Excitatory Synaptic Currents in Lumbosacral Parasympathetic Preganglionic Neurons Elicited From the Lateral Funiculus

2001 ◽  
Vol 86 (4) ◽  
pp. 1587-1593 ◽  
Author(s):  
Akira Miura ◽  
Masahito Kawatani ◽  
William C. de Groat
Keyword(s):  
Electrical Stimulation ◽  
Slow Component ◽  
Negative Slope ◽  
Slow Inward Current ◽  
Patch Clamp Recording ◽  
Lateral Funiculus ◽  
Preganglionic Neurons ◽  
Stimulation Of

Excitatory postsynaptic currents (EPSCs) in parasympathetic preganglionic neurons (PGNs) were examined using the whole cell patch-clamp recording technique in L6 and S1 spinal cord slices from neonatal rats (6–16 days old). PGNs were identified by labeling with retrograde axonal transport of a fluorescent dye (Fast Blue) injected into the intraperitoneal space 3–7 days before the experiment. Synaptic responses were evoked in PGNs by field stimulation of the lateral funiculus (LF) in the presence of bicuculline methiodide (10 μM) and strychnine (1 μM). In approximately 40% of the cells (total, 100), single-shock electrical stimulation of the LF elicited short, relatively constant latency [3.0 ± 0.1 (SE) ms] fast EPSCs consistent with a monosynaptic pathway. The remainder of the cells did not respond to stimulation. At low intensities of stimulation, the EPSCs often occurred in an all-or-none manner, indicating that they were mediated by a single axonal input. Most cells ( n = 33) exhibited only fast EPSCs (type 1), but some cells ( n = 8) had fast EPSCs with longer, more variable latency polysynaptic EPSCs superimposed on a slow inward current (type 2). Type 1 fast synaptic EPSCs were pharmacologically dissected into two components: a transient component that was blocked by 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX, 5 μM), a non-NMDA glutamatergic antagonist, and a slow decaying component that was blocked by 2-amino-5-phosphonovalerate (APV, 50 μM), a NMDA antagonist. Type 2 polysynaptic currents were reduced by 5 μM CNQX and completely blocked by combined application of 5 μM CNQX and 50 μM APV. The fast monosynaptic component of type 1 EPSCs had a linear current-voltage relationship and reversed at a membrane potential of 5.0 ± 5.9 mV ( n = 5), whereas the slow component exhibited a negative slope conductance at holding potentials greater than −20 mV. The type 1, fast synaptic EPSCs had a time to peak of 1.4 ± 0.1 ms and exhibited a biexponential decay (time constants, 5.7 ± 0.6 and 38.8 ± 4.0 ms). In the majority of PGNs ( n = 11 of 15 cells), EPSCs evoked by electrical stimulation of LF exhibited paired-pulse inhibition (range; 25–33% depression) at interstimulus intervals ranging from 50 to 120 ms. These results indicate that PGNs receive monosynaptic and polysynaptic glutamatergic excitatory inputs from axons in the lateral funiculus.

Glutamate-mediated slow synaptic currents in neonatal rat deep dorsal horn neurons in vitro

1996 ◽  
Vol 76 (3) ◽  
pp. 1465-1476 ◽  
Author(s):  
B. A. Miller ◽  
C. J. Woolf
Keyword(s):  
Dorsal Horn ◽  
Slow Component ◽  
Small Diameter ◽  
Primary Afferents ◽  
Neonatal Rat ◽  
Dorsal Horn Neurons ◽  
Stimulation Of

