Presynaptic inhibition by noradrenaline of the EPSC evoked in neonatal rat sympathetic preganglionic neurons
| Autor: | Haruo Kobayashi, Takefumi Miyazaki, Tsuneo Tosaka |
|---|---|
| Rok vydání: | 1998 |
| Předmět: |
medicine.medical_specialty
Patch-Clamp Techniques Voltage clamp Oxymetazoline Presynaptic Terminals Glutamic Acid Clonidine chemistry.chemical_compound Norepinephrine Phenylephrine Organ Culture Techniques Receptors Adrenergic alpha-2 Internal medicine medicine Prazosin Adrenergic alpha-2 Receptor Agonists Animals Patch clamp Reversal potential Molecular Biology Adrenergic alpha-Antagonists Chemistry musculoskeletal neural and ocular physiology General Neuroscience Excitatory Postsynaptic Potentials Bicuculline Adrenergic alpha-2 Receptor Antagonists Rats Endocrinology nervous system Animals Newborn Spinal Cord Anesthesia CNQX Excitatory postsynaptic potential Neurology (clinical) Adrenergic Fibers Idazoxan Adrenergic alpha-Agonists Developmental Biology medicine.drug |
| Zdroj: | Brain research. 790(1-2) |
| ISSN: | 0006-8993 |
| Popis: | Visually identified and electrophysiologically characterized sympathetic preganglionic neurons (SPNs) were recorded using the whole-cell voltage clamp technique in slices of neonatal rat spinal cord. Monosynaptic excitatory postsynaptic currents (EPSCs) were evoked by electrical stimulation of the nucleus intercalatus in the presence of strychnine (5 microM) and bicuculline (10 microM). These EPSCs were abolished by the antagonist of AMPA-type glutamate receptors, 6-cyano-7-nitro-quinoxaline-2,3-dione (CNQX; 10 microM). Bath applied noradrenaline (NA; 0.5-50 microM) dose-dependently and reversibly decreased by up to around 60% the amplitude of the EPSC, without affecting the holding current. The EPSC depression by NA was not accompanied by a change in EPSC reversal potential (around +5 mV), nor were inward currents generated by pressure application of glutamate affected by NA application. A comparable degree of EPSC depression was also seen with the alpha2-adrenoceptor agonist clonidine (5 microM), and the alpha2A-agonist oxymetazoline (5 microM), while the alpha1-agonist phenylephrine (100 microM) caused only a 22% depression. The EPSC depression caused by NA (10 microM) was completely antagonized by either the alpha-antagonist phentolamine (10 microM) or the alpha2-antagonist idazoxan (2 microM). Conversely, the beta-adrenoceptor antagonist popranolol (5 microM), and the alpha1-, alpha2B- and alpha2C-antagonist prazosin (2 microM) were without effect. These results indicate that activation of presynaptic alpha2A-adrenoceptors on inputs to SPNs decreases glutamate release. |
| Databáze: | OpenAIRE |
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