Comparative effects of inorganic divalent mercury, methylmercury and phenylmercury on membrane excitability and synaptic transmission of CA1 neurons in hippocampal slices of the rat. 1994

Y Yuan, and W D Atchison
Department of Pharmacology and Toxicology, Michigan State University, East Lansing 48824-1317.

Comparative effects of inorganic mercury (Hg2+), methylmercury (MeHg) and phenylmercuric acetate (PMA) on central synaptic transmission were examined by recording field potentials from CA1 neurons of rat hippocampal slices before and after acute bath application of mercurials at 20 and 100 microM. At 100 microM, Hg2+ decreased the amplitude of population spikes (PSs) to complete block; average time to block was 25 +/- 4 min. Application of 20 microM Hg2+ for 120 min gradually decreased PS amplitude to 33% of control. Effects of Hg2+ on excitatory postsynaptic potentials (EPSPs) were comparatively slow. Application of 100 microM Hg2+ for 120 min only reduced EPSP amplitude to 60% of control; no complete block occurred, suggesting an effect primarily on the postsynaptic CA1 cell membrane. In contrast to Hg2+, MeHg at 20 and 100 microM first increased amplitudes of PSs and EPSPs significantly and then decreased both to complete block. Average times to block of PSs and EPSPs by 100 microM MeHg were 41 +/- 4 and 42 +/- 4 min, respectively. PMA caused similar effects on PSs and EPSPs as did MeHg. However, unlike MeHg, the increased amplitudes of PSs and EPSPs by PMA were not statistically significant. At 20 microM, PMA appeared to be more effective at blocking PSs and EPSPs than were Hg2+ and MeHg. Washing slices with artificial cerebrospinal fluid containing 1 mM D-penicillamine completely reversed the effects of Hg2+ on PSs and EPSPs and effects of MeHg on EPSPs in 90 min, but only partially reversed the effects of MeHg on PSs. D-penicillamine could reverse neither the effects of PMA on PSs nor EPSPs. It is concluded that these perturbations produced damage to the associated physiological functions leading to CNS dysfunctions.

