bluuebunny/crossref_metadata_2025_split huggingface dataset:
RELEASE OF [3H]NORADRENALINE AND [3H]DOPAMINE FROM FIELD STIMULATED CEREBRAL CORTEX SLICES EFFECT OF TYROSINE HYDROXYLASE AND DOPAMINE‐β‐HYDROXYLASE INHIBITION.1
Authors: Farnebo L.‐O. , Hamberger B. , Jonsson G. 
Published: October 2006

Abstract—Rat cerebral cortex slices were incubated in vitro with [3H]dopamine (DA) or [3H]noradrenaline (NA) (10−7M), superfused by fresh buffer and stimulated by an electric field. The stimulation‐induced overflow of [3H]DA and [3H]NA was determined.In slices from untreated rats about 16 ng [3H]NA/g tissue was formed from [3H]DA, corresponding to about 5 per cent of the endogenous NA concentration. Stimulation markedly enhanced the overflow of [3H]NA. The [3H]NA newly formed from [3H]DA was overflowing to a greater extent than [3H]NA previously taken up from the incubation medium, indicating a preferential release of newly synthesized transmitter. The stimulation‐induced overflow of [3H]DA and [3H]NA was increased in slices of rats pretreated with a tyrosine hydroxylase inhibitor (H44/68). It seems that depletion of the endogenous NA stores of central NA neurons by tyrosine hydroxylase inhibition makes the [3H]cate‐cholamines more available for release. Pretreatment of the rats with the DA‐β‐hydroxylase inhibitors FLA63 or FLA69 considerably diminished the formation of [3H]NA from [3H]DA. Stimulation markedly enhanced the overflow of [3H]DA indicating that DA can act as a ‘false transmitter’ in central NA neurons after DA‐β‐hydroxylase inhibition.
INCORPORATION OF 3H‐LABELLED LEUCINE INTO THE PROTEIN FRACTION IN THE RETINA OF THE HONEYBEE DRONE
Authors: Pepe I. M. , Baumann F. 
Published: October 2006

Abstract— Protein synthesis in the retina of the honey‐bee drone was studied by incubating head slices in labelled leucine and measuring the TCA insoluble radioactivity. It was found that the protein‐bound radioactivity in illuminated retinas was half of that in dark‐adapted ones. This ratio was not affected by pre‐treatment with puromycin. It was therefore concluded that, in the drone, the main influence of illumination is to increase the rate of breakdown of proteins.Relatively high concentrations of labelled protein were found in dark‐adapted retinas when the retinula cells were hyperpolarized by bathing the preparation in a sodiumfree medium; low concentrations were found when retinula cells were depolarized by increasing the extracellular potassium concentration. These findings suggest that protein metabolism of the retina is influenced by the membrane potential of retinula cells.
DISTRIBUTION OF RIBOSOMAL MATERIAL IN INCUBATED AND ELECTRICALLY STIMULATED CEREBRAL SLICES
Authors: Ornellas M. R. , Jones D. A. 
Published: October 2006

Abstract— The distribution of ribosomal fractions has been examined in fresh cerebral cortex tissue and in slices maintained in vitro both with and without electrical stimulation. The electrical stimulation used was of a type that has previously been shown to diminish amino acid incorporation into protein.Membrane‐bound and free fractions were obtained and the ratio of their RNA contents were, for the control tissue 3, and for the electrically stimulated tissue 1, 8. Electrical stimulation was found to decrease the Mg2+ binding affinity of the free. fraction but was without effect on the bound fraction. Stimulation was also found to increase the leakage of soluble protein and RNA from the tissue and its accumulation in the incubation medium.
INHIBITION OF CHOLINE ACETYLTRANSFERASE AND ITS HISTOCHEMICAL LOCALIZATION
Authors: Kása P. , Morris D. 
Published: October 2006

