Excitatory and inhibitory postsynaptic currents of the superior salivatory nucleus innervating the salivary glands and tongue in the rat.
The excitatory and inhibitory synaptic inputs to parasympathetic preganglionic neurons in the superior salivatory (SS) nucleus were investigated in brain slices of neonatal (4-8 days old) rat using the whole-cell patch-clamp technique. The SS neurons innervating the submandibular and sublingual salivary glands and innervating the lingual artery in the anterior region of the tongue were identified by retrograde transport of a fluorescent tracer. Whole-cell currents were evoked by electrical stimulation of tissue surrounding the cell. These evoked postsynaptic currents were completely abolished by antagonists for N-methyl-D-aspartate (NMDA) glutamate, non-NMDA glutamate, gamma-aminobutyric acid type A (GABAA), and glycine receptors, suggesting that SS neurons receive glutamatergic excitatory, and GABAergic and glycinergic inhibitory synaptic inputs. In SS neurons for the salivary glands, the ratio of the NMDA component to the total excitatory postsynaptic current (EPSC) was larger than that of the non-NMDA component. This profile was reversed in the SS neurons for the tongue. In SS neurons for the salivary glands, the ratio of the GABAA component to the total IPSC was larger than the ratio of the glycine component to total inhibitory postsynaptic current (IPSC). The decay time constants of the GABAA component were slower than those for glycine. These characteristics of the excitatory and inhibitory inputs may be involved in determining the firing properties of the SS neurons innervating the salivary glands and the tongue.
Mitoh
Yoshihiro
Y
Department of Oral Physiology, Okayama University Graduate School of Medicine and Dentistry, Shikata-cho, Okayama 700-8525, Japan. ymitoh@md.okayama-u.ac.jp
Funahashi
Makoto
M
Kobashi
Motoi
M
Matsuo
Ryuji
R
D000200:Action Potentials / Q000187:drug effects / Q000502:physiology; D000818:Animals; D000831:Animals, Newborn; D002814:Chorda Tympani Nerve / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D003712:Dendrites / Q000502:physiology / Q000648:ultrastructure; D004525:Efferent Pathways / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D019706:Excitatory Postsynaptic Potentials / Q000187:drug effects / Q000502:physiology; D005456:Fluorescent Dyes; D058787:GABA-A Receptor Antagonists; D009433:Neural Inhibition / Q000187:drug effects / Q000502:physiology; D010275:Parasympathetic Nervous System / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D018408:Patch-Clamp Techniques; D011149:Pons / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D011930:Reaction Time / Q000187:drug effects / Q000502:physiology; D011963:Receptors, GABA-A / Q000378:metabolism; D018009:Receptors, Glycine / Q000037:antagonists & inhibitors; D016194:Receptors, N-Methyl-D-Aspartate / Q000037:antagonists & inhibitors / Q000378:metabolism; D012469:Salivary Glands / Q000294:innervation* / Q000502:physiology; D009435:Synaptic Transmission / Q000187:drug effects / Q000502:physiology; D014059:Tongue / Q000294:innervation* / Q000502:physiology
D005456:Fluorescent Dyes; D058787:GABA-A Receptor Antagonists; D011963:Receptors, GABA-A; D018009:Receptors, Glycine; D016194:Receptors, N-Methyl-D-Aspartate