bluuebunny/crossref_metadata_2025 huggingface dataset:
GABA IN THE OLFACTORY BULB AND OLFACTORY NUCLEUS OF THE RAT: THE DISTRIBUTION OF GAMMA‐AMINOBUTYRIC ACID, GLUTAMIC ACID DECARBOXYLASE, GABA TRANSAMINASE AND SUCCINATE SEMIALDEHYDE DEHYDROGENASE
Authors: Austin L. , Recasens M. , Mandel P.
Published: October 2006

Abstract— The distribution of GABA and enzymes involved in its metabolism was investigated in the different regions of the olfactory bulb and olfactory nucleus. The highest levels of GABA in the olfactory bulb were found in the layers rich in nerve terminals (31 μmol/g dry wt.). A similar distribution was found in the olfactory nucleus although the overall level of GABA was only a quarter of that measured in the bulb. Glutamic acid decarboxylase (GAD) levels in the various layers of the olfactory nucleus were similar in distribution to those of GABA. However, the correlation between GAD and GABA did not hold for the olfactory bulb, particularly in the granule cell layer and the medulla. The activities of GAD and the levels of GABA are significantly higher in the bulb than in the nucleus but succinic acid scmialdehyde dehydrogenase and GABA aminotransaminase activities are almost identical in both regions.
EFFECT OF DRUGS ON RAT BRAIN, CEREBROSPINAL FLUID AND BLOOD GABA CONTENT
Authors: Ferkany John W. , Butler Ian J. , Enna S. J.
Published: October 2006

Acute administration of GABA transaminase inhibitors to rats results in a dose‐dependent increase in both brain and blood GABA content and administration of isonicotinic acid hydrazide (INH), at a dose which decreases the amount of brain GABA, also lowers blood levels of this amino acid. Chronic treatment (10 days) with INH (20mg/kg), y‐acetylenic‐GABA (10 mg/kg) or aminooxyacetic acid (AOAA) (10 mg/kg) results in a significant elevation in both rat brain and blood GABA concentrations. At the doses studied, only AOAA caused a significant elevation in CSF GABA content. Co‐administration of pyridoxal phosphate (2 mg/kg) blocks the chronic INH‐induced rise in blood GABA but does not affect the increase in brain content of this amino acid. Chronic administration of di‐n‐propylacetate (20 mg/kg) did not significantly alter brain, blood or CSF GABA levels. The results suggest that, under the proper conditions, changes in blood GABA levels after administration of inhibitors of GABA synthesis or degradation may be an indirect indicator of changes in the brain content of this amino acid. Blood GABA determinations may be useful for studying the biochemical effectiveness of GABA transaminase inhibitors in man.
γ‐Hydroxybutyrate: Cerebral Metabolic, Vascular, and Protective Effects
Authors: Artru Alan A. , Steen Petter A. , Michenfelder John D.
Published: October 2006

The cerebral protection afforded by each of several preparations of γ‐hydroxybutyrate (GHB) was examined in the hypoxic (Fio2= 0.05) mouse model. The greatest increase in survival time (85%) occurred after prereatment with 300 mg/kg given as buffered β‐butyrolactone (GBL). Compared with previous studies employing the same hypoxic model, this increase was less than that observed with certain barbiturates and equal to that observed with certain anesthetics. The cerebral and systemic metabolic and vascular effects of each of several preparations of GHB were examined in a canine model. The cerebral metabolic rate for oxygen (CMRo2) tended to increase after GHB 100 mg/kg, then progressively decreased after cumulative doses of 600 mg/kg and 1100 mg/kg. The greatest depression in CMRo2 (48%) occurred with 1100 mg/kg given as unbuffered GBL. With each preparation and at every dose, a reduction in cerebral blood flow (CBF) exceeded the reduction in CMRo2 The major systemic effect was an almost two‐thirds reduction in cardiac output at the largest doses. Assuming no species difference the cerebral protection observed with GHB is probably limited by both the reduction in cardiac output and the unfavorable relationship of cerebral oxygen supply to demand (CBF/CMRo2). Brain biopsies taken after the cumulative dose of GHB 1100 mg/kg showed a trend toward lower phosphocreatine levels and higher lactate and lactate/pyruvate levels than in untreated dogs.
Glutathione and Ascorbate During Ischemia and Postischemic Reperfusion in Rat Brain
Authors: Cooper Arthur J. L. , Pulsinelli William A. , Duffy Thomas E.
Published: October 2006

Thirty minutes of total cerebral ischemia (decapitation) decreased total glutathione (GSH + GSSG) by 7% but had no detectable effect on the concentration of oxidized glutathione (GSSG), reduced ascorbate, or total ascorbate. In a model of reversible, bilateral hemispheric ischemia (four‐vessel occlusion) no changes in glutathione or ascorbate were detected after 30 min of ischemia. During 24 h of reperfusion following such an insult no detectable change in total ascorbate, reduced ascorbate, or oxidized glutathione was noted; however, total brain glutathione declined by 25%. The findings are discussed in relation to the hypothesis that the deleterious effects of ischemia are due to an increase in free radical production which in turn leads to increased lipid peroxidation.
Blood Platelets Contain a Neuron‐Specific Enolase Subunit
Authors: Marangos Paul J. , Campbell Iain C. , Schmechel Donald E. , Murphy Dennis L. , Goodwin Frederick K.
Published: October 2006

