bluuebunny/crossref_metadata_2025 huggingface dataset:
ACETYL‐CoA SYNTHESIZING ENZYME ACTIVITIES IN SINGLE NERVE CELL BODIES OF RABBIT
Authors: Hayashi Hideaki , Kato Takahiko
Published: October 2006

Activities of five enzymes (pyruvate dehydrogenase complex; citrate synthase, EC 4.1.3.7; carnitine acetyltransferase, EC 2.3.1.7; acetyl‐CoA synthetase, EC 6.2.1.1; and ATP citrate lyase, EC 4.1.3.8) were determined in cell bodies of anterior horn cells and dorsal root ganglion cells from the rabbit. For comparison, molecular layer, granular layer and white matter from rabbit and mouse cerebella and cerebral cortex and striatum from the mouse were analyzed. Samples (3–85 ng dry weight) were assayed in 180 to 370 ml of assay reagents containing CoASH and other substrates in excess. By using ‘CoA cycling’, the assay systems were devised to amplify and measure small amounts of acetyl‐CoA formed during the enzyme reactions. Carnitine acetyltransferase was the most active enzyme in single nerve cell bodies and all layer samples, except for rabbit and mouse cerebellar white matter. Citrate synthetase was the lowest in single cell bodies. The activities of carnitine acetyltransferase and acetyl‐CoA synthetase (656 and 89.8 mmoles of acetyl‐CoA formed/kg of dry weight/h at 38°C) from dorsal root ganglion cells were about 2‐fold higher than those from anterior horn cells. The activity of ATP citrate lyase (134mmol of acetyl‐CoA formed/kg of dry weight/h at 38°C) from anterior horn cells was approximately twice that from dorsal root ganglion cells. The activity of this enzyme was distributed in a wider range in anterior horn cells than dorsal root ganglion cells. The second highest activity (80.0 mmol of acetyl‐CoA formed/kg of dry weight/h at 38°C) of ATP citrate lyase was found in striatum where cholinergic interneurones are abundant. Relatively higher activities of this enzyme were found in cerebellar granular layer and white matter which are known to contain the cholinergic mossy fibers. These results suggested that cholinergic neurones contain higher activity of ATP citrate lyase which is thought to supply acetyl‐CoA to choline acetyltransferase (EC 2.3.1.6) as a substrate to form acetylcholine.
α‐DIFLUOROMETHYL DOPA, A NEW ENZYME‐ACTIVATED IRREVERSIBLE INHIBITOR OF AROMATIC L‐AMINO ACID DECARBOXYLASE
Authors: Palfreyman M. G. , Danzin C. , Bey P. , Jung M. J. , Ribereau‐Gayon G. , Aubry M. , Vevert J. P. , Sjoerdsma A.
Published: October 2006

DL‐x‐Difluoromethyl DOPA (DFMD, RMI 71801), an enzyme‐activated irreversible inhibitor of aromatic L‐amino acid decarboxylase in vitro, produces a rapid, long‐lasting and dose‐dependent inhibition of aromatic L‐amino acid decarboxylase in peripheral tissues of mice when administered i.p. or orally. Doses of 500 mg/kg i.p. produce only very slight inhibition of the enzyme activity in mouse brain whilst inhibiting the enzyme activity of peripheral tissues by more than 90%. With L‐[3H]‐DOPA co‐administration brain concentrations of L‐[3H]DOPA and 3H‐catecholamines are increased 3‐ to 8‐fold concomitant with a decrease in the peripheral decarboxylation of L‐[3H]DOPA. Under these conditions it is clear that the slight inhibition of enzyme activity in the brain is totally inadequate to inhibit the decarboxylation of L‐DOPA in this organ. Similarly, the decarboxylation of exogenously supplied 5‐hydroxytryptophan is inhibited peripherally with a consequent increase in brain serotonin concentrations. DFMD is another example of an enzyme‐activated irreversible inhibitor which due to its novel and specific mechanism of action, may offer advantages over existing decarboxylase inhibitors.
MECHANISM OF ACTION OF NOTEXIN AND NOTECHIS 11‐5 ON SYNAPTOSOMES
Authors: Sen I. , Baba A. , Schulz R. A. , Cooper J. R.
Published: October 2006

