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Agrawal S, Kumari R, Sophronea T, Kumari N, Luthra PM. Design and synthesis of benzo[d]thiazol-2-yl-methyl-4-(substituted)-piperazine-1-carbothioamide as novel neuronal nitric oxide inhibitors and evaluation of their neuroprotecting effect in 6-OHDA-induced unilateral lesioned rat model of Parkinson's disease. Biomed Pharmacother 2022; 156:113838. [DOI: 10.1016/j.biopha.2022.113838] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2022] [Revised: 10/03/2022] [Accepted: 10/06/2022] [Indexed: 11/25/2022] Open
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Miles L, Powell J, Kozak C, Song Y. Mechanosensitive Ion Channels, Axonal Growth, and Regeneration. Neuroscientist 2022:10738584221088575. [PMID: 35414308 PMCID: PMC9556659 DOI: 10.1177/10738584221088575] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Cells sense and respond to mechanical stimuli by converting those stimuli into biological signals, a process known as mechanotransduction. Mechanotransduction is essential in diverse cellular functions, including tissue development, touch sensitivity, pain, and neuronal pathfinding. In the search for key players of mechanotransduction, several families of ion channels were identified as being mechanosensitive and were demonstrated to be activated directly by mechanical forces in both the membrane bilayer and the cytoskeleton. More recently, Piezo ion channels were discovered as a bona fide mechanosensitive ion channel, and its characterization led to a cascade of research that revealed the diverse functions of Piezo proteins and, in particular, their involvement in neuronal repair.
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Affiliation(s)
- Leann Miles
- The Graduate Group in Biochemistry and Molecular Biophysics, University of Pennsylvania, Philadelphia, PA, USA
| | - Jackson Powell
- Raymond G. Perelman Center for Cellular and Molecular Therapeutics, The Children's Hospital of Philadelphia, Philadelphia, PA, USA
| | - Casey Kozak
- Raymond G. Perelman Center for Cellular and Molecular Therapeutics, The Children's Hospital of Philadelphia, Philadelphia, PA, USA
| | - Yuanquan Song
- The Graduate Group in Biochemistry and Molecular Biophysics, University of Pennsylvania, Philadelphia, PA, USA.,Raymond G. Perelman Center for Cellular and Molecular Therapeutics, The Children's Hospital of Philadelphia, Philadelphia, PA, USA.,Department of Pathology and Laboratory Medicine, University of Pennsylvania, Philadelphia, PA, USA
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Welcome MO. The bitterness of genitourinary infections: Properties, ligands of genitourinary bitter taste receptors and mechanisms linking taste sensing to inflammatory processes in the genitourinary tract. Eur J Obstet Gynecol Reprod Biol 2020; 247:101-110. [PMID: 32088528 DOI: 10.1016/j.ejogrb.2020.02.015] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2019] [Revised: 02/03/2020] [Accepted: 02/13/2020] [Indexed: 01/04/2023]
Abstract
BACKGROUND Though, first identified in the gastrointestinal tract, bitter taste receptors are now believed to be ubiquitously expressed in several regions of the body, including the respiratory tract, where they play a critical role in sensing and clearance of excess metabolic substrates, toxins, debris, and pathogens. More recently, bitter taste receptor expression has been reported in cells, tissues and organs of the genitourinary (GU) system, suggesting that these receptors may play an integral role in mediating inflammatory responses to microbial aggression in the GU tract. However, the mechanisms, linking bitter taste receptor sensing with inflammatory responses are not exactly clear. Here, I review recent data on the properties and ligands of bitter taste receptors and suggest mechanisms of bitter taste receptor signaling in the GU tract, and the molecular pathways that link taste sensing to inflammatory responses in GU tract. METHOD Computer-aided search was conducted in Scopus, PubMed, Web of Science and Google Scholar for relevant peer-reviewed articles published between 1990 and 2018, investigating the functional implication of bitter taste receptors in GU infections, using the following keywords: extra-oral bitter taste receptors, bitter taste receptors, GU bitter taste receptors, kidney OR renal OR ureteral OR urethral OR bladder OR detrusor smooth muscle OR testes OR spermatozoa OR prostate OR vaginal OR cervix OR ovarian OR endometrial OR myometrial OR placenta OR cutaneous bitter taste receptors. To identify research gaps on etiopathogenesis of GU infections/inflammation, additional search was conducted