1
|
Wright NJD. A review of the actions of Nitric Oxide in development and neuronal function in major invertebrate model systems. AIMS Neurosci 2019; 6:146-174. [PMID: 32341974 PMCID: PMC7179362 DOI: 10.3934/neuroscience.2019.3.146] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2019] [Accepted: 07/24/2019] [Indexed: 12/21/2022] Open
Abstract
Ever since the late-eighties when endothelium-derived relaxing factor was found to be the gas nitric oxide, endogenous nitric oxide production has been observed in virtually all animal groups tested and additionally in plants, diatoms, slime molds and bacteria. The fact that this new messenger was actually a gas and therefore didn't obey the established rules of neurotransmission made it even more intriguing. In just 30 years there is now too much information for useful comprehensive reviews even if limited to animals alone. Therefore this review attempts to survey the actions of nitric oxide on development and neuronal function in selected major invertebrate models only so allowing some detailed discussion but still covering most of the primary references. Invertebrate model systems have some very useful advantages over more expensive and demanding animal models such as large, easily identifiable neurons and simple circuits in tissues that are typically far easier to keep viable. A table summarizing this information along with the major relevant references has been included for convenience.
Collapse
Affiliation(s)
- Nicholas J D Wright
- Associate professor of pharmacy, Wingate University School of Pharmacy, Wingate, NC28174, USA
| |
Collapse
|
2
|
Serfőző Z, Nacsa K, Veréb Z, Battonyai I, Hegedűs C, Balogh C, Elekes K. Nitric oxide-coupled signaling in odor elicited molecular events in the olfactory center of the terrestrial snail, Helix pomatia. Cell Signal 2016; 30:67-81. [PMID: 27884734 DOI: 10.1016/j.cellsig.2016.11.017] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2016] [Revised: 11/15/2016] [Accepted: 11/18/2016] [Indexed: 12/22/2022]
Abstract
Olfaction, a chemosensory modality, plays a pivotal role in the orientation and behavior of invertebrates. The central olfactory processing unit in terrestrial stylomatophoran snails is the procerebrum, which contains NO synthesizing interneurons, whose oscillatory currents are believed to be the base of odor evoked memory formation. Nevertheless, in this model the up- and downstream events of molecular cascades that trigger and follow NO release, respectively, have not been studied. Immunocytochemistry and flow cytometry studies performed on procerebral neural perikarya isolated from the snail Helix pomatia revealed cell populations with discrete DAF-2 fluorescence, indicating the release of different amounts of NO. Glutamate increased the intensity of DAF-2 fluorescence, and the number of DAF-2 positive non-bursting interneurons, through a mechanism likely to involve an NMDA-like receptor. Similarly to glutamate, NO activation induced an increase in intracellular cGMP levels through activation of soluble guanylyl cyclase. Immunohistochemical localization of proteins possessing the phosphorylated target sequence of AGC family kinases (RXXS/T-P), among them protein kinase A (RRXS/T-P), showed striking similarities to the distribution of NOS/cGMP. Activators of cyclic nucleotide synthesis increased the AGC-kinase-dependent phosphorylation of discrete proteins with 28, 45, and 55kDamw. Importantly, exposure of snails to an attractive odorant induced hyperphosphorylation of the 28kDa protein, and increased levels of cGMP synthesis. Protein S-nitrosylation and intercellular activation of protein kinase G were also suggested as alternative components of NO signaling in the snail procerebrum. The present results from Helix pomatia indicate an important role for procerebrum NO/cGMP/PKA signaling pathways in the regulation of olfactory (food-finding) behavior.
Collapse
Affiliation(s)
- Zoltán Serfőző
- MTA Centre for Ecological Research, Balaton Limnological Institute, Tihany, Hungary.
| | - Kálmán Nacsa
- MTA Centre for Ecological Research, Balaton Limnological Institute, Tihany, Hungary
| | - Zoltán Veréb
- Institute of Biochemistry and Molecular Biology, Medical and Health Science Center, University of Debrecen, Debrecen, Hungary
| | - Izabella Battonyai
- MTA Centre for Ecological Research, Balaton Limnological Institute, Tihany, Hungary
| | - Csaba Hegedűs
- Institute of Medical Chemistry, Medical and Health Science Center, University of Debrecen, Debrecen, Hungary
| | - Csilla Balogh
- MTA Centre for Ecological Research, Balaton Limnological Institute, Tihany, Hungary
| | - Károly Elekes
- MTA Centre for Ecological Research, Balaton Limnological Institute, Tihany, Hungary
| |
Collapse
|
3
|
Wright NJD, Sides LJ, Walling K. Initial studies on the direct and modulatory effects of nitric oxide on an identified central Helix aspersa neuron. INVERTEBRATE NEUROSCIENCE 2014; 15:175. [PMID: 25380983 DOI: 10.1007/s10158-014-0175-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Received: 12/19/2013] [Accepted: 08/21/2014] [Indexed: 10/24/2022]
Abstract
The generation of the novel messenger molecule nitric oxide (NO) has been demonstrated in many tissues across phyla including nervous systems. It is produced on demand by the enzyme nitric oxide synthase often stimulated by intracellular calcium and typically affecting guanylate cyclase thought to be its principal target in an auto and/or paracrine fashion. This results in the generation of the secondary messenger cyclic guanosine monophosphate (cGMP). Nitric oxide synthase has been demonstrated in various mollusk brains and manipulation of NO levels has been shown to affect behavior in mollusks. Apart from modulation of the effect of the peptide GSPYFVamide, there appears little published on direct or modulatory effects of NO on Helix aspersa central neurons. We present here initial results to show that NO can be generated in the region around F1 in the right parietal ganglion and that NO and cGMP directly hyperpolarize this neuron. For example, application of the NO-donor S-nitroso-N-acetyl-D,L-penicillamine (SNAP; 200 µM) can cause a mean hyperpolarization of 41.7 mV, while 2 mM 8-bromo-cyclic guanosine monophosphate (8-bromo-cGMP) produced a mean hyperpolarization of 33.4 mV. Additionally, pre-exposure to NO-donors or cGMP appears to significantly reduce or even eliminates the normal hyperpolarizing K(+)-mediated response to dopamine (DA) by this neuron; 200 µM SNAP abolishes a standard response to 0.5 µM DA while 1 mM 8-bromo-cGMP reduces it 62%.