Abstract— A method for the histochemical identification of choline acetyltransferase has been investigated further by studying the effects of certain inhibitors of the enzyme both on rat brain homogenates and on the localization of the enzyme in tissue sections.It was confirmed that acetyl‐CoA hydrolase activity both in homogenates and in tissue sections is inhibited by preincubation in 1 mM‐DFP. The effects of the choline acetyltransferase inhibitors chloro‐ and bromoacetylcholine on the appearance of histochemical staining were related to their activity in homogenates and tissue slices. Bromoketone was found to inhibit choline acetyltransferase in homogenates and, less efficiently, in tissue sections but it also inhibited the hydrolysis of acetyl‐CoA by some other unknown enzyme which is inactivated by 1 mM‐DFP.The results obtained with the choline acetyltransferase inhibitors provide support for the specificity of the histochemical method.
DEHYDROEPIANDROSTERONE SULPHATE IN RAT BRAIN: INCORPORATION FROM BLOOD AND METABOLISM IN VIVO12
Authors: Kishimoto Y. , Hoshi M. 
Published: October 2006

AbstractThe incorporation of [7‐3H]dehydroepiandrosterone[35S]sulphate into brain tissue elements from the circulatory system and its metabolic fate in the brain were studied in developing rats. Approximately 0.037 % of [3H] and 0.023% of [35S] were incorporated into the brain within 15 min after the intracardiac injection of the labelled steroid. More than one‐half of the incorporated [3H] was recovered as free steroid, whereas the rest was recovered as sulphate. The 3H/35S ratio in the sulphate fraction suggested that the sulphate entered the brain with the sulphate linkage intact. Upon intracerebral injection of the double‐labelled steroid, approximately 6 per cent of the radioactivity was recovered in the brain at 30 min after the injection and 1 per cent was recovered at 1 h after the injection. Of the remaining radioactivity recovered from the brain, 5 per cent was found in the free steroid fraction, probably formed by hydrolysis of the sulphate; 90 per cent was in the sulphate ester fraction; and the rest was in the fraction of more polar compounds. To identify the metabolites, [4‐14C]dehydroepiandrosterone sulphate was injected into the rat brain. Significant amounts of radioactivity were found in androstenediol sulphate, which was isolated from the brain. This compound was apparently derived from dehydroepiandrosterone sulphate by reduction of the 17‐keto group to a 17β‐hydroxyl group without prior hydrolysis. There was suggestive evidence that free androstenediol was also formed in the brain in this experiment.
THE ACCUMULATION OF ARACHIDONATE AND DOCOSAHEXAENOATE IN THE DEVELOPING RAT BRAIN
Authors: Sinclair A. J. , Crawford M. A. 
Published: October 2006

Abstract—Fatty acids typical of grey matter lipids (C20:4 and C22:6) and of myelin lipids (C20:1 and C24:1) were estimated in developing rat brains. The polyenoic fatty acids (C20:4 and C22:6) are synthesized from the essential fatty acids (C18:2 and C18:3). The results showed that more than 50 per cent of the adult content of the brain polyenoic acids were laid down by day 15. In contrast, the fatty acids characteristic of myelin lipids did not appear in significant quantities until after this time. These findings distinguish biochemically the different periods of brain development associated firstly with cell division (formation of neurons and glial cells) and secondly with myelination. It is of special interest that the period of cell proliferation is accompanied by the appearance in brain lipids of long‐chain polyenoic acids derived from the essential fatty acids.
DEVELOPMENT OF MITOCHONDRIAL PYRUVATE METABOLISM IN RAT BRAIN
Authors: Wilbur D. O. , Patel M. S. 
Published: October 2006

