DRUG-INDUCED CHANGES IN THE CYTOPLASMIC RIBONUCLEOPROTEIN CONSTITUENTS OF BRAIN TISSUE

1965 ◽  
Vol 43 (7) ◽  
pp. 959-975 ◽  
Author(s):  
J. J. Ghosh ◽  
R. K. Datta ◽  
K. C. Bhattacharyya
Keyword(s):  
Secondary Structure ◽  
Brain Tissue ◽  
Ribosomal Rna ◽  
Brain Cortex ◽  
Macromolecular Structure ◽  
Drug Induced ◽  
Brain Cortex Slices ◽  
Cortex Slices ◽  
The Stability ◽  
Induced Changes

Studies carried out on the properties of isolated ribosomes from drug-treated brain cortex slices indicate that ribosomes from drug-treated tissues are generally more susceptible to breakdown into smaller components such as proteins, nucleic acids, acid-soluble nucleotides, etc. It seems that some factor or factors responsible for the stability of the complex macromolecular structure of ribonucleoproteins of brain tissue are affected as a result of drug treatment. Ribosomal RNA from drug-treated brain tissue has been isolated under standardized conditions and the secondary structures of RNA have been studied by methods involving thermal hyperchromicity and reaction with formaldehyde. This latter study indicates that, during the action of some of these neuropharmacological drugs, the secondary structure of ribosomal RNA of brain tissue is partially lost. The loss in the stability of cytoplasmic ribonucleoproteins in drug-treated brain tissue may partly be due to the disorganization at the level of the secondary structure of the RNA component.

scholarly journals Mescaline-induced changes of brain-cortex ribosomes. Effect of mescaline on the stability of brain-cortex ribosomes

1970 ◽  
Vol 117 (5) ◽  
pp. 961-968 ◽  
Author(s):  
R. K. Datta ◽  
J. J. Ghosh
Keyword(s):  
Enzyme Activities ◽  
Brain Cortex ◽  
Rapid Degradation ◽  
Brain Cortex Slices ◽  
Cortex Slices ◽  
The Stability ◽  
Induced Changes ◽  
Goat Brain ◽  
Absorption Characteristics ◽  
Positive Materials

1. During the action of mescaline sulphate on goat brain-cortex slices the ribosomal particles become susceptible to breakdown, releasing protein, RNA, acidsoluble nucleotides and ninhydrin-positive materials, resulting in loss of ribosomal enzyme activities. 2. Ribosomes of the mescaline-treated cortex slices undergo rapid degradation in the presence of trypsin and ribonuclease. 3. Mescaline does not alter the chemical and nucleotide compositions or the u.v.-absorption characteristics of ribosomal particles, however.

scholarly journals Mescaline-induced changes of brain-cortex ribosomes. Effect of mescaline on the hydrogen-bonded structure of ribonucleic acid of brain-cortex ribosomes

1970 ◽  
Vol 117 (5) ◽  
pp. 969-980 ◽  
Author(s):  
R. K. Datta ◽  
J. J. Ghosh
Keyword(s):  
Ribosomal Rna ◽  
Ribonucleic Acid ◽  
Brain Cortex ◽  
Total Rna ◽  
Hyperchromic Effect ◽  
Brain Cortex Slices ◽  
Cortex Slices ◽  
Induced Changes ◽  
Goat Brain ◽  
Hydrogen Bonded

1. The action of mescaline sulphate on the hydrogen-bonded structure of the RNA constituent of ribosomes of goat brain-cortex slices was studied by using the hyperchromic effect of heating and formaldehyde reaction. 2. The ribosomal total RNA species of the mescaline-treated brain-cortex slices have a smaller proportion of hydrogen-bonded structure than the ribosomal RNA species of the untreated brain-cortex slices. 3. Mescaline also appears to have affected this lowering of hydrogen-bonded structure of the ribosomal 28S RNA of brain-cortex tissue.