Collapse
Affiliation(s)
- Nicholas J D Wright
- Levine College of Health Sciences, Wingate University School of Pharmacy, 515 N. Main Street, Wingate, NC, 28174, USA,
| | | | | |
Collapse
|
4
|
Dyakonova VE, Dyakonova TL. Coordination of rhythm-generating units via NO and extrasynaptic neurotransmitter release. J Comp Physiol A Neuroethol Sens Neural Behav Physiol 2010; 196:529-41. [PMID: 20559642 DOI: 10.1007/s00359-010-0541-5] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2010] [Revised: 05/19/2010] [Accepted: 05/25/2010] [Indexed: 10/19/2022]
Abstract
The buccal ganglia of the mollusc, Lymnaea stagnalis, contain two distinct but interacting rhythm-generating units: the central pattern generator for the buccal rhythm and nitrergic B2 neurons controlling gut motility. Nitric oxide (NO) has previously been demonstrated to be involved in the activation of the buccal rhythm. Here, we found that NO-generating substances (SNP and SNAP) activated the buccal rhythm while slowing the endogenous rhythm of B2 bursters. The inhibitor of NO-synthase, L-NNA, the NO scavenger PTIO, or the inhibitor of soluble guanylyl cyclase, ODQ, each produced opposite, depolarising effects on the B2 neuron. In isolated B2 cells, only depolarising effects of substances interfering with NO production or function (PTIO, L-NNA and ODQ) were detected, whereas the NO donors had no hyperpolarising effects. However, when an isolated B2 cell was placed close to its initial position in the ganglion, hyperpolarising effects could be obtained with NO donors. This indicates that extrasynaptic release of some unidentified factor(s) mediates the hyperpolarising effects of NO donors on the B2 bursters. The results suggest that NO is involved in coordination between the radula and foregut movements and that the effects of NO are partially mediated by the volume chemical neurotransmission of as yet unknown origin.
Collapse
Affiliation(s)
- Varvara E Dyakonova
- Laboratory of Comparative Physiology, Institute of Developmental Biology of the Russian Academy of Sciences, Vavilov Str. 26, Moscow, 119991, Russia.
| | | |
Collapse
|
5
|
Abstract
NO-producing neuron exhibited an excitatory response to the decrease in NO concentration, which was induced by NO synthase inhibitor N-nitro-L-arginine or specific NO acceptor 2-phenyl-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide. Addition of NO donors to the medium inhibits neuronal activity. The excitatory effects of N-nitro-L-arginine and 2-phenyl-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide were preserved, while the inhibitory action of NO donors significantly decreased after isolation of the neuron. These findings indicate that NO regulates activity of these neurons by the negative feedback mechanism. This regulation includes the following complementary mechanisms: (1) endogenous mechanism of cell self-activation in response to the decrease in NO concentration; and (2) exogenous mechanism of cell-mediated inhibition in response to NO excess.
Collapse
Affiliation(s)
- T L Dyakonova
- N. K. Kol'tsov Institute of Developmental Biology, Russian Academy of Sciences, Moscow, Russia.
| | | |
Collapse
|
6
|
Serfözö Z, Szentmiklósi AJ, Elekes K. Characterization of nitric oxidergic neurons in the alimentary tract of the snailHelix pomatia L.: Histochemical and physiological study. J Comp Neurol 2007; 506:801-21. [DOI: 10.1002/cne.21585] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
|
7
|
Roszer T, Kiss-Tóth E, Petkó M, Szentmiklósi AJ, Bánfalvi G. Phe-met-arg-phe (FMRF)-amide is a substrate source of NO synthase in the gastropod nervous system. Cell Tissue Res 2006; 325:567-75. [PMID: 16612629 DOI: 10.1007/s00441-006-0185-5] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2005] [Accepted: 02/01/2006] [Indexed: 12/18/2022]
Abstract
The possible involvement of the L-arginine-containing Phe-met-arg-phe (FMRF)-amide (FMRFa) in neuronal nitric oxide (NO) biosynthesis was studied in a gastropod species. We found NADPH-diaphorase-positive neurons and FMRFa-containing fibers in close proximity in the enteric nervous system. Administration of L-arginine and FMRFa induced quantitatively similar nitrite production in both intact intestinal tissues and tissue homogenates. These changes could be prevented by the presence of NOARG (an NO synthase inhibitor). Neither chemically modified FMRFa (D-arginine instead of L-arginine) nor amino acid constituents of FMRFa (methionine, phenylalanine) affected basal nitrite production. FMRFa-induced alterations were reduced in the presence of Na+ channel blockers (tetrodotoxin, amiloride, lidocaine), the Na+/K+ATPase inhibitor ouabain, or protease inhibitors (leupeptine, pepstatine-a). FMRFa and its amino acid constituents were analyzed by paper chromatography. When FMRFa was added to tissue homogenates, the peptide was eliminated within 1-2 min, whereas methionine, phenylalanine, arginine, and citrulline levels were elevated simultaneously. We tested the effects of FMRFa, L-arginine, and NOARG on intestinal contractile activity. FMRFa relaxed the intestine for 1-2 min and then induced contractions for 20-40 min. In the presence of NOARG, no relaxant effect of FMRFa was recorded. As administration of L-arginine strongly inhibits the mechanical activity of the intestinal muscle, NO production presumably plays a substantial role in the action of FMRFa, at least in the initial phase. Our biochemical data indicate a direct involvement of FMRFa in NO biosynthesis. FMRFa might be hydrolyzed by extracellular peptidases and then the locally released arginine might be transported into the cells and broken-down to produce NO. Depolarization-induced NO production attributable to the activation of amiloride-sensitive Na+ channels might also be involved.