AbstractThe activities of a number of mitochondrial enzymes involved in the metabolism of pyruvate during development of the rat brain were investigated. The rates of decarboxylation of [1‐14C]pyruvate to 14CO2 via pyruvate dehydrogenase and the fixation of H14CO3− in the presence of pyruvate via pyruvate carboxylase by brain homogenates were very low in newborn rats. These rates increased markedly by about four‐fold and 15‐fold respectively during 10–35 postnatal days. The rates of the fixation of H14CO3− by cerebral homogenates were supported by the development of the activity of pyruvate carboxylase in rat brain. The activities of citrate synthase, aconitase, NAD‐malate dehydrogenase, aspartate aminotransferase, alanine aminotransferase and phosphoenol‐pyruvate carboxykinase were very low in the particulate fraction of the newborn rat brain. The activities of all these enzymes increased makedly by about three‐ to 10‐fold during 10–35 days after birth. The activity of mitochondrial phosphoenolpyruvate carboxykinase from rat brain was not precipitated by an antibody prepared against rat liver cytosolic phosphoenolpyruvate carboxykinase suggesting that cerebral mitochondrial enzyme is immunologically different from that of the cytosolic form in hepatocytes. The significance of the development of the cerebral mitochondrial metabolism is discussed in relation to biochemical maturation of the brain.
5‐HYDROXYTRYPTAMINE AND NORADRENALINE IN THE HIPPOCAMPAL REGION: EFFECT OF TRANSECTION OF AFFERENT PATHWAYS ON ENDOGENOUS LEVELS, HIGH AFFINITY UPTAKE AND SOME TRANSMITTER‐RELATED ENZYMES
Authors: Storm‐Mathisen J. , Guldberg H. C. 
Published: October 2006

AbstractThe monoaminergic fibres enter the hippocampal formation through a dorsal and a ventral route. The dorsal route consisting of fimbria, fornix superior and cingulum, was estimated to supply about 75% of the 5‐HT fibres and 40% of the noradrenaline containing (NA) fibres. The ventral route, allegedly passing through the amygdaloid area, accounts for the rest. The cingulum bundle contributes a definite part of the 5‐HT fibres but very few of the NA fibres. No evidence was found for an intrinsic origin of monoaminergic fibres in the hippocampal region. Monoamine oxidase and catechol‐O‐methyltransferase showed no change following the lesions and are considered to be localized predominantly outside the aminergic neurones. The results on DOPA decarboxylase indicate that about 50% of the enzyme is situated outside 5‐HT and NA nerves. Glutamic acid decarboxylase did not decrease even after transection of the ventral route, substantiating the earlier conclusion that this enzyme is situated in intrinsic neurones in the hippocampal region. For choline acetyltransferase and AChE the dorsal route was confirmed to be the only quantitatively important way of access. None of the enzymes studied, nor the uptake activities, were affected by cervical sympathectomy.
TRANSPORT OF PROTEINS, GLYCOPROTEINS AND CHOLINERGIC ENZYMES IN REGENERATING HYPOGLOSSAL NEURONS1
Authors: Frizell M. , Sjöstrand J. 
Published: October 2006

AbstractThe accumulation of [3H]leucine‐ and [3H]fucose‐labelled axonal proteins, acetyl‐CoA : choline O‐acetyltransferase (ChAc, EC 2.3.1.6) and acetylcholinesterase (AChE, EC 3.1.1.7) was studied proximal to a ligature applied to the hypoglossal nerve of the rabbit at different phases of nerve regeneration.After 1 week of regeneration, the accumulation of rapidly migrating [3H]leucine‐labelled proteins, ChAc and AChE was reduced as compared to that of the contralateral nerve. In contrast, the accumulation of [3H]fucose‐labelled glycoproteins was markedly increased. After a regeneration period of 4‐6 weeks, the accumulation of proteins and glycoproteins in the regenerating nerve was increased whereas the accumulation of ChAc and AChE was almost normal.The results indicate an initial depression of the synthesis and axonal transport of the bulk of rapidly migrating proteins, ChAc and AChE in the chromatolytic hypoglossal neurons whereas the synthesis and transport of rapidly migrating glycoproteins is increased. These initial changes are less pronounced during the subsequent regeneration period.
THE DISTRIBUTION OF AMINO ACIDS, Na+ AND K+ FROM SURFACE TO CENTRE IN INCUBATED SLICES OF MOUSE BRAIN
Authors: Sershen H. , Lajtha A. 
Published: October 2006