Abstract: Neuron‐specific enolase (NSE) is a cell‐specific isoenzyme of the glycolytic enzyme enolase that is present only in neurons and selected neuroendocrine cells. We now report the presence of this neuronal marker in blood platelets. The level of NSE found in human blood platelets is much lower than that found in brain tissue (0.045% of the total soluble protein for platelets versus 1.5% for cortical tissue), but is 20‐30 times higher than NSE levels found in peripheral non‐nervous tissues. Chromatographic analysis indicates that the majority of the NSE γ‐subunit in platelets is present as the hybrid αγ isoenzyme. This, coupled with the high level of non‐neuronal enolase (NNE) found in platelets, indicates that blood platelets contain both the α‐ and γ‐ subunit.
Ontogenetic Development of Histamine H1‐ Receptor Binding in Rat Brain
Authors: Tran Vinh Tan , Freeman Andrew D. , Chang Raymond S. L. , Snyder Solomon H.
Published: October 2006

Abstract: Histamine H1‐ receptors labeled with [3H]mepyramine in rat brain show an age‐dependent development. [3H]Mepyramine receptor density and histidine decarboxylase activity in whole rat brain reach adult levels at 25–30 days after birth and they attain 50% of adult level at day 10 and 17, respectively. The apparently later development of histidine decarboxylase activity in whole rat brain is partly accounted for by a biphasic developmental increase of this enzymatic activity in cerebral cortex. For all other brain regions examined, the development of histamine H1‐ receptors parallels that of histidine decarboxylase. The increase in [3H]mepyramine binding can be accounted for by an absolute increase in the numbers of the receptor sites, with no change in affinity. Subcellular fractionation studies indicate that histamine H1‐ receptors are predominantly associated with synaptosomal fractions derived from both newborn and adult rat.
Phosphatidylinositol Labelling in Response to Activation of Muscarinic Receptors in Bovine Adrenal Medulla
Authors: Mohd. Adnan N. A. , Hawthorne J. N.
Published: October 2006

Abstract: The secretion of catecholamines and the labelling of phospholipids with 32Pi has been studied in slices of bovine adrenal medulla. Both nicotinic and muscarinic drugs provoked catecholamine secretion, but only muscarinic activation was accompanied by the increased labelling of phosphatidylinositol and phosphatidic acid.
Glutathione‐S‐Transferase Activity in the Brain: Species, Sex, Regional, and Age Differences
Authors: Das Mukul , Dixit Rakesh , Seth Prahlad K , Mukhtar Hasan
Published: October 2006

Abstract: Glutathione‐S‐transferase activity in the brain of male mammals (rat and mouse) was found to be relatively lower than in that of females. In contrast, the male aves (pigeon, kite, vulture, and crow) exhibited comparatively higher activity of brain glutathione‐S‐transferase than the corresponding females. Postnatal development of cytosolic glutathione‐S‐transferase activity in the rat brain was also investigated. The day‐7 rats showed a low activity of 48 nmol/min/mg protein that gradually increased 3.2‐fold over the age of 28 days. No striking differences in brain enzyme activities were observed between the 35‐ and 90‐day‐old rats. Discrete brain regions of immature rats were found to possess considerable but lower quantities of glutathione‐S‐transferase activity than those of the adults. The activity increased with the onset of development and attained a steady state after 21 days of age.
Concentrations of Striatal Catecholamines in Rats Given Manganese Chloride Through Drinking Water
Authors: Chandra S. V. , Shukla G. S.
Published: October 2006

Abstract: Male albino rats were exposed to manganese through drinking solution containing MnCl2·4H2O (1 mg/ml) in water. The contents of catecholamines, homovanillic acid, manganese and the activity of monoamine oxidase (MAO) were measured in the corpus striatum at different time intervals up to a period of 360 days. The contents of tyrosine in the corpus striatum and serum were also estimated. Manganese treatment produced an initial increase in the contents of dopamine (DA), norepinephrine (NE), homovanillic acid (H VA) and tyrosine in the corpus striatum. This was followed by a period when concentrations were almost normal (dopamine from 120 to 240 days, norepinephrine at 180 and 240 days and homovanillic acid at 240 days after manganese administration). Thereafter the contents of these substrates declined significantly at 300 and 360 days of treatment. However, these alterations were not correlated with the concentrations of manganese in this region, which gradually increased up to 240 days, and thereafter remained constant until the termination of the experiment. The underlying biochemical mechanisms of manganese‐induced sequential changes in the striatal contents of catecholamines have been discussed in relation to the development of psychiatric and neurological phases of manganese poisoning.
δ‐Aminolaevulinic Acid Uptake, Toxicity, and Effect on [14C]γ‐Aminobutyric Acid Uptake into Neurons and Glia in Culture
Authors: Percy V. A. , Lamm M. C. L. , Taljaard J. J. F.
Published: October 2006

δ‐Aminolaevulinic acid (ALA) uptake into neurons and glia in primary culture as well as ALA toxicity and its effects on γ‐aminobutyric acid (GABA) uptake were examined. [4‐14C]ALA uptake into neurons and glia was nonsaturable, partially Na+‐ and temperature‐dependent, and appeared to comprise mainly diffusion into the cell. 2,4‐Dinitrophenol caused some inhibition of [4‐14C]ALA uptake whereas ouabain, KCN, or amino acids at 1 mM concentration were without effect. ALA (1 mM) caused a slight inhibition of [U‐14C]GABA uptake into neurons (14%) and glia (9%), but was without effect at lower concentrations. It is unlikely that, in acute porphyria, ALA reaches sufficiently high levels in nervous tissue to interfere with the reuptake of GABA into neurons or glia. ALA was shown to be toxic, judged by the loss of cells, to both neurons and glia at concentrations as low as 10 μM. Such a concentration of ALA may be expected to occur in the CSF of porphyric patients in the acute attack. However, results obtained with dispersed cells in culture may not necessarily reflect the situation in vivo where the cell may have a far greater resistance to the effects of toxic agents.
Studies on Dihydropteridine Reductase Activity in Pheochromocytoma Cells
Authors: Liang Bruce T. , Vaccaro Karen K. , Perelle Bernyce A. , Perlman Robert L.
Published: October 2006

