101
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Bukanova JV, Solntseva EI, Skrebitsky VG. Cyclic nucleotides induce long-term augmentation of glutamate-activated chloride current in molluscan neurons. Cell Mol Neurobiol 2006; 25:1185-94. [PMID: 16388331 DOI: 10.1007/s10571-005-8371-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2005] [Accepted: 09/07/2005] [Indexed: 10/25/2022]
Abstract
1. Literature data indicate that serotonin induces the long-term potentiation of glutamate (Glu) response in molluscan neurons. The aim of present work was to elucidate whether cyclic nucleotides can cause the same effect. 2. Experiments were carried out on isolated neurons of the edible snail (Helix pomatia) using a two-microelectrode voltage-clamp method. 3. In the majority of the cells examined, the application of Glu elicited a Cl- -current. The reversal potential (Er) of this current lied between -35 and -55 mV in different cells. 4. Picrotoxin, a blocker of Cl- -channels, suppressed this current equally on both sides of Er. Furosemide, an antagonist of both Cl- -channels and the Na+/K+/Cl- -cotransporter, had a dual effect on Glu-response: decrease in conductance, and shift of Er to negative potentials. 5. A short-term (2 min) cell treatment with 8-Br-cAMP or 8-Br-cGMP caused long-term (up to 30 min) change in Glu-response. At a holding potential of -60 mV, which was close to the resting level, an increase in Glu-activated inward current was observed. This potentiation seems to be related to the right shift of Er of Glu-activated Cl- -current rather than to the increase in conductance of Cl- -channels. The blocking effect of picrotoxin rested after 8-Br-cAMP treatment. 6. The change in the Cl- -homeostasis as a possible mechanism for the observed effect of cyclic nucleotides is discussed.
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Affiliation(s)
- Julia V Bukanova
- Brain Research Institute, Russian Academy of Medical Sciences, Per. Obukha 5, 105064, Moscow, Russia.
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102
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Isokawa M, Alger BE. Ryanodine Receptor Regulates Endogenous Cannabinoid Mobilization in the Hippocampus. J Neurophysiol 2006; 95:3001-11. [PMID: 16467427 DOI: 10.1152/jn.00975.2005] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Endogenous cannabinoids (eCBs) are produced and mobilized in a cytosolic calcium ([Ca2+]i)–dependent manner, and they regulate excitatory and inhibitory neurotransmitter release by acting as retrograde messengers. An indirect but real-time bioassay for this process on GABAergic transmission is DSI (depolarization-induced suppression of inhibition). The magnitude of DSI correlates linearly with depolarization-induced increase of [Ca2+]ithat is thought to be initiated by Ca2+influx through voltage-gated Ca2+channels. However, the identity of Ca2+sources involved in eCB mobilization in DSI remains undetermined. Here we show that, in CA1 pyramidal cells, DSI-inducing depolarizing voltage steps caused Ca2+-induced Ca2+release (CICR) by activating the ryanodine receptor (RyR) Ca2+-release channel. CICR was reduced, and the remaining increase in [Ca2+]iwas less effective in generating DSI, when the RyR antagonists, ryanodine or ruthenium red, were applied intracellularly, or the Ca2+stores were depleted by the Ca2+-ATPase inhibitors, cyclopiazonic acid or thapsigargin. The CICR-dependent effects were most prominent in cultured or immature acute slices, but were also detectable in slices from adult tissue. Thus we suggest that voltage-gated Ca2+entry raises local [Ca2+]isufficiently to activate nearby RyRs and that the resulting CICR plays a critical role in initiating eCB mobilization. RyR may be a key molecule for the depolarization-induced production of eCBs that inhibit GABA release in the hippocampus.
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Affiliation(s)
- Masako Isokawa
- Department of Physiology, University of Maryland, Baltimore, Maryland, USA.
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103
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Matsumoto Y, Unoki S, Aonuma H, Mizunami M. Critical role of nitric oxide-cGMP cascade in the formation of cAMP-dependent long-term memory. Learn Mem 2006; 13:35-44. [PMID: 16452652 PMCID: PMC1360131 DOI: 10.1101/lm.130506] [Citation(s) in RCA: 81] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Cyclic AMP pathway plays an essential role in formation of long-term memory (LTM). In some species, the nitric oxide (NO)-cyclic GMP pathway has been found to act in parallel and complementary to the cAMP pathway for LTM formation. Here we describe a new role of the NO-cGMP pathway, namely, stimulation of the cAMP pathway to induce LTM. We have studied the signaling cascade underlying LTM formation by systematically coinjecting various "LTM-inducing" and "LTM-blocking" drugs in crickets. Multiple-trial olfactory conditioning led to LTM that lasted for several days, while memory induced by single-trial conditioning decayed away within several hours. Injection of inhibitors of the enzyme forming NO, cGMP, or cAMP into the hemolymph prior to multiple-trial conditioning blocked LTM, whereas injection of an NO donor, cGMP analog, or cAMP analog prior to single-trial conditioning induced LTM. Induction of LTM by injection of an NO donor or cGMP analog paired with single-trial conditioning was blocked by inhibitors of the cAMP pathway, but induction of LTM by a cAMP analog was unaffected by inhibitors of the NO-cGMP pathway. Inhibitors of cyclic nucleotide-gated channel (CNG channel) or calmodulin-blocked induction of LTM by cGMP analog paired with single-trial conditioning, but they did not affect induction of LTM by cAMP analog. Our findings suggest that the cAMP pathway is a downstream target of the NO-cGMP pathway for the formation of LTM, and that the CNG channel and calcium-calmodulin intervene between the NO-cGMP pathway and the cAMP pathway.