Collapse
Affiliation(s)
- Tamás Roszer
- Department of Animal Anatomy & Physiology, Faculty of Science, Debrecen University, P.O. Box 15, H-4010 Debrecen, Hungary
| | | | | | | | | |
Collapse
|
8
|
Bodnárová M, Martásek P, Moroz LL. Calcium/calmodulin-dependent nitric oxide synthase activity in the CNS of Aplysia californica: biochemical characterization and link to cGMP pathways. J Inorg Biochem 2005; 99:922-8. [PMID: 15811509 DOI: 10.1016/j.jinorgbio.2005.01.012] [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] [Received: 12/07/2004] [Revised: 01/03/2005] [Accepted: 01/21/2005] [Indexed: 11/17/2022]
Abstract
We characterized enzymatic activity of nitric oxide synthase (NOS) in the central nervous system of Aplysia californica, a popular experimental model in cellular and system neuroscience, and provided biochemical evidence for NO-cGMP signaling in molluscs. Aplysia NOS (ApNOS) activity, determined as citrulline formation, revealed its calcium-/calmodulin-(Ca/CaM) and NADPH dependence and it was inhibited by 50% with 5mM of W7 hydrochloride (a potent Ca/CaM-dependent phosphodiesterase inhibitor). A representative set of inhibitors for mammalian NOS isoforms also suppressed NOS activity in Aplysia. Specifically, the ApNOS was inhibited by 65-92% with 500 microM of L-NAME (a competitive NOS inhibitor) whereas d-NAME at the same concentration had no effect. S-Ethylisothiourea hydrobromide (5mM), a selective inhibitor of all NOS isoforms, suppressed ApNOS by 85%, l-N6-(1-iminoethyl)lysine dihydrochloride (L-NIL, 5mM), an iNOS inhibitor, by 78% and L-thiocitrulline (5mM) (an inhibitor of nNOS and iNOS) by greater than 95%. Polyclonal antibodies raised against rat nNOS hybridized with a putative purified ApNOS (160 kDa protein) from partially purified central nervous system homogenates in Western blot studies. Consistent with other studies, the activity of soluble guanylyl cyclase was stimulated as a result of NO interaction with its heme prosthetic group. The basal levels of cGMP were estimated by radioimmunoassay to be 44.47 fmol/microg of protein. Incubation of Aplysia CNS with the NO donors DEA/NONOate (diethylammonium (Z)-1-(N,N-diethylamino) diazen-1-ium-1,2-diolate - 1mM) or S-nitroso-N-acetylpenicillamine (1mM) and simultaneous phosphodiesterase inhibition with 3-isobutyl-1-methylxanthine (1mM) prior to the assay showed a 26-80 fold increase in basal cGMP levels. Addition of ODQ (1H-[1,2,4]oxadiazolo[4,3-a] quinoxaline-1-one - 1mM), a selective inhibitor of soluble guanylyl cyclase, completely abolished this effect. This confirms that NO may indeed function as a messenger in the molluscan CNS, and that cGMP acts as one of its effectors.
Collapse
Affiliation(s)
- Michaela Bodnárová
- Whitney Laboratory for Marine Bioscience, University of Florida, 9505 Ocean Shore Blvd., St. Augustine, FL 32080, USA
| | | | | |
Collapse
|
9
|
Zsombok A, Schrofner S, Hermann A, Kerschbaum HH. A cGMP-dependent cascade enhances an L-type-like Ca2+ current in identified snail neurons. Brain Res 2005; 1032:70-6. [PMID: 15680943 DOI: 10.1016/j.brainres.2004.11.003] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/06/2004] [Indexed: 10/25/2022]
Abstract
We studied the impact of an NO-cGMP dependent signalling pathway on the high-voltage-activated (HVA) Ca(2+) current in identified neurons of the pulmonate snail, Helix pomatia, using Ba(2+) as charge carrier. The 3',5'-cyclic guanosine monophosphate (cGMP) analogues, dibutyryl-cGMP and 8-bromo-cGMP, consistently induced a biphasic response, consisting of an increase superseded by a decline of the Ba(2+) current. The NO donor, sodium nitroprusside (SNP), modulated only in a minority of neurons the Ba(2+) current. Blockade of protein kinase activity with 1-[5-isoquinolinesulfonyl]-2 methyl piperazine (H 7), a nonselective protein kinase inhibitor, or Rp-8-pCPT-cGMP, a selective protein kinase G (PKG) inhibitor, decreased, whereas Rp-cAMP, a selective protein kinase A (PKA) inhibitor, increased the Ba(2+) current upon application of cGMP analogues or SNP. Okadaic acid or calyculin, inhibitors of protein phosphatase 1 (PP1) and protein phosphatase 2A (PP2A), augmented the Ba(2+) current. Under these conditions, cGMP analogues or SNP had an additive-enhancing effect on the Ba(2+) current. When neurons were exposed to the nonselective phosphodiesterase (PDE) inhibitor 3-isobutyl-1-methylxanthine (IBMX), cGMP analogues induced a persistent increase of the Ba(2+) current, whereas SNP induced a biphasic response. These data suggest coexistence of cGMP-PKG and cGMP-PDE pathways as well as crosstalk between cGMP and 3',5'-cyclic adenosine monophosphate (cAMP) pathways, which converge on HVA Ca channels in Helix neurons. In this model, augmentation of the Ba(2+) current through HVA Ca channels is accomplished by PKA and PKG, whereas attenuation is mediated by PDEs, which prevent activation of protein kinases via hydrolysis of cyclic nucleotides.