Abstract— The activity of dihydropteridine reductase (DPR) in pheochromocytoma cells has been studied. The activity of this enzyme in crude extracts of pheochromocytoma cells is approximately 50 nmol/min/mg protein. This activity is very much greater than the activity of tyrosine 3‐monooxygenase (TH) in these extracts and the rate of conversion of tyrosine to DOPA in intact pheochromocytoma cells. Incubation of the cells with 56 mm‐K+ or with cholera toxin has previously been shown to increase the rate of catecholamine synthesis and to cause a stable activation of TH in the cells. These treatments do not produce a stable activation of DPR, as assayed in vitro. Methotrexate inhibits DPR activity in vitro with an I50 of approximately 20 μm, but has no effect on the rate of DOPA formation in intact pheochromocytoma cells. Therefore, DPR does not appear to be the rate‐limiting enzyme in the pathway of catecholamine synthesis in pheochromocytoma cells. Moreover, the activities of DPR and of TH are not regulated coordinately in these cells.
High‐Affinity Binding of [3H]Desipramine to Rat Brain: A Presynaptic Marker for Noradrenergic Uptake Sites
Authors: Rehavi M. , Skolnick P. , Brownstein M. J. , Paul S. M.
Published: October 2006

Abstract: High‐affinity binding sites (apparent KD= 1.5 nM) for [3H]desipramine have been demonstrated and characterized in membranes prepared from rat brain. The binding of [3H]desipramine was found to be saturable, reversible, heat‐sensitive, sodium‐dependent, and regionally distributed among various regions of the brain. High concentrations of [3H]desipramine binding sites were found in the septum, cerebral cortex, and hypothalamus, whereas lower concentrations were found in the medulla, cerebellum, and corpus striatum. A very good correlation (r= 0.81, P < 0.001) was observed between the potencies of a series of drugs in inhibiting high‐affinity [3H]desipramine binding and their capacity to block norepinephrine uptake into synaptosomes. In 6‐hydroxydopamine‐lesioned rats there was a marked decrease in [3H]norepinephrine uptake and [3H]desipramine binding with no significant alterations in either [3H]serotonin uptake or [3H]imipramine binding. These results suggest that the high‐affinity binding of [3HJdesipramine to rat brain membranes is pharmacologically and biochemically distinct from the high‐affinity binding of [3H]imipramine, and that there is a close relationship between the high‐affinity binding site for [3H]desipramine and the uptake site for norepinephrine.
Accumulation of Glucosylceramide and Glucosylsphingosine (Psychosine) in Cerebrum and Cerebellum in Infantile and Juvenile Gaucher Disease
Authors: Nilsson Olle , Svennerholm Lars
Published: October 2006

Abstract: Three major clinical variants of Gaucher disease have been defined: Type I, chronic nonneuronopathic; Type II, acute neuronopathic; and Type III, subacute neuronopathic. In a search for the underlying molecular basis of the neurological manifestations, the concentration and composition of cholesterol, phospholipids, neutral glycosphingolipids, and gangliosides were examined in cerebral and cerebellar cortices of five cases of Type II, eight cases of Type III, and one case of presumed Type I/III. In Type II the concentration of glucosylceramide was 140‐530 μmol/kg in cerebral cortex and 51‐450 μmol/kg in cerebellar cortex, the highest values found in the most fulminant cases. These concentrations were 20‐80 times greater than normal in cerebral cortex and 5‐40 times normal in cerebellar cortex. In Type III the concentration of glucosylceramide was 37‐65 and 59‐1750 μmol/kg in cerebral and cerebellar cortex, respectively. The highest concentrations were found in the cerebellum of patients who had survived splenectomy for several years. The ceramide composition of the accumulated glucosylceramide suggested that brain gangliosides were the major precursors of the glucosylceramide in brains of Type II but in cerebellar cortex in Type III was partly of extracerebral origin. The levels of lactosylceramide and oligohexaosylceramides were slightly raised in all brain specimens from the Gaucher cases. The ganglioside concentration was normal, whereas there was a certain increase in the proportion of GM2 and GM3 gangliosides. The brain glycosphingolipid changes in the Type I/III case were similar but slightly less than those in Type III cases of corresponding age. Glucosylsphingosine (psychosine), never detected in normal human brain, was demonstrated in brains from all the Gaucher cases. The psychosine concentration was highest in Type II cases, 3.8‐8.8 and 3.9‐12.3 μmol/kg in cerebral and cerebellar cortex, respectively, with the highest values found in the most fulminant cases. In Type III the psychosine concentration varied more widely, 0.8‐4.6 and 1.4‐6.3 μmol/kg in cerebral and cerebellar cortex, respectively. The lowest value, 0.7 μmol/kg, was found in the Type I/III case. Our method detected psychosine down to 0.01 μmol/kg, which means that the concentration of psychosine was increased at least 100‐ to 1000‐fold in Gaucher grey matter. We suggest that the accumulation of the cell‐toxic substance psychosine is the basis for the extensive neuronal cell loss in Gaucher disease, which is most striking in Type II disease.
Neuritogenic Determinant of Bovine P2 Protein in Peripheral Nerve Myelin
Authors: Uyemura Keiichi , Suzuki Masaru , Kitamura Kunio , Horie Kayoko , Ogawa Yoshihiro , Matsuyama Haruo , Nozaki Sukekatsu , Muramatsu Ichiro
Published: October 2006