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Affiliation(s)
- Yukihisa Matsumoto
- Graduate School of Life Sciences, Tohoku University, Aoba-ku, Sendai 980-8577, Japan
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104
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MAKHINSON M, OPAZO P, CARLISLE HJ, GODSIL B, GRANT SGN, O’DELL TJ. A novel role for cyclic guanosine 3',5'monophosphate signaling in synaptic plasticity: a selective suppressor of protein kinase A-dependent forms of long-term potentiation. Neuroscience 2006; 140:415-31. [PMID: 16549271 PMCID: PMC1832102 DOI: 10.1016/j.neuroscience.2006.02.018] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2005] [Revised: 02/02/2006] [Accepted: 02/08/2006] [Indexed: 10/24/2022]
Abstract
At excitatory synapses onto hippocampal CA1 pyramidal cells, activation of cyclic AMP-dependent protein kinase and subsequent down-regulation of protein phosphatases has a crucial role in the induction of long-term potentiation by low-frequency patterns of synaptic stimulation. Because the second messenger cyclic guanosine 3',5'monophosphate can regulate the activity of different forms of the cyclic AMP degrading enzyme phosphodiesterase, we examined whether increases in cyclic guanosine 3',5'monophosphate can modulate long-term potentiation induction in the mouse hippocampal CA1 region through effects on cyclic AMP signaling. Using the cyclic guanosine 3',5'monophosphate-specific phosphodiesterase inhibitor zaprinast or the nitric oxide donor S-nitroso-D,L-penicillamine to elevate cyclic guanosine 3',5'monophosphate levels we found that increases in cyclic guanosine 3',5'monophosphate strongly inhibit the induction of long-term potentiation by low-frequency patterns of synaptic stimulation where protein kinase A activation is required for long-term potentiation induction. In contrast, zaprinast and S-nitroso-D,L-penicillamine had no effect on the induction of long-term potentiation by high-frequency patterns of synaptic stimulation that induce long-term potentiation in a protein kinase A-independent manner. Directly activating protein kinase A with the phosphodiesterase-resistant cyclic AMP analog 8-Br-cAMP, blocking all phosphodiesterases with 3-isobutyl-1-methylxanthine, or inhibiting protein phosphatases rescued long-term potentiation induction in zaprinast-treated slices. Together, these results suggest that increases in cyclic guanosine 3',5'monophosphate inhibit long-term potentiation by activating phosphodiesterases that interfere with the protein kinase A-mediated suppression of protein phosphatases needed for long-term potentiation induction. Consistent with the notion that this cyclic guanosine 3',5'monophosphate-mediated inhibitory pathway is recruited by some patterns of synaptic activity, blocking cyclic guanosine 3',5'monophosphate production strongly facilitated the induction of long-term potentiation by long trains of theta-frequency synaptic stimulation. Together, our results indicate that increases in cyclic guanosine 3',5'monophosphate can act as a long-term potentiation suppressor mechanism that selectively constrains the induction of protein kinase A-dependent forms of long-term potentiation induced by low-frequency patterns of synaptic stimulation.
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Affiliation(s)
- M. MAKHINSON
- Department of Physiology, David Geffen School of Medicine at UCLA, 53-231 Center for Health Sciences, Box 951751, Los Angeles, CA 90095, USA
- Department Psychiatry and Biobehavioral Sciences, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095, USA
| | - P. OPAZO
- Department of Physiology, David Geffen School of Medicine at UCLA, 53-231 Center for Health Sciences, Box 951751, Los Angeles, CA 90095, USA
| | - H. J. CARLISLE
- Interdepartmental Ph.D. Program for Neuroscience, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095, USA
| | - B. GODSIL
- Department Psychiatry and Biobehavioral Sciences, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095, USA
| | - S. G. N. GRANT
- Wellcome Trust Sanger Institute, Cambridge, CB10 1SA, UK
| | - T. J. O’DELL
- Department of Physiology, David Geffen School of Medicine at UCLA, 53-231 Center for Health Sciences, Box 951751, Los Angeles, CA 90095, USA
- *Corresponding author. Tel: +1-310-206-4654; fax: +1-310-206-5661. E-mail address: (T. J. O’Dell)
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105
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Yu YC, Cao LH, Yang XL. Modulation by brain natriuretic peptide of GABA receptors on rat retinal ON-type bipolar cells. J Neurosci 2006; 26:696-707. [PMID: 16407567 PMCID: PMC6674405 DOI: 10.1523/jneurosci.3653-05.2006] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Natriuretic peptides (NPs) may work as neuromodulators through their associated receptors [NP receptors (NPRs)]. By immunocytochemistry, we showed that NPR-A and NPR-B were expressed abundantly on both ON-type and OFF-type bipolar cells (BCs) in rat retina, including the dendrites, somata, and axon terminals. Whole-cell recordings made from isolated ON-type BCs further showed that brain natriuretic peptide (BNP) suppressed GABAA receptor-, but not GABAC receptor-, mediated currents of the BCs, which was blocked by the NPR-A antagonist anantin. The NPR-C agonist c-ANF [des(Gln18, Ser19, Gln20, Leu21, Gly22)ANF(4-23)-NH2] did not suppress GABAA currents. The BNP effect on GABAA currents was abolished with preincubation with the pGC-A/B antagonist HS-142-1 but mimicked by application of 8-bromoguanosine-3',5'-cyclomonophosphate. These results suggest that elevated levels of intracellular cGMP caused by activation of NPR-A may mediate the BNP effect. Internal infusion of the cGMP-dependent protein kinase G (PKG) inhibitor KT5823 essentially blocked the BNP-induced reduction of GABAA currents. Moreover, calcium imaging showed that BNP caused a significant elevation of intracellular calcium that could be caused by increased calcium release from intracellular stores by PKG. The BNP effect was blocked by the ryanodine receptor modulators caffeine, ryanodine, and ruthenium red but not by the IP3 receptor antagonists heparin and xestospongin-C. Furthermore, the BNP effect was abolished after application of the blocker of endoplasmic reticulum Ca2+-ATPase thapsigargin and greatly reduced by the calmodulin inhibitors W-7 and calmidazolium. We therefore conclude that the increased calcium release from ryanodine-sensitive calcium stores by BNP may be responsible for the BNP-caused GABAA response suppression in ON-type BCs through stimulating calmodulin.
