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Regulation of choline levels in the brain
9th Meetingof the ESN
A10
37
COVALENT CROSSLINKING OF ASYMMETRIC ACBTYLCliULllf?%TERASEIN THE EXTRACELLULAR MATRIX OF AVIAN MYOTUBES. D.
Hand and
L.W.
Haynes.
University of Bristol, Woodland Road, Bristol BS8 IUG. U.K.
NQt.
OF CHOLINE
LEVELS
IN THE BRAIN
and R. A. Kbppen, R. Gonzalez J. Klein, LGffelholz University of Mainz, Dept. of Pharmacology, Mainz, Federal Republic of Germany
Zoology,
In avian skeletal muscle a significant proportion of asymmetric collagen tailed acetylcholinesterase (A-AChEI is highly resistant to extraction with high salt and detergents. Transglutaminase (tTG), a Ca** which covalently enzyme dependent crosslinks proteins through isodipeptide bonds can crosslink A-AChR to fihronectin. We confirm that affinity purified A-AChE can serve as an acyl donor substrate for tTG. The amount of non-extractable A-AChE activity in quail myotubes ras determined in the presence of agents known to increase tTG activity (e.g. retinoic acid) or to modulate tTG-mediated protein crosslinking (e.g. monodansylcadaverine). A correlation between non-extractable AAC!hE and the levels of isodipegtide in myotubes was found. We propose that tTG may be acting to anchor A-AChE in the extracellular matrix of quail muscle. THE ACTIVITY OF k&RTABOLIC E#XPYES IN RAT SOMATOSENSORY CORTEX FOLLOWING DEAFFERBNTATION BY SCIATIC NERVE TRANSECTION CORRESPOND TO CHOLINRRGIC CHANGES
;-QBS
38 REGULATION
IN
K.Krohn and Th. Rothe Paul Flechsig Inst. Dept. Neurochem., Research, University Leipzig, Germany
Brain
Extensive changes wlthin the central representations of the mammalian body surface have been shown following peripheral nerve injury. The mechanism of these reorganizational events might provide an understanding of a more general feature of the somatosensory system. Recently we determined a decrease in cholinergic presynaptic markers as well as slight alterations of muscarinic acetylcholinereceptors in rat hindlimb somatosensory cortex after transection of the sciatic nerve. Now we demonstrate that the changes in the activity of metabolic enzymes, e.g. lactatedehydrogenase and malatdehydrogenase, correspond to the laminar pattern of cholinergic alterations.
nutrient and a is an essential Choline precursor of acetylcholine and choline-containing phospholipids in the central nervous system. We have investigated the regulation of extracellular choline levels in the brain in order to find pharmacological means to inavailability and consequently crease choline acetylcholine synthesis in central cholinergic Increases of extracellular choline, diseases. are limited by efficient homeostatic however, mechanisms. Acute choline administration leads to a long-lasting increase of phosphocholine. levels in the brain. Probut not choline, longed dietary choline deficiency causes a but not choline, fall of phosphocholine, The concentrations of levels in the brain. extracellular fluid in the free choline (measured by microdialysis) and the CSF remain conditions. these constant under fairly choline increases of extracellular Prolonged the administration of can be induced by an inhibitor of choline transnicotinamide, port from CSF to blood. 40
HABITUATION OF TEE ACH%'YLCWC8LIIOFi-INDUCBlD FWMATIWi OX INO@IWXa 1,4,5TRIBPEOBPBATE IN SE-SYSY CELLB
HUNAN mWRORLAST0l6%
C. Larsson, C. Alling and P. Simonsson Department of Psychiatry and Neurochemistry, Lund University, Lund, Sweden Habituation of the acetylcholine-induced formation of inositol 1,4,5_trisphosphate [I(1,4,5)P9] was induced by stimulating the cells four times with 20 @4 acetylcholine for ten seconds each time. The habituation persisted for at least four hours. When the cells were QrestimUlated only once, a Qrestimulation with 1 mM (a 50 fold higher concentration) was necessary to induce the same degree of attenuation of the acetylcholine-induced response. The cells were incubated with the protein kinase C (PKC) activator phorbol 12-myristate 13-acetate which caused a down-regulation of the acetylcholine-induced 1(1,4,5)P, formation, an effect which was partly reversed by the PKC inhibitor H?. However, the presence of H7 or staurosporine during repetitive stimulations did not inhibit the habituation of the acetylcholine-response. Thus, PKC is presumably not involved in the habituation process induced by repetitive acetylcholine stimulations.