Abstract: Experimental allergic neuritis (EAN) is an experimentally produced demyelinating disease of peripheral nervous system. Several peptides of bovine P2 protein were tested for neuritogenic activity in Lewis rats. The hexacosapeptide CiT4 (residues 53‐78 of bovine P2 protein) showed the highest neuritogenic activity among the peptides tested. The nonapeptide (residues 70‐78) and the tridecapeptide (residues 66‐78) were synthesized using the liquid phase peptide synthesis technique. The tridecapeptide showed mild, but definite activity in inducing EAN in the rats, while the nonapeptide was inactive. The localization of the neuritogenic determinant of bovine P2 protein in Lewis rats is discussed.
Age‐Correlated Loss of Dopaminergic Binding Sites in Human Basal Ganglia
Authors: Severson J. A. , Marcusson J. , Winblad B. , Finch C. E.
Published: October 2006

Abstract: Human caudate nucleus, putamen, substantia nigra, and nucleus accumbens were analyzed for the effects of age on dopaminergic binding sites. Decreases in the number of dopaminergic binding sites were detected with age in caudate nucleus (44 specimens from three sample groups) and substantia nigra (n = 12). In caudate nucleus, the decline in [3H]2‐amino‐6,7‐dehydroxy‐1,2,3,4‐tetrahydronaphthalene sites was three times greater than for [3H]spiperone, but age changes were significant in only two of the three sampling groups. No age changes in binding were detected in the putamen (n = 44) or nucleus accumbens. Age, sex, and tissue source all significantly contributed to variance. However, cause of death, time from death to tissue freezing, and length of storage did not influence dopaminergic binding in the caudate nucleus or putamen. Relative to the life‐span, the age‐correlated decrease in dopaminergic binding sites of human brain approximates that in aging rodent striatum. Comparisons of altered dopaminergic binding with other age‐correlated changes suggest that neuronal loss may not be involved in the loss of binding sites before midlife.
On the Mechanism of the Involvement of Monoamine Oxidase in Catecholamine‐Stimulated Prostaglandin Biosynthesis in Particulate Fraction of Rat Brain Homogenates: Role of Hydrogen Peroxide
Authors: Seregi András , Serfözö Péter , Mergl Zsuzsanna , Schaefer András
Published: October 2006

Abstract: The mechanism of involvement of monoamine oxidase (MAO) in catecholamine‐stimulated prostaglandin (PG) biosynthesis was studied in the particulate fraction of rat brain homogenates. High concentrations of either noradrenaline (NA) or dopamine (DA) stimulated effectively PGF2α formation. The same amount of 2‐phenylethylamine (PEA) acted similarly, provided that it was administered together with a catecholamine analogue or metabolite possessing the 3,4‐dihydroxyphenyl nucleus–3, 4‐dihydroxyphenylalanine (DOPA), 3,4‐dihydroxyphenylacetic acid (DOPAC), 3,4‐dihydroxyphenyl‐glycol (DOPEG), 3,4‐dihydroxyphenylacetaldehyde (DOPAL), or α‐methylnoradrenaline (α‐met‐NA)–or with SnCl2. In the absence of PEA, these compounds were ineffective with regard to stimulation of PGF2α formation. Catalase, pargyline, or indomethacin abolished completely PGF2α formation elicited either by catecholamines or by PEA plus a 3,4‐dihydroxyphenyl compound or SnCl2. With regard to the stimulation of PGF2α formation in the presence of α‐met‐NA, PEA could be replaced by H2O2, generated by the glucose oxidase(GOD)‐glucose system. The effect of H2O2 was inhibited by indomethacin or catalase, but pargyline was ineffective. It is assumed that catecholamines play a dual role in the activation of PG biosynthesis in brain tissue. During the enzymatic decomposition of catecholamines MAO produces H2O2, which stimulates endoperoxide synthesis. Simultaneously, catecholamines as hydrogen donors promote the nonenzymatic transformation of endoperoxides into PGF2α. The possible physiological importance of these findings is discussed.
Changes in Monoamine Oxidase Activity in Rat Brain During Alloxan Diabetes
Authors: Mayanil C. S. K. , Kazmi S. M. I. , Baquer N. Z.
Published: October 2006

Abstract: The effect of alloxan diabetes on the activity of monoamine oxidase was studied in three regions of the rat brain at various time intervals after the onset of diabetes. It was observed that monoamine oxidase activity was decreased at early time intervals after diabetes, followed by a recovery in all three regions of the brain. A reversal of the effect was observed with insulin administration to the diabetic rats.
Stimulation of Phospholipase A2 and Secretion of Catecholamines from Brain Synaptosomes by Potassium and A23187
Authors: Bradford Peter G. , Marinetti Guido V. , Abood Leo G.
Published: October 2006

Abstract: Potassium depolarization of rat brain synaptosomes (containing incorporated l‐acyl‐2‐[14C]arachidonyl‐phosphatidylcholine) stimulated endogenous phospholipase A1 (EC 3.1.1.32) and A2 (EC 3.1.1.4), as determined by the formation of [14C]lysophosphatidylcholine, [14C]arachidonate, and [14C]prostaglandins, and also stimulated the secretion of [3H]catecholamines. The phospholipase A2 stimulation, dependent on calcium, was elicited in resting synaptosomes by A23187 and was demonstrated with incorporated 1‐acyl‐2‐[l4C]oleoyl‐phosphatidylcholine but not with incorporated [I4C]phosphatidylethanolamine or [l4C]phosphatidylserine. Inhibitors of phospholipase A2 [p‐bromophenacylbromide (10 μM), trifluoperazine (3 μM), and quinacrine (3 μM) reduced the potassium‐stimulated [3H]catecholamine release from synaptosomes to 78, 39. and 55%, respectively, of depolarized controls. The addition of lysophosphatidylcholine increased the release of [3H]norepinephrine to levels observed with potassium depolarization, whereas lysophosphatidylethanolamine, lysophosphatidylserine, and sodium dodecyl sulfate were much less effective. Potassium stimulation of synaptosomes increased the endogenous levels of free arachidonic acid and prostaglandins E2 and F2α. Indomethacin and aspirin decreased the amounts of prostaglandins formed, allowed the accumulation of free arachidonic acid, and diminished the potassium‐stimulated release of [3H]dopamine. p‐Bromophenacylbromide inhibited the formation of prostaglandin F2α. Addition of prostaglandin E2 inhibited, whereas prostaglandin F2α enhanced the release of [3H]norepinephrine. These results suggest that calcium influx induced by synaptosomal depolarization activates endogenous phospholipase A2, with subsequent formation of lysophosphatidylcholine and prostaglandins, both of which may modulate neurosecretion.
Enzyme‐Linked Immunosorbent Assay of the D2‐Glycoprotein
Authors: Ibsen Susanne , Berezin Vladimir , Nørgaard‐Pedersen Bent , Bock Elisabeth
Published: October 2006

