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.

Electrophysiological Properties of Cultured Neonatal Rat Dorsal Horn Neurons Containing GABA and Met-Enkephalin-Like Immunoreactivity

1998 ◽  
Vol 79 (3) ◽  
pp. 1583-1586 ◽  
Author(s):  
Y. H. Jo ◽  
M. E. Stoeckel ◽  
R. Schlichter
Keyword(s):  
Spinal Cord ◽  
Dorsal Horn ◽  
Spinal Cord Dorsal Horn ◽  
Neonatal Rat ◽  
Patch Clamp Technique ◽  
Membrane Hyperpolarization ◽  
Electrophysiological Properties ◽  
Dorsal Horn Neurons

Jo, Y. H., M. E. Stoeckel, and R. Schlichter. Electrophysiological properties of cultured neonatal rat dorsal horn neurons containing GABA and met-enkephalin-like immunoreactivity. J. Neurophysiol. 79: 1583–1586, 1998. We have developed a culture of neurons dissociated from the most superficial laminae of the neonatal rat spinal cord dorsal horn (DH). By using the perforated patch-clamp technique, we distinguished four types of neurons based on their firing properties in response to intracellular injection of 900 ms lasting current pulses. Type 1 neurons were characterized by a tonic firing. Type 2 neurons displayed marked spike accommodation and fired brief (<500 ms) bursts of action potentials, whereas type 3 neurons fired a single spike. Type 4 neurons exhibited different types of firing patterns, but all of them possessed a time-dependent inwardly rectifying current activated by membrane hyperpolarization. Met-enkephalin-like immunoreactivity (met-ENK-LI) and glutamic acid decarboxylase-like immunoreactivity (GAD-LI) were colocalized in 42% of the neurons ( n = 59), which were previously identified electrophysiologically. Type 1–4 neurons represented respectively 4, 64, 20, and 12% of the population of neurons colocalizing met-ENK-LI and GAD-LI. We conclude that the electrophysiological properties of DH neurons present in our cultures are similar to those described in acute slice or hemisected spinal cord preparations and that met-ENK-LI and GABA-LI are preferentially colocalized in type 2 neurons.

Local Anesthetic Inhibition of Voltage-activated Potassium Currents in Rat Dorsal Root Ganglion Neurons

2001 ◽  
Vol 94 (6) ◽  
pp. 1089-1095 ◽  
Author(s):  
Hirochika Komai ◽  
Thomas S. McDowell
Keyword(s):  
Dorsal Root Ganglion ◽  
Dorsal Horn ◽  
Local Anesthetic ◽  
Local Anesthetics ◽  
Dorsal Root ◽  
Drg Neurons ◽  
Dorsal Horn Neurons ◽  
K Currents

Background Local anesthetic actions on the K+ channels of dorsal root ganglion (DRG) and dorsal horn neurons may modulate sensory blockade during neuraxial anesthesia. In dorsal horn neurons, local anesthetics are known to inhibit transient but not sustained K+ currents. The authors characterized the effects of local anesthetics on K+ currents of isolated DRG neurons. Methods The effects of lidocaine, bupivacaine, and tetracaine on K+ currents in isolated rat DRG neurons were measured with use of a whole cell patch clamp method. The currents measured were fast-inactivating transient current (I(Af)), slow-inactivating transient current (I(As)), and noninactivating sustained current (I(Kn)). Results One group of cells (type 1) expressed I(Af) and I(Kn). The other group (type 2) expressed I(As) and I(Kn). The diameter of type 2 cells was smaller than that of type 1 cells. Lidocaine and bupivacaine inhibited all three K+ currents. Tetracaine inhibited I(As) and I(Kn) but not I(Af) For bupivacaine, the concentration for half-maximal inhibition (IC50) of I(Kn) in type 2 cells was lower than that for I(Kn) in type 1 cells (57 vs. 121 microM). Similar results were obtained for tetracaine (0.6 vs. 1.9 mM) and for lidocaine (2.2 vs. 5.1 mM). Conclusions Local anesthetics inhibited both transient and sustained K+ currents in DRG neurons. Because K+ current inhibition is known to potentiate local anesthetic-induced impulse inhibition, the lower IC50 for I(Kn) of small type 2 cells may reflect preferential inhibition of impulses in nociceptive neurons. The overall modulatory actions of local anesthetics probably are determined by their differential effects on presynaptic (DRG) and postsynaptic (dorsal horn neurons) K+ currents.