using the following keywords: GU inflammatory signaling, GU microbes, GU bacteria, GU virus, GU protozoa, GU microbial metabolites, and GU infection. The retrieved articles were filtered and further screened for relevance according to the aim of the study. A narrative review was performed for selected literatures. RESULTS Bitter taste receptors of the GU tract may constitute essential components of the pathogenetic mechanisms of GU infections/inflammation that are activated by microbial components, known as quorum sensing signal molecules. Based on accumulating evidences, indicating that taste receptors may signal downstream to activate inflammatory cascades, in addition to the nitric oxide-induced microbicidal effects produced upon taste receptor activation, it is suggested that the anti-inflammatory activities of bitter taste receptor stimulation are mediated via pathways involving the nuclear factor κB by downstream signaling of the metabolic and stress sensors, adenosine monophosphate-activated protein kinase and nicotinamide adenine dinucleotide-dependent silent mating type information regulation 2 homolog 1 (sirtuin 1), resulting to the synthesis of anti-inflammatory cytokines/chemokines, and antimicrobial factors, which ultimately, under normal conditions, leads to the elimination of microbial aggression. CONCLUSIONS GU bitter taste receptors may represent critical players in GU tract infections/inflammation. Bitter taste receptors may serve as important therapeutic target for treatment of a number of infectious diseases that affect the GU tract.
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Affiliation(s)
- Menizibeya O Welcome
- Department of Physiology, Faculty of Basic Medical Sciences, College of Health Sciences, Nile University of Nigeria, Abuja, Nigeria.
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Burjanadze G, Shengelia M, Dachanidze N, Mikadze M, Menabde K, Koshoridze N. Creatine–facilitated protection of stress caused by disrupted circadian rhythm. BIOL RHYTHM RES 2018. [DOI: 10.1080/09291016.2017.1333198] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Affiliation(s)
- George Burjanadze
- Faculty of Exact and Natural Sciences, Department of Biology, Ivane Javakhishvili Tbilisi State University, Tbilisi, Georgia
| | - Mariam Shengelia
- Faculty of Exact and Natural Sciences, Department of Biology, Ivane Javakhishvili Tbilisi State University, Tbilisi, Georgia
| | - Natalia Dachanidze
- Faculty of Exact and Natural Sciences, Department of Biology, Ivane Javakhishvili Tbilisi State University, Tbilisi, Georgia
| | - Mariam Mikadze
- US MD Program, Tbilisi State Medical University, Tbilisi, Georgia
| | - Ketevan Menabde
- Faculty of Exact and Natural Sciences, Department of Biology, Ivane Javakhishvili Tbilisi State University, Tbilisi, Georgia
| | - Nana Koshoridze
- Faculty of Exact and Natural Sciences, Department of Biology, Ivane Javakhishvili Tbilisi State University, Tbilisi, Georgia
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Harisa GI. Mitigation of lead-induced neurotoxicity by the naringin: erythrocytes as neurons substitute markers. Biol Trace Elem Res 2014; 159:99-106. [PMID: 24828744 DOI: 10.1007/s12011-014-9996-5] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/21/2014] [Accepted: 04/24/2014] [Indexed: 12/31/2022]
Abstract
This study aimed to investigate the effect of lead (Pb) on neuronal nitric oxide synthase (nNOS) activity using erythrocytes as neurons surrogate markers. Moreover, the protective effect of naringin (NAR) against lead acetate (PbAc)-induced neurotoxicity was investigated. Human erythrocytes were incubated with L-arginine (L-Arg), Nω-nitro-L-Arginine methyl ester ( L-NAME), NAR, PbAc, PbAc+L-Arg, PbAc+NAR, or PbAc+L-Arg+NAR. The present results revealed that incubation of erythrocytes with PbAc inhibited NOS activity and decreased nitrite levels as an index for nitric oxide (NO) production to values similar that of L-NAME as known NOS inhibitor. Likewise, PbAc induced a significant decrease in activities of ATPases and acetylcholinesterase compared to control cells. Furthermore, PbAc exposure significantly increased protein carbonyl content (PCC) and malondialdehyde (MDA) levels while significantly decrease the levels of reduced glutathione (GSH). On the contrary, incubation of erythrocytes with PbAc in the presence of L-Arg+NAR synergistically ameliorated the investigated parameters compared to erythrocytes incubated with PbAc alone. These data suggest that NAR can restore NO bioavailability in a situation of Pb-induced cellular damage. This attributed to antioxidant activity and restoration NOS activity.