Abstract: D2 is a glycoprotein enriched in neuronal membranes and probably involved in intercellular adhesion. An immunochemical relationship between D2 and the neuronal cell adhesion molecule from chick has been demonstrated. Changes in D2 concentration in human body fluids correlate to certain neurological diseases.We here report the purification of the D2 membrane proteins from fetal and adult human brain and the demonstration of physicochemical differences between the two proteins. Enrichments of 133 times (fetal D2) and 350 times (adult D2) were found. Specific rabbit antisera against the purified D2 proteins were produced, and this enabled the setting up of an enzyme‐linked immunosorbent assay for D2 quantification in human brain extracts, cerebrospinal fluids, sera, and amniotic fluids.
Histamine in the Insect Nervous System: Distribution, Synthesis and Metabolism
Authors: Elias Michael S. , Evans Peter D.
Published: October 2006

Abstract: The distribution of histamine in the nervous systems of the locust, the cockroach, and the sphinx moth was mapped and the capacity of locust nervous tissue to synthesise and metabolise histamine was assessed. In all three species the highest levels of histamine were present in the retina and in the lamina neuropil of the optic lobe. Lower levels of histamine were detectable throughout the nervous system. In the locust the retina was shown to synthesise considerable quantities of histamine. The optic lobe and metathoracic ganglion synthesised smaller, though significant, amounts of histamine. Metabolic in activation of histamine in locust nervous tissue was shown to occur primarily via oxidation to imidazole‐4‐acetic acid and via N‐acetylation to N‐acetyl histamine. Whereas the retina and the optic lobe formed the two metabolic products in approximately equal proportions, the metathoracic ganglion produced almost three times as much N‐acetyl histamine as imidazole‐4‐acetic acid.
Changes in Free Fatty Acids and Diglycerides in Mouse Brain at Birth and During Anoxia
Authors: de Turco Elena B. Rodriguez , Bazan Nicolas G.
Published: October 2006

Abstract: Within the first few hours of life in the mouse, marked changes were seen in brain endogenous free fatty acids (FFA). A 21% decrease in the total FFA pool occurred during the 1st h of life, and a constant value was maintained thereafter to 10 h. Polyunsaturated fatty acids displayed a different pattern of change. There was 27% less free ararhidonic acid at birth (0 h) than 1 h later. Similar values were obtained for docosahexaenoic acid at birth and at 10 h, although palmitoleic and oleic acids decreased markedly after 1 h. The polyunsaturated fatty acyl chains of diglycerides (DG) showed a statistically significant increase as a function of time after birth, despite an unchanged total DG pool size. The brains of pups subjected to 40 min of N2‐anoxia immediately after delivery exhibited a decrease in FFA, especially the monoenoic components, but 60 min of anoxia yielded higher FFA levels. Anoxia induced at 10 h increased FFA and arachidonic acid was higher than when anoxia was induced at 0 h. FFA accumulation was further stimulated by raising the environmental temperature during anoxia. When anoxia was induced, DG exhibited a net increase in palmitate, oleate, and palmitoleate at 0 and 10 h. No arachidonoyl‐DG accumulated at 0 h, even after 60 min of anoxia, and stearate was unchanged at 0 and 10 h. The lipid changes observed in the brain during the first hours of life suggest that the enzymatic reactions that promote accumulation of free arachidonic and docosahexaenoic acids and arachidonoyl‐DG in the mature brain are present at low levels at the time of delivery. The sluggish modifications found in our study may be related to the longer resistance of newborns to oxygen deficiency.
S‐100‐Mediated Inhibition of Brain Protein Phosphorylation
Authors: Patel Jitendra , Marangos Paul J. , Heydorn William E. , Chang Garrick , Verma Ajay , Jacobowitz David
Published: October 2006

Abstract: The effects of the glial‐specific, calcium‐binding, S‐100 protein on brain membrane and supernatant protein phosphorylation were assessed. S‐100 concentrations as low as 5 μg/ml caused a marked inhibition of the phosphorylation of a soluble brain protein having a molecular weight of 73,000 daltons (73K). This protein was designated the S‐100 protein‐modulated phosphoprotein (SMP). Half‐maximal inhibition of the phosphorylation of SMP by S‐100 was obtained at concentrations of 12 μg/ml (0.57 (μM). The inhibition of SMP phosphorylation by S‐100 was calcium‐dependent, with a calculated calcium Ka of 2.0 ± 0.3 μM. SMP phosphorylation was also inhibited by calmodulin, but only partially and with a much lower potency. The inhibition of SMP phosphorylation by S‐100 was not inhibited by fluphenazine, whereas the effect of calmodulin was. SMP was found in many brain areas, with the highest levels seen in the corpus callosum. Various peripheral tissues, such as kidney; liver; and pineal, pituitary, and adrenal glands, did not contain detectable SMP levels. At higher S‐100 concentrations, >10μg/ml, the phosphorylation of several other soluble proteins was markedly inhibited. These proteins have molecular weights of 56K, 50K, and 47K. The phosphorylation of these proteins was enhanced by calmodulin. These data suggest that the S‐100 protein may function to modulate the phosphorylation of brain proteins in a manner analogous to (although in a reciprocal fashion) that of calmodulin.
Effects of Postmortem Delay and Temperature on Neurotransmitter Receptor Binding in a Rat Model of the Human Autopsy Process
Authors: Whitehouse P. J. , Lynch D. , Kuhar M. J.
Published: October 2006

