Developmental changes of some enzymes related to energy transduction in free and synaptic mitochondria of rat brain

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DEVELOPMENTAL CHANGES OF SOME ENZYMES RELATED TO ENERGY TRANSDUCTION IN FREE AND SYNAPTIC MITOCHONDRIA OF RAT BRAIN. Curti D., Dagani F., Marzatico F., Zanada F., Lombardo B.* (Institute of Pharmacology, University of Pavia, and *Institute of Biochemistry, University of Catania, Italy). The changes of some enzymes r e l a t e d to e n e r g y t r a n s d u c t J o n in rat brain subcellular fractions at 5, i0, 15, 20 a n d 30 d a y s o f p o s t n a t a l development was investigated. The following enzyme activities in f r e e and synaptic mitochondrJa obtained from cerebral hemispheres and cerebellum were evaluated: citrate synthase (EC 4 . 1 . 3 . 7 ) ; succ~nate dehydrogen a s e (EC 1 . 3 . 9 9 . 1 ) ; rotenone insensitive NADH-cytochrome c reductase (EC 1 . 6 . 9 9 . 3 ) cytochrome oxJdase (EC 1 . 9 . 3 . 1 ) ; glutamate dehydrogenase (EC 1 . 4 . 1 . 3 ) . The activities of lactate dehydrogenase (EC 1 . 1 . 1 . 2 7 ) , acetylcholJne esterase (EC 3 . 1 . 1 . 7 ) and cytochrome oxidase were measured on synaptosomes before lysis. The specific activities of c~trate synthase, g l u t a m a t e dehydrogenase, cytochrome oxJdase Jn f r e e m J t o c h o n d r J a increased during development. A different pattern of these enzymatic activities in f r a c t i o n enriched Jn s y n a p t i c mJtochondrJa was observed.

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EFFECTS ON NERVE GROWTH FACTOR DEPENDENT DIFFERENTIATION OF CHICKEN DORSAL ROOT NEURONS IN VITRO. P. Dohert~, J.G. Dickson, T.P. Flanigan & F.S. Walsh, Molecular Neurobiology Laboratory Institute of Neurology, Queen Square, London WCIN 3BG. An ELISA assay for neurofilament protein (NFP) has been used to quantify nerve growth factor dependent trophism in dissociated primary cultures of 9 day embryonic chick dorsal root ganglia in both control and ganglioside treated cultures. At day 5 in vitro NFP levels were 40-200% greater in cultures grown in the presence of exogenous NGF (0.05-20ng/ml). A 2.3 fold increase in NFP levels was apparent between day 5 and i0 for cultures grown in the continuous presence of 5ng/ml NGF with withdrawal of NGF at day 5 significantly reducing (P2ng/ml was 2-3 times greater (P
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EFFECTS OF EXOGENOUSGA~GLIOSIDESON PROLIFERATION A~D ~ATURATI~ OF NEURONS IN PRIMARYCULTURES Mich~le DURAl, Suzanne HARTH, Dominique L(~BAR~, Raphael ~ASSARELLIand Henri DREYFUS

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UNITE 44 ZNSERM and CENTRE DE NEUROCHIMIE DU CNRS, 5 RUE BLAISE PASCAL, 61084 STRASBOURG CEDEX, FRANCE Gangiiosides,

sialic

acid containing glycosphingolipids present at the surface of many c e l l

neurons and synoptic plasma membrane. They might p a r t i c i p a t e to d i f f e r e n t i a t i o n , r a t i o n o f neuronal c e l l s .

types, are s p e c i a l l y concentrated in

maturation and when added exogenously to regene-

The early e f f e c t of gongliosides and t h e i r involvement i n the p r o l i f e r a t i o n

c e l l c u l t u r e s has been studied adding a mixture or single species of brain gongiiosides

and maturation of neuronal

(@AI, GTlb, 5.10-7M up to lO-StA) to d i s -

sociated c e l l s from 8 day~old chick embryo cerebral hemispheres seeded on p o l y l y s i n e coated P e t r i dishes and grown in the presence of defined medium of Bottenstein and Sara (B-S). The results show that at a same concentration o f gangliosides, brane than other species. Moreover,

GT]b was more e a s i l y bound (or incorporated) in the neuronal mem-

2.]0-6M GTlb stimulated c e l l p r o l i f e r a t i o n

a 25~ increase i n DNA. AFter 3 d . i . c . ,

at 3 days i n c u l t u r e

nings which were mere numerous in the presence of GT]b than with other gangliosides. t i o n a l thickenings,

(d.i.c.)as

electron microscopy observations indicated the appearance of the f i r s t

symmetrical thickenings,

From 3 to 6 or 9 d . i . c . ,

desmosome-like junctions and s y n a p t i c - l i k e

i t was judged by junctional

thicke-

the number o f junc-

contacts increased. When neurons were

seeded i n ~VEN (~ulbecco's modified Eagle's medium) containing 20% f o e t a l c a l f serum during ] day and grown i n the absence of

in B-S syntheticmedium, cell proliferationand differentiationwere delayed. Neurons grown in the presence of GT]b increased their siolic acid content in glycolipidsand giycoproteins.The modificationof gongliosides

membrane glycoconJugates during the maturation o f neurons due to the presence of gongliosides was shown by on increase of the

fixation of lectins. The increased fixationof Con A, for example, was about 70% and 25% at day | after seeding the neurons with GTlb and QAJ respectively.The results strongly support the Focilitoryeffect of ~ongliosidesin maturationand their involvement in membranedynamics as suggestedby the changes in total glycoconjugotescontent.