The neurochemical activity of notexin and notechis II‐5 was investigated using a synaptosomal preparation of rat cerebral cortices. In preparations preincubated with [3H]choline in order to label acetylcholine, the toxins caused a rapid release of the transmitter which was calcium‐dependent. The toxins were also potent inhibitors of high affinity choline uptake. Both agents produced a marked depolarization of the synaptosomal preparation as measured by a fluorescent dye and at high concentrations lysed the preparation. At a concentration of 0.1 μM, notexin and notechis II‐5 caused a 50% increase in the efflux of lactate dehydrogenase activity. These results, together with electron microscopic observations, indicated that the toxins disrupt the synaptosomal membranes presumably by their inherent phospholipase activity. The release of acetylcholine and inhibition of choline uptake, together with the depolarization of synaptosomal membranes noted in this study, could explain the observed electrophysiological effects of these toxins.
EFFECT OF ELECTROSHOCK ON THYMIDINE INCORPORATION INTO RAT BRAIN DNA
Authors: Giuditta A. , Abrescia P. , Rutigliano B.
Published: October 2006

Administration of electroconvulsive shocks in rats induces a marked inhibition of the process of thymidine incorporation into cortical DNA. The inhibitory effect reaches its maximum after 10–15 min. Percentage incorporation returns to normal values within one hour of the treatment. These findings may suggest the participation of a metabolically active fraction of DNA in neural functions.
CHOLINE ACETYLTRANSFERASE AND THE HIGH AFFINITY UPTAKE OF CHOLINE IN CORPUS STRIATUM OF RESERPINISED RATS1
Authors: Burgess E. J. , Atterwill C. K. , Prince A. K.
Published: October 2006

Rats treated with reserpine show increased Vmax for the high affinity uptake of choline into small slices of corpus striatum. The choline acetyltransferase activity of whole homogenates of striatum is also increased. These changes are consistent with increased cholinergic neuronal activity in the striatum and seem likely to be adaptations mediating increased rates of synthesis of acetylcholine. The maximal increases found occurred concurrently, consistent with coupling of the high affinity uptake of choline and its acetylation in cholinergic nerve terminals of the rat. That increased high affinity uptake is accompanied by increased choline acetyltransferase activity, suggests the input of choline is not the sole determinant of rates of synthesis of acetylcholine, in spite of the large Vmas for striatal choline acetyltransferase, compared with that for high affinity uptake. These results seem best explained by kinetic coupling, in the rat, of the high affinity uptake of choline with a limited pool of choline acetyltransferase preferentially localised at the nerve terminal plasma membrane.
ISOLATION AND PURIFICATION OF CHOLINERGIC RECEPTOR PROTEOLIPIDS FROM RAT GASTROCNEMIUS TISSUE1
Authors: Taylor Richard F.
Published: October 2006

Four organic solvent extraction methods have been used to isolate receptor proteolipids from rat gastrocnemius tissue. The resulting proteolipids have high binding capacities and specificities for a number of cholinergic ligands including acetylcholine, α‐bungarotoxin. tubocurarine and deca‐methonium. The proteolipids have been purified by repeated Sephadex LH‐20, Sepharose‐CL and affinity chromatography in organic solvent systems. Protein, carbohydrate and lipid phosphorous analysis of the receptors throughout the purification procedure show that the relative proportions of these components varied with extraction method. The purified receptor proteolipid resulting from wet tissue extraction has been characterized as a somatic, nicotinic cholinergic receptor by its specificity and binding kinetics toward a variety of drugs and toxins. The presence of carbohydrate in the receptor proteolipid preparations throughout the purification procedure may indicate that the cholinergic receptor from rat gastrocnemius tissue is a glycoproteolipid.
ISOLATION AND PURIFICATION OF A VERATRIDINE BINDING PROTEOGLYCOLIPID FROM RAT GASTROCNEMIUS TISSUE1
Authors: Taylor Richard F.
Published: October 2006