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Affiliation(s)
- Gamaleldin I Harisa
- Department of Pharmaceutics, Kayyali Chair for Pharmaceutical Industry, College of Pharmacy, King Saud University, P.O. Box 2457, Riyadh, 11451, Saudi Arabia,
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Nava-Ruíz C, Alcaraz-Zubeldia M, Méndez-Armenta M, Vergara P, Díaz-Ruìz A, Ríos C. Nitric oxide synthase immunolocalization and expression in the rat hippocampus after sub-acute lead acetate exposure in rats. ACTA ACUST UNITED AC 2010; 62:311-6. [DOI: 10.1016/j.etp.2009.04.006] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2009] [Revised: 04/15/2009] [Accepted: 04/28/2009] [Indexed: 10/20/2022]
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Ivanina AV, Eilers S, Kurochkin IO, Chung JS, Techa S, Piontkivska H, Sokolov EP, Sokolova IM. Effects of cadmium exposure and intermittent anoxia on nitric oxide metabolism in eastern oysters, Crassostrea virginica. J Exp Biol 2010; 213:433-44. [DOI: 10.1242/jeb.038059] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
SUMMARY
Nitric oxide (NO) is an intracellular signaling molecule synthesized by a group of enzymes called nitric oxide synthases (NOS) and involved in regulation of many cellular functions including mitochondrial metabolism and bioenergetics. In invertebrates, the involvement of NO in bioenergetics and metabolic responses to environmental stress is poorly understood. We determined sensitivity of mitochondrial and cellular respiration to NO and the effects of cadmium (Cd) and intermittent anoxia on NO metabolism in eastern oysters, Crassostrea virginica. NOS activity was strongly suppressed by exposure to 50 μg l–1 Cd for 30 days (4.76 vs 1.19 pmol NO min–1 mg–1 protein in control and Cd-exposed oysters, respectively) and further decreased during anoxic exposure in Cd-exposed oysters but not in their control counterparts. Nitrate/nitrite content (indicative of NO levels) decreased during anoxic exposure to less than 10% of the normoxic values and recovered within 1 h of re-oxygenation in control oysters. In Cd-exposed oysters, the recovery of the normoxic NO levels lagged behind, reflecting their lower NOS activity. Oyster mitochondrial respiration was inhibited by exogenous NO, with sensitivity on a par with that of mammalian mitochondria, and ADP-stimulated mitochondrial respiration was significantly more sensitive to NO than resting respiration. In isolated gill cells, manipulations of endogenous NOS activity either with a specific NOS inhibitor (aminoguanidine) or a NOS substrate (l-arginine) had no effect on respiration, likely due to the fact that mitochondria in the resting state are relatively NO insensitive. Likewise, Cd-induced stimulation of cellular respiration did not correlate with decreased NOS activity in isolated gill cells. High sensitivity of phosphorylating (ADP-stimulated) oyster mitochondria to NO suggests that regulation of bioenergetics is an evolutionarily conserved function of NO and that NO-dependent regulation of metabolism may be most prominent under the conditions of high metabolic flux when the ADP-to-ATP ratio is high.