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MESH Headings
- Animals
- Atrial Natriuretic Factor/pharmacology
- Caffeine/pharmacology
- Calcium/metabolism
- Calcium Channels
- Calcium Signaling/drug effects
- Calcium-Transporting ATPases/antagonists & inhibitors
- Calmodulin/antagonists & inhibitors
- Calmodulin/physiology
- Carbazoles/pharmacology
- Cyclic GMP/analogs & derivatives
- Cyclic GMP/pharmacology
- Cyclic GMP-Dependent Protein Kinases/physiology
- GABA-A Receptor Antagonists
- Guanylate Cyclase/drug effects
- Guanylate Cyclase/physiology
- Heparin/pharmacology
- Imidazoles/pharmacology
- Indoles/pharmacology
- Inositol 1,4,5-Trisphosphate Receptors
- Macrocyclic Compounds
- Male
- Membrane Potentials/drug effects
- Natriuretic Peptide, Brain/antagonists & inhibitors
- Natriuretic Peptide, Brain/pharmacology
- Natriuretic Peptide, Brain/physiology
- Oxazoles/pharmacology
- Patch-Clamp Techniques
- Peptide Fragments/pharmacology
- Peptides, Cyclic/pharmacology
- Polysaccharides/pharmacology
- Protein Kinase Inhibitors/pharmacology
- Rats
- Rats, Sprague-Dawley
- Receptors, Atrial Natriuretic Factor/drug effects
- Receptors, Atrial Natriuretic Factor/physiology
- Receptors, Cytoplasmic and Nuclear/antagonists & inhibitors
- Receptors, GABA/physiology
- Receptors, GABA-A/drug effects
- Retinal Bipolar Cells/drug effects
- Retinal Bipolar Cells/physiology
- Ruthenium Red/pharmacology
- Ryanodine/pharmacology
- Ryanodine Receptor Calcium Release Channel/drug effects
- Thapsigargin/pharmacology
- gamma-Aminobutyric Acid/pharmacology
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Affiliation(s)
- Yong-Chun Yu
- Institute of Neurobiology, Fudan University, Shanghai 200433, China
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106
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Hu XD, Ge YX, Hu NW, Zhang HM, Zhou LJ, Zhang T, Li WM, Han YF, Liu XG. Diazepam inhibits the induction and maintenance of LTP of C-fiber evoked field potentials in spinal dorsal horn of rats. Neuropharmacology 2006; 50:238-44. [PMID: 16324725 DOI: 10.1016/j.neuropharm.2005.09.010] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2004] [Revised: 09/25/2005] [Accepted: 09/26/2005] [Indexed: 11/16/2022]
Abstract
The benzodiazepine diazepam impairs memory and long-term potentiation (LTP) in the hippocampus. Here, we investigate the effect of diazepam on LTP of C-fiber evoked field potentials in spinal dorsal horn, which is relevant to pathological pain. LTP of C-fiber evoked field potentials was recorded in the superficial layers of spinal dorsal horn in urethane-anesthetized Sprague--Dawley rats. Diazepam was applied locally at the recording spinal segments before and after LTP induction by tetanic stimulation. We found (1) Diazepam completely blocked LTP induction. (2) Diazepam and midazolam reversed spinal LTP, when applied at 30 min after LTP induction and depressed but could not reverse spinal LTP, when applied at 3 h after LTP induction. (3) Pretreatment with benzodiazepine receptor antagonist flumazenil or GABA(A) receptor antagonist bicuculline completely blocked the inhibitory effects of diazepam on spinal LTP. In contrast, when the inhibitory effect of diazepam was fully established, neither of these antagonists was capable of reversing the inhibition by diazepam. (4) Spinal application of the GABA(A) receptor agonist 3-amino-1-propanesulfonic acid (3-APSA) at a dose of 50 microg, produced a transient inhibition of spinal LTP. These results suggest that diazepam might prevent and depress spinal plastic change produced by noxious stimulation via activation of the GABA(A) -benzodiazepine receptor complex.