Membrane properties of deep dorsal horn neurons from neonatal rat spinal cord in vitro

1997 ◽  
Vol 767 (2) ◽  
pp. 214-219 ◽  
Author(s):  
Shawn Hochman ◽  
Sandra M Garraway ◽  
Susan Pockett
Keyword(s):  
Spinal Cord ◽  
Dorsal Horn ◽  
Neonatal Rat ◽  
Membrane Properties ◽  
Rat Spinal Cord ◽  
Dorsal Horn Neurons

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.

scholarly journals Effect of Different Fermentation Condition on Estimated Glycemic Index, In Vitro Starch Digestibility, and Textural and Sensory Properties of Sourdough Bread

Foods ◽  
2021 ◽  
Vol 10 (3) ◽  
pp. 514
Author(s):  
Hilal Demirkesen-Bicak ◽  
Muhammet Arici ◽  
Mustafa Yaman ◽  
Salih Karasu ◽  
Osman Sagdic
Keyword(s):  
Glycemic Index ◽  
Sensory Properties ◽  
Starch Digestibility ◽  
In Vitro Starch Digestibility ◽  
Whole Wheat ◽  
Sourdough Bread ◽  
Estimated Glycemic Index

This study aimed to evaluate the influence of sourdough fermentation on the estimated glycemic index (eGI), in vitro starch digestibility, and textural and sensory properties of eight experimentally prepared sourdough breads. Wheat and whole wheat flour bread samples were produced under different fermentation conditions (25 °C and 30 °C) and fermentation methods (type-1 and type-2). In type-1 fermentation, sourdough was obtained via spontaneous fermentation. Indigenous strains (Lactobacillus brevis ELB99, Lactiplantibacillus plantarum ELB75, and Saccharomyces cerevisiae TGM55) were used for type-2 fermentation. Fermentation type and temperature significantly affected eGI, the hydrolysis index (HI), the starch fraction, and the textural properties of the samples (p < 0.05). The resistant starch (RS) content increased after fermentation, while rapidly digestible starch (RDS), HI, and eGI decreased. RS values were significantly higher in type-2 than in type-1 at the same temperature for both flour types (p < 0.05). At 25 °C, RS values were higher in both fermentation types. In the white flour samples, eGI values were in the range of 60.8–78.94 and 62.10–78.94 for type-1 and type-2, respectively. The effect of fermentation type on eGI was insignificant (p < 0.05). In the whole flour samples, fermentation type and temperature significantly affected eGI (p < 0.05). The greatest eGI decreases were in whole wheat sourdough bread at 30 °C using type-2 (29.74%). The 30 °C and type-2 samples showed lower hardness and higher specific volume. This study suggests that fermentation type and temperature could affect the eGI and the textural and sensory properties of sourdough bread, and these factors should be considered during bread production. The findings also support the consumption of wheat and whole wheat breads produced by type-2 fermentation due to higher RS and slowly digestible starch (SDS) and lower RDS and eGI values.

scholarly journals First Report ofEurycoma longifoliaJack Root Extract Causing Relaxation of Aortic Rings in Rats

2016 ◽  
Vol 2016 ◽  
pp. 1-9 ◽  
Author(s):  
Bae Huey Tee ◽  
See Ziau Hoe ◽  
Swee Hung Cheah ◽  
Sau Kuen Lam
Keyword(s):  
Erectile Function ◽  
Receptor Activation ◽  
Root Extract ◽  
Ang Ii ◽  
Angiotensin I ◽  
Eurycoma Longifolia ◽  
Vasodilatory Effect