Effects of acetylcholine on potassium-induced changes of GABA and taurine uptakes and release in cerebral cortex slices from the rat

1977 ◽  
Vol 55 (3) ◽  
pp. 356-362 ◽  
Author(s):  
A. M. Benjamin ◽  
J. H. Quastel
Keyword(s):  
Brain Cortex ◽  
Brain Slices ◽  
Suppressive Effect ◽  
Endogenous Gaba ◽  
Sodium Gradient ◽  
Brain Cortex Slices ◽  
Cortex Slices ◽  
Induced Changes ◽  
The Brain ◽  
Uptake And Release

Acetylcholine, in presence of eserine, has little or no effect on the potassium-ion-suppressed concentrative uptakes of GABA and taurine by rat brain cortex slices in contrast with its effect on those of L-glutamate, L-aspartate, and glycine. Potassium ions at a concentration of 30 μequiv./ml in the incubation medium has a marked suppressive effect on the uptakes of GABA and taurine when there is no apparent change in the sodium ion content of the brain tissue. It is concluded that some factor, besides the change in sodium gradient, operates in the mechanism of potassium suppression of GABA and taurine uptakes. Acetylcholine diminishes the potassium-evoked release of endogenous GABA and taurine from brain slices. Its action is Ca2+ dependent and is diminished by atropine. Acetylcholine does not affect the potassium-accelerated release of GABA from brain slices previously loaded with this amino acid. The differences in uptake and release phenomena exhibited by GABA and taurine from those of L-glutamate and L-aspartate may be due to differences between the mechanisms, as well as the sites, of cerebral uptake and release of these two groups of amino acids.

Effects of Cerebral Stimuli on Adenine Incorporation into Nucleotides and RNA in Brain Slices from the Rat

1972 ◽  
Vol 50 (6) ◽  
pp. 672-683 ◽  
Author(s):  
N. B. Glick ◽  
J. H. Quastel
Keyword(s):  
Brain Tissue ◽  
Incubation Medium ◽  
Rna Synthesis ◽  
Brain Cortex ◽  
Specific Activity ◽  
Brain Slices ◽  
Brain Cortex Slices ◽  
Specific Activities ◽  
Cortex Slices ◽  
The Brain

Comparisons have been made of the rates of incorporation of [8-14C]adenine into RNA and of the specific activities of labelled ATP, in rat brain cortex slices incubated under conditions affecting nucleotide and RNA synthesis.The presence of 50 mM KCl in the incubation medium causes a considerable reduction of the rate of [8-14C]-adenine incorporation into RNA, with no diminution of the specific activity of the cerebral ATP or of the rate of nucleotide formation from adenine. It is inferred that cerebral RNA synthesis is suppressed by 50 mM KCl in the incubation medium.When K+ is omitted from the incubation medium or in the presence of 198 mM NaCl or 5 mM sodium L-glutamate, both the rate of [8-14C]adenine incorporation into RNA and the specific activity of cerebral ATP are diminished to approximately the same extent. This suggests that the process of RNA synthesis in the brain tissue is but little affected either by the increased ceil concentration of Na+ or by the diminished ATP concentration that obtain under these incubation conditions. The process, however, of [8-14C]adenine incorporation into cell nucleotides is markedly suppressed.The presence of protoveratrine (10 μM) causes at least 40% reduction in the rates of [8-14C]adenine incorporation into both RNA and nucleotides with little reduction in the specific activity of the cerebral ATP. The effects of protoveratrine are abolished by tetrodotoxin, indicating that the effects of protoveratrine are confined to the neurons.It is concluded that reductions of the specific activity of cerebral ATP derived from labelled adenine are due to the diminished rates of nucleotide formation from adenine that occur under specific incubation conditions. Such reductions may give rise to the observed diminutions in the rates of incorporation of labelled adenine into RNA. The relatively small fail in the specific activity of isolated ATP after incubation of brain tissue in the presence of protoveratrine is attributed to the localization of the effects of this drug to the neurons, in which the content and specific activity of ATP are suppressed, while those in the glia are undiminished.

scholarly journals Mescaline-induced changes of brain-cortex ribosomes. Role of spermidine in counteracting the destabilizing effect of mescaline on brain-cortex ribosomes

1971 ◽  
Vol 125 (1) ◽  
pp. 213-219 ◽  
Author(s):  
R. K. Datta ◽  
W. Antopol ◽  
J. J. Ghosh
Keyword(s):  
Brain Cortex ◽  
Heat Denaturation ◽  
Brain Cortex Slices ◽  
Cortex Slices ◽  
Induced Changes ◽  
Goat Brain