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Affiliation(s)
- Xiao-Dong Hu
- Department of Physiology, Zhongshan Medical School of Sun Yat-sen University, 74 Zhongshan Rd 2, Guangzhou 510089, PR China
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107
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Rutten K, Vente JD, Sik A, Ittersum MMV, Prickaerts J, Blokland A. The selective PDE5 inhibitor, sildenafil, improves object memory in Swiss mice and increases cGMP levels in hippocampal slices. Behav Brain Res 2006; 164:11-6. [PMID: 16076505 DOI: 10.1016/j.bbr.2005.04.021] [Citation(s) in RCA: 88] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2005] [Revised: 04/27/2005] [Accepted: 04/29/2005] [Indexed: 11/20/2022]
Abstract
Previous studies have shown memory enhancing effects of phosphodiesterase type 5 (PDE5) inhibitors in rats. However, differences in nitric oxide (NO)-mediated cyclic GMP (cGMP) signaling in the hippocampus have been described between rats and mice. In the present study we investigated the memory enhancing effects of the PDE5 inhibitor, sildenafil on memory performance in Swiss mice using the object recognition task. Sildenafil (0.3, 1 and 3 mg/kg) was administered orally directly after the first trial. The memory for the objects was retested 24 h later when mice show no memory for the familiar object. Sildenafil improved the object discrimination performance of Swiss mice at a dose of 1 mg/kg. Hippocampal slices of Swiss mice incubated with sildenafil (10 microM) increased cGMP levels in varicosities in the CA3 region of the hippocampus and a number of short, thin fibers. Addition of DEA/NO, an NO donor (10 microM), in the presence of sildenafil (10 microM) strongly increased cGMP immunoreactivity of varicosities in the CA3 region. Double immunostaining of cGMP with the presynaptic marker synaptophysin did not reveal any co-localization of these markers under any circumstance. Taken together, inhibition of PDE5 improves object recognition memory in mice. Furthermore, a postsynaptic role of cGMP could be involved in this respect.
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Affiliation(s)
- K Rutten
- Department of Psychiatry and Neuropsychology, Brain and Behavior Institute, Maastricht University, The Netherlands.
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108
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Zhang XC, Zhang YQ, Zhao ZQ. Different roles of two nitric oxide activated pathways in spinal long-term potentiation of C-fiber-evoked field potentials. Neuropharmacology 2006; 50:748-54. [PMID: 16427664 DOI: 10.1016/j.neuropharm.2005.11.021] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2005] [Revised: 11/13/2005] [Accepted: 11/30/2005] [Indexed: 11/30/2022]
Abstract
There is accumulating evidence implicating the involvement of nitric oxide (NO) in spinal central sensitization. The long-term potentiation (LTP) of spinal C-fiber-evoked field potentials is considered as a fundamental mechanism of sensitization of nociceptive neurons in the spinal cord. The present study examined the roles of soluble guanylate cyclase (sGC) or ADP-ribosyltransferase (ADPRT), two potential NO targets, in spinal LTP. The results showed that (1) administration of sGC inhibitors, methyl blue (MB, 4mM, 20 microl) or 1H-[1,2,4]oxadiazolo[4,3-a]-quiloxalin-1-one (ODQ, 10 microM, 20 microl) before tetanic stimulation, significantly inhibited the induction of spinal LTP, and this was reversed by 8-Br-cGMP, a membrane-permeable cGMP analog. However, the maintenance of spinal LTP was not changed when application of ODQ 2h after tetanic stimulation. (2) Although our previous experiments have identified a key role for NO in the induction of spinal LTP, NO synthase (NOS) inhibitor, L-NAME (1mM, 20 microl) or hemoglobin (2mg/ml, 20 microl), a scavenger of NO, had no effect on established spinal LTP when applied 2h after the induction of spinal LTP. (3) The mono-ADPRT inhibitor, nicotinamide (10mM, 20 microl), had no effect on the induction and maintenance of spinal LTP. However, the poly-ADPRT inhibitor, benzamide (100 microM, 20 microl), inhibited its maintenance, but not its induction. The results suggest that NO-stimulated guanylyl cyclase activity plays a critical role in the induction of LTP of C-fiber-evoked field potentials in the spinal cord, whereas NO-related poly-ADPRT activity contributes to the maintenance of spinal LTP.
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Affiliation(s)
- Xi-Chun Zhang
- Institute of Neurobiology, Fudan University, 220 Handan Road, Shanghai 200433, People's Republic of China
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109
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Hofmann F, Feil R, Kleppisch T, Schlossmann J. Function of cGMP-Dependent Protein Kinases as Revealed by Gene Deletion. Physiol Rev 2006; 86:1-23. [PMID: 16371594 DOI: 10.1152/physrev.00015.2005] [Citation(s) in RCA: 327] [Impact Index Per Article: 18.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Over the past few years, a wealth of biochemical and functional data have been gathered on mammalian cGMP-dependent protein kinases (cGKs). In mammals, three different kinases are encoded by two genes. Mutant and chimeric cGK proteins generated by molecular biology techniques yielded important biochemical knowledge, such as the function of the NH2-terminal domains of cGKI and cGKII, the identity of the cGMP-binding sites of cGKI, and the substrate specificity of the enzymes. Genetic approaches have proven especially useful for the analysis of the biological functions of cGKs. Recently, some of the in vivo targets and mechanisms leading to changes in neuronal adaptation, smooth muscle relaxation and growth, intestinal water secretion, bone growth, renin secretion, and other important functions have been identified. These data show that cGKs are signaling molecules involved in many biological functions.