Collapse
Affiliation(s)
- Andrea Zsombok
- Division of Animal Physiology, Department of Cellular Biology, University of Salzburg, Hellbrunnerstr. 34, 5020 Salzburg, Austria
| | | | | | | |
Collapse
|
10
|
Onufriev MV, Gulyaeva NV, Terenina NB, Tolstenkov OO, Gustafsson MKS. The effect of a nitric oxide donor on the synthesis of cGMP in Hymenolepis diminuta: a radiometric study. Parasitol Res 2004; 95:22-4. [PMID: 15614585 DOI: 10.1007/s00436-004-1245-y] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2004] [Accepted: 09/23/2004] [Indexed: 10/26/2022]
Abstract
The formation of cGMP in homogenates of the adult rat-tapeworm Hymenolepis diminuta was followed with a radiometric assay during 3 h after stimulation with the nitric oxide donor sodium nitroprusside (SNP) and in the presence of isobutylmethylxanthine (IBMX). The level of cGMP was stable in worms incubated with IBMX during the first hour. After 3 h of incubation, the level of cGMP had declined by 27%. Addition of SNP stimulated the formation of cGMP during the first hour of incubation. After 3 h of incubation, a two-fold decline in cGMP formation was observed. The rate of nitric oxide (NO) release by the worm was determined by a spectrophotometric assay for the accumulation of nitrites and nitrates, the stable degradation products of NO, using the Griess reaction. The results are discussed from the perspective of the current concept on the role of the nitrergic mechanisms in the flatworm nervous system.
Collapse
Affiliation(s)
- Mikhail V Onufriev
- Institute of Higher Nervous Activity and Neurophysiology, Department of Functional Biochemistry, Russian Academy of Sciences, 5a Butlerov Street, 117865, Moscow, Russia
| | | | | | | | | |
Collapse
|
11
|
Schrofner S, Zsombok A, Hermann A, Kerschbaum HH. Nitric oxide decreases a calcium-activated potassium current via activation of phosphodiesterase 2 in Helix U-cells. Brain Res 2004; 999:98-105. [PMID: 14746926 DOI: 10.1016/j.brainres.2003.11.038] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
In the present study, we investigated the underlaying mechanism of nitric oxide (NO) and cGMP on the decline of a Ca2+-activated potassium (KCa) current in U-cells of the right parietal ganglion of the pulmonate snail, Helix pomatia. Using a two-electrode voltage-clamp technique, we activated a KCa-current either by opening of endogenous voltage-gated Ca2+-channels during depolarizing voltage steps or by ionophoretic injection of Ca2+ via a third electrode containing 100 mM Ca2+. KCa-current amplitude in U-cells was sensitive to Ba2+, TEA, iberiotoxin, kaliotoxin and charybdotoxin (ChTX), but not to 4-aminopyridine (4-AP) (up to 30 mM) and apamin (up to 300 nM). Thus, the biophysical and pharmacological profile of the KCa-current in U-cells shares similarities with the large-conductance KCa channel (BKCa). The NO-donor sodium nitroprusside (SNP) or S-nitro-N-acetylpenicillamine (SNAP) as well as NO-gas decreased the KCa-current amplitude and decreased the rate of KCa-current activation elicited by Ca2+-injection. Decline of the current amplitude and decrease of activation of KCa-current were qualitatively mimicked by the membrane-permeable cGMP analogue dibutyryl-cGMP (db-cGMP). NO-induced decrease of KCa-current was blocked by methylene blue (50 microM), an inhibitor of the guanylyl-cyclase, and by erytho-9-(2-hydroxyl-3-nonyl) adenine (EHNA) (100 microM), an inhibitor of the cGMP-stimulated phosphodiesterase 2 (PDE2). These experiments suggest that the NO-mediated decrease of KCa-current in U-cells results from synthesis of cGMP by activation of a guanylyl-cyclase and subsequent activation of PDE2.
Collapse
MESH Headings
- 3',5'-Cyclic-AMP Phosphodiesterases/drug effects
- 3',5'-Cyclic-AMP Phosphodiesterases/metabolism
- Animals
- Calcium/metabolism
- Calcium/pharmacology
- Calcium Channels/drug effects
- Calcium Channels/physiology
- Calcium Signaling/drug effects
- Calcium Signaling/physiology
- Cyclic GMP/biosynthesis
- Cyclic Nucleotide Phosphodiesterases, Type 2
- Ganglia, Invertebrate/cytology
- Ganglia, Invertebrate/drug effects
- Ganglia, Invertebrate/enzymology
- Guanylate Cyclase/drug effects
- Guanylate Cyclase/metabolism
- Helix, Snails/cytology
- Helix, Snails/drug effects
- Helix, Snails/enzymology
- Membrane Potentials/drug effects
- Membrane Potentials/physiology
- Nervous System/cytology
- Nervous System/drug effects
- Nervous System/enzymology
- Neurons/drug effects
- Neurons/enzymology
- Nitric Oxide/metabolism
- Nitric Oxide Donors/pharmacology
- Organ Culture Techniques
- Potassium Channel Blockers/pharmacology
- Potassium Channels, Calcium-Activated/drug effects
- Potassium Channels, Calcium-Activated/physiology
Collapse
Affiliation(s)
- Siegfried Schrofner
- Department of Molecular Neurobiology and Cellular Physiology, Institute of Zoology, University of Salzburg, Hellbrunnerstr. 34, 5020 Salzburg, Austria
| | | | | | | |
Collapse
|
12
|
White AR, Curtis SA, Walker RJ. Evidence for a possible role for nitric oxide in the modulation of heart activity in Achatina fulica and Helix aspersa. Comp Biochem Physiol C Toxicol Pharmacol 2004; 137:95-108. [PMID: 15050921 DOI: 10.1016/j.cca.2003.11.009] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/01/2003] [Revised: 11/24/2003] [Accepted: 11/25/2003] [Indexed: 10/26/2022]
Abstract
The effects of nitric oxide (NO) donors, S-nitroso-N-acetylpenicillamine, S-nitroso-l-glutathione, sodium nitroprusside and sodium nitrite were investigated on the activity of the isolated hearts of Achatina fulica and Helix aspersa. NO donors inhibited heart activity in a concentration-dependent manner. The only exception was sodium nitroprusside, which excited H. aspersa heart. The inhibitory effects of these NO donors were reduced by the NO scavenger, methylene blue, the guanylyl cyclase inhibitor, 1H-(1,2,4) Oxadiazolo(4,3-a)quinoxalin-1-one (ODQ), and potentiated by 8-Br-cGMP and the phosphodiesterase inhibitor 3-isobutyl-1-methylxanthine (IBMX). Acetylcholine also inhibited the heart activity, and this inhibition was reduced by methylene blue and ODQ. Positive NADPH-diaphorase staining was located in the outer pericardial layer of the heart of A. fulica. The present results provide evidence that NO may modulate the activity of gastropod hearts, and this modulation may modify the inhibitory action of acetylcholine on heart activity.
