Nitric Oxide Modulation of Supraoptic Oxytocin and Vasopressin Neurons Involves Potentiation of Gabaergic Synaptic Inputs.

Hypertension ◽  
2000 ◽  
Vol 36 (suppl_1) ◽  
pp. 700-700
Author(s):  
Javier E Stern ◽  
Mike Ludwig
Keyword(s):  
Nitric Oxide ◽  
Synaptic Activity ◽  
Cellular Mechanisms ◽  
Synaptic Currents ◽  
No Donor ◽  
Salt Loading ◽  
Inhibitory Feedback ◽  
Vasopressin Neurons

P41 There is growing evidence that nitric oxide (NO) in the central nervous system functions as a local neuromodulator in water balance and osmotic regulation. However, the precise mechanisms by which these actions are mediated are still poorly understood. Neuronal nitric oxide synthase (nNOS) is abundantly expressed in the supraoptic (SON) and paraventricular (PVN) nuclei. nNOS expression is up-regulated in conditions known to stimulate oxytocin (OT) and vasopressin (VP) hormone release, such as salt loading and water deprivation. Since several studies have shown that NO mainly decreases the excitability of OT and VP neurons, NO may function as a local inhibitory feedback on activated SON neurons. In the present study we combined in vivo and in vitro electrophysiological studies to investigate whether NO-induced inhibition of SON neurons is mediated by activation of GABAergic inputs in the SON. In vivo retrodialysis of the NO-donor SNP into the SON inhibited the firing activity of both OT and VP neurons. This inhibition was largely blocked by retrodialysis of the GABA A receptor antagonist bicuculline. In order to understand the cellular mechanisms linking NO and GABAergic systems in the SON, in vitro patch clamp recordings of GABA A synaptic currents were obtained from immunochemically identified neurons in hypothalamic slices. The frequency and amplitude of miniature GABA A synaptic currents in both OT and VP neurons were significantly increased by SNP. These results suggest that NO inhibition of neuronal excitability of OT and VP neurons is largely mediated by pre- and postsynaptic potentiation of GABAergic synaptic activity in the SON. Thus, the proposed NO-GABAergic inhibitory feedback in the SON might constitute an important mechanism by which NO regulates osmotic and fluid balance homeostasis.

NO inhibits supraoptic oxytocin and vasopressin neurons via activation of GABAergic synaptic inputs

2001 ◽  
Vol 280 (6) ◽  
pp. R1815-R1822 ◽  
Author(s):  
Javier E. Stern ◽  
Mike Ludwig
Keyword(s):  
Neuronal Excitability ◽  
Cell Types ◽  
Synaptic Activity ◽  
No Donor ◽  
Whole Cell Patch Clamp ◽  
Electrophysiological Recordings ◽  
Neuronal Types ◽  
Vasopressin Neurons

To study modulatory actions of nitric oxide (NO) on GABAergic synaptic activity in hypothalamic magnocellular neurons in the supraoptic nucleus (SON), in vitro and in vivo electrophysiological recordings were obtained from identified oxytocin and vasopressin neurons. Whole cell patch-clamp recordings were obtained in vitro from immunochemically identified oxytocin and vasopressin neurons. GABAergic synaptic activity was assessed in vitro by measuring GABAA miniature inhibitory postsynaptic currents (mIPSCs). The NO donor and precursor sodium nitroprusside (SNP) and l-arginine, respectively, increased the frequency and amplitude of GABAA mIPSCs in both cell types ( P ≤ 0.001). Retrodialysis of SNP (50 mM) onto the SON in vivo inhibited the activity of both neuronal types ( P ≤ 0.002), an effect that was reduced by retrodialysis of the GABAA-receptor antagonist bicuculline (2 mM, P≤ 0.001). Neurons activated by intravenous infusion of 2 M NaCl were still strongly inhibited by SNP. These results suggest that NO inhibition of neuronal excitability in oxytocin and vasopressin neurons involves pre- and postsynaptic potentiation of GABAergic synaptic activity in the SON.

