Cannabinoide und neurale Signalübertragung

2004 ◽  
Vol 50 (5) ◽  
pp. 297-308
Author(s):  
Ilka Wallmichrath ◽  
Bela Szabo
Keyword(s):  
Patch Clamp ◽  
G Protein ◽  
Präsynaptische Hemmung

<B>Fragestellung:</B> Der primäre Angriffspunkt von Cannabinoiden im Nervensystem ist der G-Protein gekoppelte CB1-Cannabinoidrezeptor. Er ist im zentralen und peripheren Nervensystem weit verbreitet. Unser Ziel war es, zu klären, wie Cannabinoide die synaptische Übertragung zwischen Neuronen beeinflussen. Die Rolle von endogenen Cannabinoiden (Endocannabinoiden) bei der synaptischen Übertragung wollten wir ebenfalls charakterisieren. </P><P> <B>Methodik:</B> Die Mehrzahl der Untersuchungen wurden mit elektrophysiologischen Methoden, insbesondere der Patch-Clamp-Technik, an Hirnschnitten durchgeführt. </P><P> <B>Ergebnisse:</B> Die am häufigsten beobachtete neuronale Wirkung von Cannabinoiden war die Hemmung der synaptischen Übertragung. Aktivierung von CB1-Rezeptoren hemmte die Freisetzung verschiedener Transmitter aus ihren präsynaptischen Axonterminalen. Auch Endocannabinoide, die im postsynaptischen Neuron synthetisiert wurden, hemmten die Transmitterfreisetzung aus dem präsynaptischen Axonterminal. </P><P> <B>Schlussfolgerungen:</B> Die präsynaptische Hemmung der Neurotransmitterfreisetzung durch Cannabinoide ist ubiquitär im Nervensystem. Eine neue Form der Kommunikation zwischen Neuronen ist die Hemmung der Neurotransmission durch Endocannabionoide, die aus dem postsynaptischen Neuron freigesetzt werden.

scholarly journals Activation of G protein-coupled estrogen receptor induces endothelium-independent relaxation of coronary artery smooth muscle

2011 ◽  
Vol 301 (5) ◽  
pp. E882-E888 ◽  
Author(s):  
Xuan Yu ◽  
Handong Ma ◽  
Scott A. Barman ◽  
Alexander T. Liu ◽  
Minga Sellers ◽  
...  
Keyword(s):  
Estrogen Receptor ◽  
Smooth Muscle ◽  
Coronary Artery ◽  
Patch Clamp ◽  
G Protein ◽  
Coronary Arteries ◽  
Rt Pcr ◽  
Potassium Efflux ◽  
G Protein Coupled

Estrogens can either relax or contract arteries via rapid, nongenomic mechanisms involving classic estrogen receptors (ER). In addition to ERα and ERβ, estrogen may also stimulate G protein-coupled estrogen receptor 1 (GPER) in nonvascular tissue; however, a potential role for GPER in coronary arteries is unclear. The purpose of this study was to determine how GPER activity influenced coronary artery reactivity. In vitro isometric force recordings were performed on endothelium-denuded porcine arteries. These studies were augmented by RT-PCR and single-cell patch-clamp experiments. RT-PCR and immunoblot studies confirmed expression of GPER mRNA and protein, respectively, in smooth muscle from either porcine or human coronary arteries. G-1, a selective GPER agonist, produced a concentration-dependent relaxation of endothelium-denuded porcine coronary arteries in vitro. This response was attenuated by G15, a GPER-selective antagonist, or by inhibiting large-conductance calcium-activated potassium (BKCa) channels with iberiotoxin, but not by inhibiting NO signaling. Last, single-channel patch-clamp studies demonstrated that G-1 stimulates BKCa channel activity in intact smooth muscle cells from either porcine or human coronary arteries but had no effect on channels isolated in excised membrane patches. In summary, GPER activation relaxes coronary artery smooth muscle by increasing potassium efflux via BKCa channels and requires an intact cellular signaling mechanism. This novel action of estrogen-like compounds may help clarify some of the controversy surrounding the vascular effects of estrogens.