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Affiliation(s)
- A. V. Ivanina
- Biology Department, University of North Carolina at Charlotte, 9201 University City Boulevard, Charlotte, NC 28223, USA
| | - S. Eilers
- Biology Department, University of North Carolina at Charlotte, 9201 University City Boulevard, Charlotte, NC 28223, USA
| | - I. O. Kurochkin
- Biology Department, University of North Carolina at Charlotte, 9201 University City Boulevard, Charlotte, NC 28223, USA
| | - J. S. Chung
- Center of Marine Biotechnology, University of Maryland Biotechnology Institute, 701 East Pratt Street, Baltimore, MD 21202, USA
| | - S. Techa
- Center of Marine Biotechnology, University of Maryland Biotechnology Institute, 701 East Pratt Street, Baltimore, MD 21202, USA
| | - H. Piontkivska
- Department of Biological Sciences, Kent State University, Kent, OH 44242-0001, USA
| | - E. P. Sokolov
- Department of General Surgery, Carolinas Medical Center, 1000 Blythe Boulevard, Charlotte, NC 28203-5871, USA
| | - I. M. Sokolova
- Biology Department, University of North Carolina at Charlotte, 9201 University City Boulevard, Charlotte, NC 28223, USA
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Valentovicová K, Halusková L, Huttová J, Mistrík I, Tamás L. Effect of cadmium on diaphorase activity and nitric oxide production in barley root tips. JOURNAL OF PLANT PHYSIOLOGY 2010; 167:10-4. [PMID: 19674814 DOI: 10.1016/j.jplph.2009.06.018] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/24/2009] [Revised: 06/23/2009] [Accepted: 06/24/2009] [Indexed: 05/11/2023]
Abstract
The effect of Cd on NADPH-diaphorase activity and nitric oxide (NO) production was investigated in barley root tips. The Cd-induced increase of NADPH-diaphorase activity occurred at the elongation zone and increased further in the differentiation zone of barley root tips. This activity was associated primarily with the microsomal membrane fraction of crude extract. In situ analysis revealed that the diaphorase activity was localized in the metaxylem and metaphloem elements and to some cells of the pericycle and parenchyma of root tips. Cd-induced NO generation was observed in pericycle, parenchymatic stelar cells and companion cells of protophloem. The results suggest that the Cd-induced generation of NO functions in Cd toxicity through the ectopic and accelerated differentiation of root tips, causing the shortening of the root elongation zone and a subsequent reduction in root growth.
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Affiliation(s)
- Katarína Valentovicová
- Institute of Botany, Slovak Academy of Sciences, Dúbravská cesta 14, SK-84523 Bratislava, Slovak Republic.
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Liu PS, Watanabe S, Kirino Y. Caffeine-Induced Modulation of Network Oscillation in a Molluscan Olfactory Center. Zoolog Sci 2007; 24:1247-50. [DOI: 10.2108/zsj.24.1247] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2006] [Accepted: 08/09/2007] [Indexed: 11/17/2022]
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Spratt DE, Taiakina V, Guillemette JG. Calcium-deficient calmodulin binding and activation of neuronal and inducible nitric oxide synthases. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2007; 1774:1351-8. [PMID: 17890165 DOI: 10.1016/j.bbapap.2007.07.019] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/26/2007] [Revised: 06/25/2007] [Accepted: 07/23/2007] [Indexed: 11/17/2022]
Abstract
The nitric oxide synthase (NOS) enzymes are bound and activated by the Ca(2+)-binding protein, calmodulin (CaM). We have utilized CaM mutants deficient in binding Ca(2+) with mutations in the N-lobe (CaM(12)), the C-lobe (CaM(34)), or both lobes of CaM (CaM(1234)) to determine their effect on the binding and activation of the Ca(2+)-dependent neuronal (nNOS) and Ca(2+)-independent inducible NOS (iNOS) isoforms. Four different kinetic assays were employed to monitor the effect of these CaM mutants on electron transfer rates in NOS. Protein-protein interactions between CaM and NOS were studied using steady-state fluorescence and spectropolarimetry to monitor the binding of these CaM mutants to nNOS and iNOS CaM-binding domain peptides. The CaM mutants were unable to activate nNOS, however, our CD results show that the C-terminal lobe of CaM is capable of binding to nNOS peptide in the presence of Ca(2+). Our results prove for the first time without the use of chelators that apo-CaM is capable of binding to iNOS peptides and holoenzymes.