A lipoidal‐protein complex has been isolated from rat gastrocnemius tissue which exhibits a highly specific binding capacity for [3H]veratridine. Purification of the complex has been accomplished by a number of chromatographic steps including affinity chromatography in organic solvents utilizing a resin synthesized by oxirane coupling of veratridine to Sephadex LH‐20. The purified complex binds veratridine but not tetrodotoxin or a number of cholinergic ligands. Veratridine binding to the complex is inhibited by aconitine but not tetrodotoxin or cholinergic ligands. The complex has both veratridine saturable (KD= 13 μm) and non‐saturable (KD1 Mm) binding components. Preliminary chemical analysis showed that the complex is a proteoglycolipid with a protein: carbohydrate: phosphorous ratio of 1.5:1.1:1.0. A discussion is presented favoring the identity of the isolated proteoglycoiipid as a portion of the macromolecular complex comprising the axonal sodium action potential ionophore.
THE IN VITRO FORMATION OF ACETYL‐ASPARTYL‐PEPTIDO‐SEROTONIN COMPLEXES BY PIG HYPOTHALAMIC TISSUE EXTRACTS
Authors: Edminson P. D.
Published: October 2006

Abstract—

Peptido‐serotonin complexes are formed on incubation of pig hypothalamic tissue extracts with acetyl‐aspartate, the amino acids glu. ser, gly and ala. an ATP‐regenerating system and serotonin. The purification and partial characterisation of two acetyl‐aspartyl‐peptido‐serotonin complexes is described.
REVERSAL OF AXONAL TRANSPORT IN REGENERATING NERVES1
Authors: Bulger V. T. , Bisby M. A.
Published: October 2006

Abstract— Orthograde and retrograde axonal transport were studied in rat sciatic nerves which had been crushed and either allowed to regenerate, or prevented from doing so by tightly ligaturing the nerve. At various intervals after crushing the nerve. L‐[3H]leucine was injected into the lumbosacral spinal cord. and the subsequent transport of labeled protein in motoneuron axons was quantitated by measuring the accumulation of labeled protein at collection crushes made proximal to the original nerve crush.

Accumulations proximal to the collection crushes (orthograde transport) 9‐11 h after injection (p.i.). decreased within I day of nerve injury, but returned to normal values as regeneration proceeded. In non‐regenerating nerves accumulations remained depressed for at least 30 days.

Accumulations distal to the collection crushes (retrograde transport) 9‐11 h pi. increased over the first 5 days following injury but returned to normal values as regeneration proceeded. In non‐regenerating nerves accumulations remained elevated. The time‐course of retrograde transport of newly‐synthesized protein also returned to normal during nerve regeneration.

It is suggested that changes in retrograde transport during regeneration may inform the neuron cell body of the progress of regeneration and elicit appropriate metabolic responses. among which may be the changes in orthograde transport that follow axotomy.
HIGH AFFINITY l‐[3H]GLUTAMATE BINDING TO POSTSYNAPTIC RECEPTOR SITES ON RAT CEREBELLAR MEMBRANES
Authors: Foster A. C. , Roberts P. J.
Published: October 2006