Diverse Signal Transduction Pathways Mediated by Endogenous P2 Receptors in Cultured Rat Cerebral Cortical Neurons

1998 ◽  
Vol 79 (5) ◽  
pp. 2513-2521 ◽  
Author(s):  
Tomoyuki Nishizaki ◽  
Masahiro Mori
Keyword(s):  
Signal Transduction ◽  
Patch Clamp ◽  
Phospholipase C ◽  
G Protein ◽  
Cortical Neurons ◽  
Single Channel ◽  
Signal Transduction Pathways ◽  
Cerebral Cortical Neurons ◽  
Single Channel Currents ◽  
Channel Currents

Nishizaki, Tomoyuki and Masahiro Mori. Diverse signal transduction pathways mediated by endogenous P2 receptors in cultured rat cerebral cortical neurons. J. Neurophysiol. 79: 2513–2521, 1998. The present study was conducted to assess the intracellular signaling pathways mediated by receptors for ATP, uridine triphosphate (UTP), and 2-methylthio ATP (2-MeSATP), by monitoring patch-clamp currents and intracellular calcium mobilization in cultured rat cortical cerebral neurons. All three agonists evoked potassium currents and increased the intracellular free Ca2+ concentration ([Ca2+]i), and these effects were inhibited by the broad G-protein inhibitor guanosine-5′- O-(2-thiodiphosphate) (GDPβS) but not by the Gi/o-protein inhibitor pertussis toxin (PTX). UTP-evoked currents were inhibited by either the phospholipase C inhibitor neomycin or the selective protein kinase C (PKC) inhibitor GF109203X, and the rise in cytosolic Ca2+ was inhibited by either neomycin or the inositol 1,4,5-trisphosphate (IP3) receptor antagonist heparin, indicating that the UTP receptor involved phospholipase C-mediated phosphatidylinositol signaling. In contrast, 2-MeSATP–induced currents and rise in cytosolic Ca2+ were not inhibited by either neomycin, or GF109203X, or heparin. 2-MeSATP elicited single-channel currents in the cell-attached patch-clamp configuration and also in excised patches. The G-protein activator GTPγS induced single-channel currents in a fashion that mimicked the effect of 2-MeSATP. These data suggest that 2 MeSATP activated potassium channels by a direct action of G-protein βγ subunits and increased [Ca2+]i by a mechanism independent of phospholipase C stimulation and IP3 production. ATP-evoked currents were partially inhibited by either neomycin or GF109203X, although the rise in cytosolic Ca2+ was not affected by these inhibitors. ATP produced single-channel currents with two major classes of the slope conductance (86 and 95 pS) in cell-attached patches, each of which is consistent with that achieved by 2-MeSATP (85 pS) or UTP (96 pS); the currents with the lower conductance were observed in the outside-out patch-clamp configuration. These results indicate that P2 receptors for UTP and 2-MeSATP are linked to a PTX-insensitive G-protein involving different signal transduction pathways and that ATP responses are mediated by both of these P2 receptors.

Formation and Structure of Casein Micelles in Lactating Mammary Tissue

1970 ◽  
Vol 28 ◽  
pp. 150-151
Author(s):  
Robert J. Carroll ◽  
Marvin P. Thompson ◽  
Harold M. Farrell
Keyword(s):  
Size Distribution ◽  
G Protein ◽  
Milk Proteins ◽  
Mammary Tissue ◽  
Colloidal System ◽  
Casein Micelles ◽  
The Stability

Milk is an unusually stable colloidal system; the stability of this system is due primarily to the formation of micelles by the major milk proteins, the caseins. Numerous models for the structure of casein micelles have been proposed; these models have been formulated on the basis of in vitro studies. Synthetic casein micelles (i.e., those formed by mixing the purified αsl- and k-caseins with Ca2+ in appropriate ratios) are dissimilar to those from freshly-drawn milks in (i) size distribution, (ii) ratio of Ca/P, and (iii) solvation (g. water/g. protein). Evidently, in vivo organization of the caseins into the micellar form occurs in-a manner which is not identical to the in vitro mode of formation.

High-voltage electron microscopy of patch-clamped membranes

1987 ◽  
Vol 45 ◽  
pp. 582-583
Author(s):  
F. Sachs ◽  
M. J. Song
Keyword(s):  
Electron Microscopy ◽  
Cell Membrane ◽  
Patch Clamp ◽  
High Voltage Electron Microscopy ◽  
Small Patch ◽  
Cellular Electrophysiology ◽  
Voltage Electron ◽  
Electron Microscopes ◽  
Patch Technique ◽  
Membrane Patch

Cellular electrophysiology has been revolutionized by the introduction of patch clamp techniques. The patch clamp records current from a small patch of the cell membrane which has been sucked into a glass pipette. The membrane patch, a few micons in diameter, is attached to the glass by a seal which is electrically, diffusionally and mechanically tight. Because of the tight electrical seal, the noise level is low enough to record the activity of single ion channels over a time scale extending from 10μs to days. However, although the patch technique is over ten years old, the patch structure is unknown. The patch is inside a glass pipette where it has been impossible to see with standard electron microscopes. We show here that at 1 Mev the glass pipette is transparent and the membrane within can be seen with a resolution of about 30 A.

