Hydrogen Sulfide Ameliorates Developmental Impairments of Rat Offspring with Prenatal Hyperhomocysteinemia

Maternal high levels of the redox active amino acid homocysteine-called hyperhomocysteinemia (hHCY)-can affect the health state of the progeny. The effects of hydrogen sulfide (H2S) treatment on rats with maternal hHCY remain unknown. In the present study, we characterized the physical development, reflex ontogeny, locomotion and exploratory activity, muscle strength, motor coordination, and brain redox state of pups with maternal hHCY and tested potential beneficial action of the H2S donor-sodium hydrosulfide (NaHS)-on these parameters. Our results indicate a significant decrease in litter size and body weight of pups from dams fed with methionine-rich diet. In hHCY pups, a delay in the formation of sensory-motor reflexes was observed. Locomotor activity tested in the open field by head rearings, crossed squares, and rearings of hHCY pups at all studied ages (P8, P16, and P26) was diminished. Exploratory activity was decreased, and emotionality was higher in rats with hHCY. Prenatal hHCY resulted in reduced muscle strength and motor coordination assessed by the paw grip endurance test and rotarod test. Remarkably, administration of NaHS to pregnant rats with hHCY prevented the observed deleterious effects of high homocysteine on fetus development. In rats with prenatal hHCY, the endogenous generation of H2S brain tissues was lower compared to control and NaHS administration restored the H2S level to control values. Moreover, using redox signaling assays, we found an increased level of malondialdehyde (MDA), the end product of lipid peroxidation, and decreased activity of antioxidant enzymes such as superoxide dismutase (SOD) and glutathione peroxidase (GPx) in the brain tissues of rats of the hHCY group. Notably, NaHS treatment restored the level of MDA and the activity of SOD and GPx. Our data suggest that H2S has neuroprotective/antioxidant effects against homocysteine-induced neurotoxicity providing a potential strategy for the prevention of developmental impairments in newborns

Gasotransmitters in regulation of neuromuscular transmission

© Springer-Verlag Berlin Heidelberg 2012. All rights are reserved. Nitric oxide (NO), carbon monoxide (CO), and hydrogen sulfide (H2S) are endogenously synthesized and serve as signaling molecules of autocrine and paracrine regulation in many systems. All three gases are produced in central nervous systems in response to neural excitation and regulate neurotransmitter release and are involved in the regulation of synaptic plasticity acting on pre- or postsynaptic levels. The modulatory mechanisms of these gases are different. In this chapter, we present the literature and our own data concerning the effects and mechanisms of these gases in the peripheral nervous system focusing on neuromuscular synapses. In motor nerve endings it was shown that NO decreased transmitter release while CO had the opposite effect. It was further shown that the main result of NO and CO action is a change of the cyclic adenosine monophosphate (cAMP) level which increased or decreased by cyclic guanosine monophosphate (cGMP) -dependent phosphodiesterases (PDEs) (2 or 3). H2S induced an increase of acetylcholine release and whose effect was mediated by cAMP and Ca2+. It is suggested that all three gases are produced at the neuromuscular junction and regulate transmitter release from motor nerve ending

The role of nitric oxide in the regulation of neurotransmitter release and processes of exo- and endocytosis of synaptic vesicles in mouse motor nerve endings

In experiments with mouse diaphragm muscle, the effects of a nitric oxide (NO) donor, S-nitroso- N-acetyl-DL-penicillamine (SNAP), and an NO-synthase blocker, NG-nitro-L-arginine methyl ester (LNAME), on transmitter release and processes of exo- and endocytosis of synaptic vesicles in the motornerve ending were studied using electrophysiological and fluorescence techniques. During single stimulation of the motor nerve, SNAP reduced and LNAME did not change the amplitude of the endplate currents and both of the drugs did not affect spontaneous transmitter release. During high-frequency stimulation (20 Hz, 3 min) SNAP increased and LNAME slowed the depression of the amplitudes of endplate potentials (EPPs) compared to the dynamics of EPPs in the control. In experiments using the fluorescent dye FM 1-43, it was shown that the NO donor induced a decrease and LNAME induced an increase in the fluorescence intensity of motor-nerve endings loaded with dye during stimulation at a frequency of 20 Hz for 30 s compared to the control. At the same time, the rate of dye unloading from the terminals that were preloaded with FM 1-43 was higher after preliminary application of SNAP and lower after preliminary application of LNAME. It was suggested that exogenous and endogenous NO in the mouse neuromuscular synapse caused the depression of neurotransmitter release as a result of the suppression of synaptic-vesicle recycling due to a decrease in endocytosis or/and mobilization of synaptic vesicles from a recycling pool to the exocytosis sites. © 2013 Pleiades Publishing, Ltd

Modulated by gasotransmitters: BK channels

© Springer-Verlag Berlin Heidelberg 2012. All rights are reserved. Calcium-activated potassium BK channels interconnect cellular activity, calcium signaling, and cell metabolism. Major virtues of these channels are their adaptability to different functions, their versatile physiology, and their capacity being modulated. The channels are present in a large variety of cells and organs in different forms of life from bacteria to men. Scientists attracted to these channels have produced a great wealth of information regarding their structure and function. Mutations at channels proteins are involved in a number of diseases (channelopathies), like diabetes, epilepsy, or heart failure. The gasotransmitters NO, CO, and H2S all act on BK channels directly or indirectly via signaling pathways. In this chapter, we will briefly summarize some of the basic properties of BK channels and focus on aspects of BK channel modulation by gasotransmitters and their implications in physiology and pathophyiology

Role of cGMP- and cAMP-dependent systems in the effects of nitric oxide on transmitter release and potassium currents in the frog neuromuscular junction