1. The role of glutamate in slow excitatory synaptic transmission between small-diameter primary afferents and deep dorsal horn neurons was examined in neonatal rat spinal cord in vitro with the use of the whole cell voltage-clamp technique. 2. Single-shock electrical stimulation of large-diameter A beta-fibers evoked a short-latency (< 10 ms) fast (< 500 ms) excitatory postsynaptic current (EPSC). Stimulation of small-diameter A delta- and C fibers resulted, in addition, in a slowly rising and decaying EPSC (lasting up to 14 s) following the fast EPSC. The slow EPSC was never observed with stimulation of A beta-fibers. 3. Two patterns of EPSCs were observed, "type 1" and "type 2," which differed in their time course (lasting up to 1 and 14 s, respectively). The type 1 response was biphasic, with a fast monosynaptic component followed by an invariant, presumably monosynaptic, late slow component. The type 2 response was multiphasic, with a fast monosynaptic component followed by a slow component composed of fast polysynaptic currents superimposed on a slow current. 4. The fast monosynaptic component had a linear conductance, whereas the late slower component of the A beta-fiber-evoked response had a negative slope conductance at holding potentials more negative than -23 mV. Both currents reversed at a membrane potential of -1.2 +/- 2.8 (SE) mV. 5. With the use of selective non-N-methyl-D-aspartate (non-NMDA) and NMDA receptor antagonists [6-cyano-7-nitroquinox-aline-2,3-dione (CNQX) or 2,3-dihydroxy-6-nitro-7-sulphamoyl-benzo (F) quinoxaline and D(-)-2-amino-5-phosphonopentanoic acid (D-AP5), respectively] we showed that both the early fast (A beta-fiber evoked) and the late slow (A delta- and C fiber evoked) components were mediated by non-NMDA and NMDA receptors. CNQX suppressed both the early fast and late slow components of the compound EPSC, whereas D-AP5 suppressed the polysynaptic currents of the early fast component and the late slow component without significantly affecting the early fast monosynaptic component. 6. Slow EPSCs summated on low-frequency (1 or 10 Hz), repetitive stimulation and produced long-duration "tail" currents on cessation of the stimulus. The amount of temporal summation was proportional to the duration of the slow EPSC and the frequency of stimulation. 7. Our results suggest that slow ionotropic-glutamate-receptor-mediated EPSCs produced by the stimulation of small-diameter primary afferents play an important role in activity-dependent synaptic plasticity in the dorsal horn.

scholarly journals Differential expression and regulation of ryanodine receptor and myo-inositol 1,4,5-trisphosphate receptor Ca2+ release channels in mammalian tissues and cell lines

1997 ◽  
Vol 327 (1) ◽  
pp. 251-258 ◽  
Author(s):  
John J. MACKRILL ◽  
R. A. John CHALLISS ◽  
D. A. O'CONNELL ◽  
F. Anthony LAI ◽  
Stefan R. NAHORSKI
Keyword(s):  
Cell Lines ◽  
Mammalian Cell ◽  
Release Channel ◽  
Chronic Stimulation ◽  
Channel Proteins ◽  
Mammalian Cell Lines ◽  
Rabbit Tissues ◽  
Stimulation Of

Ryanodine receptors (RyRs) and Ins(1,4,5)P3 receptors (Ins(1,4,5)P3Rs) represent two multigene families of channel proteins that mediate the release of Ca2+ ions from intracellular stores. In the present study, the expression patterns of these channel proteins in mammalian cell lines and tissues were investigated by using isoform-specific antibodies. All cell lines examined expressed two or more Ins(1,4,5)P3R isoforms, with the type 1 Ins(1,4,5)P3R being ubiquitous. RyR isoforms were detected in only six out of eight cell lines studied. Similarly, of the nine rabbit tissues examined, RyR protein expression was detected only in brain, heart, skeletal muscle and uterus. Specific [3H]ryanodine binding was found in a number of rabbit tissues, although it was not detected in mammalian cell lines. Subcellular fractionation of SH-SY5Y human neuroblastomas revealed that the type 2 RyR and type 1 Ins(1,4,5)P3R co-localize among the fractions of a sucrose-cushion separation of crude microsomal membrane fractions. Manipulation of SH-SY5Y cells by chronic stimulation of muscarinic acetylcholine receptor (mAChR) results in a decrease in their type 1 Ins(1,4,5)P3R levels but not in the abundance of the type 2 RyR. Differentiation of these neuroblastomas by using retinoic acid did not detectably alter their expression of Ca2+-release channel proteins. Finally, differentiation of BC3H1 cells affects the expression of their Ca2+-release channel proteins in an isoform-specific manner. In summary, this study demonstrates that mammalian cell lines display distinct patterns of Ca2+-release channel protein expression. The abundance of these proteins is differentially regulated during phenotypic modifications of a cell, such as differentiation or chronic stimulation of mAChR.

scholarly journals Medullary raphe nuclei activate the lumbosacral defecation center through the descending serotonergic pathway to regulate colorectal motility in rats

2018 ◽  
Vol 314 (3) ◽  
pp. G341-G348 ◽  
Author(s):  
Hiroyuki Nakamori ◽  
Kiyotada Naitou ◽  
Yuuki Horii ◽  
Hiroki Shimaoka ◽  
Kazuhiro Horii ◽  
...  
Keyword(s):  
Spinal Cord ◽  
Electrical Stimulation ◽  
Raphe Nuclei ◽  
Lumbosacral Spinal Cord ◽  
Pelvic Nerves ◽  
Medullary Raphe ◽  
Raphé Nuclei ◽  
Type 3 ◽  
Stimulation Of