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Affiliation(s)
- F Hofmann
- Institut für Pharmakologie und Toxicologie, Technische Universität München, Biedersteiner Strasse 29, D-80802 Munich, Germany.
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110
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Chan JYH, Chang AYW, Chan SHH. New insights on brain stem death: From bedside to bench. Prog Neurobiol 2005; 77:396-425. [PMID: 16376477 DOI: 10.1016/j.pneurobio.2005.11.004] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2005] [Revised: 10/31/2005] [Accepted: 11/03/2005] [Indexed: 01/07/2023]
Abstract
As much as brain stem death is currently the clinical definition of death in many countries and is a phenomenon of paramount medical importance, there is a dearth of information on its mechanistic underpinnings. A majority of the clinical studies are concerned only with methods to determine brain stem death. Whereas a vast amount of information is available on the cellular and molecular mechanisms of cell death, rarely are these studies directed specifically towards the understanding of brain stem death. This review presents a framework for translational research on brain stem death that is based on systematically coordinated clinical and laboratory efforts that center on this phenomenon. It begins with the identification of a novel clinical marker from patients that is related specifically to brain stem death. After realizing that this "life-and-death" signal is related to the functional integrity of the brain stem, its origin is traced to the rostral ventrolateral medulla (RVLM). Subsequent laboratory studies on this neural substrate in animal models of brain stem death provide credence to the notion that both "pro-life" and "pro-death" programs are at work during the progression towards death. Those programs (mitochondrial functions, nitric oxide, peroxynitrite, superoxide anion, coenzyme Q10, heat shock proteins and ubiquitin-proteasome system) hitherto identified from the RVLM are presented, along with their cellular and molecular mechanisms. It is proposed that outcome of the interplay between the "pro-life" and "pro-death" programs (dying) in this neural substrate determines the final fate of the individual (being dead). Thus, identification of additional programs in the RVLM and delineation of their regulatory mechanisms should shed new lights on future directions for clinical management of life-and-death.
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Affiliation(s)
- Julie Y H Chan
- Department of Medical Education and Research, Kaohsiung Veterans General Hospital, Kaohsiung 81346, Taiwan, ROC
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111
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Schafe GE, Bauer EP, Rosis S, Farb CR, Rodrigues SM, LeDoux JE. Memory consolidation of Pavlovian fear conditioning requires nitric oxide signaling in the lateral amygdala. Eur J Neurosci 2005; 22:201-11. [PMID: 16029210 DOI: 10.1111/j.1460-9568.2005.04209.x] [Citation(s) in RCA: 72] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
Nitric oxide (NO) has been widely implicated in synaptic plasticity and memory formation. In studies of long-term potentiation (LTP), NO is thought to serve as a 'retrograde messenger' that contributes to presynaptic aspects of LTP expression. In this study, we examined the role of NO signaling in Pavlovian fear conditioning. We first show that neuronal nitric oxide synthase is localized in the lateral nucleus of the amygdala (LA), a critical site of plasticity in fear conditioning. We next show that NO signaling is required for LTP at thalamic inputs to the LA and for the long-term consolidation of auditory fear conditioning. Collectively, the findings suggest that NO signaling is an important component of memory formation of auditory fear conditioning, possibly as a retrograde signal that participates in presynaptic aspects of plasticity in the LA.
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Affiliation(s)
- Glenn E Schafe
- Department of Psychology, Yale University, 2 Hillhouse Ave, Box 208205, New Haven, CT 06520, USA.
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112
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Hidalgo C, Donoso P, Carrasco MA. The ryanodine receptors Ca2+ release channels: cellular redox sensors? IUBMB Life 2005; 57:315-22. [PMID: 16036616 DOI: 10.1080/15216540500092328] [Citation(s) in RCA: 76] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The release of Ca2+ from intracellular stores mediated by ryanodine receptors (RyR) Ca2+ release channels is essential for striated muscle contraction and contributes to diverse neuronal functions including synaptic plasticity. Through Ca2+-induced Ca2+-release, RyR can amplify and propagate Ca2+ signals initially generated by Ca2+ entry into cardiac muscle cells or neurons. In contrast, RyR activation in skeletal muscle is under membrane potential control and does not require Ca2+ entry. Non-physiological or endogenous redox molecules can change RyR function via modification of a few RyR cysteine residues. This critical review will address the functional effects of RyR redox modification on Ca2+ release in skeletal muscle and cardiac muscle as well as in the activation of signaling cascades and transcriptional regulators required for synaptic plasticity in neurons. Specifically, the effects of endogenous redox-active agents, which induce S-nitrosylation or S-glutathionylation of particular channel cysteine residues, on the properties of muscle RyRs will be discussed. The effects of endogenous redox RyR modifications on cardiac preconditioning will be analyzed as well. In the hippocampus, sequential activation of ERKs and CREB is a requisite for Ca2+-dependent gene expression associated with long lasting synaptic plasticity. Results showing that reactive oxygen/nitrogen species modify RyR channels from neurons and the RyR-mediated sequential activation of neuronal ERKs and CREB produced by hydrogen peroxide and other stimuli will be also discussed.
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Affiliation(s)
- Cecilia Hidalgo
- FONDAP Center of Molecular Studies of the Cell, Instituto de Ciencias Biomédicas, Facultad de Medicina, Universidad de Chile, Santiago, Chile.
