Biomaterial Database

Metabotropic glutamate receptor-mediated excitation and inhibition of sympathetic preganglionic neurones. 1998

M F Nolan, and S D Logan

Department of Biomedical Sciences, Institute of Medical Sciences, Foresterhill, Aberdeen, UK. m.f.nolan@abdn.ac.uk

The effects of metabotropic glutamate receptor (mGluR) subtype selective compounds on the excitability of sympathetic preganglionic neurones (SPNs) were investigated. Non-selective mGluR agonists (1S,3R)-aminocyclopentane-1,3-dicarboxylic acid and (2S,1'S,2'S)-2-(carboxycyclopropyl)glycine, induced dose-dependent depolarisations in 96 and 75% of SPNs, respectively and hyperpolarisations in 2 and 21% of SPNs. Both agonists could induce subthreshold membrane potential oscillations in previously non-oscillating SPNs and either increased or reduced the frequency of spontaneously occurring oscillations. A selective group I mGluR agonist, 3,5-dihydroxyphenylglycine, depolarised all SPNs tested, induced oscillations in membrane potential of otherwise non-oscillating SPNs and increased the frequency of spontaneous oscillations. Agonists with selectivity for group II mGluRs (1S,3S)-aminocyclopentane-1,3-dicarboxylic acid and (S)-4-carboxy-3-hydroxy-phenylglycine ((S)-4C3HPG) did not induce depolarising responses. However (S)-4C3HPG induced hyperpolarising responses associated with a reduction in the frequency of spontaneous oscillations in two of six SPNs tested. Depolarising and hyperpolarising responses were maintained in the presence of tetrodotoxin indicating a direct action of the agonists upon SPNs. In individual SPNs responses of opposite polarity could be induced from the same initial membrane potential using different agonists, indicating that the opposing responses involved different ionic mechanisms. The broad spectrum mGluR antagonist (S)-alpha-methyl-4-carboxyphenylglycine and the selective group I mGluR antagonist (S)-4-carboxyphenylglycine reversibly depressed mGluR agonist induced depolarisations. These results indicate that SPNs express two mGluR populations with opposing actions on neuronal excitability: group I mGluRs depolarise SPNs and can drive oscillatory membrane potential activity; a minority of SPNs express group II mGluRs which mediate membrane hyperpolarisations and reduce the frequency of membrane potential oscillations.

UI	MeSH Term	Description	Entries
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
D003515	Cycloleucine	An amino acid formed by cyclization of leucine. It has cytostatic, immunosuppressive and antineoplastic activities.	1-Aminocyclopentanecarboxylic Acid,Aminocyclopentanecarboxylic Acid,NSC 1026,1 Aminocyclopentanecarboxylic Acid,Acid, 1-Aminocyclopentanecarboxylic,Acid, Aminocyclopentanecarboxylic
D000600	Amino Acids, Dicarboxylic		Dicarboxylic Amino Acids,Acids, Dicarboxylic Amino
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
D001339	Autonomic Fibers, Preganglionic	NERVE FIBERS which project from the central nervous system to AUTONOMIC GANGLIA. In the sympathetic division most preganglionic fibers originate with neurons in the intermediolateral column of the SPINAL CORD, exit via ventral roots from upper thoracic through lower lumbar segments, and project to the paravertebral ganglia; there they either terminate in SYNAPSES or continue through the SPLANCHNIC NERVES to the prevertebral ganglia. In the parasympathetic division the fibers originate in neurons of the BRAIN STEM and sacral spinal cord. In both divisions the principal transmitter is ACETYLCHOLINE but peptide cotransmitters may also be released.	Autonomic Fiber, Preganglionic,Fiber, Preganglionic Autonomic,Fibers, Preganglionic Autonomic,Preganglionic Autonomic Fiber,Preganglionic Autonomic Fibers
D013116	Spinal Cord	A cylindrical column of tissue that lies within the vertebral canal. It is composed of WHITE MATTER and GRAY MATTER.	Coccygeal Cord,Conus Medullaris,Conus Terminalis,Lumbar Cord,Medulla Spinalis,Myelon,Sacral Cord,Thoracic Cord,Coccygeal Cords,Conus Medullari,Conus Terminali,Cord, Coccygeal,Cord, Lumbar,Cord, Sacral,Cord, Spinal,Cord, Thoracic,Cords, Coccygeal,Cords, Lumbar,Cords, Sacral,Cords, Spinal,Cords, Thoracic,Lumbar Cords,Medulla Spinali,Medullari, Conus,Medullaris, Conus,Myelons,Sacral Cords,Spinal Cords,Spinali, Medulla,Spinalis, Medulla,Terminali, Conus,Terminalis, Conus,Thoracic Cords
D017207	Rats, Sprague-Dawley	A strain of albino rat used widely for experimental purposes because of its calmness and ease of handling. It was developed by the Sprague-Dawley Animal Company.	Holtzman Rat,Rats, Holtzman,Sprague-Dawley Rat,Rats, Sprague Dawley,Holtzman Rats,Rat, Holtzman,Rat, Sprague-Dawley,Sprague Dawley Rat,Sprague Dawley Rats,Sprague-Dawley Rats
D051381	Rats	The common name for the genus Rattus.	Rattus,Rats, Laboratory,Rats, Norway,Rattus norvegicus,Laboratory Rat,Laboratory Rats,Norway Rat,Norway Rats,Rat,Rat, Laboratory,Rat, Norway,norvegicus, Rattus
D018094	Receptors, Metabotropic Glutamate	Cell surface proteins that bind glutamate and act through G-proteins to influence second messenger systems. Several types of metabotropic glutamate receptors have been cloned. They differ in pharmacology, distribution, and mechanisms of action.	Glutamate Receptors, Metabotropic,Metabotropic Glutamate Receptors,Receptors, Glutamate, Metabotropic,Metabotropic Glutamate Receptor,Glutamate Receptor, Metabotropic,Receptor, Metabotropic Glutamate
D018408	Patch-Clamp Techniques	An electrophysiologic technique for studying cells, cell membranes, and occasionally isolated organelles. All patch-clamp methods rely on a very high-resistance seal between a micropipette and a membrane; the seal is usually attained by gentle suction. The four most common variants include on-cell patch, inside-out patch, outside-out patch, and whole-cell clamp. Patch-clamp methods are commonly used to voltage clamp, that is control the voltage across the membrane and measure current flow, but current-clamp methods, in which the current is controlled and the voltage is measured, are also used.	Patch Clamp Technique,Patch-Clamp Technic,Patch-Clamp Technique,Voltage-Clamp Technic,Voltage-Clamp Technique,Voltage-Clamp Techniques,Whole-Cell Recording,Patch-Clamp Technics,Voltage-Clamp Technics,Clamp Technique, Patch,Clamp Techniques, Patch,Patch Clamp Technic,Patch Clamp Technics,Patch Clamp Techniques,Recording, Whole-Cell,Recordings, Whole-Cell,Technic, Patch-Clamp,Technic, Voltage-Clamp,Technics, Patch-Clamp,Technics, Voltage-Clamp,Technique, Patch Clamp,Technique, Patch-Clamp,Technique, Voltage-Clamp,Techniques, Patch Clamp,Techniques, Patch-Clamp,Techniques, Voltage-Clamp,Voltage Clamp Technic,Voltage Clamp Technics,Voltage Clamp Technique,Voltage Clamp Techniques,Whole Cell Recording,Whole-Cell Recordings