Colorectal motility is regulated by two defecation centers located in the brain and spinal cord. In previous studies, we have shown that administration of serotonin (5-HT) in the lumbosacral spinal cord causes enhancement of colorectal motility. Because spinal 5-HT is derived from neurons of the medullary raphe nuclei, including the raphe magnus, raphe obscurus, and raphe pallidus, we examined whether stimulation of the medullary raphe nuclei enhances colorectal motility via the lumbosacral defecation center. Colorectal pressure was recorded with a balloon in vivo in anesthetized rats. Electrical stimulation of the medullary raphe nuclei failed to enhance colorectal motility. Because GABAergic neurons can be simultaneously activated by the raphe stimulation and released GABA masks accelerating actions of the raphe nuclei on the lumbosacral defecation center, a GABAA receptor antagonist was preinjected intrathecally to manifest excitatory responses. When spinal GABAA receptors were blocked by the antagonist, electrical stimulation of the medullary raphe nuclei increased colorectal contractions. This effect of the raphe nuclei was inhibited by intrathecal injection of 5-hydroxytryptamine type 2 (5-HT2) and type 3 (5-HT3) receptor antagonists. In addition, injection of a selective 5-HT reuptake inhibitor in the lumbosacral spinal cord augmented the raphe stimulation-induced enhancement of colorectal motility. Transection of the pelvic nerves, but not transection of the colonic nerves, prevented the effect of the raphe nuclei on colorectal motility. These results demonstrate that activation of the medullary raphe nuclei causes augmented contractions of the colorectum via 5-HT2 and 5-HT3 receptors in the lumbosacral defecation center. NEW & NOTEWORTHY We have shown that electrical stimulation of the medullary raphe nuclei causes augmented contractions of the colorectum via pelvic nerves in rats. The effect of the medullary raphe nuclei on colorectal motility is exerted through activation of 5-hydroxytryptamine type 2 and type 3 receptors in the lumbosacral defecation center. The descending serotoninergic raphespinal tract represents new potential therapeutic targets against colorectal dysmotility such as irritable bowel syndrome.

Excitatory Synaptic Currents in Lumbosacral Parasympathetic Preganglionic Neurons Evoked by Stimulation of the Dorsal Commissure

2003 ◽  
Vol 89 (1) ◽  
pp. 382-389 ◽  
Author(s):  
Akira Miura ◽  
Masahito Kawatani ◽  
William C. De Groat
Keyword(s):  
Time Constant ◽  
Decay Time ◽  
Fast Component ◽  
Time To Peak ◽  
Current Voltage ◽  
Current Voltage Relationship ◽  
Voltage Relationship ◽  
Stimulation Of

Excitatory pathways from the dorsal commissure (DCM) to L6–S1 parasympathetic preganglionic neurons (PGN) were examined using whole-cell patch-clamp recording techniques in spinal cord slices from neonatal rats. PGN were identified by retrograde axonal transport of a fluorescent dye injected into the intraperitoneal space. Excitatory postsynaptic currents (EPSCs) were evoked in PGN by stimulation of DCM in the presence of bicuculline methiodide (10 μM) and strychnine (1 μM) to block inhibitory pathways. Electrical stimulation of DCM evoked two types of inward currents. In the majority of PGN ( n = 66), currents (mean amplitude, 47.9 ± 4.7 pA) occurred at a short and relatively constant latency (3.8 ± 0.1 ms) and presumably represent monosynaptic EPSCs (Type 1). However, in other neurons ( n = 20), a different type of EPSC (Type 2) was noted, consisting of a fast monosynaptic component followed by a prolonged inward current with superimposed fast transients presumably representing excitatory inputs mediated by polysynaptic pathways. Type 1 EPSCs were pharmacologically dissected into two components. A fast component was blocked by 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX, 5μM) and a slowly decaying component was blocked by 2-amino-5-phosphonovalerate (APV, 50 μM). The fast component of Type 1 EPSCs had a linear current-voltage relationship and reversed at a membrane potential of −7.6 ± 1.3 mV ( n = 5). The fast component of Type 2 EPSCs was also blocked by 5 μM CNQX and the remaining slower component was blocked by 50 μM APV. When the DCM was stimulated in the presence of 50 μM APV, the time to peak and decay time constant in Type 1 EPSCs were 1.9 ± 0.2 and 4.1 ± 0.8 ms, respectively. Examination of the NMDA receptor-mediated component of the EPSCs in the presence of 5 μM CNQX revealed a current-voltage relationship that had a region of negative slope conductance (from −20 to −80 mV), which was abolished in Mg2+-free external solution. The time to peak and decay time constant of this component were 14.2 ± 2.0 and 91.0 ± 12.4 ms, respectively. Type 1 EPSCs in some PGN responded in an all-or-none manner and presumably represented unitary synaptic responses; whereas Type 2 EPSCs always exhibited a graded stimulus intensity–response relationship. Paired-pulse facilitation (50-ms interstimulus intervals; 141 ± 5.6% increase, n = 8) of EPSCs was observed. These results indicate that PGN receive monosynaptic and polysynaptic glutamatergic excitatory inputs from neurons and/or axonal pathways in the DCM.