Collapse
Affiliation(s)
- A R White
- School of Biological Sciences, Biomedical Sciences Building, University of Southampton, Bassett Crescent East, Southampton SO16 7PX, UK
| | | | | |
Collapse
|
13
|
Fujie S, Yamamoto T, Murakami J, Hatakeyama D, Shiga H, Suzuki N, Ito E. Nitric oxide synthase and soluble guanylyl cyclase underlying the modulation of electrical oscillations in a central olfactory organ. ACTA ACUST UNITED AC 2004; 62:14-30. [PMID: 15316917 DOI: 10.1002/neu.20046] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
We have isolated and characterized the cDNAs for nitric oxide synthase (NOS) and soluble guanylyl cyclase (sGC) from the terrestrial slug Limax marginatus, and examined the presence and distribution of their mRNAs in the central nervous system using histological techniques and a reverse transcription-polymerase chain reaction method. Our results showed that both bursting and nonbursting neurons in the procerebral lobes contain the mRNAs for both NOS and sGC. We further found that the oscillation frequency of electrical activity in the procerebral lobes increases with increasing intracellular concentrations of cyclic GMP (cGMP). Taken together with previous data on the NO-induced cGMP-like immunoreactivity and on the anatomical distribution of neurites and the localization of synapses of bursting and nonbursting neurons, our present results suggest that NO-induced changes in cGMP concentration modulate the oscillation frequency in the procerebral lobes by acting on the olfactory input pathways, but possibly not on the output pathways, in slugs. .
Collapse
Affiliation(s)
- Sayoko Fujie
- Division of Biological Sciences, Graduate School of Science, Hokkaido University, North 10, West 8, Kita-ku, Sapporo 060-0810, Japan
| | | | | | | | | | | | | |
Collapse
|
14
|
Röszer T, Jenei Z, Gáll T, Nagy O, Czimmerer Z, Serfözö Z, Elekes K, Bánfalvi G. A Possible Stimulatory Effect of FMRFamide on Neural Nitric Oxide Production in the Central Nervous System of Helix lucorum L. BRAIN, BEHAVIOR AND EVOLUTION 2003; 63:23-33. [PMID: 14673196 DOI: 10.1159/000073757] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/28/2003] [Accepted: 08/01/2003] [Indexed: 11/19/2022]
Abstract
The anatomical and functional relationship between neurons expressing nitric oxide (NO) synthase and molluscan cardioexcitatory (FMRFamide)-like neuropeptides was studied in the central ganglia of Helix lucorum (Pulmonata, Gastropoda), applying NADPHdiaphorase (NADPHd) histochemistry to visualize NO synthase and immunocytochemistry to demonstrate FMRFamide (FMRFa) at the light microscopic level. The NO production of the ganglia was detected by the colorimetric Griess determination of nitrite, a breakdown product of NO. Effects of the NO synthase substrate amino acid L-arginine, the NO synthase inhibitor Nomega-nitro-L-arginine (NOARG), synthetic FMRFa and the FMRFa sensitive ion channel blocker amiloride hydrochloride on nitrite production were also tested. NADPHd reaction labeled nerve cells and fibers in the procerebra, mesocerebra and metacerebra within the cerebral ganglia, and cell clusters in the postcerebral ganglia. FMRFa immunolabeling could be observed within subpopulations of NADPHd positive cells and in pericellular varicose fibers surrounding NADPHd stained neurons. Nitrite production of the ganglia was stimulated by L-arginine (10- 20 mM) but was decreased by NOARG (1-2 mM). Synthetic FMRFa (0.830-3.340 mM) increased the nitrite production in a dose dependent manner, but was ineffective in the presence of NOARG. Amiloride hydrochloride (7.890 mM) reduced the FMRFa evoked nitrite production in all ganglia. This is the first description of an anatomical relationship between putative NO producing and FMRFa containing cells, suggesting a possible regulatory role of FMRFa in the NO mediated signaling in an invertebrate nervous system.