Abstract—

l[3H]glutamate binding was investigated in membrane preparations derived from rat cerebellum, an area of the brain where it is likely that a high density of postsynaptic glutamate receptors occurs. Glutamate was hound specifically and, in freshly prepared membranes, was optimal under physiological conditions of pH and temperature and was associated with the synaptic membrane fraction of the cell. Specific binding occurred through a single, high‐affinity process with a KD, of 744 nM and a capacity of 73 pmol/mg protein. Unlike the findings reported for GABA, the specific binding of glutamate to fresh membranes did not involve an uptake site. Comparison of the potencies of a wide range of compounds with known pharmacological activities, demonstrated that their ability to displace specific glutamate binding was consistent with specific interactions with glutamate receptors.
Potassium stimulated calcium dependent release of immunoreactive somatostatin from incubated rat hypothalamus
Authors: Berelowitz M. , Kronheim S. , Pimstone B. , Sheppard M.
Published: October 2006

Somatostatin (somatotropin release inhibiting factor, SRIF) is present in the median eminence of the hypothalamus in high concentration (Kronheim et al., 1976), is visualized in nerve endings (Hökfelt et al., 1974) and has been found to be concentrated in the synaptosome fraction of hypothalamic homogenates (Epelbaum et al., 1977; Berelowitz et al., 1978), suggesting a true neurosecretory role. To further explore this possibility we have studied the release of immunoreactive SRIF from the incubated rat hypothalamus (Bradbury et al., 1974: Rotsztein et al., 1977), basally and in response to depolarising concentrations of potassium, and have assessed the calcium dependence of this release.
INCREASE IN LARGE NEUTRAL AMINO ACID TRANSPORT INTO BRAIN BY INSULIN
Authors: De Montis M. G. , Olianas M. C. , Haber B. , Tagliamonte A.
Published: October 2006

Abstract—

The administration of oral glucose to fasted rats produced a decline of all large neutral amino acid levels in serum, including that of the free fraction of tryptophan. In addition to this well known effect, it also decreased the brain concentrations of leucine, isoleucine and valine, while increasing those of tryptophan, tyrosine and phenylalanine. The total concentration of large neutral amino acids in serum was decreased by 44%, while it was slightly increased in brain. Analogous results were obtained in 4 rats injected with exogenous insulin. Moreover, the administration of either glucagon or isoproterenol to rats force‐fed with glucose produced a decline in total serum tryptophan concentration proportional to that of the rise in FFA, while it increased free serum tryptophan and brain tryptophan levels. It can be concluded that insulin stimulates the transport of large neutral amino acids from blood to brain and that the level of free serum tryptophan also controls the entry of tryptophan into the brain under the influence of insulin.
CHARACTERISTICS AND REGIONAL DISTRIBUTIONS OF TWO DISTINCT [3H]NALOXONE BINDING SITES IN THE RAT BRAIN
Authors: Squires R. F. , Braestrup C.
Published: October 2006

Abstract—

Using [3H]naloxone at a concentration of 4.5 nm, the potent opiate agonist etorphine as well as the potent antagonist diprenorphine displace only about 75% of specific naloxone binding P2 fractions from rat whole forebrain, without additive effect. Several other opiates and antagonists completely displace specific naloxone binding. This indicates that etorphine and diprenorphine specifically bind to one and the same naloxone binding site (type I) while leaving another naloxone binding site (type II) unaffected. Type I binding sites are much more thermo‐labile than type II. [3H]Naloxone binding to type I sites is unaffected by incubation temperature in the range 10 to 25°C. while binding type II sites decreases rapidly with increasing incubation temperature, no specific type II binding being detectable at or above 20°C. The two naloxone receptor types also differ with respect to pH dependence, and affinity for naloxone with types I and II having affinity constants (Kd) of 2 and 16 nm, respectively, at 0°C. The two binding sites have different regional distributions with high relative levels of type II receptors in cerebellum and low relative levels in pons‐medulla and striatum. In whole rat brain there are about 4 times as many type II receptors as type I. These results suggest that naloxone and several other opiate agonists and antagonists bind to two distinct receptor types which are probably not agonist/antagonist aspects of the same receptor.
EFFECTS OF SYMPATHECTOMY ON AXOPLASMIC TRANSPORT OF SELECTED ENZYMES INCLUDING MAO AND OTHER MITOCHONDRIAL ENZYMES
Authors: Schmidt Robert E. , Ross C. David , McDougal David B.
Published: October 2006