Autologous nitric oxide protects mouse and human keratinocytes from ultraviolet B radiation-induced apoptosis

2003 ◽  
Vol 284 (5) ◽  
pp. C1140-C1148 ◽  
Author(s):  
Richard Weller ◽  
Ann Schwentker ◽  
Timothy R. Billiar ◽  
Yoram Vodovotz
Keyword(s):  
Nitric Oxide ◽  
Soluble Guanylate Cyclase ◽  
Ultraviolet B ◽  
Skin Damage ◽  
Wild Type ◽  
No Donor ◽  
Ultraviolet B Radiation ◽  
Inducible Nos

Nitric oxide (NO) can either prevent or promote apoptosis, depending on cell type. In the present study, we tested the hypothesis that NO suppresses ultraviolet B radiation (UVB)-induced keratinocyte apoptosis both in vitro and in vivo. Irradiation with UVB or addition of the NO synthase (NOS) inhibitor N G-nitro-l-arginine methyl ester (l-NAME) increased apoptosis in the human keratinocyte cell line CCD 1106 KERTr, and apoptosis was greater when the two agents were given in combination. Addition of the chemical NO donor S-nitroso- N-acetyl-penicillamine (SNAP) immediately after UVB completely abrogated the rise in apoptosis induced by l-NAME. An adenoviral vector expressing human inducible NOS (AdiNOS) also reduced keratinocyte death after UVB. Caspase-3 activity, an indicator of apoptosis, doubled in keratinocytes incubated with l-NAME compared with the inactive isomer, d-NAME, and was reduced by SNAP. Apoptosis was also increased on addition of 1,H-[1,2,4]oxadiazolo[4,3- a]quinoxalin-1-one (ODQ), an inhibitor of soluble guanylate cyclase. Mice null for endothelial NOS (eNOS) exhibited significantly higher apoptosis than wild-type mice both in the dermis and epidermis, whereas mice null for inducible NOS (iNOS) exhibited more apoptosis than wild-type mice only in the dermis. These results demonstrate an antiapoptotic role for NO in keratinocytes, mediated by cGMP, and indicate an antiapoptotic role for both eNOS and iNOS in skin damage induced by UVB.

Effects of Nitric Oxide on Blood Flow and Mucociliary Activity in the Human Nose

1998 ◽  
Vol 107 (1) ◽  
pp. 40-46 ◽  
Author(s):  
Thomas Runer ◽  
Sven Lindberg
Keyword(s):  
Nitric Oxide ◽  
Blood Flow ◽  
Beat Frequency ◽  
Ciliary Beat Frequency ◽  
Maximum Increase ◽  
No Donor ◽  
Doppler Flowmetry ◽  
Human Nose

In an animal model, nitric oxide (NO) has been shown to increase mucociliary activity in vivo and ciliary beat frequency in vitro. The aim of the present study was to investigate the effects of NO on blood flow and mucociliary activity in the human nose. The concentration of NO in nasal air was measured with a chemiluminescence technique after nebulizing the NO donor sodium nitroprusside (SNP) at a dose of 3.0 mg into the nose in six volunteers, and was found to increase by 50.1% ± 10.0% (mean ± SEM; p <.001) after the SNP challenge. Blood flow measured by laser Doppler flowmetry increased by 67.3% ± 15.5% (p <.05) after challenge with SNP at 1.0 mg, and by 75.4% ± 18.5% at 3.0 mg (p <.01; n = 6). The higher dose, which produced no subjective side effects, was then used in the mucociliary experiments. The maximum increase in nasal mucociliary activity was 57.2% ± 6.7% at 3.0 mg of SNP (n = 5). The findings support the view that NO regulates mucociliary activity and blood flow in the human nasal mucosa.

scholarly journals Glucagon-Like Peptide 2 (GLP-2) Stimulates Postprandial Chylomicron Production and Postabsorptive Release of Intestinal Triglyceride Storage Pools via Induction of Nitric Oxide Signaling in Male Hamsters and Mice

Endocrinology ◽  
2015 ◽  
Vol 156 (10) ◽  
pp. 3538-3547 ◽  
Author(s):  
Joanne Hsieh ◽  
Karin E. Trajcevski ◽  
Sarah L. Farr ◽  
Christopher L. Baker ◽  
Elizabeth J. Lake ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Early Mobilization ◽  
No Donor ◽  
Nitric Oxide Signaling ◽  
Insulin Resistant ◽  
Postprandial State ◽  
Glucagon Like Peptide ◽  
Storage Pools

