Biomaterial Database

Muscarinic receptors involved in the subthreshold cholinergic actions of neostriatal spiny neurons. 2002

Alejandra Figueroa, and Elvira Galarraga, and José Bargas

Dept. de Biofísica, Instituto de Fisiología Celular, UNAM, México City, D.F. México, 04510.

Administration of the peptide MT-1 (48 nM), a selective agonist of muscarinic M(1)-type receptors, mimicked the subthreshold actions of muscarine (1 microM) on neostriatal neurons, i.e., it produced a reduction in subthreshold inward rectification leading to an enhancement in input resistance (R(N)) and evoked discharge. In all recorded cells, MT-1 effects remained in the presence of the specific peptidergic antagonist of the M(4)-type receptor, MT-3 (10 nM), but were blocked by the specific M(1)-type receptor antagonist MT-7 (5 nM). These results suggest that most muscarinic facilitatory actions in the subthreshold voltage range occur through M(1)-type receptors. However, in a fraction of cells (40%) muscarine produced an excitability enhancement not blocked by MT-7. This additional facilitatory action, not present when using MT-1, was blocked by MT-3, suggesting it was mediated by M(4)-type receptor activation. This facilitation could not be blocked by Cs(+), TTX, or Cd(2+), but only by a reduction in extracellular sodium. This result is the first evidence that M(4)-type receptor activation enhances a cationic inward current in a fraction of neostriatal projection neurons.

UI	MeSH Term	Description	Entries
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
D009116	Muscarine	A toxic alkaloid found in Amanita muscaria (fly fungus) and other fungi of the Inocybe species. It is the first parasympathomimetic substance ever studied and causes profound parasympathetic activation that may end in convulsions and death. The specific antidote is atropine.
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
D011976	Receptors, Muscarinic	One of the two major classes of cholinergic receptors. Muscarinic receptors were originally defined by their preference for MUSCARINE over NICOTINE. There are several subtypes (usually M1, M2, M3....) that are characterized by their cellular actions, pharmacology, and molecular biology.	Muscarinic Acetylcholine Receptors,Muscarinic Receptors,Muscarinic Acetylcholine Receptor,Muscarinic Receptor,Acetylcholine Receptor, Muscarinic,Acetylcholine Receptors, Muscarinic,Receptor, Muscarinic,Receptor, Muscarinic Acetylcholine,Receptors, Muscarinic Acetylcholine
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
D017072	Neostriatum	The phylogenetically newer part of the CORPUS STRIATUM consisting of the CAUDATE NUCLEUS and PUTAMEN. It is often called simply the striatum.
D017208	Rats, Wistar	A strain of albino rat developed at the Wistar Institute that has spread widely at other institutions. This has markedly diluted the original strain.	Wistar Rat,Rat, Wistar,Wistar 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
D018721	Muscarinic Agonists	Drugs that bind to and activate muscarinic cholinergic receptors (RECEPTORS, MUSCARINIC). Muscarinic agonists are most commonly used when it is desirable to increase smooth muscle tone, especially in the GI tract, urinary bladder and the eye. They may also be used to reduce heart rate.	Cholinergic Agonists, Muscarinic,Cholinergic Agonist, Muscarinic,Cholinergic Muscarinic Agonists,Muscarinic Agonist,Agonist, Muscarinic,Agonist, Muscarinic Cholinergic,Agonists, Cholinergic Muscarinic,Agonists, Muscarinic,Agonists, Muscarinic Cholinergic,Muscarinic Agonists, Cholinergic,Muscarinic Cholinergic Agonist,Muscarinic Cholinergic Agonists
D066298	In Vitro Techniques	Methods to study reactions or processes taking place in an artificial environment outside the living organism.	In Vitro Test,In Vitro Testing,In Vitro Tests,In Vitro as Topic,In Vitro,In Vitro Technique,In Vitro Testings,Technique, In Vitro,Techniques, In Vitro,Test, In Vitro,Testing, In Vitro,Testings, In Vitro,Tests, In Vitro,Vitro Testing, In