Abstract— Axoplasmic transport in guanethidine sympathectomized and control rats was investigated by monitoring the accumulations of various enzyme activities proximal to a ligature placed on the sciatic nerve. Sympathectomy affected the accumulations of three different mitochondrial enzymes quite differently: the accumulation of monoamine oxidase (MAO, EC 1.4.3.4) activity was inhibited 65% or more, that of hexokinase (HK, EC 2.7.1.1) activity was only inhibited 26%, while accumulation of glutamic dehydrogenase (GDH, EC 1.4.1.3) activity was unaffected by Sympathectomy. Accumulation of AChE (EC 3.1.1.7) activity was depressed 40%, but accumulations of the activities of the lysosomal enzyme, acid phosphatase (acid P'tase, EC 3.1.3.2), and of the cytosolic enzyme, choline acetyltransferase (CAT, EC 2.3.1.6) were unchanged.

Despite impressive inhibition of MAO accumulation, the intrinsic activity of this enzyme in sciatic nerve was unaffected by Sympathectomy. The existence in nerve of isozymes of MAO was demonstrated using the inhibitors clorgyline and deprenyl. Transported MAO activity was almost entirely type A; intrinsic activity was 2/3 type A and 1/3 type B.

The differential response of the accumulations of the three mitochondrial enzyme activities measured was interpreted to indicate the existence, within neurons, of mitochondria with different enzyme complements.
ISOLATION AND CHARACTERIZATION OF GLUCOCEREBROSIDES FROM ADULT RAT BRAIN1
Authors: Korniat Elizabeth K. , Hof Liselotte
Published: October 2006

Abstract— By chromatography on borate‐coated silicic acid, glucocerebrosides, galactocerebrosides, sulfatides and sphingomyelins from brain tissue could be efficiently separated. Adult rat brain was found to contain 54.1 ± 1.5 nmol of glucocerebrosides per gram fresh weight. Ninety percent of the glucocere‐broside fatty acids were palmitate, stearate and oleate; fatty acids with chain lengths above C20 were virtually absent. No hydroxy fatty acids were found. The long chain bases of adult rat brain glucocerebrosides consisted of 74.6% C18‐sphingosine, 24.4% C18‐sphinganine and 1.1% C20‐sphingosine. These results are compared to those obtained from glucocerebrosides from immature rat brains (Abe & Norton, 1974) and discussed in respect to changes occurring during brain development.
SOLUBILIZATION OF TRYPTOPHAN‐5‐MONOOXYGENASE FROM THE PINEAL GLANDS AND EXISTENCE OF AN ACTIVATING SUBSTANCE IN THE TISSUE EXTRACT1
Authors: Hori Shinichiro , Ohotani Sachiko
Published: October 2006

Abstract—

A particle bound tryptophan‐5‐monooxygenase in bovine pineal glands was solubilized by a combination of high pH (PH 8.5), high salt concentration (0.5 M‐KCl or NaCl), and sonication (20 kHz, 200 W, 30min), We recovered 75% or more of the monooxygenase activity of the tissue homogenate in the 105,000 g supernatant thus confirming our previous study (Horiet al., 1976). The solubilized enzyme preparation contained an activating substance which was also particle bound and which activated the monooxygenase when preincubated together with the enzyme and dithiothreitol.