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113
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Feil R, Hofmann F, Kleppisch T. Function of cGMP-dependent protein kinases in the nervous system. Rev Neurosci 2005; 16:23-41. [PMID: 15810652 DOI: 10.1515/revneuro.2005.16.1.23] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
The second messenger cyclic guanosine-3',5'-monophosphate (cGMP) mediates many effects of nitric oxide in the nervous system. cGMP may act through various intracellular receptors, among them a family of serine/threonine kinases, the cGMP-dependent protein kinases (cGKs). Hitherto, three mammalian cGKs have been identified: cGKIalpha, cGKIbeta and cGKII. Discrete functions of cGKI and cGKII are determined by their distinct expression patterns and targeting to specific substrates. This review provides an overview about the expression and functions of cGKs in the nervous system. Main emphasis is put on the discussion of phenotypes observed in cGK-deficient mouse models that lack cGKI and/or cGKII globally or selectively in brain regions of interest. Recent data demonstrate important functions of cGKI in (1) the development and sensitization of nociceptive neurons, and (2) synaptic plasticity and learning. There is also evidence suggesting that cGKII in the suprachiasmatic nucleus of the hypothalamus is involved in the regulation of circadian rhythmicity. Thus, cGKs serve key functions in the transduction of cGMP signals into cellular responses in distinct regions of the nervous system.-
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Affiliation(s)
- Robert Feil
- Institut für Pharmakologie und Toxikologie, Technische Universität München, München, Germany
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114
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Huang JS, Chuang LY, Guh JY, Chen CJ, Yang YL, Chiang TA, Hung MY, Liao TN. Effect of nitric oxide-cGMP-dependent protein kinase activation on advanced glycation end-product-induced proliferation in renal fibroblasts. J Am Soc Nephrol 2005; 16:2318-29. [PMID: 15958724 DOI: 10.1681/asn.2005010030] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022] Open
Abstract
Renal interstitial fibrosis is believed to play a key role in the development of diabetic nephropathy (DN), and advanced glycation end-products (AGE) may contribute importantly to this. Recent reports have shown that nitric oxide (NO) is closely linked to the renal interstitial fibrosis of DN. In this study, the mechanisms by which NO and its downstream signals mediate the AGE-induced proliferative response in normal rat kidney fibroblasts (NRK-49F) are examined. AGE decreased NO production, cyclic guanosine 5'monophosphate (cGMP) synthesis, and cGMP-dependent protein kinase (PKG) activation time- and dose-dependently. These effects were not observed when cells were treated with nonglycated BSA. NO and inducible nitric oxide synthase (iNOS) stimulated by NO donors S-nitroso-N-acetylpenicillamine (SNAP)/sodium nitroprusside (SNP) and PKG activator 8-para-chlorophenylthio-cGMP (8-pCPT-cGMP) prevented both AGE-induced proliferation and Janus kinase 2 (JAK2)-signal transducers and activators of transcription 5 (STAT5) activation but not p42/p44 mitogen-activated protein kinase (MAPK) activation. The ability of NO-PKG to inhibit AGE-induced cell cycle progression was verified by the observation that SNAP, SNP, and 8-pCPT-cGMP inhibited both cyclin D1 and cdk4 activation. Furthermore, induction of NO-PKG significantly increased p21Waf1/Cip1 expression in AGE-treated NRK-49F cells. The data suggest that the NO-PKG pathway inhibits AGE-induced proliferation by suppressing activation of JAK2-STAT5 and cyclin D1/cdk4 and induction of p21Waf1/Cip1.
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Affiliation(s)
- Jau-Shyang Huang
- Department of Biological Science and Technology, Chung Hwa College of Medical Technology, 89 Wen-Hwa, 1st Street, Jen-Te Hsiang, Tainan Hsien 717, Taiwan, Republic of China.
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115
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Chan JYH, Chan SHH, Li FCH, Tsai CY, Cheng HL, Chang AYW. Phasic cardiovascular responses to mevinphos are mediated through differential activation of cGMP/PKG cascade and peroxynitrite via nitric oxide generated in the rat rostral ventrolateral medulla by NOS I and II isoforms. Neuropharmacology 2005; 48:161-72. [PMID: 15617736 DOI: 10.1016/j.neuropharm.2004.08.012] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2004] [Accepted: 08/18/2004] [Indexed: 01/09/2023]
Abstract
The organophosphate insecticide mevinphos (Mev) acts on the rostral ventrolateral medulla (RVLM), where sympathetic vasomotor tone originates, to elicit phasic cardiovascular responses via nitric oxide (NO) generated by NO synthase (NOS) I and II. We evaluated the contribution of soluble guanylyl cyclase (sGC)/cyclic guanosine monophosphate (cGMP)/protein kinase G (PKG) cascade and peroxynitrite in this process. PKG expression in ventrolateral medulla of Sprague-Dawley rats manifested an increase during the sympathoexcitatory phase (Phase I) of cardiovascular responses induced by microinjection of Mev bilaterally into the RVLM that was antagonized by co-administration of 7-nitroindazole or Nomega-propyl-L-arginine, two selective NOS I inhibitors or 1-H-[1,2,4]oxadiaolo[4,3-a]quinoxalin-1-one (ODQ), a selective sGC antagonist. Co-microinjection of ODQ or two PKG inhibitors, KT5823 or Rp-8-Br-cGMPS, also blunted the Mev-elicited sympathoexcitatory effects. However, the increase in nitrotyrosine, a marker for peroxynitrite, and the sympathoinhibitory circulatory actions during Phase II Mev intoxication were antagonized by co-administration of S-methylisothiourea, a selective NOS II inhibitor, Mn(III)-tetrakis-(4-benzoic acid) porphyrin, a superoxide dismutase mimetic, 5,10,15,20-tetrakis-N-methyl-4'-pyridyl)-porphyrinato iron (III), a peroxynitrite decomposition catalyst, or L-cysteine, a peroxynitrite scavenger. We conclude that sGC/cGMP/PKG cascade and peroxynitrite formation may participate in Mev-induced phasic cardiovascular responses as signals downstream to NO generated respectively by NOS I and II in the RVLM.