Abstract—The effect of tissue damage on the uptake of amino acids by brain slices was investigated by measuring uptake in slices of different thickness and measuring the distribution of [14C]‐labelled amino acid on the surface and in the centre of incubated slices. The uptake of glutamate, aspartate, and GABA was greater in 0.1 mm‐thick slices than in 0.42 mm‐thick slices in short and in long (up to 120 min) incubations; the uptake of other amino acids was equal or greater in the 0.42 mm‐thick slices. The water content of incubated slices did not change greatly from surface to centre; inulin space was greater at the surface, and in slices from cortex, especially higher at the cut surface. Na+ and K+ concentrations were also higher at the surface. In the rest of the slice space, inulin, Na+ and K+ distribution was quite uniform. The distribution of ATP was inhomogeneous: in thinner slices the centre concentration was higher; in thicker slices the centre concentration was lower. Amino acid uptake initially (at 5 min) was higher at the surface, especially in the thicker slices; after longer time (30 min) incubation, the distribution of lysine and leucine was uniform, and glutamate uptake was greater at the surface. The inhomogeneity of distribution increased with increasing thickness of the slices. We concluded that the uptake of some amino acids (perhaps those for which, beside a low affinity transport, also a higher affinity transport system exists) is greater in thinner slices and greater on the surface of slices, and there is an initially inhomogeneous distribution during amino acid uptake. The uptake on the surface constitutes only a small portion of the total uptake, and tissue damage does not explain the greater uptake of amino acids by slices in comparison to the brain in vivo. This shows the higher transport capacity of cells in the brain and emphasizes the importance of mechanisms controlling the metabolite composition of the extracellular fluid in finally influencing the metabolite composition of the brain itself.
EFFECT OF UNDERNUTRITION ON AMINO ACID COMPARTMENTATION IN THE DEVELOPING RAT BRAIN
Authors: Roach Mary K. , Corbin Jannie , Pennington W. 
Published: October 2006

Abstract—Rat pups undernourished through 21 days of age show abnormal patterns of cerebral amino acid metabolism. The pattern of incorporation of radioactivity from l‐[U‐14C]leucine into amino acids derived from tricarboxylic acid cycle intermediates was altered, with significantly more 14C being incorporated into glutamate and aspartate in the underfed rats than in controls. Glutamate compartmentation, manifested in the ratio of specific radioactivities of glutamine to glutamate, developed more slowly in the. diet‐restricted group. These results are similar to those seen in neonatally‐thyroidectomized rats and suggest decreased growth of neuronal processes. This impairment of amino acid metabolism returns to normal after a 7‐week period of adequate nutrition.
KINETIC ANALYSIS OF PHENYLALANINE‐INDUCED INHIBITION IN THE SATURABLE INFLUX OF TYROSINE, TRYPTOPHAN, LEUCINE AND HISTIDINE INTO BRAIN CORTEX SLICES FROM ADULT AND 7‐DAY‐OLD RATS
Authors: Vahvelainen M.‐L. , Oja S. S. 
Published: October 2006

Abstract—An attempt was made to isolate the saturable uptake from the unidirectional influx of amino acids into tissue slices and to estimate the transport constants and maximal velocities of saturable transport. The method was applied to studies on the inhibition of phenylalanine in the saturable influx of tyrosine, tryptophan, histidine and leucine into brain cortex slices from adult and 7‐day‐old rats. In both age groups phenylalanine inhibited the influx of the other amino acids, and vice versa. The apparent transport constants of the other amino acids increased in the presence of phenylalanine more noticeably in the slices from 7‐day‐old rats than in those from adult rats, whereas the concomitant influx of phenylalanine was inhibited less in the slices from 7‐day‐old rats. In immature animals in vivo competition between amino acids may play a more marked role in the supply of amino acids from plasma to brain, as the transport systems in brain slices from 7‐day‐old rats become saturated with extracellular amino acids more readily than do the transport systems in brain slices from adult rats.
LOWERED MONOAMINE OXIDASE ACTIVITY IN BRAINS FROM ALCOHOLIC SUICIDES
Authors: Gotttries C. G. , Oreland L. , Wiberg Å. , Winblad B. 
Published: October 2006

