Biomaterial Database

Anterograde and retrograde effects of synapse formation on calcium currents and neurite outgrowth in cultured leech neurons. 1992

R L Cooper, and F Fernández-de-Miguel, and W B Adams, and J G Nicholls

Department of Pharmacology, Biocenter, University of Basle, Switzerland.

The aim of our experiments has been to analyse how formation of chemical synapses affects the distribution of calcium (Ca2+) currents and neurite outgrowth of leech Retzius cells. Previous results showed that Ca2+ currents measured in the initial process or 'stump' of postsynaptic cells were significantly smaller than those in corresponding sites on presynaptic neurons. In the present experiments, neurons were plated together in close apposition as pairs or as triads, with the tip of one Retzius cell touching the soma of another. Ca2+ currents from selected areas of the neuronal surfaces were measured by loose-patch recording before and after the formation of chemically mediated synaptic connections, which developed in about 8 h. With three cells arranged in a row, the last of the series, which was purely postsynaptic (i.e. with no target), also showed a dramatic reduction in Ca2+ currents in its initial segment, compared with the currents seen in either the first cell (purely presynaptic) or the second cell of the chain (which was both postsynaptic to the first cell and presynaptic to the third). This suggests that retrograde as well as anterograde effects on Ca2+ currents occurred as a result of synapse formation: the Ca2+ currents in the middle cell did not decrease although a synapse had been formed on it. To test for additional consequences of synapse formation, neurite outgrowth was measured in postsynaptic cells and in single cells plated on an extract of extracellular matrix containing laminin (ECM-laminin). After 48 h, the total length of neuritic outgrowth in postsynaptic cells was only about one third of that in single cells.(ABSTRACT TRUNCATED AT 250 WORDS)

UI	MeSH Term	Description	Entries
D007865	Leeches	Annelids of the class Hirudinea. Some species, the bloodsuckers, may become temporarily parasitic upon animals, including man. Medicinal leeches (HIRUDO MEDICINALIS) have been used therapeutically for drawing blood since ancient times.	Hirudinea,Hirudineas,Leeche
D008564	Membrane Potentials	The voltage differences across a membrane. For cellular membranes they are computed by subtracting the voltage measured outside the membrane from the voltage measured inside the membrane. They result from differences of inside versus outside concentration of potassium, sodium, chloride, and other ions across cells' or ORGANELLES membranes. For excitable cells, the resting membrane potentials range between -30 and -100 millivolts. Physical, chemical, or electrical stimuli can make a membrane potential more negative (hyperpolarization), or less negative (depolarization).	Resting Potentials,Transmembrane Potentials,Delta Psi,Resting Membrane Potential,Transmembrane Electrical Potential Difference,Transmembrane Potential Difference,Difference, Transmembrane Potential,Differences, Transmembrane Potential,Membrane Potential,Membrane Potential, Resting,Membrane Potentials, Resting,Potential Difference, Transmembrane,Potential Differences, Transmembrane,Potential, Membrane,Potential, Resting,Potential, Transmembrane,Potentials, Membrane,Potentials, Resting,Potentials, Transmembrane,Resting Membrane Potentials,Resting Potential,Transmembrane Potential,Transmembrane Potential Differences
D008959	Models, Neurological	Theoretical representations that simulate the behavior or activity of the neurological system, processes or phenomena; includes the use of mathematical equations, computers, and other electronic equipment.	Neurologic Models,Model, Neurological,Neurologic Model,Neurological Model,Neurological Models,Model, Neurologic,Models, Neurologic
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
D002118	Calcium	A basic element found in nearly all tissues. It is a member of the alkaline earth family of metals with the atomic symbol Ca, atomic number 20, and atomic weight 40. Calcium is the most abundant mineral in the body and combines with phosphorus to form calcium phosphate in the bones and teeth. It is essential for the normal functioning of nerves and muscles and plays a role in blood coagulation (as factor IV) and in many enzymatic processes.	Coagulation Factor IV,Factor IV,Blood Coagulation Factor IV,Calcium-40,Calcium 40,Factor IV, Coagulation
D002478	Cells, Cultured	Cells propagated in vitro in special media conducive to their growth. Cultured cells are used to study developmental, morphologic, metabolic, physiologic, and genetic processes, among others.	Cultured Cells,Cell, Cultured,Cultured Cell
D000818	Animals	Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA.	Animal,Metazoa,Animalia
D013569	Synapses	Specialized junctions at which a neuron communicates with a target cell. At classical synapses, a neuron's presynaptic terminal releases a chemical transmitter stored in synaptic vesicles which diffuses across a narrow synaptic cleft and activates receptors on the postsynaptic membrane of the target cell. The target may be a dendrite, cell body, or axon of another neuron, or a specialized region of a muscle or secretory cell. Neurons may also communicate via direct electrical coupling with ELECTRICAL SYNAPSES. Several other non-synaptic chemical or electric signal transmitting processes occur via extracellular mediated interactions.	Synapse
D015220	Calcium Channels	Voltage-dependent cell membrane glycoproteins selectively permeable to calcium ions. They are categorized as L-, T-, N-, P-, Q-, and R-types based on the activation and inactivation kinetics, ion specificity, and sensitivity to drugs and toxins. The L- and T-types are present throughout the cardiovascular and central nervous systems and the N-, P-, Q-, & R-types are located in neuronal tissue.	Ion Channels, Calcium,Receptors, Calcium Channel Blocker,Voltage-Dependent Calcium Channel,Calcium Channel,Calcium Channel Antagonist Receptor,Calcium Channel Antagonist Receptors,Calcium Channel Blocker Receptor,Calcium Channel Blocker Receptors,Ion Channel, Calcium,Receptors, Calcium Channel Antagonist,VDCC,Voltage-Dependent Calcium Channels,Calcium Channel, Voltage-Dependent,Calcium Channels, Voltage-Dependent,Calcium Ion Channel,Calcium Ion Channels,Channel, Voltage-Dependent Calcium,Channels, Voltage-Dependent Calcium,Voltage Dependent Calcium Channel,Voltage Dependent Calcium Channels
D016501	Neurites	In tissue culture, hairlike projections of neurons stimulated by growth factors and other molecules. These projections may go on to form a branched tree of dendrites or a single axon or they may be reabsorbed at a later stage of development. "Neurite" may refer to any filamentous or pointed outgrowth of an embryonal or tissue-culture neural cell.	Neurite