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Affiliation(s)
- Donald E Spratt
- Department of Chemistry, University of Waterloo, Waterloo, Ontario, Canada
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11
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Kursula P, Majava V. A structural insight into lead neurotoxicity and calmodulin activation by heavy metals. Acta Crystallogr Sect F Struct Biol Cryst Commun 2007; 63:653-6. [PMID: 17671360 PMCID: PMC2335165 DOI: 10.1107/s1744309107034525] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2007] [Accepted: 07/14/2007] [Indexed: 11/10/2022]
Abstract
Calmodulin is a calcium sensor that is also capable of binding and being activated by other metal ions. Of specific interest in this respect is lead, which is known to be neurotoxic and to have a very high affinity towards calmodulin. Crystal structures of human calmodulin complexed with lead and barium ions have been solved. The results will help in understanding the activation mechanisms of calmodulin by different heavy metals and will provide a detailed view of a putative target for lead neurotoxicity in humans.
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Affiliation(s)
- Petri Kursula
- Department of Biochemistry, University of Oulu, Oulu, Finland.
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12
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Izgü F, Altinbay D, Sertkaya A. Enzymic activity of the K5-type yeast killer toxin and its characterization. Biosci Biotechnol Biochem 2006; 69:2200-6. [PMID: 16306703 DOI: 10.1271/bbb.69.2200] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
K5-type yeast killer toxin secreted by P. anomala NCYC 434 cells has a broad killing spectrum. Competitive inhibiton of killer activity showed that glucans, mainly the beta-1,3 glucan, represent the primary toxin binding site within the cell wall of sensitive cells. Its hydrolytic activity on laminarin in an exo-like fashion revealed that the toxin exerts its killing effect by exo-beta-1,3-glucanase activity. Its specific activity on laminarin was 120 U/mg, and the Michaelis constants K(m) and V(max) for laminarin hydrolysis were 0.25 mg/ml and 370 micromol/min/mg. The toxin exerted its cytocidal effect after 2 h contact with the target cells. Production of the toxin by the cells was induced only when they were grown in culture media rich in beta-glucan sources, and the addition of glucose increased the specific production rate. The enzymic activity of the toxin was fully inhibited by Hg(+2), but increased with some other metal ions, most of all by Pb(+2).
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Affiliation(s)
- Fatih Izgü
- Department of Biological Sciences, Middle East Technical University, Ankara, Turkey.