UI MeSH Term Description Entries
D008055 Lipids A generic term for fats and lipoids, the alcohol-ether-soluble constituents of protoplasm, which are insoluble in water. They comprise the fats, fatty oils, essential oils, waxes, phospholipids, glycolipids, sulfolipids, aminolipids, chromolipids (lipochromes), and fatty acids. (Grant & Hackh's Chemical Dictionary, 5th ed) Lipid
D008297 Male Males
D008627 Mercuric Chloride Mercury chloride (HgCl2). A highly toxic compound that volatizes slightly at ordinary temperature and appreciably at 100 degrees C. It is corrosive to mucous membranes and used as a topical antiseptic and disinfectant. Mercury Dichloride,Corrosive Sublimate,HgCl2,Mercuric Perchloride,Mercury Bichloride,Mercury Perchloride,Sublimate,Bichloride, Mercury,Chloride, Mercuric,Dichloride, Mercury,Perchloride, Mercuric,Perchloride, Mercury,Sublimate, Corrosive
D008767 Methylmercury Compounds Organic compounds in which mercury is attached to a methyl group. Methyl Mercury Compounds,Compounds, Methyl Mercury,Compounds, Methylmercury,Mercury Compounds, Methyl
D009435 Synaptic Transmission The communication from a NEURON to a target (neuron, muscle, or secretory cell) across a SYNAPSE. In chemical synaptic transmission, the presynaptic neuron releases a NEUROTRANSMITTER that diffuses across the synaptic cleft and binds to specific synaptic receptors, activating them. The activated receptors modulate specific ion channels and/or second-messenger systems in the postsynaptic cell. In electrical synaptic transmission, electrical signals are communicated as an ionic current flow across ELECTRICAL SYNAPSES. Neural Transmission,Neurotransmission,Transmission, Neural,Transmission, Synaptic
D009474 Neurons The basic cellular units of nervous tissue. Each neuron consists of a body, an axon, and dendrites. Their purpose is to receive, conduct, and transmit impulses in the NERVOUS SYSTEM. Nerve Cells,Cell, Nerve,Cells, Nerve,Nerve Cell,Neuron
D010662 Phenylmercuric Acetate A phenyl mercury compound used mainly as a fungicide. Has also been used as a herbicide, slimicide, and bacteriocide. Acetoxyphenylmercury,Falisan-Nassbeize,Verdasan,Acetate, Phenylmercuric,Falisan Nassbeize,FalisanNassbeize
D002462 Cell Membrane The lipid- and protein-containing, selectively permeable membrane that surrounds the cytoplasm in prokaryotic and eukaryotic cells. Plasma Membrane,Cytoplasmic Membrane,Cell Membranes,Cytoplasmic Membranes,Membrane, Cell,Membrane, Cytoplasmic,Membrane, Plasma,Membranes, Cell,Membranes, Cytoplasmic,Membranes, Plasma,Plasma Membranes
D005071 Evoked Potentials Electrical responses recorded from nerve, muscle, SENSORY RECEPTOR, or area of the CENTRAL NERVOUS SYSTEM following stimulation. They range from less than a microvolt to several microvolts. The evoked potential can be auditory (EVOKED POTENTIALS, AUDITORY), somatosensory (EVOKED POTENTIALS, SOMATOSENSORY), visual (EVOKED POTENTIALS, VISUAL), or motor (EVOKED POTENTIALS, MOTOR), or other modalities that have been reported. Event Related Potential,Event-Related Potentials,Evoked Potential,N100 Evoked Potential,P50 Evoked Potential,N1 Wave,N100 Evoked Potentials,N2 Wave,N200 Evoked Potentials,N3 Wave,N300 Evoked Potentials,N4 Wave,N400 Evoked Potentials,P2 Wave,P200 Evoked Potentials,P50 Evoked Potentials,P50 Wave,P600 Evoked Potentials,Potentials, Event-Related,Event Related Potentials,Event-Related Potential,Evoked Potential, N100,Evoked Potential, N200,Evoked Potential, N300,Evoked Potential, N400,Evoked Potential, P200,Evoked Potential, P50,Evoked Potential, P600,Evoked Potentials, N100,Evoked Potentials, N200,Evoked Potentials, N300,Evoked Potentials, N400,Evoked Potentials, P200,Evoked Potentials, P50,Evoked Potentials, P600,N1 Waves,N2 Waves,N200 Evoked Potential,N3 Waves,N300 Evoked Potential,N4 Waves,N400 Evoked Potential,P2 Waves,P200 Evoked Potential,P50 Waves,P600 Evoked Potential,Potential, Event Related,Potential, Event-Related,Potential, Evoked,Potentials, Event Related,Potentials, Evoked,Potentials, N400 Evoked,Related Potential, Event,Related Potentials, Event,Wave, N1,Wave, N2,Wave, N3,Wave, N4,Wave, P2,Wave, P50,Waves, N1,Waves, N2,Waves, N3,Waves, N4,Waves, P2,Waves, P50
D006624 Hippocampus A curved elevation of GRAY MATTER extending the entire length of the floor of the TEMPORAL HORN of the LATERAL VENTRICLE (see also TEMPORAL LOBE). The hippocampus proper, subiculum, and DENTATE GYRUS constitute the hippocampal formation. Sometimes authors include the ENTORHINAL CORTEX in the hippocampal formation. Ammon Horn,Cornu Ammonis,Hippocampal Formation,Subiculum,Ammon's Horn,Hippocampus Proper,Ammons Horn,Formation, Hippocampal,Formations, Hippocampal,Hippocampal Formations,Hippocampus Propers,Horn, Ammon,Horn, Ammon's,Proper, Hippocampus,Propers, Hippocampus,Subiculums

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