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Affiliation(s)
- J Y H Chan
- Department of Medical Education and Research, Kaohsiung Veterans General Hospital, Kaohsiung 813, Taiwan, Republic of China
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116
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Wang HG, Lu FM, Jin I, Udo H, Kandel ER, de Vente J, Walter U, Lohmann SM, Hawkins RD, Antonova I. Presynaptic and postsynaptic roles of NO, cGK, and RhoA in long-lasting potentiation and aggregation of synaptic proteins. Neuron 2005; 45:389-403. [PMID: 15694326 DOI: 10.1016/j.neuron.2005.01.011] [Citation(s) in RCA: 169] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2004] [Revised: 12/06/2004] [Accepted: 01/09/2005] [Indexed: 11/21/2022]
Abstract
Recent results suggest that long-lasting potentiation at hippocampal synapses involves the rapid formation of clusters or puncta of presynaptic as well as postsynaptic proteins, both of which are blocked by antagonists of NMDA receptors and an inhibitor of actin polymerization. We have investigated whether the increase in puncta involves retrograde signaling through the NO-cGMP-cGK pathway and also examined the possible roles of two classes of molecules that regulate the actin cytoskeleton: Ena/VASP proteins and Rho GTPases. Our results suggest that NO, cGMP, cGK, actin, and Rho GTPases including RhoA play important roles in the potentiation and act directly in both the presynaptic and postsynaptic neurons, where they contribute to the increase in puncta of synaptic proteins. cGK phosphorylates synaptic VASP during the potentiation, whereas Rho GTPases act both in parallel and upstream of cGMP, in part by maintaining the synaptic localization of soluble guanylyl cyclase.
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Affiliation(s)
- Hong-Gang Wang
- Center for Neurobiology and Behavior, Columbia University, New York, NY 10032, USA
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117
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Verkhratsky A. Physiology and Pathophysiology of the Calcium Store in the Endoplasmic Reticulum of Neurons. Physiol Rev 2005; 85:201-79. [PMID: 15618481 DOI: 10.1152/physrev.00004.2004] [Citation(s) in RCA: 561] [Impact Index Per Article: 29.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
The endoplasmic reticulum (ER) is the largest single intracellular organelle, which is present in all types of nerve cells. The ER is an interconnected, internally continuous system of tubules and cisterns, which extends from the nuclear envelope to axons and presynaptic terminals, as well as to dendrites and dendritic spines. Ca2+release channels and Ca2+pumps residing in the ER membrane provide for its excitability. Regulated ER Ca2+release controls many neuronal functions, from plasmalemmal excitability to synaptic plasticity. Enzymatic cascades dependent on the Ca2+concentration in the ER lumen integrate rapid Ca2+signaling with long-lasting adaptive responses through modifications in protein synthesis and processing. Disruptions of ER Ca2+homeostasis are critically involved in various forms of neuropathology.
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Affiliation(s)
- Alexei Verkhratsky
- The University of Manchester, Faculty of Biological Sciences, United Kingdom.
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118
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Grassi C, D'Ascenzo M, Azzena GB. Modulation of Ca(v)1 and Ca(v)2.2 channels induced by nitric oxide via cGMP-dependent protein kinase. Neurochem Int 2004; 45:885-93. [PMID: 15312983 DOI: 10.1016/j.neuint.2004.03.019] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
The unconventional gaseous transmitter nitric oxide (NO) markedly influences most of mechanisms involved in the regulation of intracellular Ca2+ homeostasis. In excitable cells, Ca2+ signaling mainly depends on the activity of voltage-gated Ca2+ channels (VGCCs). In the present paper, we will review data from our laboratory and others characterizing NO-induced modulation of Ca(v)1 (L-type) and Ca(v)2.2 (N-type) channels. In particular, we will explore experimental evidence indicating that NO's inhibition of channel gating is produced via cGMP-dependent protein kinase and examine some of the numerous cell functions that are potentially influenced by the action of NO on Ca2+ channels.
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Affiliation(s)
- Claudio Grassi
- Institute of Human Physiology, Medical School, Catholic University S. Cuore, Largo F. Vito 1, I-00168 Rome, Italy.
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119
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Abstract
Already 30 years ago, it became apparent that there exists a relationship between acetylcholine and cGMP in the brain. Acetylcholine plays a role in a great number of processes in the brain, however, the role of cGMP in these processes is not known. A review of the data shows that, although the connection between NO-mediated cGMP synthesis and acetylcholine is firmly established, the complexities of the heterosynaptic pathways and the oligosynaptic structures involved preclude a clear definition of the role of cGMP in the functioning of acetylcholine presently.
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Affiliation(s)
- Jan de Vente
- Department of Psychiatry and Neuropsychology, European Graduate School of Neuroscience (EURON), Maastricht University, UNS50, P.O. Box 616, 6200 MD Maastricht, The Netherlands.