Collapse
Affiliation(s)
- Tamás Röszer
- Department of Animal Anatomy and Physiology, Faculty of Natural Sciences, Debrecen University, Debrecen, Hungary.
| | | | | | | | | | | | | | | |
Collapse
|
15
|
Gustafsson MKS, Terenina NB, Reuter M, Movsessian SO. NO nerves and their targets in a tapeworm: An immunocytochemical study of cGMP in Hymenolepis diminuta. Parasitol Res 2003; 90:148-52. [PMID: 12756551 DOI: 10.1007/s00436-003-0826-5] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2002] [Accepted: 12/03/2002] [Indexed: 11/25/2022]
Abstract
We studied the pattern of cGMP immunostaining (IS) after stimulation with a nitric oxide donor in the presence of an inhibitor of phosphodiesterase in adult Hymenolepis diminuta. cGMP-IS was detected in the peripheral nervous system, especially in nerve fibres close to the body muscle fibres. cGMP-IS also occurred in terminals beneath the basal lamina of the tegument and between the muscle fibres of the suckers. The pattern of cGMP-IS was compared to that of 5-HT-IS and GYIRFamide-IS. TRITC-conjugated phalloidin was used to stain the musculature.
Collapse
|
16
|
Abstract
SUMMARY
Nitric oxide (NO) is a gaseous intercellular messenger produced by the enzyme nitric oxide synthase. It has been implicated as a neuromodulator in several groups of animals, including gastropods, crustaceans and mammals. In this study, we investigated the effects of NO on the swim motor program produced by isolated brains and by semi-intact preparations of the nudibranch Melibe leonina. The NO donors sodium nitroprusside (SNP, 1 mmol l–1) and S-nitroso-N-acetylpenicillamine (SNAP, 1 mmol l–1) both had a marked effect on the swim motor program expressed in isolated brains, causing an increase in the period of the swim cycle and a more erratic swim rhythm. In semi-intact preparations, the effect of NO donors was manifested as a significant decrease in the rate of actual swimming. An NO scavenger, reduced oxyhemoglobin, eliminated the effects of NO donors on isolated brains, supporting the assumption that the changes in swimming induced by donors were actually due to NO. The cGMP analogue 8-bromoguanosine 3′,5′-cyclic monophosphate (1 mmol l–1) produced effects that mimicked those of NO donors, suggesting that NO is working via a cGMP-dependent mechanism. These results, in combination with previous histological studies indicating the endogenous presence of nitric oxide synthase, suggest that NO is used in the central nervous system of Melibe leonina to modulate swimming.
Collapse
Affiliation(s)
- James M Newcomb
- Zoology Department and Center for Marine Biology, University of New Hampshire, Durham, NH 03824, USA.
| | | |
Collapse
|
17
|
Stefano GB, Ottaviani E. The biochemical substrate of nitric oxide signaling is present in primitive non-cognitive organisms. Brain Res 2002; 924:82-9. [PMID: 11743998 DOI: 10.1016/s0006-8993(01)03227-9] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Nitric oxide has been shown to have diverse actions in the mammalian nervous, immune and vascular systems. These include antimicrobial and antiviral activities as well as the modulation of cell adherence. In the nervous system, nitric oxide modulates neurotransmitter release, neurosecretion and behavioral activities such as feeding. In the present review, we discuss the finding that invertebrate organisms also contain nitric oxide and that they appear to use this multidimensional molecule in a similar manner as noted for mammals. Therefore, nitric oxide signaling appears to have emerged first in these primitive non-cognitive organisms. We conclude that basal nitric oxide functioning was established in these organisms and that this molecule was later employed in man, including its involvement in cognitive neural processes.
Collapse
Affiliation(s)
- George B Stefano
- Neuroscience Research Institute, State University of New York College at Old Westbury, Old Westbury, NY 11568-0210, USA.
| | | |
Collapse
|
18
|
Hermann A, Erxleben C. Nitric oxide activates voltage-dependent potassium currents of crustacean skeletal muscle. Nitric Oxide 2001; 5:361-9. [PMID: 11485374 DOI: 10.1006/niox.2001.0358] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Nitric oxide (NO), a radical gas, acts as a multifunctional intra- and intercellular messenger. In the present study we investigated the effects of NO on muscle membrane potassium currents of isolated single muscle fibers from the marine isopods, Idotea baltica, using two-electrode voltage clamp recording techniques. Voltage-activated potassium currents consist of an outward current with fast activation and inactivation kinetics and a delayed, persistent outward current. Both currents were blocked by extracellular 4-aminopyridine and tetraethylammonium; the currents were not blocked by charybdotoxin or apamin. Application of the NO donors S-nitroso-N-acetylpenicillamine (SNAP) or hydroxylamine increased both the early and the delayed outward current in a dose- and time-dependent manner. PTIO, a NO scavenger, suppressed the effect of SNAP. N-Acetyl-dl-penicillamine, a related control compound which does not liberate NO, had no significant effect on outward currents. Methylene blue, a guanylyl cyclase inhibitor, prevented the increase of the outward current while 8-bromo-cGMP increased the current. Our experiments show that potassium currents of Idotea muscle are increased by NO donors. They suggest that NO by stimulating cGMP production mediates the effects on membrane currents involved in regulation of invertebrate muscle excitability.
Collapse
Affiliation(s)
- A Hermann
- Department of Molecular Neurobiology & Cellular Physiology, Institute of Zoology, University of Salzburg, Hellbrunnerstrasse 34, Salzburg, A-5020, Austria.
| | | |
Collapse
|
19
|
Xie M, Hermann A, Richter K, Engel E, Kerschbaum HH. Nitric oxide up-regulates ferritin mRNA level in snail neurons. Eur J Neurosci 2001; 13:1479-86. [PMID: 11328343 DOI: 10.1046/j.0953-816x.2001.01526.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
We cloned and sequenced the ferric ion-binding protein, ferritin, from the nervous system of the pulmonate snail, Helix pomatia. Helix H-ferritin cDNA contains a 519-bp open reading frame (ORF) and predicts an iron-responsive element (IRE) at the 5'-untranslated region (5'-UTR) of the ferritin mRNA. The deduced amino acid sequence revealed 86% similarity with Lymnaea stagnalis ferritin and about 70% similarity with vertebrate H-ferritin. While secreted ferritin isoforms contain a signalling sequence at their N-terminal end, Helix ferritin does not contain this sorting signal indicating that it is restricted to the cytoplasm. The amino acid ligands at positions Glu25, Tyr30, Glu59, Glu60, His63, Glu105 and Gln139 indicate an active ferroxidase site in Helix ferritin. In situ hybridization visualized ferritin mRNA in neuronal cell bodies but not in the neuropil. In contrast, ferritin-immunoreactive protein was localized in cell bodies and neurites. We further demonstrate that the NO donors S-nitroso-N-acetylpenicillamine (SNAP), or hydroxylamine (HA), increase the intracellular ferritin mRNA level by about 55%. In conclusion, our findings show that Helix neurons express an intracellular H-ferritin isoform and suggest that iron and NO metabolism are coupled.