Measurement of spontaneous neuronal membrane activity by time lapse confocal microscopy

1995 ◽  
Vol 53 ◽  
pp. 972-973
Author(s):  
R H. Selinfreund ◽  
A. H. Cornell-Bell
Keyword(s):  
Membrane Potential ◽  
Confocal Microscopy ◽  
Patch Clamp ◽  
Electrical Activity ◽  
Time Lapse ◽  
Neuronal Firing ◽  
Neuronal Membrane ◽  
Pituitary Cells ◽  
Patch Clamp Recording ◽  
Spontaneous Electrical Activity

Cellular electrophysiological properties are normally monitored by standard patch clamp techniques . The combination of membrane potential dyes with time-lapse laser confocal microscopy provides a more direct, least destructive rapid method for monitoring changes in neuronal electrical activity. Using membrane potential dyes we found that spontaneous action potential firing can be detected using time-lapse confocal microscopy. Initially, patch clamp recording techniques were used to verify spontaneous electrical activity in GH4\C1 pituitary cells. It was found that serum depleted cells had reduced spontaneous electrical activity. Brief exposure to the serum derived growth factor, IGF-1, reconstituted electrical activity. We have examined the possibility of developing a rapid fluorescent assay to measure neuronal activity using membrane potential dyes. This neuronal regeneration assay has been adapted to run on a confocal microscope. Quantitative fluorescence is then used to measure a compounds ability to regenerate neuronal firing.The membrane potential dye di-8-ANEPPS was selected for these experiments. Di-8- ANEPPS is internalized slowly, has a high signal to noise ratio (40:1), has a linear fluorescent response to change in voltage.

A compendium of G-protein–coupled receptors and cyclic nucleotide regulation of adipose tissue metabolism and energy expenditure

2020 ◽  
Vol 134 (5) ◽  
pp. 473-512 ◽  
Author(s):  
Ryan P. Ceddia ◽  
Sheila Collins
Keyword(s):  
Adipose Tissue ◽  
Energy Expenditure ◽  
Signaling Pathways ◽  
G Protein ◽  
Uncoupling Protein ◽  
Beige Adipocytes ◽  
Nucleotide Regulation ◽  
Ucp1 Expression ◽  
Thermogenic Adipocytes ◽  
G Protein Coupled

Abstract With the ever-increasing burden of obesity and Type 2 diabetes, it is generally acknowledged that there remains a need for developing new therapeutics. One potential mechanism to combat obesity is to raise energy expenditure via increasing the amount of uncoupled respiration from the mitochondria-rich brown and beige adipocytes. With the recent appreciation of thermogenic adipocytes in humans, much effort is being made to elucidate the signaling pathways that regulate the browning of adipose tissue. In this review, we focus on the ligand–receptor signaling pathways that influence the cyclic nucleotides, cAMP and cGMP, in adipocytes. We chose to focus on G-protein–coupled receptor (GPCR), guanylyl cyclase and phosphodiesterase regulation of adipocytes because they are the targets of a large proportion of all currently available therapeutics. Furthermore, there is a large overlap in their signaling pathways, as signaling events that raise cAMP or cGMP generally increase adipocyte lipolysis and cause changes that are commonly referred to as browning: increasing mitochondrial biogenesis, uncoupling protein 1 (UCP1) expression and respiration.

Transferrin-induced endocytosis in stably transfected HeLa cells expressing wild-type and C282Y-mutant HFE measured by patch-clamp capacitance techniques

2001 ◽  
Vol 120 (5) ◽  
pp. A564-A565
Author(s):  
L SCHWAKE ◽  
A HENKEL ◽  
H RIEDEL ◽  
B HADASCHIK ◽  
T SCHLENKER ◽  
...  
Keyword(s):  
Patch Clamp ◽  
Hela Cells ◽  
Wild Type
Sign in / Sign up

Export Citation Format

Share Document