuria in a mouse model of preeclampsia.

Preeclampsia is a prevalent and potentially devastating disorder of pregnancy. Characterized by a sudden spike in blood pressure and urinary protein levels, it is associated with significant obstetric complications. BPH/5 is an inbred mouse model of preeclampsia with borderline hypertension before pregnancy. BPH/5 mice develop hypertension, proteinuria, and endothelial dysfunction during late gestation (after E14.5). We hypothesized that BPH/5 mice might exhibit early feto-placental abnormalities before the onset of maternal disease. All placental cell lineages were present in BPH/5 mice. However, the fetal and placental weights were reduced, with abnormalities in all the placental zones observed starting early in gestation (E9.5-E12.5). The fractional area occupied by the junctional zone was significantly reduced at all gestational timepoints. Markedly fewer CDKN1C-stained trophoblasts were seen invading the proximal decidual zone, and this was accompanied by reductions in Cdkn1c gene expression. Trophoblast giant cell morphology and cytokeratin staining were not altered, although the mRNA levels of several giant cell-specific markers were significantly downregulated. The labyrinth layer displayed decreased branching morphogenesis of endothelial cells, with electron microscopy evidence of attenuated trophoblast layers. The maternal decidual arteries showed increased wall-to-lumen ratios with persistence of actin-positive smooth muscle cells. These changes translated into dramatically increased vascular resistance in the uterine arteries, as measured by pulse-wave Doppler. Collectively, these results support the hypothesis that defects at the maternal-fetal interface are primary causal events in preeclampsia, and further suggest the BPH/5 model is important for investigations of the underlying pathogenic mechanisms in preeclampsia.

Animals↗

PubMed2006

A role for Akt in the rapid regulation of inflammatory and apoptotic pathways in mouse bladder.

Akt is linked to both inflammatory and neoplastic pathways. Akt activation is dependent on the phosphatidylinositol-3 kinase (PI3K) signaling pathways. Upon phosphorylation by PI3K, Akt can phosphorylate nuclear factor kappa B (NF-kappaB) and members of the forkhead family of transcription factors, which includes AFX. Our goal is to examine the effect of Escherichia coli lipopolysaccharide (LPS) on early cellular signaling in inflammatory (NF-kappaB) and apoptotic pathways (AFX) in a mouse-bladder model and in T-24 urothelial cancer cells. Female C57BL/6 mice were given an intraperitoneal (IP) injection of LPS or LPS free water and sacrificed 0-120 minutes later. Bladders were harvested, and immunohistochemistry (IHC) and/or immunoblotting performed using antibodies to PI3K, inhibitor kappa B-alpha (IkappaB-alpha), and total and phosphorylated Akt, NF-kappaB and AFX. Levels of IkappaB-alpha and total and phosphorylated Akt and NF-kappaB were determined in T-24 cells treated with LPS for 0-120 minutes. Bladders and T-24 cells were treated with PI3K inhibitors in some experiments. Protein amounts in different samples were normalized to immunoreactive actin. Phosphorylated and non-phosphorylated species of Akt, NF-kappaB, and AFX were localized to the urothelium. IP LPS injection rapidly (within 30 minutes) increased Akt phosphorylation. IP LPS injection decreased IkappaB-alpha levels, and increased NF-kappaB and AFX phosphorylation. Wortmannin effectively blocked phosphorylation of Akt in LPS-treated mice, and also reduced phosphorylation of AFX and, to a lesser extent, NF-kappaB. After treatment with LPS, Akt and NF-kappaB phosphorylation was rapidly increased in T-24 cells. Akt phosphorylation, and to a lesser extent NF-kappaB phosphorylation, were blocked by LY-294,002. LPS/PI3K/Akt is a cellular signaling pathway which rapidly activates downstream pathways of inflammation and neoplasia in bladder urothelium.

Animals↗

PubMed2006

Age related changes in the functional, biochemical and molecular properties of alpha1-adrenoceptors in the rat genitourinary tract.