Collapse
Affiliation(s)
- M Xie
- Department of Molecular Neurobiology & Cellular Physiology, Institute of Zoology, University of Salzburg, Hellbrunnerstr. 34, 5020 Salzburg, Austria
| | | | | | | | | |
Collapse
|
20
|
Van Wagenen S, Rehder V. Regulation of neuronal growth cone filopodia by nitric oxide depends on soluble guanylyl cyclase. ACTA ACUST UNITED AC 2001. [DOI: 10.1002/1097-4695(20010215)46:3<206::aid-neu1003>3.0.co;2-s] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
|
21
|
Zsombok A, Schrofner S, Hermann A, Kerschbaum HH. Nitric oxide increases excitability by depressing a calcium activated potassium current in snail neurons. Neurosci Lett 2000; 295:85-8. [PMID: 11090980 DOI: 10.1016/s0304-3940(00)01606-2] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
In gastropods, the interneuronal messenger, nitric oxide (NO), modulates spike frequency and synaptic transmission. We have characterized the effect of NO on ion currents underlying neuronal excitability, using current-clamp and two-electrode voltage-clamp techniques. Identified neurons of the pulmonate snail, Helix pomatia, respond to the NO donor sodium nitroprusside (SNP) by increasing the firing frequency and decreasing the latency. Voltage-clamp experiments revealed that SNP or S-nitro-N-acetylpenicillamine (SNAP) depressed the macroscopic outward current, while the control compound N-acetylpenicillamine (NAP) had no effect. Current voltage curves generated from voltage steps to different membrane potentials ranging from -40 to +180 mV showed an N-shaped outward current. Superfusion of ganglia with Ca(2+) free Helix solution abolished the N-shape, indicating the contribution of a Ca(2+) activated K(+) current (I(K,Ca)). Exposure of neurons to SNP or SNAP diminished the N-shape, indicating that NO affects I(K,Ca). The depressing effect of SNP on the outward current was slow and reached steady state in about 5 min. In conclusion, our findings indicate that NO enhances excitability in Helix nervous system by decreasing I(K,Ca).
Collapse
Affiliation(s)
- A Zsombok
- Department of Molecular Neurobiology and Cellular Physiology, Institute of Zoology, University of Salzburg, Hellbrunnerstrasse 34, 5020, Salzburg, Austria
| | | | | | | |
Collapse
|
22
|
Moroz LL, Norekian TP, Pirtle TJ, Robertson KJ, Satterlie RA. Distribution of NADPH‐diaphorase reactivity and effects of nitric oxide on feeding and locomotory circuitry in the pteropod mollusc,
Clione limacina. J Comp Neurol 2000. [DOI: 10.1002/1096-9861(20001113)427:2<274::aid-cne8>3.0.co;2-#] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Affiliation(s)
- Leonid L. Moroz
- The Whitney Laboratory, Department of Neuroscience, University of Florida, St. Augustine, Florida 32080‐8623
| | - Tigran P. Norekian
- Department of Biology, Arizona State University, Tempe, Arizona 85287‐1501
- Friday Harbor Laboratories, Friday Harbor, Washington 98250
| | - Thomas J. Pirtle
- Department of Biology, Arizona State University, Tempe, Arizona 85287‐1501
- Friday Harbor Laboratories, Friday Harbor, Washington 98250
| | - Kirk J. Robertson
- Department of Biology, Arizona State University, Tempe, Arizona 85287‐1501
- Friday Harbor Laboratories, Friday Harbor, Washington 98250
| | - Richard A. Satterlie
- Department of Biology, Arizona State University, Tempe, Arizona 85287‐1501
- Friday Harbor Laboratories, Friday Harbor, Washington 98250
| |
Collapse
|
23
|
Sawada M, Ichinose M, Anraku M. Inhibition of the glutamate-induced K(+) current in identified Onchidium neurons by nitric oxide donors. J Neurosci Res 2000; 60:642-8. [PMID: 10820435 DOI: 10.1002/(sici)1097-4547(20000601)60:5<642::aid-jnr9>3.0.co;2-#] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Nitric oxide (NO) acts as a neurotransmitter and neuromodulator in the nervous system of many vertebrates and invertebrates. The effects of extracellularly applied sodium nitroprusside (SNP) and diethylamine NO (C(2)H(5))(2)N[N(O)NO]-Na(+) (DEA/NO), NO donors, on a glutamate (Glu)-induced K(+) current in identified Onchidium neurons were investigated using voltage clamp and pressure ejection techniques. Bath-applied SNP (10 microM) and DEA/NO (5-10 microM) reduced the Glu-induced K(+) current without affecting the resting membrane conductance and holding current. The Glu-induced K(+) current also was inhibited by the focal application of SNP to the neuron somata. The suppressing effects of NO donors were concentration-dependent and completely reversible. Pretreatment with hemoglobin (50 microM), a nitric oxide scavenger, and 1H-[1,2, 4]oxadiazolo[4,3-a]quinoxalin-1-one (ODQ; 1 microM), a specific inhibitor of NO-stimulated guanylate cyclase, decreased the SNP-induced inhibition of the Glu-induced current. Bath-applied 50 microM 3-isobutyl-1-methylxanthine (IBMX), a nonspecific phosphodiesterase inhibitor, or intracellular injection of 1 mM guanosine 3',5'-cyclic monophosphate (cGMP) inhibited the Glu-induced current, mimicking the effect of NO donors. These results demonstrate that SNP and DEA/NO inhibit the Glu-induced K(+) current and that the mechanism of NO inhibition of the Glu-induced current involves cGMP-dependent protein kinase.
