scholarly journals In Vitro Screening of Psychoactive Drugs by [35S]GTPγS Binding in Rat Brain Membranes

2007 ◽  
Vol 30 (12) ◽  
pp. 2328-2333 ◽  
Author(s):  
Ryouichi Nonaka ◽  
Fumiko Nagai ◽  
Akio Ogata ◽  
Kanako Satoh
Keyword(s):  
Rat Brain ◽  
Psychoactive Drugs ◽  
In Vitro Screening ◽  
Brain Membranes ◽  
Rat Brain Membranes ◽  
Gtpγs Binding

scholarly journals Inhibition of neural phospholipase D activity by aminoglycoside antibiotics

1991 ◽  
Vol 279 (1) ◽  
pp. 319-321 ◽  
Author(s):  
M Liscovitch ◽  
V Chalifa ◽  
M Danin ◽  
Y Eli
Keyword(s):  
Side Effects ◽  
Rat Brain ◽  
Phospholipase D ◽  
Aminoglycoside Antibiotics ◽  
Dependent Manner ◽  
Concentration Dependent Manner ◽  
Brain Membranes ◽  
Rat Brain Membranes ◽  
Isolated Rat

The effects of aminoglycoside antibiotics on phospholipase D (PLD) activity were investigated in permeabilized NG108-15 cells and in isolated rat brain membranes. Neomycin inhibited guanosine 5′-[gamma-thio]triphosphate-stimulated PLD activity in digitonin-permeabilized NG108-15 cells in a concentration-dependent manner (50% inhibition at 100 microM). Neomycin similarly inhibited PLD activity present in rat brain membranes and assayed in vitro with [3H]phosphatidylcholine as substrate (50% inhibition at 65 microM). Other aminoglycosides tested (kanamycin, geneticin and streptomycin) were nearly equipotent inhibitors of rat brain PLD. These results indicate that aminoglycoside antibiotics inhibit phosphatidylcholine-PLD activity with comparable and sometimes greater potency than their well known inhibition of phosphoinositide-phospholipase C. The possibility that PLD inhibition could mediate some of the toxic side effects of aminoglycosides is suggested.

Interaction of putative anxiolytic agents with central adenosine receptors

1981 ◽  
Vol 59 (8) ◽  
pp. 897-900 ◽  
Author(s):  
Michael Williams ◽  
Edwin A. Risley ◽  
Joel R. Huff
Keyword(s):  
Rat Brain ◽  
Adenosine Receptors ◽  
Molecular Mechanisms ◽  
Binding Assays ◽  
Receptor Level ◽  
Brain Membranes ◽  
Rat Brain Membranes ◽  
Adenosine Antagonist ◽  
Benzodiazepine Anxiolytics

The benzodiazepine anxiolytics flurazepam and diazepam and CL 218872, zopiclone and two β-carboline ethyl carboxyl esters, compounds which are potent displacers of specific [3H]diazepam binding from rat brain membranes, have little or no activity in displacing [3H]2-chloroadenosine ([3H]2-CADO) from central A1-adenosine receptors. Conversely, the purine agonists, 1-N6-phenylisopropyladenosine, N6-cyclohexyladenosine, 2-chloroadenosine. and the adenosine antagonist 8-phenyltheophylline have no significant effect on [3H]diazepam binding. Etazolate (SQ 20009) and Avermectin B1a which enhance [3H]diazepam binding in vitro were also without significant effect on [3H]2-CADO binding. The lack of correlation of the activities of the compounds examined in the two binding assays is discussed in relation to the hypothesis that purine-like compounds may be involved in the molecular mechanisms related to anxiolytic action at the receptor level.

Phosphorylation states of Cdc42 and RhoA regulate their interactions with Rho GDP dissociation inhibitor and their extraction from biological membranes

2002 ◽  
Vol 361 (2) ◽  
pp. 243-254 ◽  
Author(s):  
Marie-Annick FORGET ◽  
Richard R. DESROSIERS ◽  
Denis GINGRAS ◽  
Richard BÉLIVEAU
Keyword(s):  
Ionic Strength ◽  
Rat Brain ◽  
Small Gtpases ◽  
Rho Proteins ◽  
Yeast Saccharomyces Cerevisiae ◽  
Rhoa Activity ◽  
Brain Membranes ◽  
Rat Brain Membranes ◽  
Gdp Dissociation Inhibitor

The Rho GDP dissociation inhibitor (RhoGDI) regulates the activation—inactivation cycle of Rho small GTPases, such as Cdc42 and RhoA, by extracting them from the membrane. To study the roles of Mg2+, phosphatidylinositol 4,5-bisphosphate (PIP2), ionic strength and phosphorylation on the interactions of RhoGDI with Cdc42 and RhoA, we developed a new, efficient and reliable method to produce prenylated Rho proteins using the yeast Saccharomyces cerevisiae. It has been previously reported that protein kinase A (PKA)-treatment of isolated membranes increased RhoA extraction from membranes by RhoGDI [Lang, Gesbert, Delespine-Carmagnat, Stancou, Pouchelet and Bertoglio (1996) EMBO J. 16, 510–519]. In the present study, we used an in vitro affinity chromatography system to show that phosphorylation of RhoA and Cdc42 significantly increased their interaction with RhoGDI under physiological conditions of ionic strength. This increase was independent of the nucleotide (GDP or guanosine 5′-[γ-thio]triphosphate) loaded on to the Rho proteins, as well as of Mg2+ and PIP2. Moreover, dephosphorylation of rat brain membranes by alkaline phosphatase significantly decreased the extraction of RhoA and Cdc42 by RhoGDI. Subsequent re-phosphorylation by PKA restored the extraction levels, indicating the reversibility of this process. These results clearly demonstrate that the phosphorylation states of Cdc42 and RhoA regulate their interactions with RhoGDI and, consequently, their extraction from rat brain membranes. We therefore suggest that phosphorylation is a mechanism of regulation of Cdc42 and RhoA activity that is independent of GDP—GTP cycling.

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