PURPOSE: Because age related changes occur in the properties of alpha(1)-adrenoceptor in several mammalian tissues and alpha(1)-adrenoceptor antagonists are extensively used to treat lower urinary tract symptoms secondary to benign prostatic hyperplasia, we investigated age related changes in the functional, biochemical and molecular properties of alpha(1)-adrenoceptor in the rat genitourinary tract. MATERIALS AND METHODS: The characteristics of alpha(1)-adrenoceptor in the ventral and dorsolateral prostate, and bladder base and dome of 3 and 22-month-old rats were determined using an isolated muscle bath, radioligand receptor binding and real-time reverse transcriptase-polymerase chain reaction techniques. RESULTS: Old rats had significantly higher body weight, lower testosterone, a smaller ventral prostate and a larger bladder dome than young rats. Although there was no significant age dependent difference in the properties of alpha(1)-adrenoceptor in the bladder base and dome, total alpha(1)-adrenoceptor density, mRNA expression of all 3 alpha(1)-adrenoceptor subtypes (alpha(1A), alpha(1B) and alpha(1D)) and the maximum contractile responses to phenylephrine were significantly lower in the ventral and dorsolateral prostate of 22 vs 3-month-old rats. CONCLUSIONS: Age related differences in the molecular, biochemical and functional properties of alpha(1)-adrenoceptors in the rat genitourinary tract may indicate potential differences in the response to alpha(1)-adrenoceptor antagonists with aging, ie a decrease in the therapeutic response in old vs young rats in the response to alpha(1)-adrenoceptor antagonists when used to treat lower urinary tract symptoms secondary to benign prostatic hyperplasia.

Age Factors↗

PubMed2006

Vascular effects of a common gene variant of extracellular superoxide dismutase in heart failure.

A common gene variant of human extracellular superoxide dismutase (ecSOD), in approximately 5% of humans, is associated with increased risk of ischemic heart disease. The purpose of this study was to examine vascular effects of ecSOD with effects of the ecSOD variant (ecSOD(R213G)) in rats with heart failure. Seven weeks after coronary artery ligation, we studied rats with heart failure and sham-operated rats. Adenoviral vectors expressing human ecSOD, ecSOD(R213G), or a control virus were injected intravenously. In the aorta from rats with heart failure, responses to acetylcholine (69 +/- 4% relaxation, means +/- SE) and basal levels of nitric oxide (NO) (vasoconstrictor responses to a NO synthase inhibitor) were greatly impaired, and levels of superoxide and peroxynitrite were increased. Gene transfer of ecSOD restored responses to acetylcholine (92 +/- 2% relaxation) and basal levels of NO to normal and reduced levels of superoxide [from 2.3 +/- 0.2 to 0.9 +/- 0.2 relative light units per second per millimeter squared (RLU x s(-1) x mm(-2))] and peroxynitrite (from 2.4 +/- 0.2 to 0.9 +/- 0.1 RLU x s(-1) x mm(-2)) in the aorta from rats with heart failure. Gene transfer of ecSOD(R213G) produced little or no improvement. Responses to nitroprusside were not different among the groups. Expression of endogenous mRNA for SODs (CuZnSOD, MnSOD, and ecSOD) and endothelial NOS in the aorta was not different among the groups. In contrast to ecSOD, gene transfer of ecSOD(R213G) in rats with heart failure has minimal beneficial effect on oxidative stress, endothelial function, or basal bioavailability of NO. We speculate that greatly diminished efficacy of ecSOD(R213G) in protection against oxidative stress and endothelial dysfunction may contribute to increased risk of cardiovascular disease in humans with ecSOD(R213G).

Acetylcholine↗

PubMed2006

Pacemaker activity in the upper urinary tract.

Ureteral peristaltic activity begins with the origin of electrical activity at pacemaker sites. These sites are located in the proximal portion of the urinary collecting system. The 'atypical' smooth muscle cells at these sites fire 'pacemaker' potentials at a frequency higher than the 'driven' action potentials recorded from typical smooth muscle cells. In contrast to typical smooth muscle cells, these atypical pacemaker cells have less than 40% of their cellular area occupied by contractile filaments and demonstrate a sparse immunoreactivity for alpha-smooth muscle actin. Expression of c-Kit, a tyrosine kinase receptor, correlates with the onset of organized ureteral peristalsis in the embryo. Capsaicin-sensitive sensory afferents and the endogenous release of tachykinins and prostaglandins are involved in the maintenance of normal ureteral peristalsis.