Collapse
Affiliation(s)
- M Sawada
- Department of Physiology, Shimane Medical University, Izumo, Japan.
| | | | | |
Collapse
|
24
|
Gelperin A. Oscillatory dynamics and information processing in olfactory systems. J Exp Biol 1999; 202 (Pt 14):1855-64. [PMID: 10377267 DOI: 10.1242/jeb.202.14.1855] [Citation(s) in RCA: 76] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Oscillatory dynamics is a universal design feature of olfactory information-processing systems. Recent results in honeybees and terrestrial slugs suggest that oscillations underlie temporal patterns of olfactory interneuron responses critical for odor discrimination. Additional general design features in olfactory information-processing systems include (1) the use of central processing areas receiving direct olfactory input for odor memory storage and (2) modulation of circuit dynamics and olfactory memory function by nitric oxide. Recent results in the procerebral lobe of the terrestrial slug Limax maximus, an olfactory analyzer with oscillatory dynamics and propagating activity waves, suggest that Lucifer Yellow can be used to reveal a band-shaped group of procerebral neurons involved in the storage of an odor memory. A model has been constructed to relate wave propagation and odor memory bands in the procerebral lobe of L. maximus and to relate these findings to glomerular odor representations in arthropods and vertebrates.
Collapse
Affiliation(s)
- A Gelperin
- Biological Computation Research Department, Room 1C464, Bell Laboratories, Lucent Technologies, Murray Hill, NJ 07974, USA.
| |
Collapse
|
25
|
Pisu MB, Conforti E, Fenoglio C, Necchi D, Scherini E, Bernocchi G. Nitric oxide-containing neurons in the nervous ganglia of Helix aspersa during rest and activity: immunocytochemical and enzyme histochemical detection. J Comp Neurol 1999; 409:274-84. [PMID: 10379920 DOI: 10.1002/(sici)1096-9861(19990628)409:2<274::aid-cne8>3.0.co;2-e] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Nitric oxide synthase (NOS) immunoreactivity and staining for nicotinamide adenine dinucleotide phosphate-diaphorase (NADPH-diaphorase) activity are two cytochemical markers for nitric oxide (NO)-containing neurons. The authors examined the changes in the distribution of NOS immunolabeling and NADPH-diaphorase reactivity in the cerebral and buccal ganglia of the terrestrial snail Helix aspersa during resting and active phases. During inactivity and after 1 day of activity, in the mesocerebrum and metacerebrum of the snails, there were several reactive neurons for both markers; after 7 days of activity, the number of reactive neurons was lower. Opposite results were obtained in the buccal ganglia, in which increased staining and numbers of reactive neurons were present in the active snails (after 1 day and 7 days of activity). Although the staining patterns for the two reactions were similar, colocalization was not always observed. The comparison between inactive and active animals provided a more precise survey of NOS-containing neurons in the snail cerebral ganglia than previously described. Moreover, it suggested that not only is NO involved in distinct nervous circuits, but, as a ubiquitous molecule, it also plays a role in neuroprotection and neuropeptide release.
Collapse
Affiliation(s)
- M B Pisu
- Dipartimento di Biologia Animale Centro di Studio per l'Istochimica del C.N.R., Università di Pavia, Italy
| | | | | | | | | | | |
Collapse
|
26
|
Nitric oxide stimulates cGMP production and mimics synaptic responses in metacerebral neurons of Aplysia. J Neurosci 1999. [PMID: 10234014 DOI: 10.1523/jneurosci.19-10-03818.1999] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Nitric oxide (NO) acts as a neurotransmitter and neuromodulator in the nervous systems of many vertebrates and invertebrates. We investigated the mechanism of NO action at an identified synapse between a mechanoafferent neuron, C2, and the serotonergic metacerebral cell (MCC) in the cerebral ganglion of the mollusc Aplysia californica. Stimulation of C2 produces a decreasing conductance, very slow EPSP in the MCC. C2 is thought to use histamine and NO as cotransmitters at this synapse, because both agents mimic the membrane responses. Now we provide evidence that treatment with NO donors stimulates soluble guanylyl cyclase (sGC) in the MCC, and as a result cGMP increases. S-Nitrosocysteine (SNC, an NO donor) and 8-bromo-cGMP (8-Br-cGMP) both induced the membrane depolarization and increase in input resistance that are characteristic of the very slow EPSP. Two inhibitors of sGC, 6-anilino-5,8-quinolinequinone (LY83583) and 1H-[1,2,4]oxadiazolo[4, 3-a]quinoxaline-1-one (ODQ), suppressed both the very slow EPSP and the membrane responses to SNC but not the histamine membrane responses. NO-induced cGMP production was determined in the MCC using cGMP immunocytochemistry (cGMP-IR). In the presence of 3-isobutyl-1-methylxanthine (IBMX), 10 microM SNC was sufficient to induce cGMP-IR, and the staining intensity increased as the SNC dose was increased. This cGMP-IR was suppressed by ODQ in a dose-dependent manner and completely blocked by 10 microM ODQ. Histamine did not induce cGMP-IR. The results suggest that NO stimulates sGC-dependent cGMP synthesis in the MCC and that cGMP mediates the membrane responses. The cotransmitter histamine induces essentially the same membrane responses but seems to use a separate and distinct second messenger pathway.
Collapse
|