Synaptic inputs to morphologically identified myenteric neurons in guinea pig rectum from pelvic nerves

1997 ◽  
Vol 273 (1) ◽  
pp. G49-G55 ◽  
Author(s):  
K. Tamura
Keyword(s):  
Morphological Characteristics ◽  
Pelvic Nerve ◽  
Low Frequencies ◽  
Myenteric Neurons ◽  
Synaptic Inputs ◽  
Pelvic Nerves ◽  
Single Spike ◽  
Stimulation Of

Neurobiotin-filled microelectrodes were used to investigate electrical and synaptic behavior and morphological characteristics of rectal myenteric neurons that received synaptic inputs from the pelvic nerves. Stimulation of the pelvic nerve at low frequencies (< 3.3 Hz) evoked nicotinic fast excitatory postsynaptic potentials (fast EPSPs) in 45.3% of rectal neurons. Pelvic fast EPSPs were found in S/type 1, AH/type 2, type 3, or single-spike neurons that had a single long process preferentially projecting in the orad direction. Stimulation of the pelvic nerve at higher frequencies (5–20 Hz) elicited slow membrane excitation in 13.9% of the neurons. They were either AH/type 2 neurons with Dogiel II morphology or S/type 1 neurons with a single long process. Hexamethonium (100 microM) blocked pelvic fast EPSPs more quickly than those evoked by fiber tract stimulation but did not affect slow excitatory response. The results suggested the presence of more than one nicotinic-cholinergic synapse in the pelvic nerve pathway and the possible release of a noncholinergic excitatory substance from the afferent nerve terminals. It is possible that a subpopulation of rectal neurons, which receive a fast EPSP and have a single long process that projects in the orad direction, might be interneurons that mediate the defecation reflex.

Hyperinsulinaemia is Associated with Stimulation of Cholesterol Synthesis in Both Type 1 and Type 2 Diabetes

1993 ◽  
Vol 10 (5) ◽  
pp. 412-419 ◽  
Author(s):  
J.C. Stinson ◽  
D. Owens ◽  
P. Collins ◽  
A. Johnson ◽  
G.H. Tomkin
Keyword(s):  
Type 2 Diabetes ◽  
Cholesterol Synthesis ◽  
Stimulation Of

Electrophysiological study on the effects of leptin in rat dorsal motor nucleus of the vagus

2007 ◽  
Vol 292 (6) ◽  
pp. R2136-R2143 ◽  
Author(s):  
Tzu-Ling Li ◽  
Lih-Chu Chiou ◽  
You Shuei Lin ◽  
Jing-Ru Hsieh ◽  
Ling-Ling Hwang
Keyword(s):  
Potassium Conductance ◽  
Reversal Potential ◽  
Negative Slope ◽  
Motor Nucleus ◽  
Neonatal Rats ◽  
Patch Clamp Recording ◽  
Central Target ◽  
Preganglionic Neurons ◽  
Dorsal Motor Nucleus ◽  
Outward Currents

Immunoreactivity of leptin receptor (Ob-R) has been detected in rat dorsal motor nucleus of the vagus (DMNV). Here, we confirmed the presence of Ob-R immunoreactivity on retrograde-labeled parasympathetic preganglionic neurons in the DMNV of neonatal rats. The present study investigated the effects of leptin on DMNV neurons, including parasympathetic preganglionic neurons, by using whole cell patch-clamp recording technique in brain stem slices of neonatal rats. Leptin (30–300 nM) induced membrane depolarization and hyperpolarization, respectively, in 14 and 15 out of 80 DMNV neurons tested. Both leptin-induced inward and outward currents persisted in the presence of TTX, indicating that leptin affected DNMV neurons postsynaptically. The current-voltage (I–V) curve of leptin-induced inward currents is characterized by negative slope conductance and has an average reversal potential of −90 ± 3 mV. The reversal potential of the leptin-induced inward current was shifted to a more positive potential level in a high-potassium medium. These results indicate that a decrease in potassium conductance is likely the main ionic mechanism underlying the leptin-induced depolarization. On the other hand, the I–V curve of leptin-induced outward currents is characterized by positive slope conductance and has an average reversal potential of −88 ± 3 mV, suggesting that an increase in potassium conductance may underlie leptin-induced hyperpolarization. Most of the leptin-responsive DMNV neurons were identified as being parasympathetic preganglionic neurons. These results suggest that the DMNV is one of the central target sites of leptin, and leptin can regulate parasympathetic outflow from the DMNV by directly acting on the parasympathetic preganglionic neurons of the DMNV.

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