Action Potentials↗

PubMed2005

Effect of insulin treatment on tissue size of the genitourinary tract in BB rats with spontaneously developed and streptozotocin-induced diabetes.

To examine the differences between spontaneous and streptozotocin (STZ)-induced diabetes, four parallel studies were performed; three studies of diabetes-prone BB (BBDP/Wor) rats maintained for 8, 16, and 32 weeks and one study of STZ-injected diabetes-resistant BB (BBDR/Wor) rats maintained for 32 weeks. Each diabetic study has three groups of rats: a control group; a euglycemic group, which received sufficient amounts of insulin; and a hyperglycemic group, which received a suboptimal dose of insulin. The extent of tissue weight changes was generally shown to be less dramatic in the euglycemic diabetic than in the hyperglycemic diabetic rats. STZ-induced diabetes increased the bladder weight more dramatically (up to 3-fold) than did spontaneous diabetes (up to 2-fold). Furthermore, a significant decrease in the size of the adrenal gland (20%) and testis (10%) is observed only with spontaneous diabetes, whereas a significant decrease in the size of the ventral prostate (30%) is observed only with STZ-induced diabetes, although the serum testosterone levels are similar in both groups. Our data demonstrate that there are differences in the effect of insulin treatment on the tissue size of the genitourinary tract between spontaneously developed and streptozotocin-induced diabetes in BB rats.

Animals↗

PubMed2005

The effects of chronic fluoxetine treatment on chronic mild stress-induced cardiovascular changes and anhedonia.

BACKGROUND: Depression has a complex bidirectional association with heart disease. Previously we have shown notable cardiovascular changes in the chronic mild stress (CMS) rodent model of depression. Here we investigated the effects of a serotonin-specific reuptake inhibitor on a behavioral index of depression (anhedonia) and cardiac function in rats exposed to CMS. METHODS: Male Sprague-Dawley rats were exposed to either 4 weeks of control conditions or CMS, consisting of unpredictable periods of mild stressors, while being treated concurrently with 4 weeks of daily fluoxetine (10 mg/kg, sc) or vehicle. RESULTS: Chronic fluoxetine treatment prevented anhedonia in rats exposed to CMS, versus the CMS group treated with vehicle. However, treatment with fluoxetine in the CMS group only partially prevented specific cardiovascular changes associated with CMS, including elevated resting heart rate (HR), exaggerated pressor and HR responses to air jet stress, reduced cardiac output and stroke volume, and HR exaggerated responses to beta-adrenergic receptor blockade. CONCLUSIONS: These findings provide evidence that 4 weeks of fluoxetine treatment can prevent behavioral responses and can partially prevent cardiovascular changes associated with CMS, providing insight into the role of serotonin in the link between depression and cardiovascular dysfunction.

Animals↗

PubMed2005

A survivin gene signature predicts aggressive tumor behavior.

Gene signatures that predict aggressive tumor behavior at the earliest stages of disease, ideally before overt tissue abnormalities, are urgently needed. To search for such genes, we generated a transgenic model of survivin, an essential regulator of cell division and apoptosis overexpressed in cancer. Transgenic expression of survivin in the urinary bladder did not cause histologic abnormalities of the urothelium. However, microarray analysis revealed that survivin-expressing bladders exhibited profound changes in gene expression profile affecting extracellular matrix and inflammatory genes. Following exposure to a bladder carcinogen, N-butyl-N-(4-hydroxybutyl) nitrosamine (OH-BBN), survivin transgenic animals exhibited accelerated tumor progression, preferential incidence of tumors as compared with premalignant lesions, and dramatically abbreviated survival. Conversely, transgenic expression of a survivin Thr34-->Ala dominant-negative mutant did not cause changes in gene expression or accelerated tumor progression after OH-BBN treatment. Therefore, survivin expression induces global transcriptional changes in the tissue microenvironment that may promote tumorigenesis. Detection of survivin or its associated gene signature may provide an early biomarker of aggressive tumor behavior before the appearance of tissue abnormalities.

Animals↗

PubMed2005

Reduction of heart rate by chronic beta1-adrenoceptor blockade promotes growth of arterioles and preserves coronary perfusion reserve in postinfarcted heart.

