Jorge N. Larocca

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The methods used to prepare myelin involve homogenization of the tissue in isotonic sucrose solution, followed by the isolation of myelin membranes by a series of steps that include density gradient centrifugation and differential centrifugation. Homogenization of nervous tissue in isotonic sucrose causes the myelin sheath to peel from the axon and form(More)
Oligodendrocytes, the myelin-producing cells of the central nervous system, express muscarinic acetylcholine receptors (mAChR). Activation of this neurotransmitter receptor by the stable acetylcholine analog carbachol (CCh) triggers transducing events, modulating c-fos expression and cellular proliferation. To elucidate the signal transduction pathways(More)
Intracellular membrane trafficking plays an essential role in the biogenesis and maintenance of myelin. Members of the Rab protein family are important components of the systems that regulate intracellular vesicle transport. We examine the function of rRab22b, a novel rat Rab protein cloned from an oligodendrocyte cDNA library, by visualizing and(More)
Vesicle transport plays an important role in the formation of myelin. Transport of proteins, including proteolipid protein and myelin associated glycoprotein, from their site of synthesis in the endoplasmic reticulum in the perikaryon of the oligodendrocytes, to myelin, takes place via carrier vesicles. The mechanisms that regulate vesicle transport in(More)
Intracellular membrane trafficking plays an essential role in the structural and functional organization of oligodendrocytes, which synthesize a large amount of membrane to form myelin. Rab proteins are key components in intracellular vesicular transport. We cloned a novel Rab protein from an oligodendrocyte cDNA library, designating it Rab40c because of(More)
This study focused on the molecular and pharmacological characterization of muscarinic acetylcholine receptors expressed by progenitors and differentiated oligodendrocytes. We also analyzed the role of muscarinic receptors in regulating downstream signal transduction pathways and the functional significance of receptor expression in oligodendrocytes. RT-PCR(More)
In examining the signaling transduction pathway of adrenoceptors in oligodendrocyte progenitors, we have found that stimulation of alpha(1)-adrenoceptors with norepinephrine (NE), in the presence of 3 microM propranolol, increased the activity of mitogen-activated protein kinases (MAPKs). This stimulation was concentration- and time-dependent, with maximal(More)
Following a previous report on detection of muscarinic receptors in myelin with the implied presence of G proteins, we now demonstrate by more direct means the presence of such proteins and their quantification. Using [35S]guanosine 5'-O-(3-thiotriphosphate) ([35S]GTP gamma S) as the binding ligand, purified myelin from bovine brain was found to contain(More)
Purified myelin from rat brainstem, prelabeled in vivo by intracerebral injection of [3H]myoinositol, showed enhanced breakdown of phosphoinositides on treatment with 5'-guanylylimidodiphosphate [Gpp-(NH)p] and Ca2+. Concentration variation of the former in the presence of Ca2+ showed a dose-dependent release of inositol 1,4-bisphosphate (IP2) and inositol(More)