A10
37
COVALENT CROSSLINKING OF ASYMMETRIC ACBTYLCliULllf?%TERASEIN THE EXTRACELLULAR MATRIX OF AVIAN MYOTUBES. D.
Hand and
L.W.
Haynes.
University of Bristol, Woodland Road, Bristol BS8 IUG. U.K.
NQt.
OF CHOLINE
LEVELS
IN THE BRAIN
and R. A. Kbppen, R. Gonzalez J. Klein, LGffelholz University of Mainz, Dept. of Pharmacology, Mainz, Federal Republic of Germany
Zoology,
In avian skeletal muscle a significant proportion of asymmetric collagen tailed acetylcholinesterase (A-AChEI is highly resistant to extraction with high salt and detergents. Transglutaminase (tTG), a Ca** which covalently enzyme dependent crosslinks proteins through isodipeptide bonds can crosslink A-AChR to fihronectin. We confirm that affinity purified A-AChE can serve as an acyl donor substrate for tTG. The amount of non-extractable A-AChE activity in quail myotubes ras determined in the presence of agents known to increase tTG activity (e.g. retinoic acid) or to modulate tTG-mediated protein crosslinking (e.g. monodansylcadaverine). A correlation between non-extractable AAC!hE and the levels of isodipegtide in myotubes was found. We propose that tTG may be acting to anchor A-AChE in the extracellular matrix of quail muscle. THE ACTIVITY OF k&RTABOLIC E#XPYES IN RAT SOMATOSENSORY CORTEX FOLLOWING DEAFFERBNTATION BY SCIATIC NERVE TRANSECTION CORRESPOND TO CHOLINRRGIC CHANGES
;-QBS
38 REGULATION
IN
K.Krohn and Th. Rothe Paul Flechsig Inst. Dept. Neurochem., Research, University Leipzig, Germany
Brain
Extensive changes wlthin the central representations of the mammalian body surface have been shown following peripheral nerve injury. The mechanism of these reorganizational events might provide an understanding of a more general feature of the somatosensory system. Recently we determined a decrease in cholinergic presynaptic markers as well as slight alterations of muscarinic acetylcholinereceptors in rat hindlimb somatosensory cortex after transection of the sciatic nerve. Now we demonstrate that the changes in the activity of metabolic enzymes, e.g. lactatedehydrogenase and malatdehydrogenase, correspond to the laminar pattern of cholinergic alterations.
nutrient and a is an essential Choline precursor of acetylcholine and choline-containing phospholipids in the central nervous system. We have investigated the regulation of extracellular choline levels in the brain in order to find pharmacological means to inavailability and consequently crease choline acetylcholine synthesis in central cholinergic Increases of extracellular choline, diseases. are limited by efficient homeostatic however, mechanisms. Acute choline administration leads to a long-lasting increase of phosphocholine. levels in the brain. Probut not choline, longed dietary choline deficiency causes a but not choline, fall of phosphocholine, The concentrations of levels in the brain. extracellular fluid in the free choline (measured by microdialysis) and the CSF remain conditions. these constant under fairly choline increases of extracellular Prolonged the administration of can be induced by an inhibitor of choline transnicotinamide, port from CSF to blood. 40
HABITUATION OF TEE ACH%'YLCWC8LIIOFi-INDUCBlD FWMATIWi OX INO@IWXa 1,4,5TRIBPEOBPBATE IN SE-SYSY CELLB
HUNAN mWRORLAST0l6%
C. Larsson, C. Alling and P. Simonsson Department of Psychiatry and Neurochemistry, Lund University, Lund, Sweden Habituation of the acetylcholine-induced formation of inositol 1,4,5_trisphosphate [I(1,4,5)P9] was induced by stimulating the cells four times with 20 @4 acetylcholine for ten seconds each time. The habituation persisted for at least four hours. When the cells were QrestimUlated only once, a Qrestimulation with 1 mM (a 50 fold higher concentration) was necessary to induce the same degree of attenuation of the acetylcholine-induced response. The cells were incubated with the protein kinase C (PKC) activator phorbol 12-myristate 13-acetate which caused a down-regulation of the acetylcholine-induced 1(1,4,5)P, formation, an effect which was partly reversed by the PKC inhibitor H?. However, the presence of H7 or staurosporine during repetitive stimulations did not inhibit the habituation of the acetylcholine-response. Thus, PKC is presumably not involved in the habituation process induced by repetitive acetylcholine stimulations.