Adequate growth of coronary vasculature in the remaining left ventricular (LV) myocardium after myocardial infarction (post-MI) is a crucial factor for myocyte survival and performance. We previously demonstrated that post-MI coronary angiogenesis can be stimulated by bradycardia induced with the ATP-sensitive K(+) channel antagonist alinidine. In this study, we tested the hypothesis that heart rate reduction with beta-blockade may also induce coronary growth in the post-MI heart. Transmural MI was induced in 12-mo-old male Sprague-Dawley rats by occlusion of the left anterior descending coronary artery. Bradycardia was induced by administration of the beta-adrenoceptor blocker atenolol (AT) via drinking water (30 mg/day). Three groups of rats were compared: 1) control/sham (C/SH), 2) MI, and 3) MI + AT. In the MI + AT rats, heart rate was consistently reduced by 25-28% compared with C/SH rats. At 4 wk after left anterior descending coronary ligation, infarct size was similar in MI and MI + AT rats (67.1 and 61.5%, respectively), whereas a greater ventricular hypertrophy occurred in bradycardic rats, as indicated by a higher ventricular weight-to-body weight ratio (3.4 +/- 0.1 vs. 2.8 +/- 0.1 mg/g in MI rats). Analysis of LV function revealed a smaller drop in ejection fraction in the MI + AT than in the MI group ( approximately 24 vs. approximately 35%). Furthermore, in MI + AT rats, maximal coronary conductance and coronary perfusion reserve were significantly improved compared with the MI group. The better myocardial perfusion indexes in MI + AT rats were associated with a greater increase in arteriolar length density than in the MI group. Thus chronic reduction of heart rate induced with beta-selective blockade promotes growth of coronary arterioles and, thereby, facilitates regional myocardial perfusion in post-MI hearts.

Adrenergic beta-Antagonists↗

PubMed2005

Clinical and histological significance of the testicular remnant found on inguinal exploration after diagnostic laparoscopy in the absence of a patent processus vaginalis.

PURPOSE: We reviewed the histological findings of cord structures excised at inguinal exploration after diagnostic laparoscopy in patients with a nonpalpable testis with the vas deferens and spermatic vessels exiting the internal inguinal ring in the absence of a patent processus vaginalis. MATERIALS AND METHODS: A retrospective review of 809 laparoscopic explorations for nonpalpable testes between 1981 and 2003 was conducted. The histological findings of the excised remnants of those patients with a closed processus vaginalis were reviewed. RESULTS: A total of 110 patients underwent excision of a testicular remnant at inguinal exploration in association with a closed processus vaginalis. Of the specimens 31 (28%) were on the right side and 79 (72%) were on the left side. The incidence of viable germ cell elements was 8 of 110 (7%). The presence of hemosiderin, calcification and fibrosis was identified in all 8 remnants with viable germ cell elements. CONCLUSIONS: The incidence of viable germ cell elements in the excised remnant when the vas deferens and spermatic vessels are identified exiting a closed internal ring in patients with a nonpalpable testis is 7%. To our knowledge no prior study has evaluated the incidence of viable germ cell elements in remnants associated with a closed internal inguinal ring. Based on these findings, we advocate inguinal exploration and excision of testicular remnants in these patients.

Adolescent↗

PubMed2005

Gene transfer of extracellular superoxide dismutase improves endothelial function in rats with heart failure.

Oxidative stress is associated with endothelial dysfunction in heart failure. The goals of this study were to determine whether 1) gene transfer of extracellular superoxide dismutase (ecSOD) reduces levels of superoxide and improves endothelial function in the aorta and mesenteric artery in rats with heart failure, and 2) the heparin-binding domain (HBD) of ecSOD, by which ecSOD binds to cells, is required for protective effects of ecSOD. Seven weeks after coronary ligation, in rats with heart failure and sham-operated rats, we injected adenoviral vectors intravenously that express ecSOD, ecSOD with deletion of the HBD (ecSODDeltaHBD), or a control vector. Four days after injection of viruses, responses to acetylcholine, ADP, and sodium nitroprusside were examined in rings of the aorta and mesenteric artery. ecSOD bound to endothelium and increased SOD activity in the aorta after gene transfer of ecSOD, not ecSODDeltaHBD. Gene transfer of ecSOD, but not ecSODDeltaHBD, reduced levels of superoxide and improved relaxation to acetylcholine and ADP in the aorta and mesenteric artery from rats with heart failure. Improvement of relaxation to acetylcholine in the mesenteric artery from rats with heart failure after gene transfer of ecSOD was mediated in part by hydrogen peroxide. The major finding of this study is that the HBD of ecSOD is necessary for protection against endothelial dysfunction in rats with heart failure. We speculate that a common gene variant in the HBD of ecSOD, which is a risk factor for ischemic heart disease, may be a risk factor for vascular maladaptation and endothelial dysfunction in heart failure.

