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Factors influencing the behaviour of cerebellar cells in culture
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Effect of methylmercuric chloride (CH3HgCI) on cAMP-systems of neuroblastoma and glioma cells in culture. Prasad, KoN., Center for Vitamins and Cancer Research, Dept. of Radiology, School of Medicine, Univ. of Colo. Health Sciences Ctr., 4200 East 9th Ave., Denver,CO 80262 The intracellular level of cAMP increased by about 2-fold in CH3HgCl-treated neuroblastoma (NBP~) and glioma (C-6) cells in culture. The above change did not occur within a few ~ours of treatment, rather it is observed 3 days after treatment. CH3HgCI also reduced the PGEl-response in chronically treated glioma cells, but it failed to produce a similar effect in chronically treated NB cells. Dopamine - and norepinephrine - responses in NB cells and norepinephrine - response in glioma cells were unaffected after chronic treatment of these cells by CH HgCI. In addition, 3 cAMP-dependent and - independent phosphorylations of specific proteins were very sensitive to CH HgCI in both glioma and NB cells. The increases and decreases in the levels of p~osphorylation of proteins were observed after chronic treatment of cells with small concentrations (0.05-01 ~M) of CH HgCI. These data show that the cultures of NB and glioma cells may be useful in i~entifying the sensitive biological parameters that are affected by heavy metals.
P h a s e I a n d p h a s e I I r e a c t i o n s in b r a i n a n d t h e i r i n v o l v e m e n t in neurotoxicity of selected chemicals. Seth, P. I n d u s t r i a l T o x i c o l o g y R e s e a r c h C e n t r e , P.O, B o x 80, L u c k n o w 226 001, I N D I A . The x e n o b i o t i c m e t a b o l i z i n g e n z y m e s in b r a i n may p l a y a k e y role in determining t h e r e s p o n s e o f b r a i n to t o x i c c h e m i c a l s b y m o d u l a t i n g their concentrations or of their metabolites near appropriate receptor sites. T o i n v e s t i g a t e t h e c a p a b i l i t y o f b r a i n to h a n d l e the x e n o b i o tics, s o m e e n z y n ~ s o f p h a s e I a n d p h a s e il o f x e n o b i o t i c m e t a b o l i s m were studied. Significant activities of NADPH-dependent microsomal aryl hydrocarbon hydroxylase(AHH), NADH-dependent mitochondrial AHH and glutathione-S-transferase(C~T) w e r e d e t e c t e d in rat b r a i n . The activit y o f A H H w h i c h w a s low a t 7 - 1 0 d a y s o f a g e s h o w e d a g r a d u a l i n c r e a s e with age and steady states were achieved by 48-56 days. The steady s t a t e o f G S T a c t i v i t y w h i c h w a s low at 7 d a y s o f a g e w a s a c h i e v e d b y 21 d a y s . B o t h A H H a n d G S T s h o w e d s o m e v a r i a t i o n s in d i s t r i b u t i o n in various brain regions. M a l e rats e x h i b i t e d a g r e a t e r a c t i v i t y o f G S T than females. Neuretoxicants, acrylamide and styrene, modified the activity of these enzymes. T h e p r e t r e a t m e n t o f rats w i t h i n d u c e r s a n d i n h i b i t o r s o f m i x e d f1~nction o x i d a s e s r e s u l t e d i n a m o d i f i e d n e u r o b e h a vioral response of acrylamide.
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PRESENTAT
IONS
F__actors influencing the behaviour of cerebellar cells in culture. R. Balazs, V. Gallo, Ann Kingsbury, C.K. Atterwill & P.L. Woodhams MRC Developmental Neurobiology Unit, 33 John's Mews, London WCIN 2NS. The survival and morphological development of cells derived from P8 rat eerebellumwere studied with respect to variations in the substratum_(plastic, polycation, collagen, fibronectin, FCS precoatlng) and in medium composition ~CS (S+) or serum-free N2 medium of BottensteinandSato (S-), variation in [K+], polyunsaturated fatty acids, serum albumin, mitoticinhibitors]. Marked differences were observed inthesocialbehaviourofcells, the length of their survival and the organization of the neuronal surface, in terms of surface iodinated polypeptide profiles. Long term survival (>2 weeks) of neuronal enriched cultures was obtained on polycation substratum either in a S+ medlumwhen the [K +] was raised to 25mMor in the S- medium in the presence of physiological [K+]. It was postulated that the different K+ requirements under these two conditions are due to "freezing" of the maturation of nerve cells grown in S- at a stage prior to that when functional synaptic contacts are necessary for survival. Consistently with this hypothesis it was found that the expression of transmlssion-associated functions, such as evoked transmitter release, was evident in the S+, but not in the S - cultures by 12 DIV. Other functions related to the excitability of nerve cells, such as the density of voltage de~ende~t Na + channels developed similarly under the two conditions, but the intracellular [Na ]/[K ] ratio was relatively high in the S- cultures.