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Sharifi AM, Mousavi SH, Bakhshayesh M, Tehrani FK, Mahmoudian M, Oryan S. Study of correlation between lead-induced cytotoxicity and nitric oxide production in PC12 cells. Toxicol Lett 2005; 160:43-8. [PMID: 16039808 DOI: 10.1016/j.toxlet.2005.06.008] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2005] [Accepted: 06/06/2005] [Indexed: 12/21/2022]
Abstract
Despite reduction in its exposure, lead remains a major health problem. The primary target of lead toxicity is the central nervous system. The cellular, intracellular and molecular mechanisms of lead neurotoxicity are numerous, such as induction of apoptosis and interfering with Ca2+ dependent enzyme like nitric oxide synthase (NOS). To investigate the cytotoxic effect of lead on rat pheochromocytoma (PC12) cells, as a suitable model for neuroscience study, and possible correlation between lead toxicity and nitric oxide (NO) production, this study was performed. The current results showed that lead could induce cytotoxicity as well as NO production in a dose dependent manner in PC12 cells after 24h. The cytotoxicity was positively correlated with increased NOx (nitrite and nitrate) production in these cells. L-NAME, a NOS inhibitor, treatment (2.5 mM) could reverse this cytotoxicity. It can be concluded that lead-induced cytotoxicity in PC12 cells could partly be mediated by higher NO production.
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Affiliation(s)
- Ali M Sharifi
- Department of Pharmacology and Cellular and Molecular Research Center, School of Medicine, Iran University of Medical Sciences, P.O. Box 14155-6183, Tehran, Iran.
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Seebacher F, Franklin CE. Prostaglandins are important in thermoregulation of a reptile (Pogona vitticeps). Proc Biol Sci 2003; 270 Suppl 1:S50-3. [PMID: 12952634 PMCID: PMC1698025 DOI: 10.1098/rsbl.2003.0007] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
The effectiveness of behavioural thermoregulation in reptiles is amplified by cardiovascular responses, particularly by differential rates of heart beat in response to heating and cooling (heart-rate hysteresis). Heart-rate hysteresis is ecologically important in most lineages of ectothermic reptile, and we demonstrate that heart-rate hysteresis in the lizard Pogona vitticeps is mediated by prostaglandins. In a control treatment (administration of saline), heart rates during heating were significantly faster than during cooling at any given body temperature. When cyclooxygenase 1 and 2 enzymes were inhibited, heart rates during heating were not significantly different from those during cooling. Administration of agonists showed that thromboxane B(2) did not have a significant effect on heart rate, but prostacyclin and prostaglandin F(2alpha) caused a significant increase (3.5 and 13.6 beats min(-1), respectively) in heart rate compared with control treatments. We speculate that heart-rate hysteresis evolved as a thermoregulatory mechanism that may ultimately be controlled by neurally induced stimulation of nitric oxide production, or maybe via photolytically induced production of vitamin D.
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Affiliation(s)
- Frank Seebacher
- School of Biological Sciences A08, University of Sydney, Sydney, NSW 2006, Australia.
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Si ML, Lee TJF. Pb2+ inhibition of sympathetic alpha 7-nicotinic acetylcholine receptor-mediated nitrergic neurogenic dilation in porcine basilar arteries. J Pharmacol Exp Ther 2003; 305:1124-31. [PMID: 12626657 DOI: 10.1124/jpet.102.046854] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Chronic exposure to inorganic lead (Pb2+) has been shown to facilitate peripheral vasoconstriction causing hypertension. Effect of lead on cerebral vascular function has not been reported. We have suggested in isolated porcine cerebral arteries that alpha 7-nicotinic acetylcholine receptors (alpha 7-nAChRs) on perivascular sympathetic nerves mediate calcium influx in these neurons, resulting in release of norepinephrine. The released norepinephrine then acts on presynaptic beta2-adrenoceptors located on the neighboring nitrergic nerve terminals, causing nitric oxide (NO) release and vasodilation. Because Pb2+ has been shown to inhibit alpha 7-nAChR-mediated responses in the central nervous system, effects of Pb2+ on alpha 7-nAChR-mediated nitrergic neurogenic dilation in isolated porcine basilar arteries and calcium influx in cultured superior cervical ganglion (SCG) cells of the pig were examined using in vitro tissue bath and confocal microscopic techniques. The results indicated that Pb2+ (but not Cd2+, Zn2+, or Al3+) in a concentration-dependent manner blocked relaxation of endothelium-denuded basilar arterial rings induced by nicotine (100 microM) and choline (1 mM) without affecting relaxation induced by sodium nitroprusside or isoproterenol. Furthermore, significant calcium influx in cultured SCG cells induced by choline and nicotine was attenuated specifically by Pb2+ with IC50 values comparable with those from tissue bath study. These results provide evidence supporting that lead is a likely antagonist for alpha 7-nAChRs that are found on postganglionic sympathetic adrenergic nerve terminals of SCG origin. Furthermore, these results indicate that lead can attenuate dilation of cerebral arteries by blocking sympathetic nerve-mediated release of NO from the perivascular nitrergic nerves.