Animals↗

PubMed2005

Regulation of cyclic nucleotides in the urinary tract.

Cyclic nucleotide levels are controlled through their synthesis from nucleotide triphosphates by cyclases and their degradation to 5'-monophosphates by phosphodiesterases (PDEs). Components controlling cyclic AMP-induced relaxation in the urinary tract include receptors, inhibitory and stimulatory G-proteins, isoforms of adenylyl cyclase and PDEs. The responsiveness of PDEs to a variety of physiological challenges is related to the presence of multiple families of isoenzymes with specific localization within tissues and within cells. At least 11 families of PDEs encode more than 50 PDE proteins produced in mammalian cells. In the urinary tract, characterization of PDE isoforms has lagged behind other systems and much of the literature was published prior to identification of PDE7, 8, 9, 10, 11. Specific PDE inhibitors regulate smooth muscle function in the bladder, urethra, prostate and ureter. The pharmacological potential of these inhibitors may include treatment of urge incontinence and the low compliance bladder, and treatment of prostate cancer. G-proteins also regulate cyclic AMP production. Changes in specific G- protein isoforms with aging, most prominently Gialpha2, cause decreased relaxation response in the aging bladder. As we have seen here with aging and certainly in other disease processes, levels of the components of adenylyl cyclase/phosphodiesterase/protein kinase can change and thus affect the relaxation response. By exploitation of differences in PDE expression in disease, such as the overexpression of PDEs in cancer, treatment options may present themselves.

Adenylyl Cyclases↗

PubMed2004

Bradycardia induces angiogenesis, increases coronary reserve, and preserves function of the postinfarcted heart.

BACKGROUND: We tested the hypothesis that induction of chronic bradycardia would trigger an upregulation of key growth factors and receptors, which would then lead to angiogenesis and improve coronary reserve in the left ventricle after myocardial infarction. METHODS AND RESULTS: Bradycardia was induced in rats by administering alinidine via osmotic pumps beginning 1 day after coronary artery ligation. Echocardiographic analysis was conducted before and after treatment. Morphometric analysis was used in perfusion-fixed hearts to document arteriolar and capillary growth. Western blots were used to evaluate growth factor and receptor changes. During the first week of treatment, vascular endothelial growth factor (VEGF), VEGF receptor 1 (Flt-1), and basic fibroblast growth factor proteins were higher in the treated group, whereas VEGF receptor 2 (Flk-1), angiopoietin-1, and angiopoietin-2 were not affected by treatment. After 3 weeks, VEGF protein remained elevated, and bradycardia was associated with a higher capillary length density in the border (40%) and remote (14%) regions and a higher arteriolar length density in the septum (62%), despite a greater increase in left ventricular mass. Although arteriolar length density increased in all size classes, the greatest increase occurred in the smallest (terminal) arterioles. This vascular growth was associated with a 23% greater coronary reserve. Echocardiography revealed a smaller increase in ventricular volume and a greater preservation of ejection fraction in rats treated with bradycardia. CONCLUSIONS: Pharmacologic induction of bradycardia enhances vascularity and coronary reserve, preserves function of surviving myocardium, and therefore, is a noninvasive, therapeutic avenue that provides an alternative to gene therapy.

Angiopoietin-1↗

PubMed2004

Rapid up-regulation of endothelial nitric-oxide synthase in a mouse model of Escherichia coli lipopolysaccharide-induced bladder inflammation.