Abstract—Monoamine oxidase (MAO) activity in the brains of 15 suicides, of whom 8 were alcoholics, was compared to a control material of 20 individuals without known mental disorder. At autopsy 13 different parts of the brain were macroscopicaily dissected out and the MAO activity in the samples estimated with β‐phenylethylamine and tryptamine as substrates.The MAO activity in all parts of the brain investigated was found to be significantly lower in the alcoholic suicides as compared to the controls, while there was no significant difference between the non‐alcoholic suicides and controls. Different variables which might have influenced the MAO activity were investigated. There was no significant correlation between age and tryptamine‐oxidizing activity, but a positive correlation between age and β‐phenylethylamine‐oxidizing activity was found. There was also a significant difference between the series in the time lapse between death and autopsy and in the time during which the dead body was kept at room temperature. However, neither of these variables could explain the differences between the series. The results thus demonstrate a connection between low MAO activity in the brain and suicidal behaviour among alcoholics.
CHANGES IN THE LEVELS OF DNA, RNA, PROTEIN AND DNases IN DEVELOPING AND OLD CHICK BRAIN
Authors: Shrivastaw K. P. , Rao K. Subba 
Published: October 2006

Abstract—The levels of DNA, RNA, protein and activities of acid and alkaline DNases in developing and old chicken brain were studied. A rapid increase in DNA content was found in the embryonic brain until just prior to hatching. Thereafter, with a transient plateau around the day of hatching, the DNA continued to increase but at a very slow rate. Two‐year‐old brain was found to have a markedly higher level of DNA as compared to the 10th day postnatal value. RNA showed a steady increase up to the 20th day of embryonic life. Protein levels showed a gradual increase throughout the period studied. Both acid and alkaline DNases exhibited maximum activity during embryonic life, i.e. at a time when rapid cellular proliferation was occurring. With advancing age, the acid DNase activity showed a marked decline thus exhibiting no correlation to the high level of DNA found in the old brain. The alkaline DNase activity, however, was still at a significant level in the 2‐year‐old brain.
THIAMINE PHOSPHATE METABOLISM AND POSSIBLE COENZYME‐INDEPENDENT FUNCTIONS OF THIAMINE IN BRAIN1
Authors: Berman K. , Fishman R. A. 
Published: October 2006

Abstract—The effect of depolarization of rat brain cortex slices on the relative distribution of thiamine among its various phosphate esters and on the efflux of thiamine was studied as a probe of possible coenzyme‐independent neurophysiological functions of thiamine. Electrical pulses for 30 min increased lactate production but did not affect the levels of thiamine esters. Depolarization with 41 mM‐potassium decreased thiamine diphosphate by only 3 percent (P= 0.05). Thiamine triphosphate levels (TTP) were unaffected by depolarization but doubled during incubation for 1 h in which time efflux of 40 percent of the total thiamine from the slices as unesterified thiamine occurred. Depolarization by potassium released a small but highly variable portion of the thiamine content of superfused cortex slices above the basal rate of efflux. The basal efflux was partially sodium dependent. Thiamine efflux was unaffected by acetylcholine, ouabain, or tetrodotoxin, compounds previously reported to increase thiamine efflux. The incorporation of 32P1 into the endogenous thiamine phosphates of cortex slices was studied. Incorporation into thiamine diphosphate reached only 20 percent of the specific activity of its precursor, ATP, after 2h of incubation while the incorporation into TTP approached equilibrium with ATP in 15‐30 min indicating that the TTP pool was the most rapidly turning over of the thiamine phosphates. The data suggest that only a small portion of the TDP pool undergoes rapid turnover and serves as a precursor for TTP. The rapid turnover of TTP phosphoryl groups is consistent with specific functions for this compound related to its potential for phosphorylation reactions. An analog of TTP with the β, γ oxygen bridge replaced by a methylene group decreased TDP levels and increased thiamine when incubated with cortex slices, but did not effect thiamine monophosphate or triphosphate levels indicating inhibition of thiamine pyrophosphokinase.
MODIFICATIONS IN SOLUBLE PROTEIN KINASE AND CYCLIC‐AMP BINDING CAPACITY OF DEVELOPING RAT BRAIN
Authors: Takahashi T. , Matsuzaki S. , Nunez J. 
Published: October 2006