Effect of methylmercuric chloride (CH3HgCI) on cAMP-systems of neuroblastoma and glioma cells in culture. Prasad, KoN., Center for Vitamins and Cancer Research, Dept. of Radiology, School of Medicine, Univ. of Colo. Health Sciences Ctr., 4200 East 9th Ave., Denver,CO 80262 The intracellular level of cAMP increased by about 2-fold in CH3HgCl-treated neuroblastoma (NBP~) and glioma (C-6) cells in culture. The above change did not occur within a few ~ours of treatment, rather it is observed 3 days after treatment. CH3HgCI also reduced the PGEl-response in chronically treated glioma cells, but it failed to produce a similar effect in chronically treated NB cells. Dopamine - and norepinephrine - responses in NB cells and norepinephrine - response in glioma cells were unaffected after chronic treatment of these cells by CH HgCI. In addition, 3 cAMP-dependent and - independent phosphorylations of specific proteins were very sensitive to CH HgCI in both glioma and NB cells. The increases and decreases in the levels of p~osphorylation of proteins were observed after chronic treatment of cells with small concentrations (0.05-01 ~M) of CH HgCI. These data show that the cultures of NB and glioma cells may be useful in i~entifying the sensitive biological parameters that are affected by heavy metals.
P h a s e I a n d p h a s e I I r e a c t i o n s in b r a i n a n d t h e i r i n v o l v e m e n t in neurotoxicity of selected chemicals. Seth, P. I n d u s t r i a l T o x i c o l o g y R e s e a r c h C e n t r e , P.O, B o x 80, L u c k n o w 226 001, I N D I A . The x e n o b i o t i c m e t a b o l i z i n g e n z y m e s in b r a i n may p l a y a k e y role in determining t h e r e s p o n s e o f b r a i n to t o x i c c h e m i c a l s b y m o d u l a t i n g their concentrations or of their metabolites near appropriate receptor sites. T o i n v e s t i g a t e t h e c a p a b i l i t y o f b r a i n to h a n d l e the x e n o b i o tics, s o m e e n z y n ~ s o f p h a s e I a n d p h a s e il o f x e n o b i o t i c m e t a b o l i s m were studied. Significant activities of NADPH-dependent microsomal aryl hydrocarbon hydroxylase(AHH), NADH-dependent mitochondrial AHH and glutathione-S-transferase(C~T) w e r e d e t e c t e d in rat b r a i n . The activit y o f A H H w h i c h w a s low a t 7 - 1 0 d a y s o f a g e s h o w e d a g r a d u a l i n c r e a s e with age and steady states were achieved by 48-56 days. The steady s t a t e o f G S T a c t i v i t y w h i c h w a s low at 7 d a y s o f a g e w a s a c h i e v e d b y 21 d a y s . B o t h A H H a n d G S T s h o w e d s o m e v a r i a t i o n s in d i s t r i b u t i o n in various brain regions. M a l e rats e x h i b i t e d a g r e a t e r a c t i v i t y o f G S T than females. Neuretoxicants, acrylamide and styrene, modified the activity of these enzymes. T h e p r e t r e a t m e n t o f rats w i t h i n d u c e r s a n d i n h i b i t o r s o f m i x e d f1~nction o x i d a s e s r e s u l t e d i n a m o d i f i e d n e u r o b e h a vioral response of acrylamide.
POSTER
PRESENTAT
IONS
F__actors influencing the behaviour of cerebellar cells in culture. R. Balazs, V. Gallo, Ann Kingsbury, C.K. Atterwill & P.L. Woodhams MRC Developmental Neurobiology Unit, 33 John's Mews, London WCIN 2NS. The survival and morphological development of cells derived from P8 rat eerebellumwere studied with respect to variations in the substratum_(plastic, polycation, collagen, fibronectin, FCS precoatlng) and in medium composition ~CS (S+) or serum-free N2 medium of BottensteinandSato (S-), variation in [K+], polyunsaturated fatty acids, serum albumin, mitoticinhibitors]. Marked differences were observed inthesocialbehaviourofcells, the length of their survival and the organization of the neuronal surface, in terms of surface iodinated polypeptide profiles. Long term survival (>2 weeks) of neuronal enriched cultures was obtained on polycation substratum either in a S+ medlumwhen the [K +] was raised to 25mMor in the S- medium in the presence of physiological [K+]. It was postulated that the different K+ requirements under these two conditions are due to "freezing" of the maturation of nerve cells grown in S- at a stage prior to that when functional synaptic contacts are necessary for survival. Consistently with this hypothesis it was found that the expression of transmlssion-associated functions, such as evoked transmitter release, was evident in the S+, but not in the S - cultures by 12 DIV. Other functions related to the excitability of nerve cells, such as the density of voltage de~ende~t Na + channels developed similarly under the two conditions, but the intracellular [Na ]/[K ] ratio was relatively high in the S- cultures.