Increases in the signaling molecule nitric oxide (NO) during inflammation may be linked not only to inducible nitric-oxide synthase (iNOS) but also to endothelial (e)NOS. Escherichia coli lipopolysaccharide (LPS) induces an inflammatory response in the bladder and rapidly increases phosphorylation of Akt/protein kinase B (Akt), a key enzyme regulating proliferation, apoptosis, and inflammation. Activated Akt phosphorylates human eNOS at serine 1177 and subsequently increases NOS activity. Because Akt and eNOS are both localized in the bladder urothelium, phosphorylation of eNOS by Akt provides an attractive mechanism for rapid increases in urinary NO production. Female mice were intraperitoneally injected with LPS (25 mg/kg) or pyrogen-free water (control). Four hours before LPS injection, some mice were injected with wortmannin, which inhibits Akt phosphorylation. Levels of urinary cyclic GMP, a downstream product of NO, increase 75% within 1 h after intraperitoneal injection of LPS, and this increase is blocked by wortmannin. Bladder eNOS and phosphorylated eNOS protein increase 94 and 151%, respectively, 1 h after LPS treatment, whereas iNOS was not detected. Wortmannin decreases eNOS phosphorylation by 60%. Furthermore, bladder Ca(2+)-dependent NOS activity (eNOS, neuronal NOS) is increased 79 +/- 20% 1 h after LPS treatment, whereas there is no increase in Ca(2+)-independent (iNOS) activity (n = 4). Increases in urinary cyclic GMP, NOS activity, and eNOS protein and phosphorylation 1 h after induction of inflammation with LPS, indicate that eNOS plays a role in the early response to bladder inflammation.

Animals↗

PubMed2004

Age-related changes in the properties of the endothelin receptor system at protein and mRNA levels in the rat vas deferens.

As age-related changes occur in the properties of the endothelin (ET) receptor system in several mammalian tissues, and as there are significant amounts of functional ET receptors in the vas deferens, we investigated the age-related changes in the ET receptor system at the protein and mRNA levels in the rat vas deferens. The ET system was investigated in the vasa deferentia of 3 weeks, 3 months and 22 months old rats. ET receptors were characterized and quantified at the protein level by radioligand receptor binding, and gene transcript levels of ET-1, ET-3, ET converting enzyme-1 (ECE-1), and ET(A) and ET(B) receptor subtypes were quantified by real-time reverse transcription polymerase chain reaction (RT-PCR). The results of radioligand receptor binding assays demonstrate that there is a higher density of total ET receptors in the vas deferens of 3 weeks old rats than in 3 months and 22 months old rats, and that the predominant ET receptor is of the ET(A) subtype in all three ages. Real-time RT-PCR data show that the predominant mRNA expression of ETs and their receptors in all age groups studied are ET-1 and the ET(A) receptor subtype, respectively. Furthermore, ET-1, ET-3, ECE-1, and ET(A) and ET(B) receptor subtype mRNAs are expressed at higher levels in the 3 weeks old rats as compared with the other two age groups. These results demonstrate the presence of age-related changes in the properties of the ET receptor system at both protein and mRNA levels in the rat vas deferens.

Aging↗

PubMed2004

Neural regulation of the proinflammatory cytokine response to acute myocardial infarction.

Within minutes of acute myocardial infarction (MI), proinflammatory cytokines increase in the brain, heart, and plasma. We hypothesized that cardiac afferent nerves stimulated by myocardial injury signal the brain to increase central cytokines. Urethane-anesthetized male Sprague-Dawley rats underwent ligation of the left anterior descending coronary artery (LAD) or sham LAD ligation after bilateral cervical vagotomy, sham vagotomy, or application of a 10% phenol solution to the epicardial surface of the myocardium at risk. MI caused a significant increase in tumor necrosis factor (TNF)-alpha and interleukin (IL)-1beta in the plasma and heart, which was blunted by vagotomy. MI also caused a significant increase in hypothalamic TNF-alpha and IL-1beta, which was not affected by vagotomy. In contrast, epicardial phenol blocked MI-induced increases in hypothalamic TNF-alpha and IL-1beta without affecting increases in the plasma and heart. These findings demonstrate that the appearance of proinflammatory cytokines in the brain after MI is independent of blood-borne cytokines and suggest that cardiac sympathetic afferent nerves activated by myocardial ischemia signal the brain to increase cytokine production. In addition, an intact vagus nerve is required for the full expression of proinflammatory cytokines in the injured myocardium and in the circulation. We conclude that the sympathetic and parasympathetic innervation of the heart both contribute to the acute proinflammatory response to MI.

Acute Disease↗