Abstract: Studies of neurotransmitter and drug receptor alterations in neurodegenerative disorders have contributed to our understanding of the pathophysiology of these conditions. The effect of postmortem delay in freezing tissue after death and prolonged storage of tissue prior to analysis on receptor binding assays are potential artifacts that may limit interpretation of the effects of disease on receptor populations. We used a rat model of the human autopsy process to study the effects of increasing postmortem delay and storage time on N‐methylscopolamine (NMS), p‐aminoclonidine (PAC), flunitrazepam (FLU), and spiperone binding in a variety of rat brain regions. The rat brains were cooled using a temperature‐controlled environment and thermistor probe to follow cooling curves obtained in human brain. Brains were cooled to either room temperature (22°C) or refrigerator temperature (4°C). For three of the four receptors, receptor binding decreased as postmortem delay before freezing increased, particularly in tissue cooled to room temperature. Unlike binding at other receptor sites, FLU binding increased with increasing postmortem delay to freezing. Different effects on KD and Bmax were noted for each ligand studied. No effects of the freezing process itself or storage at ‐80°C were detectable.
Phencyclidine and Analogues: Effects on Brain Protein Synthesis
Authors: Deutsch Dale G. , Koul Omanand , Kersten Roger S.
Published: October 2006

Abstract: Phencyclidine and four analogues were tested for their capacity to inhibit total protein synthesis in a brain homogenate. At 1.0 mM they were all found to be potent inhibitors with values ranging from 36% to 96% inhibition. At this high concentration two of the analogues were equal to or more effective than the classic protein synthesis inhibitors cycloheximide and emetine. At lower concentrations the inhibition dropped off sharply to 18% at 1.0 × 10−4M and 9% at 1.0 × 10−5M for phencyclidine. If the inhibition observed in the brain homogenate occurs in vivo it may account for the high incidence of memory loss reported with phencyclidine use.
Uptake of Exogenous Aspartate into Circumventricular Organs but Not Other Regions of Adult Mouse Brain
Authors: Price Madelon T. , Pusateri Mary Ellen , Crow Sue Ella , Buchsbaum Susan , Olney John W. , Lowry Oliver H.
Published: October 2006

Abstract: Adult mice were treated intraperitoneally with aspartate (Asp) at one of several doses (0.47–3.75 mmol/kg) and 30 min later given a subcutaneous Asp injection at the same dose. This treatment regimen resulted in steady state blood Asp elevations, a given dose producing the same degree of elevation at both 30 and 60 min. The lowest and highest doses, respectively, produced fourfold and 55‐fold elevations of serum Asp. In selected circumventricular organ (CVO) regions of brain which lack blood brain barriers, tissue Asp levels rose 1.5 and 3 times above control values following the lowest and highest doses, respectively, whereas tissue Asp remained unchanged in non‐CVO brain regions. Thus, even very moderate Asp dosing causes marked increases in CVO Asp. In order to analyze the pattern of Asp uptake into CVO, Asp was assayed in numerous subdivisions of each CVO, and maps were constructed which reflected microregional concentration differences. The pattern of Asp distribution suggests that Asp enters brain via fenestrated capillaries serving certain portions of CVO and then spreads into adjacent brain tissue. In separate experiments, we administered a single high dose of Asp (15 mmol/kg) to both adult and infant mice and measured Asp in serum and select brain regions 60 min later. Asp concentrations in serum and CVO (but not other brain regions) rose markedly at both ages but the increases were greater in serum and therefore also in CVO of infants. This may explain in part the observation that a given dose of Asp destroys a larger number of CVO neurons in infant than in adult mice. Our findings support a growing body of evidence that CVO are an important communication link between blood and brain.
Taurine Modulation of the Benzodiazepine‐γ‐Aminobutyric Acid Receptor Complex in Brain Membranes
Authors: Medina †Jorge H. , De Robertis Eduardo
Published: October 2006

Abstract: In unwashed brain membranes taurine produced an inhibition of [3H]flunitrazepam ([3H]FNZ) binding with IC50 ranging between 31.5 and 11.9 μM; the IC20 varied between 18 and 26 nM. This inhibitory effect was of a mixed type, with a reduction in Bmax and an increase in KD. Various precursors and metabolites of taurine have a less inhibitory effect. Taurine also has little inhibitory effect (IC50 above 500 μM) on the binding of [3H]ethyl‐β‐carboline‐3‐carboxylate. In extensively washed membranes, 10−5M taurine produces a 16–21% increase in the binding of [3H]FNZ while 10−5M γ‐ami‐nobutyric acid (GABA) increases it between 31 and 42%. However, if 10−5M GABA plus 10−5M taurine is included in the assay there is a dramatic inhibitory effect. Taurine causes an inhibition of the GABAergic enhancement of [3H]FNZ binding with an IC50 between 7.3 and 7.8 μM. Binding experiments with [3H]taurine done under different conditions failed to detect a Na+‐independent and specific [3H]taurine receptor. These results suggest that endogenous taurine, the second most abundant free amino acid in brain, may play an important modulatory role in the GABA‐benzodiazepine receptor complex.
Parallel but Separate Release of Catecholamines and Acetylcholinesterase from Stimulated Adrenal Chromaffin Cells in Culture
Authors: Mizobe Fumio , Iwamoto Machiko , Livett Bruce G.
Published: October 2006