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120
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Prickaerts J, Sik A, van Staveren WCG, Koopmans G, Steinbusch HWM, van der Staay FJ, de Vente J, Blokland A. Phosphodiesterase type 5 inhibition improves early memory consolidation of object information. Neurochem Int 2004; 45:915-28. [PMID: 15312986 DOI: 10.1016/j.neuint.2004.03.022] [Citation(s) in RCA: 119] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
The nitric oxide (NO)-cyclic GMP (cGMP) signaling pathway is assumed to play an important role in processes underlying learning and memory. We used phosphodiesterase type 5 (PDE5) inhibitors to study the role of cGMP in object- and spatial memory. Our results and those reported in other studies indicate that elevated hippocampal cGMP levels are required to improve the memory performance of rodents in object recognition and passive avoidance learning, but not in spatial learning. The timing of treatment modulates the effects on memory and strongly supports a role for cGMP in early stages of memory formation. Alternative explanations for the improved memory performance of PDE5 inhibitors are also discussed. Immunocytochemical studies showed that in vitro slice incubations with PDE5 inhibitors increase NO-stimulated cGMP levels mainly in hippocampal varicose fibers. Reviewing the available data on the localization of the different components of the NO-cGMP signaling pathway, indicates a complex interaction between NO and cGMP, which may be independent of each other. It is discussed that further studies are needed, immunocytochemical and behavioral, to better understand the cGMP-mediated molecular mechanisms underlying memory formation.
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Affiliation(s)
- Jos Prickaerts
- Department of Psychiatry and Neuropsychology, Maastricht University, P.O. Box 616, 6200 MD Maastricht, The Netherlands.
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121
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Aracena P, Sánchez G, Donoso P, Hamilton SL, Hidalgo C. S-glutathionylation decreases Mg2+ inhibition and S-nitrosylation enhances Ca2+ activation of RyR1 channels. J Biol Chem 2003; 278:42927-35. [PMID: 12920114 DOI: 10.1074/jbc.m306969200] [Citation(s) in RCA: 107] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
We have analyzed the effects of the endogenous redoxactive agents S-nitrosoglutathione and glutathione disulfide, and the NO donor NOR-3, on calcium release kinetics mediated by ryanodine receptor channels. Incubation of triad-enriched sarcoplasmic reticulum vesicles isolated from mammalian skeletal muscle with these three agents elicits different responses. Glutathione disulfide significantly reduces the inhibitory effect of Mg2+ without altering Ca2+ activation of release kinetics, whereas NOR-3 enhances Ca2+ activation of release kinetics without altering Mg2+ inhibition. Incubation with S-nitrosoglutathione produces both effects; it significantly enhances Ca2+ activation of release kinetics and diminishes the inhibitory effect of Mg2+ on this process. Triad incubation with [35S]nitrosoglutathione at pCa 5 promoted 35S incorporation into 2.5 cysteine residues per channel monomer; this incorporation decreased significantly at pCa 9. These findings indicate that S-nitrosoglutathione supports S-glutathionylation as well as the reported S-nitrosylation of ryanodine receptor channels (Sun, J., Xu, L., Eu, J. P., Stamler, J. S., and Meissner, G. (2003) J. Biol. Chem. 278, 8184-8189). The combined results suggest that S-glutathionylation of specific cysteine residues can modulate channel inhibition by Mg2+, whereas S-nitrosylation of different cysteines can modulate the activation of the channel by Ca2+. Possible physiological and pathological implications of the activation of skeletal Ca2+ release channels by endogenous redox species are discussed.
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Affiliation(s)
- Paula Aracena
- Centro Fondo de Investigación Avanzada en Areas Prioritarias de Estudios Moleculares de la Célula, Facultad de Medicina, Universidad de Chile, Casilla 70005, Santiago 7, Chile
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122
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Hippocampal cGMP-dependent protein kinase I supports an age- and protein synthesis-dependent component of long-term potentiation but is not essential for spatial reference and contextual memory. J Neurosci 2003. [PMID: 12853418 DOI: 10.1523/jneurosci.23-14-06005.2003] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
cGMP-dependent protein kinase I (cGKI) is expressed in the hippocampus, but its role in hippocampal long-term potentiation (LTP) is controversial. In addition, whether cGKI is involved in spatial learning has not been investigated. To address these issues, we generated mice with a hippocampus-specific deletion of cGKI (cGKIhko mice). Unlike conventional cGKI knock-out mice, cGKIhko mice lack gastrointestinal and cardiovascular phenotypes and have a normal life expectancy, which enables us to analyze hippocampal synaptic plasticity and learning in young and adult animals. Hippocampal LTP after repetitive episodes of theta burst stimulation was impaired in adult (12-14 weeks of age) but not in juvenile (3-4 weeks of age) cGKIhko mice. The difference in LTP between adult control and cGKIhko mice was abolished by the protein synthesis inhibitor anisomycin, suggesting that the impairment of LTP in adult cGKIhko mice reflects a defect in late-phase LTP. Despite their deficit in LTP, adult cGKIhko mutants showed normal performance in a discriminatory water maze and had intact contextual fear conditioning. These results suggest that hippocampal cGKI supports an age- and protein synthesis-dependent form of hippocampal LTP, whereas it is dispensable for hippocampus-dependent spatial reference and contextual memory.
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