The intestinal overproduction of apolipoprotein B48 (apoB48)-containing chylomicron particles is a common feature of diabetic dyslipidemia and contributes to cardiovascular risk in insulin resistant states. We previously reported that glucagon-like peptide-2 (GLP-2) is a key endocrine stimulator of enterocyte fat absorption and chylomicron output in the postprandial state. GLP-2's stimulatory effect on chylomicron production in the postabsorptive state has been confirmed in human studies. The mechanism by which GLP-2 regulates chylomicron production is unclear, because its receptor is not expressed on enterocytes. We provide evidence for a key role of nitric oxide (NO) in mediating the stimulatory effects of GLP-2 during the postprandial and postabsorptive periods. Intestinal chylomicron production was assessed in GLP-2-treated hamsters administered the pan-specific NO synthase (NOS) inhibitor L-NG-nitroarginine methyl ester (L-NAME), and in GLP-2-treated endothelial NOS knockout mice. L-NAME blocked GLP-2-stimulated apoB48 secretion and reduced triglycerides (TGs) in the TG-rich lipoprotein (TRL) fraction of the plasma in the postprandial state. Endothelial NOS-deficient mice were resistant to GLP-2 stimulation and secreted fewer large apoB48-particles. When TG storage pools were allowed to accumulate, L-NAME mitigated the GLP-2-mediated increase in TRL-TG, suggesting that NO is required for early mobilization and secretion of stored TG and preformed chylomicrons. Importantly, the NO donor S-nitroso-L-glutathione was able to elicit an increase in TRL-TG in vivo and stimulate chylomicron release in vitro in primary enterocytes. We describe a novel role for GLP-2-mediated NO-signaling as a critical regulator of intestinal lipid handling and a potential contributor to postprandial dyslipidemia.

Role of BKCa Channels in Cephalic Vasodilation Induced by CGRP, NO and Transcranial Electrical Stimulation In The Rat

Cephalalgia ◽  
2007 ◽  
Vol 27 (10) ◽  
pp. 1120-1127 ◽  
Author(s):  
A Gozalov ◽  
I Jansen-Olesen ◽  
D Klaerke ◽  
J Olesen
Keyword(s):  
Nitric Oxide ◽  
Electrical Stimulation ◽  
Selective Inhibitor ◽  
Transcranial Electrical Stimulation ◽  
Bkca Channels ◽  
No Donor ◽  
Calcitonin Gene

Both calcitonin gene-related peptide (CGRP) and nitric oxide (NO) are potent vasodilators that have been shown to induce headache in migraine patients. Their antagonists are effective in the treatment of migraine attacks. In the present study, we hypothesize that vasodilation induced by the NO donor glyceryltrinitrate (GTN) or by CGRP is partially mediated via large conductance calcium-activated potassium (BKCa) channels. The effects of the BKCa channel selective inhibitor iberiotoxin on dural and pial vasodilation induced by CGRP, GTN and endogenously released CGRP by transcranial electrical stimulation (TES) were examined. Iberiotoxin significantly attenuated GTN-induced dural and pial artery dilation in vivo and in vitro, but had no effect on vasodilation induced by CGRP and TES. Our results show that GTN- but not CGRP-induced dural and pial vasodilation involves opening of BKCa channels in rat.

scholarly journals Nitrite reductase activity of hemoglobin as a systemic nitric oxide generator mechanism to detoxify plasma hemoglobin produced during hemolysis

2008 ◽  
Vol 295 (2) ◽  
pp. H743-H754 ◽  
Author(s):  
Peter C. Minneci ◽  
Katherine J. Deans ◽  
Sruti Shiva ◽  
Huang Zhi ◽  
Steven M. Banks ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Nitrite Reductase ◽  
Reductase Activity ◽  
Vascular Complications ◽  
Blood Substitutes ◽  
Intravascular Hemolysis ◽  
No Donor ◽  
Nitrite Reductase Activity

Hemoglobin (Hb) potently inactivates the nitric oxide (NO) radical via a dioxygenation reaction forming nitrate (NO3−). This inactivation produces endothelial dysfunction during hemolytic conditions and may contribute to the vascular complications of Hb-based blood substitutes. Hb also functions as a nitrite (NO2−) reductase, converting nitrite into NO as it deoxygenates. We hypothesized that during intravascular hemolysis, nitrite infusions would limit the vasoconstrictive properties of plasma Hb. In a canine model of low- and high-intensity hypotonic intravascular hemolysis, we characterized hemodynamic responses to nitrite infusions. Hemolysis increased systemic and pulmonary arterial pressures and systemic vascular resistance. Hemolysis also inhibited NO-dependent pulmonary and systemic vasodilation by the NO donor sodium nitroprusside. Compared with nitroprusside, nitrite demonstrated unique effects by not only inhibiting hemolysis-associated vasoconstriction but also by potentiating vasodilation at plasma Hb concentrations of <25 μM. We also observed an interaction between plasma Hb levels and nitrite to augment nitroprusside-induced vasodilation of the pulmonary and systemic circulation. This nitrite reductase activity of Hb in vivo was recapitulated in vitro using a mitochondrial NO sensor system. Nitrite infusions may promote NO generation from Hb while maintaining oxygen delivery; this effect could be harnessed to treat hemolytic conditions and to detoxify Hb-based blood substitutes.