Abstract: A pharmacological study was made of the effects of veratridine and lasalocid on the release of catecholamines, acetylcholinesterase (AChE) and dopamine‐β‐hydroxylase (DBH) from cultures of isolated bovine adrenal chromaffin cells. Exposure of the cultures to veratridine resulted in concomitant release of catecholamines and AChE into the external medium in a dose‐dependent and Ca2 +‐dependent manner. A Ca2+ iono‐phore, lasalocid, also produced a dose‐dependent and parallel release of both catecholamines and AChE. The release of the two components was accompanied by release of DBH. The present results provide pharmacological evidence for a parallel release of catecholamines, AChE, and DBH from cultured adrenal chromaffin cells, and the stoichiometry of the release evoked by different secretagogues suggests that AChE and catecholamines are released from different cellular compartments.
Neosurugatoxin, a Specific Antagonist of Nicotinic Acetylcholine Receptors
Authors: Hayashi E. , Isogai M. , Kagawa Y. , Takayanagi N. , Yamada S.
Published: October 2006

Abstract: Neosurugatoxin (NSTX) (3 nM‐30 nM), recently isolated from the Japanese ivory mollusc (Babylonia japonica) exerted a potent antinicotinic action in the isolated guinea pig ileum. Specific [3H]nicotine binding to rat forebrain membranes was saturable, reversible, and of high affinity. Nicotinic cholinergic agonists exhibited a markedly greater affinity for [3H]nicotine binding sites than a muscarinic agonist, oxotremorine. Although α‐bungarotoxin had no effect on [3H]nicotine binding, low concentrations (1 nM‐1 μM) of NSTX inhibited [3H]nicotine binding in the forebrain membranes and its IC50 value was 69 ± 6 nM. On the other hand, NSTX did not affect muscarinic receptor binding in the brain. These data indicate that NSTX may be of appreciable interest as a neurotoxin with a selective affinity for ganglionic nicotinic receptors.
Two‐Dimensional Electrophoresis of Cerebrospinal Fluid and Ventricular Fluid Proteins, Identification of Enriched and Unique Proteins, and Comparison with Serum
Authors: Walsh Michael J. , Limos Leonore , Tourtellotte Wallace W.
Published: October 2006

Abstract: The proteins of cerebrospinal fluid (CSF) and ventricular fluid have been analyzed by two‐dimensional electrophoresis (2DE) and the patterns compared with autologous serum. Fourteen proteins were specifically identified by immunoprecipitation followed by 2DE, or by blotting 2DE gels to nitrocellulose and detection by peroxidase staining. Proteins in CSF and serum with high and low affinity for the ligands, protein A, Cibacron Blue, and concanavalin A, were also characterized by 2DE. The 2DE profiles of CSF and serum proteins were similar and indicated that a relatively nonselective filtration mechanism based on protein size is the major determinant for the overall pattern of CSF proteins. The classic CSF‐enriched or CSF‐specific proteins, β‐trace, prealbumin, transferrin, and β‐2‐microglobulin, were identified according to 2DE coordinates. Charge differences between CSF and serum for transferrin and prealbumin were identified. In addition, a large number of additional CSF‐enriched or CSF‐specific proteins of high, intermediate, and low molecular weight, all predominantly anodic in mobility, were identified. Three acidic protein complexes, heterogeneous in charge and molecular weight, were characterized as constituents of normal CSF, and two of these are increased in patients with inflammatory diseases of the CNS. All three proteins and several other proteins unique to CSF bound to Cibacron Blue‐Sepharose. The use of 2DE in conjunction with affinity chromatography and sensitive protein stains enlarged the number of proteins previously identified as unique to CSF. By a modified 2DE and silver staining procedure, most of these proteins were visible without prior concentration of CSF.
BAY K 8644, a 1,4‐Dihydropyridine Ca2+ Channel Activator: Dissociation of Binding and Functional Effects in Brain Synaptosomes
Authors: Rampe D. , Janis R. A. , Triggle D. J.
Published: October 2006

K+‐stimulated 45Ca2+ uptake into rat brain and guinea pig cerebral cortex synaptosomes was measured at 10 s and 90 s at K+ concentrations of 5–75 mM. Net increases in 45Ca2+ uptake were observed in rat and guinea pig brain synaptosomes. 45Ca2+ uptake under resting or depolarizing conditions was not increased by the 1,4‐dihydropyridine BAY K 8644, which has been shown to activate Ca2+ channels in smooth and cardiac muscle. High‐affinity [3H]nitrendipine binding in guinea pig synaptosomes (KD= 1.2 × 10‐10M, Bmax= 0.56 pmol mg‐1 protein) was competitively displaced with high affinity (IC50, 2.3 × 10‐9M) by BAY K 8644. Thus high‐affinity Ca2+ channel antagonist and activator binding sites exist in synaptosome preparations, but their relationship to functional Ca2+ channels is not clear.
Properties and Regional Distribution of Pyruvate Dehydrogenase Kinase in Rat Brain
Authors: Sheu Kwan‐Fu Rex , Lai James C. K. , Blass John P.
Published: October 2006