We studied the molecular mechanisms responsible for nitric oxide (NO)-evoked modulation of the synaptic function in the frog neuromuscular junction using inhibitors of adenylate and guanylate cyclases and analogs of cyclic nucleotides. It was shown that application of an exogenous donor of NO, sodium nitroprusside, decreased transmitter release and increased the amplitude of voltage-dependent potassium current of the nerve endings. Our results indicate that NO regulates transmitter release and potassium current in the frog neuromuscular junction both via cAMP- and cGMP-dependent mechanisms

Effects of pyrocatechol on neuromuscular transmission

Effects of pyrocatechol on neuromuscular transmission were studied both in the frog pectoral-cutaneous muscle and in the mouse phrenic-diaphragmatic preparation by means of extracellular microelectrode recording of synaptic signals. Pyrocatechol applied in a concentration of 0.05 mM increased the frequency of miniature end-plate currents (MEPC) and the amplitude of end-plate current (EPC) by increasing its quantum content. Pyrocatechol also increased the duration of presynaptic response. When voltage-dependent potassium channels had been blocked, pyrocatechol affected neither the EPC quantum content nor the duration of presynaptic response. It is suggested that the pyrocatechol-induced enhancement of transmitter release results from modulatory effects of pyrocatechol on voltage-dependent potassium current in the membrane of a nerve terminal. © 1995 Plenum Publishing Corporation

Effects of hydrogen sulfide on the processes of exo- and endocytosis of synaptic vesicles in mouse motor nerve endings

The effects of sodium hydrosulfide(NaHS),the donor of hydrogen sulfide(H2S),on the exo-endocytosis cycle of the synaptic vesicles in the motor nerve ending of mouse diaphragm were explored using intracellular microelectrode technique and fluorescent microscopy. NaHS increased the frequency of miniature end-plate potentials(MEPPs) without changing its amplitude-time parameters and the amplitude of the postsynaptic responses undersingle stimulus condition(0.3 Hz),giving evidence on enhancing synaptic vesicle exocytosis. During high-frequency stimulation(50 Hz) NaHS induced more significant decline of neurotransmitter secretion,which can be due to the lower rate of synaptic vesicle mobilization from the recycling pool to the exocytic cites. NaHS also decreased the uptake of the fluorescent endocytic dye FM 1-43, which indicates the reduced endocytosis of the synaptic vesicles. Thus,the donor of H2S increased exocytosis and decreased the processes of the synaptic vesicles' endocytosis and mobilization in the mouse motor nerve ending

Role of calcium and potassium channels in effects of hydrogen sulfide on frog myocardial contractility

The effects of sodium hydrosulfide NaHS, a donor of hydrogen sulfide H 2S, on the force of muscle contraction were examined on isolated myocardial strips from frog ventricles. NaHS decreased the amplitude of muscle contractions in a dose-dependent manner under normal conditions and during inhibition of Ca channels with nifedipine. In contrast, under conditions of blockade of ATP-dependent potassium channels with glibenclamide, NaHS exerted a positive inotropic effect from the first minute of application. Neither blockade, nor activation of ATP-dependent K-channels with glibenclamide modulated the negative inotropic effect of NaHS. Inhibition of K-channels with tetraethylammonium (TEA) (3, 5, 10 mM) or 4-aminopyridine increased the amplitude of myocardial contractions. Preliminary application of 4-aminopyridine or TEA (3 mM) did not eliminate NaHS-induced negative inotropic effect, although higher TEA concentrations (5 or 10 mM) prevented it. The data indicate that the targets of H2S in frog myocardium are ATP-dependent, Ca-activated, and voltage-dependent K-channels. © 2011 Springer Science+Business Media, Inc

Hydrogen sulfide increases calcium-activated potassium (BK) channel activity of rat pituitary tumor cells

Hydrogen sulfide (H2S) is the third gasotransmitter found to be produced endogenously in living cells to exert physiological functions. Large conductance (maxi) calcium-activated potassium channels (BK), which play an important role in the regulation of electrical activity in many cells, are targets of gasotransmitters. We examined the modulating action of H2S on BK channels from rat GH3 pituitary tumor cells using patch clamp techniques. Application of sodium hydrogen sulfide as H2S donor to the bath solution in whole cell experiments caused an increase of calcium-activated potassium outward currents. In single channel recordings, H2S increased BK channel activity in a concentration-dependent manner. Hydrogen sulfide induced a reversible increase in channel open probability in a voltagedependent, but calcium independent manner. The reducing agent, dithiothreitol, prevented the increase of open probability by H 2S, whereas, the oxidizing agent thimerosal increased channel open probability in the presence of H2S. Our data show that H2S augments BK channel activity, and this effect can be linked to its reducing action on sulfhydryl groups of the channel protein

Gasotransmitters: Physiology and pathophysiology

© Springer-Verlag Berlin Heidelberg 2012. All rights are reserved. Since the epochal discovery of the radical and highly toxic gas nitric oxide (NO) as a signaling molecule, two other no less toxic gases - carbon monoxide (CO) and hydrogen sulfide (H2S) - have been found to also be involved in a plethora of physiological and pathophysiological functions. The gases termed gasotransmitters play an increasingly important role in understanding how signalling into and between cells is modulated and fine-tuned. The advent of gasotransmitters has profoundly changed our way of thinking about biosynthesis, liberation, storage and action mechanisms in cellular signaling. In recent years an impressive amount of new data, distributed throughout the existing literature, has been generated. For this book the editors have recruited distinguished colleagues in the field to summarize and review important biological, pharmacological and medical functions and their implications, as well as methods for the detection of gasotransmitters