AlthoughEurycoma longifoliahas been studied for erectile function, the blood pressure- (BP-) lowering effect has yet to be verified. Hence, this study aims at investigating the BP-lowering properties of the plant with a view to develop an antihypertensive agent that could also preserve erectile function. Ethanolic root extract was partitioned by hexane, dichloromethane (DCM), ethyl acetate, butanol, and water. The DCM fraction, found to be potent in relaxing phenylephrine- (PE-) precontracted rat aortic rings, was further purified by column chromatography. Subfraction DCM-II, being the most active in relaxing aortae, was studied for effects on the renin-angiotensin and kallikrein-kinin systems in aortic rings. The effect of DCM-II on angiotensin-converting enzyme (ACE) activity was also evaluatedin vitro. Results showed that DCM-II reduced (p<0.05) the contractions evoked by angiotensin I and angiotensin II (Ang II). In PE-precontracted rings treated with DCM-II, the Ang II-induced contraction was attenuated (p<0.05) while bradykinin- (BK-) induced relaxation enhanced (p<0.001).In vitro, DCM-II inhibited (p<0.001) the activity of ACE. These data demonstrate that the vasodilatory effect of DCM-II appears to be mediatedviainhibition of Ang II type 1 receptor and ACE as well as enhancement of Ang II type 2 receptor activation and BK activity.

scholarly journals Differential Activation of CD8+Tumor-Specific Tc1 and Tc2 Cells by an IL-10-Producing Murine Plasmacytoma

1998 ◽  
Vol 6 (3-4) ◽  
pp. 331-342 ◽  
Author(s):  
Christoph Specht ◽  
Hans-Gerd Pauels ◽  
Christian Becker ◽  
Eckehart Kölsch
Keyword(s):  
T Cells ◽  
Immune Responses ◽  
Tumor Cells ◽  
T Cell Subsets ◽  
Early Stages ◽  
Specific Tolerance

The involvement of counteractiveCD8+T-cell subsets during tumor-specific immune responses was analyzed in a syngeneic murine plasmacytoma model.CD8+Tc cells against the immunogenic IL-10-producing BALB/c plasmacytoma ADJ-PC-5 can be easily induced by immunization of BALB/c mice with X-irradiated ADJ-PC-5 tumor cellsin vivoandin vitro. However, the failure of recipient mice to mount a protective Tc response against the tumor during early stages of a real or simulated tumor growth is not due to immunological ignorance, but depends on the induction of tumor-specific tolerance, involving a population of tumorinducedCD8+T cells that are able to inhibit the generation of tumor-specific Tc cells in a primary ADJ-PC-5-specific MLTC, using IFN-γas a suppressive factor. Whereas most longterm cultivated CD8+ADJ-PC-5-specific Tc lines produce type-1 cytokines on stimulation, at least two of them, which were derived from a primary MLTC, display a type-2 cytokine spectrum. Furthermore, the primaryin vitroTc response against ADJ-PC-5 cells shows characteristics of a Tc2 response. The Tc response is strictly depending on tumor-derived IL-10.CD8+Tc cells that are induced in a primary MLTC do not produce IFN-γ, and the tumor-specific Tc response is enhanced by IL-4 but suppressed by IFN-γor IL-12. In contrast, ADJ-PC- 5-specificCD8+Tc cells from immunized mice are IFN-γproducing Tc1 cells. Since the primaryin vitroTc response against the tumor is suppressed even by the smallest numbers of irradiated ADJ-PC-5-specific Tc1 cells via IFN-γthese Tc1 cells behave similar to the suppressiveCD8+T cells that are induced during early stages of ADJ-PC-5 tumorigenesis.

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