1. The effect of spermidine on the mescaline-induced changes of brain-cortex ribosomes was studied by adding spermidine during the treatment of goat brain-cortex slices with mescaline. 2. Mescaline treatment of brain-cortex slices removed a portion of the endogenous spermidine from ribosomes and this removal was significantly prevented when spermidine was present during mescaline treatment. 3. Spermidine present during mescaline treatment of brain-cortex slices counteracted, to some extent, the destabilizing effect of mescaline on ribosomes with respect to heat denaturation. 4. Mescaline treatment of brain-cortex slices made ribosomes more susceptible to breakdown, releasing protein and RNA, and resulting in loss of ribosomal enzymic activities. However, spermidine present during mescaline treatment counteracted moderately the mescaline-induced ribosomal susceptibility to breakdown and ribosomal loss of enzymic activities. 5. Ribosomes of mescaline-treated cortex slices were rapidly degraded by ribonuclease and trypsin. However, if spermidine was present during mescaline treatment of brain-cortex slices the rates of degradation diminished.

BIOCHEMICAL STUDIES ON TOFRANIL

1961 ◽  
Vol 39 (3) ◽  
pp. 551-558 ◽  
Author(s):  
P. N. Abadom ◽  
K. Ahmed ◽  
P. G. Scholefield
Keyword(s):  
Rat Brain ◽  
Rat Liver ◽  
Brain Cortex ◽  
Respiratory Activity ◽  
Liver Mitochondria ◽  
Brain Mitochondria ◽  
Inhibitory Effect ◽  
Rat Liver Mitochondria ◽  
Brain Cortex Slices ◽  
Cortex Slices

Tofranil inhibits the respiratory activity of rat brain cortex slices incubated in a glucose-containing medium. It also inhibits the uptake and incorporation of glycine-1-C14at concentrations which have only a slight inhibitory effect on the respiration of slices. Tofranil also inhibits oxidative phosphorylation in both rat liver and rat brain mitochondria but at higher concentrations respiration is greatly affected. Tofranil differs quantitatively from chlorpromazine in its greater inhibitory effect on the ATP–Pi32exchange reaction and its lesser effect on the cytochrome c oxidase activity of rat liver mitochondria.

EFFECTS OF ACETYLSALICYLATE AND 2,4-DINITROPHENOL ON METABOLISM AND TRANSPORT IN RAT BRAIN CORTEX IN VITRO

1963 ◽  
Vol 41 (2) ◽  
pp. 435-454 ◽  
Author(s):  
O. Gonda ◽  
J. H. Quastel
Keyword(s):  
Amino Acids ◽  
Rat Brain ◽  
Brain Cortex ◽  
Transport Processes ◽  
Rat Brain Cortex ◽  
High K ◽  
Increased Sensitivity ◽  
Brain Cortex Slices ◽  
Cortex Slices

The effects of acetylsalicylate and of 2,4-dinitrophenol on the metabolism and transport processes of rat brain cortex slices incubated at 37° in glucose–Ringer media under various conditions have been investigated. The following processes are suppressed by acetylsalicylate (5 mM) or dinitrophenol (0.05 mM) to a much greater extent in media containing 105 mM KCl or 10 mM NH4Cl (which stimulate brain respiration) than in normal media:(a) respiration;(b) incorporation of phosphate into ATP and ADP;(c) conversion of creatine to phosphocreatine;(d) uptake of glutamate or of creatine from the medium to the tissue.The two drugs increase the leakage of amino acids from rat brain cortex slices into the medium, the effects being greatest in the presence of 105 mM KCl or 5 mM glutamate or in the absence of glucose. They change the yields of labelled amino acids from labelled glucose or labelled glutamate.Labelled glutamate is converted to labelled aspartate, γ-aminobutyrate and glutamine in rat brain cortex slices, the addition of glucose bringing about increased yields of glutamine and γ-aminobutyrate and a decreased yield of aspartate. The formation of labelled glutamine from either labelled glutamate or from labelled glucose is suppressed by acetylsalicylate or dinitrophenol, the effects being greater in the presence of 105 mM KCl or 10 mM NH4Cl.The increased sensitivity of the stimulated tissue metabolism to the drugs, in the presence of high K+, or of NH4+or of glutamate, is probably explained by the fact that there is a fall, under these conditions, in the tissue phosphocreatine level. There is, therefore, less reserve phosphocreatine to maintain the level of ATP when neuronal oxidative phosphorylation is suppressed by the addition of acetylsalicylate or of dinitrophenol.

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