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Affiliation(s)
- Min-Liang Si
- Department of Pharmacology, Southern Illinois University School of Medicine, Springfield, IL 62794, USA
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Abstract
Nitric oxide synthase (NOS) is an example of a family of heme-containing monooxygenases that, under the restricted control of a specific substrate, can generate free radicals. While the generation of nitric oxide (NO*) depends solely on the binding of L-arginine, NOS produces superoxide (O(2)*(-)) and hydrogen peroxide (H(2)O(2)) when the concentration of the substrate is low. Not surprisingly, effort has been put forth to understand the pathway by which NOS generates NO*, O(2)*(-) and H(2)O(2), including the role of substrate binding in determining the pathways by which free radicals are generated. By binding within the distal heme pocket near the sixth coordination position of the NOS heme iron, L-arginine alters the coordination properties of the heme iron that promotes formation of the perferryl complex NOS-[Fe(5+)=O](3+). This reactive iron intermediate has been shown to abstract a hydrogen atom from a carbon alpha to a heteroatom and generate carbon-centered free radicals. The ability of NOS to produce free radicals during enzymic cycling demonstrates that NOS-[Fe(5+)=O](3+) behaves like an analogous iron-oxo complex of cytochrome P-450 during aliphatic hydroxylation. The present review discusses the mechanism(s) by which NOS generates secondary free radicals that may initiate pathological events, along with the cell signaling properties of NO*, O(2)*(-) and H(2)O(2).
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Affiliation(s)
- Supatra Porasuphatana
- Department of Toxicology, Faculty of Pharmaceutical Sciences, Khon Kaen University, Khon Kaen 40002, Thailand.
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17
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Rosen GM, Tsai P, Weaver J, Porasuphatana S, Roman LJ, Starkov AA, Fiskum G, Pou S. The role of tetrahydrobiopterin in the regulation of neuronal nitric-oxide synthase-generated superoxide. J Biol Chem 2002; 277:40275-80. [PMID: 12183447 DOI: 10.1074/jbc.m200853200] [Citation(s) in RCA: 77] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Tetrahydrobiopterin (H(4)B) is a critical element in the nitric-oxide synthase (NOS) metabolism of l-arginine to l-citrulline and NO(.). It has been hypothesized that in the absence of or under nonsaturating levels of L-arginine where O(2) reduction is the primary outcome of NOS activation, H(4)B promotes the generation of H(2)O(2) at the expense of O(2)(-.). The experiments were designed to test this hypothesis. To test this theory, two different enzyme preparations, H(4)B-bound NOS I and H(4)B-free NOS I, were used. Initial rates of NADPH turnover and O(2) utilization were found to be considerably greater in the H(4)B-bound NOS I preparation than in the H(4)B-free NOS I preparation. In contrast, the initial generation of O(2)(-.) from the H(4)B-free NOS I preparation was found to be substantially greater than that measured using the H(4)B-bound NOS I preparation. Finally, by spin trapping nearly all of the NOS I produced O(2)(-.), we found that the initial rate of H(2)O(2) production by H(4)B-bound NOS I was considerably greater than that for H(4)B-free NOS I.
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Affiliation(s)
- Gerald M Rosen
- Department of Pharmaceutical Sciences, University of Maryland School of Pharmacy, 725 West Lombard Street, Baltimore, MD 21201, USA.
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