Abstract—Histone and casein phosphoprotein‐kinase activities were determined in rat brain soluble fraction at various stages of development.Cyclic AMP‐independent or basal histone kinase activity increased, whereas cyclic AMP‐dependent activity decreased in whole soluble fraction with the age. On the contrary, whole soluble cyclic AMP‐dependent and ‐independent casein kinases activities did not show any difference during development.The percentage of activation by cyclic AMP of histone kinase activity and [3H] cyclic‐AMP binding activity in the soluble fraction decreased markedly during development.By DEAE‐cellulose chromatography the histone kinase was separated mainly into 4 peaks; the fourth peak was strongly stimulated by cyclic AMP. Stimulation by cyclic AMP was higher in the 4‐day‐old rat brains than in the 9‐ and 30‐day‐old. In the 9‐day‐old rats the ratio of cyclic AMP‐dependent histone kinase in respect to the cyclic AMP‐independent enzyme was higher than in 4‐ and 30‐day‐old rats.Casein kinase activities in the brains of 9‐ and 30‐day‐old rats were separated by DEAE‐cellulose chromatography into three peaks of which the third one was stimulated by cyclic AMP. Little, if any, difference was observed for casein kinase during the development. These results suggest that brain histone and casein kinase are different enzymes:
SUBCELLULAR DISTRIBUTION AND ACTIVATION BY NON‐IONIC DETERGENTS OF GUANYLATE CYCLASE IN CEREBRAL CORTEX OF RAT
Authors: Deguchi T. , Amano E. , Nakane M. 
Published: October 2006

Abstract—Non‐ionic detergents stimulated particulate guanylate cyclase activity in cerebral cortex of rat 8‐ to 12‐fold while stimulation of soluble enzyme was 1.3‐ to 2.5‐fold. Among various detergents, Lubrol PX was the most effective one. The subcellular distribution of guanylate cyclase activity was examined with or without 0.5% Lubrol PX. Without Lubrol PX two‐thirds of the enzyme activity was detected in the soluble fraction. In the presence of Lubrol PX, however, two‐thirds of guanylate cyclase activity was recovered in the crude mitochondrial fraction. Further fractionation revealed that most of the particulate guanylate cyclase activity was associated with synaptosomes. The sedimentation characteristic of the particulate guanylate cyclase activity was very close to those of choline acetyltransferase and acetylcholine esterase activities, two synaptosomal enzymes. When the crude mitochondrial fraction was subfractionated after osmotic shock, most of guanylate cyclase activity as assayed in the absence of Lubrol PX was released into the soluble fraction while the rest of the enzyme activity was tightly bound to synaptic membrane fractions. The total guanylate cyclase activity recovered in the synaptosomal soluble fraction was 6 to 7 times higher than that of the starting material. The specific enzyme activity reached more than 1000 pmol per min per mg protein, which was 35‐fold higher than that of the starting material. The membrane bound guanylate cyclase activity was markedly stimulated by Lubrol PX. Guanylate cyclase activity in the synaptosomal soluble fraction, in contrast, was suppressed by the addition of Lubrol PX. The observation that most of guanylate cyclase activity was detected in synaptosomes, some of which was tightly bound to the synaptic membrane fraction upon hypoosmotic treatment, is consistent with the concept that cyclic GMP is involved in neural transmission.