Abstract: A method is described to measure directly in rat brain the activity of pyruvate dehydrogenase kinase (PDHa kinase; EC 2.7.1.99), which catalyzes the inactivation of pyruvate dehydrogenase complex (PDHC, EC 1.2.4.1, EC 2.3.1.12, and EC 1.6.4.3). The activity showed the expected dependence on added ATP and divalent cation, and the expected inhibition by dichloroacetate, pyruvate, and thiamin pyrophosphate. These results, and the properties of pyruvate dehydrogenase phosphate phosphatase (EC 3.1.3.43), indicate that the mechanisms of control of phosphorylation of PDHC seem qualitatively similar in brain to those in other tissues. Regionally, PDHa kinase is more active in cerebral cortex and hippocampus, and less active in hypothalamus, pons and medulla, and olfactory bulbs. Indeed, the PDHa kinase activity in olfactory bulbs is uniquely low, and is more sensitive to inhibition by pyruvate and dichloroacetate than that in the cerebral cortex. Thus, there are significant quantitative differences in the enzymatic apparatus for controlling PDHC activity in different parts of the brain.
Effect of Membrane Polyunsaturation on Carrier‐Mediated Transport in Cultured Retinoblastoma Cells: Alterations in Taurine Uptake
Authors: Yorek Mark A. , Strom David K. , Spector Arthur A.
Published: October 2006

Summary: Neural cell membranes naturally contain a large amount of polyunsaturated fatty acid, but the functional significance of this is unknown. An increase in membrane polyunsaturation has been shown previously to affect the high‐affinity transport systems for choline and glycine in cultured human Y79 retinoblastoma cells. To test the generality of membrane polyunsaturation effects on transport, we investigated the uptake of other putative neurotransmitters and amino acids by these cells. Taurine, glutamate, and leucine were taken up by both high‐ and low‐affinity transport systems, whereas serine, γ‐aminobutyrate, and α‐aminoisobutyrate were taken up only by low‐affinity systems. The high‐affinity taurine and glutamate and low‐affinity serine uptake systems were Na+ dependent. Arachidonic acid (20:4) supplementation of Y79 cells produced enrichment of all the major microsomal phosphoglycerides with 20:4, while docosahexaenoic acid (22:6) supplementation produced large increases in the 22:6 content of all fractions except the inositol phosphoglycerides. Enrichment with these polyunsaturated fatty acids facilitated taurine uptake by lowering the K′ of its high‐affinity transport system. By contrast, enrichment with oleic acid did not affect taurine uptake. Glutamate, leucine, serine, γ‐aminobutyrate, and α‐aminoisobutyrate uptake were not affected when the cells were enriched with any of these fatty acids. These findings demonstrate that only certain transport systems are sensitive to the polyunsaturated fatty acid content of the retinoblastoma cell membrane. The various transport systems either respond differently to changes in membrane lipid unsaturation, or they are located in lipid domains that are modified to different extents by changes in unsaturation.
Lipid Peroxidation In Vivo Induced by Reversible Global Ischemia in Rat Brain
Authors: Watson Brant D. , Busto Raul , Goldberg William J. , Santiso Mercedes , Yoshida Shinichi , Ginsberg Myron D.
Published: October 2006

Abstract: It has been hypothesized that ischemia, followed by reperfusion, facilitates peroxidative free‐radical chain processes in brain. To resolve this question, rats were subjected to reversible global ischemia. From coronal sections of brains frozen in situ, small (ca. 2 mg) amounts of tissue were sampled from neocortex, hippocampus, and thalamus of both cerebral hemispheres of four groups of rats exposed to 30 min cerebral ischemia followed by 0, 30, 60, and 240 min of reperfusion, and from a control group subjected to the same operative procedures, except for the induction of ischemia. Heptane‐solubilized total lipid extracts from these samples were analyzed spectroscopically in the 190–330 nm range for content of isolated (nonconjugated) double bonds and of conjugated diene structures; the latter are formed from isolated double bonds during peroxidation of unsaturated fatty acids. Spectra derived from tissue regions of rats subjected to ischemia, or ischemia followed by reperfusion, were compared to averaged, region‐specific control spectra and were normalized to the original content of isolated double bonds in the peroxidized samples. The resultant difference spectra were analyzed in terms of ratios of conjugated diene concentration to the concentration of isolated double bonds originally at risk in the specific tissue zones considered. The peak representing conjugated diene formation was centered at 238 ± 1 nm and was usually well resolved when the molar ratio [conjugated diene]/[isolated double bonds], expressed as a percentage ([CD]/[IDB]), was greater than 0.25%. The incidence of resolvable conjugated diene peaks was much greater in the reperfused groups (18 of 124 samples total; 0.25% [CD]/[IDB] 1.34%), compared to the nonreperfused group (1 of 38 samples; [CD]/[IDB] = 0.62%). No specific regional susceptibility to conjugated diene formation was observed. It also was shown by computer averaging over all the tissue zones sampled that, if one had used large samples consisting of pooled brain tissue for analysis of lipid peroxides and/or their reaction products, the conjugated diene peak would have been attenuated below distinctly resolvable levels. These results constitute the first demonstration of lipid peroxidation induced by reversible global ischemia. The observation that the effect is highly focal and not generalized throughout the brain suggests that special conditions of reperfusibility and reoxygenation must be satisfied for lipid peroxidation to be detectable in an ischemic milieu.
Characterization of Human Brain S100 Protein Fraction: Amino Acid Sequence of S100β
Authors: Jensen Roy , Marshak Daniel R. , Anderson Clint , Lukas Thomas J. , Watterson D. Martin
Published: October 2006

Abstract: Two major components of human brain S100 fraction were purified by HPLC and an amino acid sequence was elucidated for the S100β component. Human S100 proteins showed absorption spectra and amino acid compositions similar to S100α and S100β from bovine brain. However, the relative amounts of the human proteins were 4% S100α and 96% S100β by weight, while the bovine protein distribution was 47% S100α and 53% S100β by weight. An amino acid sequence of human S100β was established by analysis of overlapping fragments generated by cyanogen bromide and trypsin cleavage. Three amino acid sequence differences between the human and bovine S100β were found at residues 7, 62, and 80. These differences were chemically conservative and compatible with minimum single base changes in the codon structures. These results document that S100β is a conserved protein among mammals and provide the necessary foundation for current clinical studies.