Biomaterial Database

Developmental changes in serotonergic receptor-mediated modulation of embryonic chick motoneurons in vitro. 1997

T Hayashi, and B Mendelson, and K D Phelan, and R D Skinner, and E Garcia-Rill

Department of Anatomy, University of Arkansas for Medical Sciences, Little Rock 72205-7199, USA.

Intracellular recordings were obtained from antidromically identified motoneurons in an embryonic chick spinal cord slice preparation at two developmental stages (embryonic days 12 and 18, E12 and E18) which bracket a critical period in spinal cord growth. The resting membrane potential of chick motoneurons did not change significantly between E12 and E18, but there was a significant decrease in neuronal input resistance. A small inward rectification was present in cells of both ages, although a lower proportion of E12 motoneurons exhibited inward rectification compared to E18 motoneurons. Injection of depolarizing current pulses revealed that most E12 motoneurons exhibited spike adaptation, while the majority of E18 motoneurons showed high frequency tonic firing. Bath application of serotonin (5-HT) and its agonists 5-carboxamido-tryptamine (5-CT, a 5-HT1 agonist) and alpha-methyl 5-HT (a 5-HT2 agonist) produced hyperpolarizing responses accompanied by decreased input resistance in all E12 motoneurons studied. The same three agonists produced depolarizing responses and increased input resistance in all E18 motoneurons studied. The effects of serotonergic agonists on motoneuronal excitability were tested using depolarizing current pulses. In most cases, serotonergic agonists caused a decrease in firing frequency during the hyperpolarizing response in E12 neurons. At E18, bath application of 5-HT, 5-CT or alpha-methyl 5-HT produced an increase in firing frequency in all motoneurons during the depolarizing response. Our results indicate that both 5-HT1 and 5-HT2 receptor subtypes contribute to modulation of chick motoneuron excitability and appear to reverse the polarity of their effects on membrane potential after a critical period in development of the spinal cord.

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
D009046	Motor Neurons	Neurons which activate MUSCLE CELLS.	Neurons, Motor,Alpha Motorneurons,Motoneurons,Motor Neurons, Alpha,Neurons, Alpha Motor,Alpha Motor Neuron,Alpha Motor Neurons,Alpha Motorneuron,Motoneuron,Motor Neuron,Motor Neuron, Alpha,Motorneuron, Alpha,Motorneurons, Alpha,Neuron, Alpha Motor,Neuron, Motor
D011985	Receptors, Serotonin	Cell-surface proteins that bind SEROTONIN and trigger intracellular changes which influence the behavior of cells. Several types of serotonin receptors have been recognized which differ in their pharmacology, molecular biology, and mode of action.	5-HT Receptor,5-HT Receptors,5-Hydroxytryptamine Receptor,5-Hydroxytryptamine Receptors,Receptors, Tryptamine,Serotonin Receptor,Serotonin Receptors,Tryptamine Receptor,Tryptamine Receptors,Receptors, 5-HT,Receptors, 5-Hydroxytryptamine,5 HT Receptor,5 HT Receptors,5 Hydroxytryptamine Receptor,5 Hydroxytryptamine Receptors,Receptor, 5-HT,Receptor, 5-Hydroxytryptamine,Receptor, Serotonin,Receptor, Tryptamine,Receptors, 5 HT,Receptors, 5 Hydroxytryptamine
D002642	Chick Embryo	The developmental entity of a fertilized chicken egg (ZYGOTE). The developmental process begins about 24 h before the egg is laid at the BLASTODISC, a small whitish spot on the surface of the EGG YOLK. After 21 days of incubation, the embryo is fully developed before hatching.	Embryo, Chick,Chick Embryos,Embryos, Chick
D000704	Analysis of Variance	A statistical technique that isolates and assesses the contributions of categorical independent variables to variation in the mean of a continuous dependent variable.	ANOVA,Analysis, Variance,Variance Analysis,Analyses, Variance,Variance Analyses
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
D012701	Serotonin	A biochemical messenger and regulator, synthesized from the essential amino acid L-TRYPTOPHAN. In humans it is found primarily in the central nervous system, gastrointestinal tract, and blood platelets. Serotonin mediates several important physiological functions including neurotransmission, gastrointestinal motility, hemostasis, and cardiovascular integrity. Multiple receptor families (RECEPTORS, SEROTONIN) explain the broad physiological actions and distribution of this biochemical mediator.	5-HT,5-Hydroxytryptamine,3-(2-Aminoethyl)-1H-indol-5-ol,Enteramine,Hippophaine,Hydroxytryptamine,5 Hydroxytryptamine
D017366	Serotonin Receptor Agonists	Endogenous compounds and drugs that bind to and activate SEROTONIN RECEPTORS. Many serotonin receptor agonists are used as ANTIDEPRESSANTS; ANXIOLYTICS; and in the treatment of MIGRAINE DISORDERS.	5-HT Agonists,5-Hydroxytryptamine Agonists,Serotonin Agonists,5-HT Agonist,5-Hydroxytrytamine Agonist,Receptor Agonists, Serotonin,Serotonergic Agonist,Serotonergic Agonists,Serotonin Agonist,Serotonin Receptor Agonist,5 HT Agonist,5 HT Agonists,5 Hydroxytryptamine Agonists,5 Hydroxytrytamine Agonist,Agonist, 5-HT,Agonist, 5-Hydroxytrytamine,Agonist, Serotonergic,Agonist, Serotonin,Agonist, Serotonin Receptor,Agonists, 5-HT,Agonists, 5-Hydroxytryptamine,Agonists, Serotonergic,Agonists, Serotonin,Agonists, Serotonin Receptor,Receptor Agonist, Serotonin
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