Search results for "Guanosine monophosphate"
showing 10 items of 26 documents
Extracellular cyclic GMP and its derivatives GMP and guanosine protect from oxidative glutamate toxicity.
2013
Cell death in response to oxidative stress plays a role in a variety of neurodegenerative diseases and can be studied in detail in the neuronal cell line HT22, where extracellular glutamate causes glutathione depletion by inhibition of the glutamate/cystine antiporter system xc(-), elevation of reactive oxygen species and eventually programmed cell death caused by cytotoxic calcium influx. Using this paradigm, we screened 54 putative extracellular peptide or small molecule ligands for effects on cell death and identified extracellular cyclic guanosine monophosphate (cGMP) as a protective substance. Extracellular cGMP was protective, whereas the cell-permeable cGMP analog 8-pCPT-cGMP or the …
Accumulation of purine catabolites in solid tumors exposed to therapeutic hyperthermia
1996
Intensified adenosine triphosphate (ATP) degradation following therapeutic hyperthermia is often observed in solid tumors. As a result, accumulation of purine catabolites can be expected together with formation of protons at several stages during degradation to the final product, uric acid. Proton formation in turn can contribute to the development of heat-induced acidosis. Furthermore, oxidation of hypoxanthine and xanthine may result in generation of reactive oxygen species, which may lead to DNA damage, lipid peroxidation and protein denaturation, thus also contributing to heat-induced cytotoxicity. In hyperthermia experiments a tumor-size-dependent, significant increase in the levels of…
Nitric oxide modulates striatal neuronal activity via soluble guanylyl cyclase: an in vivo microiontophoretic study in rats.
2003
It is now well established that nitric oxide (NO) acts as a neuromodulator in the central nervous system. To assess the role of NO in modulating striatal activity, single-unit recording was combined with iontophoresis to study presumed spiny projection neurons in urethane-anesthetized male rats. Striatal neurons recorded were essentially quiescent and were therefore activated to fire by the iontophoretic administration of glutamate, pulsed in cycles of 30 sec on and 40 sec off. In this study, iontophoresis of 3-morpholinosydnonimine hydrochloride (SIN 1), a nitric oxide donor, produced reproducible, current-dependent inhibition of glutamate-induced excitation in 12 of 15 striatal neurons, r…
The ineffectiveness of the NO-cyclic GMP signaling pathway in the atrial myocardium
1995
1. This study was performed to determine whether nitric oxide (NO) has direct effects on force of contraction (Fc) in atrial myocardium from rats, rabbits, guinea-pigs, frogs, and man. 2. Glyceryl trinitrate, isosorbide dinitrate, 3-morpholino-sydnonimine hydrochloride (SIN-1), and S-nitroso-N-acetylpenicillamine (SNAP) did not significantly reduce Fc in the various preparations investigated, either given alone or after stimulation of alpha- or beta-adrenoceptors. 3. SNAP did not change the time course of contractions in rat, guinea-pig and human preparations. 4. 8-Bromo-guanosine-3':5'-cyclic monophosphate (8-Br-cyclic GMP) produced a negative inotropic effect in rat, guinea-pig and human …
Involvement of cyclic guanosine monophosphosphate (cGMP) and cytosolic guanylate cyclase in the regulation of synaptic ribbon numbers in rat pineal g…
1992
In the rat pineal gland N-acetyltransferase (NAT) activity and synaptic ribbon (SR) numbers display a circadian rhythm. It is well-known that NAT activity is regulated by adrenergic mechanisms involving cyclic adenosine monophosphate (cAMP) as a second messenger. However, the mechanism involved in the regulation of SR numbers has not been established so far. In the present in vitro study, we have investigated the effects of 8-bromo-cyclic guanosine monophosphate (8-bromo-cGMP), a cyclic guanosine monophosphate (cGMP) analog, and stimulation of guanylate cyclase on SR numbers. Incubation with 8-bromo-cGMP increased SR numbers in a dose- and time-dependent manner. Further, stimulation of the …
A possible role for cyclic guanosine monophosphate in the rat pineal gland.
1990
Abstract Adrenergic stimulation of pinealocytes induces an increase of both cyclic adenosine monophosphate (cAMP) and cyclic guanosine monophosphate (cGMP). However, for cGMP no biological effects have been demonstrated so far. Therefore we tested the effects of the analog 8-bromo-cGMP on synaptic ribbon numbers and on melatonin synthesis as reflected by N -acetyltransferase (NAT) activity in the rat pineal gland in vitro. Incubation for 6 h with 8-bromo-cGMP did not change the activity of serotonin NAT but in increased the number of synaptic ribbons. These results indicate that cGMP is involved as a second messenger in the regulation of synaptic ribbon numbers in the rat pineal gland.
Lack of effect of oxytocin on the numbers of ?synaptic? ribbons, cyclic guanosine monophosphate and serotonin N-acetyltransferase activity in organ-c…
1993
In addition to the stimulating influence of the sympathetic system on the function of the mammalian pineal gland, neuropeptides such as neuropeptide Y, vasoactive intestinal polypeptide and arginine-vasopressin (AVP) are thought to function as modulators. Since AVP has been shown to influence pineal melatonin synthesis, the aim of the present study was to investigate the possible effects of the second hypothalamic nonapeptide oxytocin (OT), which likewise has been detected in the pineal gland. We therefore studied "synaptic" ribbon (SR) numbers, N-acetyltransferase (NAT) activity and the intracellular concentration of cyclic guanosine monophosphate (cGMP) following in vitro incubation of ra…
Effect of beta-N-oxalylamino-L-alanine on cerebellar cGMP level in vivo.
1993
Beta-N-oxalylamino-L-alanine (BOAA), a non-protein amino acid present in the seeds of Lathyrus Sativus (LS), is one of several neuroactive glutamate analogs reported to stimulate excitatory receptors and, in high concentrations, cause neuronal degeneration. In the present study, the in vivo acute effects of synthetic BOAA and LS seed extract were investigated on rat cerebellar cyclic GMP following intraperitoneal (10-100 mg/kg) or oral (100 mg/kg) administration of subconvulsive doses of toxin. Furthermore, the BOAA content in LS seeds and in the cerebellum of injected rats was determined by high performance liquid chromatograph analysis. A dose- and time-dependent increase of cerebellar cy…
Postsynaptic NO/cGMP Increases NMDA Receptor Currents via Hyperpolarization-Activated Cyclic Nucleotide-Gated Channels in the Hippocampus
2013
The nitric oxide (NO)/cyclic guanosine monophosphate (cGMP) signaling cascade participates in the modulation of synaptic transmission. The effects of NO are mediated by the NO-sensitive cGMP-forming guanylyl cyclases (NO-GCs), which exist in 2 isoforms with indistinguishable regulatory properties. The lack of long-term potentiation (LTP) in knock-out (KO) mice deficient in either one of the NO-GC isoforms indicates the contribution of both NO-GCs to LTP. Recently, we showed that the NO-GC1 isoform is located presynaptically in glutamatergic neurons and increases the glutamate release via hyperpolarization-activated cyclic nucleotide (HCN)-gated channels in the hippocampus. Electrophysiologi…
Inflammation in the Human Periodontium Induces Downregulation of the α1- and β1-Subunits of the sGC in Cementoclasts
2021
Nitric oxide (NO) binds to soluble guanylyl cyclase (sGC), activates it in a reduced oxidized heme iron state, and generates cyclic Guanosine Monophosphate (cGMP), which results in vasodilatation and inhibition of osteoclast activity. In inflammation, sGC is oxidized and becomes insensitive to NO. NO- and heme-independent activation of sGC requires protein expression of the &alpha