Nitric oxide regulates endothelium-dependent vasodilator responses in rabbit hindquarters vascular bed in vivo

1996 ◽  
Vol 271 (1) ◽  
pp. H133-H139 ◽  
Author(s):  
G. A. Cohen ◽  
A. J. Hobbs ◽  
R. M. Fitch ◽  
M. J. Zinner ◽  
G. Chaudhuri ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Physiological Role ◽  
No Synthase ◽  
No Donor ◽  
Aortic Endothelial Cells ◽  
Vascular Bed ◽  
Feedback Modulator ◽  
Vasodilator Action

The objective of this study was to determine whether nitric oxide (NO) could function as a negative feedback modulator of endothelium-dependent vasodilation in vivo. To this end, the influence of exogenous NO on vasodilator responses in the rabbit hindquarters vascular bed was determined. Previous in vitro studies have demonstrated that NO inhibits both neuronal NO synthase from rat cerebellum as well as NO synthase derived from bovine aortic endothelial cells. The present study was conducted in the rabbit hindquarters vascular bed under conditions of constant blood flow so that changes in pressure directly reflected changes in vascular resistance. Under these in vivo conditions, the NO donor agent S-nitroso-N-acetylpenicillamine (SNAP) reversibly attenuated responses to the endothelium-dependent vasodilators, acetylcholine and bradykinin. In contrast, SNAP did not influence the endothelium-independent vasodilator response to SNAP itself or to 8-bromoguanosine 3',5'-cyclic monophosphate. These observations indicate clearly that NO interferes with endothelium-dependent vasodilator action and support the view that endogenous NO may actually play a physiological role in regulating vascular tone.

scholarly journals Pendrin protein abundance in the kidney is regulated by nitric oxide and cAMP

2012 ◽  
Vol 303 (6) ◽  
pp. F812-F820 ◽  
Author(s):  
Monika Thumova ◽  
Vladimir Pech ◽  
Otto Froehlich ◽  
Diana Agazatian ◽  
Xiaonan Wang ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Pressor Response ◽  
Fluorescent Microscopy ◽  
Phosphodiesterase Inhibitor ◽  
Protein Abundance ◽  
No Donor ◽  
Camp Content

Pendrin is a Cl−/HCO3− exchanger, expressed in the apical regions of some intercalated cell subtypes, and is critical in the pressor response to angiotensin II. Since angiotensin type 1 receptor inhibitors reduce renal pendrin protein abundance in mice in vivo through a mechanism that is dependent on nitric oxide (NO), we asked if NO modulates renal pendrin expression in vitro and explored the mechanism by which it occurs. Thus we quantified pendrin protein abundance by confocal fluorescent microscopy in cultured mouse cortical collecting ducts (CCDs) and connecting tubules (CNTs). After overnight culture, CCDs maintain their tubular structure and maintain a solute gradient when perfused in vitro. Pendrin protein abundance increased 67% in CNT and 53% in CCD when NO synthase was inhibited ( NG-nitro-l-arginine methyl ester, 100 μM), while NO donor (DETA NONOate, 200 μM) application reduced pendrin protein by ∼33% in the CCD and CNT. When CNTs were cultured in the presence of the guanylyl cyclase inhibitor 1H-[1,2,4] oxadiazolo[4,3-a]quinoxalin-1-one (10 μM), NO donors did not alter pendrin abundance. Conversely, pendrin protein abundance rose when cAMP content was increased by the application of an adenylyl cyclase agonist (forskolin, 10 μM), a cAMP analog (8-bromo-cAMP, 1 mM), or a phosphodiesterase inhibitor (BAY60-7550, 50 μM). Since NO reduces cellular cAMP in the CNT, we asked if NO reduces pendrin abundance by reducing cAMP. With blockade of cGMP-stimulated phosphodiesterase II, NO did not alter pendrin protein abundance. We conclude that NO acts through cAMP to reduce pendrin total protein abundance by enhancing cAMP degradation.

scholarly journals CYP1B1 and endothelial nitric oxide synthase combine to sustain proangiogenic functions of endothelial cells under hyperoxic stress

2010 ◽  
Vol 298 (3) ◽  
pp. C665-C678 ◽  
Author(s):  
Yixin Tang ◽  
Elizabeth A. Scheef ◽  
Zafer Gurel ◽  
Christine M. Sorenson ◽  
Colin R. Jefcoate ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Nitric Oxide ◽  
Nitric Oxide Synthase ◽  
Wild Type ◽  
Enos Expression ◽  
No Donor ◽  
Enos Activity ◽  
Oxide Synthase

We have recently shown that deletion of constitutively expressed CYP1B1 is associated with attenuation of retinal endothelial cell (EC) capillary morphogenesis (CM) in vitro and angiogenesis in vivo. This was largely caused by increased intracellular oxidative stress and increased production of thrombospondin-2, an endogenous inhibitor of angiogenesis. Here, we demonstrate that endothelium nitric oxide synthase (eNOS) expression is dramatically decreased in the ECs prepared from retina, lung, heart, and aorta of CYP1B1-deficient (CYP1B1−/−) mice compared with wild-type (CYP1B1+/+) mice. The eNOS expression was also decreased in retinal vasculature of CYP1B1−/− mice. Inhibition of eNOS activity in cultured CYP1B1+/+ retinal ECs blocked CM and was concomitant with increased oxidative stress, like in CYP1B1−/− retinal ECs. In addition, expression of eNOS in CYP1B1−/− retinal ECs or their incubation with a nitric oxide (NO) donor enhanced NO levels, lowered oxidative stress, and improved cell migration and CM. Inhibition of CYP1B1 activity in the CYP1B1+/+ retinal ECs resulted in reduced NO levels and attenuation of CM. In contrast, expression of CYP1B1 increased NO levels and enhanced CM of CYP1B1−/− retinal ECs. Furthermore, attenuation of CYP1B1 expression with small interfering RNA proportionally lowered eNOS expression and NO levels in wild-type cells. Together, our results link CYP1B1 metabolism in retinal ECs with sustained eNOS activity and NO synthesis and/or bioavailability and low oxidative stress and thrombospondin-2 expression. Thus CYP1B1 and eNOS cooperate in different ways to lower oxidative stress and thereby to promote CM in vitro and angiogenesis in vivo.

scholarly journals A non-canonical chemical feedback self-limits nitric oxide-cyclic GMP signaling in health and disease

2018 ◽  
Author(s):  
Vu Thao-Vi Dao ◽  
Mahmoud H. Elbatreek ◽  
Martin Deile ◽  
Pavel I. Nedvetsky ◽  
Andreas Güldner ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Cyclic Gmp ◽  
Soluble Guanylate Cyclase ◽  
Feedback Inhibition ◽  
No Donor ◽  
Cgmp Signaling ◽  
Dependent Protein ◽  
Direct Feedback

AbstractNitric oxide (NO)-cyclic GMP (cGMP) signaling is a vasoprotective pathway therapeutically targeted for example in pulmonary hypertension. Its dysregulation in disease is incompletely understood. Here we show in pulmonary artery endothelial cells that feedback inhibition by NO of the NO receptor, the cGMP forming soluble guanylate cyclase (sGC), may contribute to this. Both endogenous NO from endothelial NO synthase or exogenous NO from NO donor compounds decreased sGC protein and activity. This was not mediated by cGMP as the NO-independent sGC stimulator or direct activation of cGMP-dependent protein kinase did not mimic it. Thiol-sensitive mechanisms were also not involved as the thiol-reducing agent, N-acetyl-L-cysteine did not prevent this feedback. Instead, both in-vitro and in-vivo and in health and acute respiratory lung disease, chronically elevated NO led to the inactivation and degradation of sGC whilst leaving the heme-free isoform, apo-sGC, intact or even increasing its levels. Thus, NO regulates sGC in a bimodal manner, acutely stimulating and chronically inhibiting, as part of self-limiting direct feedback that is cGMP-independent. In high NO disease conditions, this is aggravated but can be functionally recovered in a mechanism-based manner by apo-sGC activators that re-establish cGMP formation.

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