The solubilized tryptophan‐5‐monooxygenase was purified about 6‐fold over the tissue homogenate using ammonium sulphate fractionation and column chromatography on hydroxylapatite and Sephacryl S‐200. The activating substance was separated from the monooxygenase during hydroxylapatite column chromatography. The activating substance was shown to be different from phospholipids, such as L‐α‐lysophosphatidyl choline and L‐α‐phosphatidyl‐L‐serine, and from heparin or bovine serum albumin, although bovine serum albumin significantly activated the monooxygenase. Further experiments have suggested that both the monooxygenase and the activating substance are modified by dithiothreitol and that these modified materials interact to give the active form of the monooxygenase.
ACYL AND ALK‐1′‐ENYL GROUP COMPOSITION OF ETHANOLAMINE PHOSPHOGLYCERIDES OF HUMAN BRAIN
Authors: Pullarkat Raju K. , Reha Henry
Published: October 2006

Abstract—

Ethanolamine phosphogylcerides (EPG) of human brain gray and white matter were analyzed for their alk‐1′‐enyl group and fatty acid compositions in sn‐glycerol positions 1 and 2. Gray matter contained more 18:0 (54%) and less 18:1 (24.5%) alk‐1′‐enyl residues than white matter (16% and 57%. Sixty per cent of alk‐1′‐enyl 18.1 in gray matter was the (n‐7), against 71%, in white matter. Both gray and white matter contained small amounts of 18:1 (n‐5) and (n‐3) isomers.

The fatty acids in position I of the phosphatidylethanolamines were more saturated than the corresponding alk‐1′‐enyl groups of the plasmalogens. The ratios of monoenoic fatty acid isomers in position 1 were markedly different from those of the corresponding alk‐1′‐enyl groups in gray matter. The fatty acid patterns in position 2 of plasmalogen and phosphatidylethanolamines of white matter were similar except for 22:4(n‐6) which was concentrated in the plasmalogen (16% against 10%, in the phosphatidyl ethanolamine). In gray matter, the same trend was noted.

The data suggest that alk‐1′‐enyl residues and the fatty acids in position 1 as well as the fatty acids in position 2 of alk‐1′‐enyl acyl and diacyl type EPG in both gray and white matter are, at least in part, of different provenance.
METABOLISM OF MALONIC ACID IN RAT BRAIN AFTER INTRACEREBRAL INJECTION
Authors: Koeppen Arnulf H. , Mitzen Edward J. , Papandrea John D.
Published: October 2006

Abstract—

Labeled malonic acid ([1‐14C] and [2‐14C]) was injected into the left cerebral hemisphere of anesthetized adult rats in order to determine the metabolic fate of this dicarboxylic acid in central nervous tissue. The animals were allowed to survive for 2, 5, 10. 15 or 30min. Blood was sampled from the torcular during the experimental period and labeled metabolites were extracted from the brain after intracardiac perfusion.

There was a very rapid efflux of unreacted malonate in the cerebral venous blood. Labeled CO2 was recovered from the venous blood and the respired air after the injection of [1‐14C]malonate but not after [2‐14C]malonate. The tissue extracts prepared from the brain showed only minimal labeling of fatty acids and sterols. Much higher radioactivity was present in glutamate, glutamine, aspartate, and GABA. The relative specific activities (RSA) of glutamine never rose above 1.00. Aspartate was labeled very rapidly and revealed evidence of 14CO2 fixation in addition to labeling through the Krebs cycle. GABA revealed higher RSA after [1‐14C]malonate than after [2‐14C]malonate. Sequential degradations of glutamate and aspartate proved that labeling of these amino acids occurred from [1‐14C] acetyl‐CoA and [2‐14C] acetyl‐CoA, respectively, via the Krebs cycle. Malonate activation and malonyl‐CoA decarboxylation in vivo were similar to experiments with isolated mitochondria. However, labeled malonate was not incorporated into the amino acids of free mitochondria. The results were compared to data obtained after intracerebral injection of [1‐14C]acetate and [2‐14C]acetate.
ON THE ORIGIN OF VANILLYLMANDELIC ACID AND 3‐METHOXY‐4‐HYDROXY‐PHENYLGLYCOL IN THE RAT BRAIN
Authors: Adér J.‐P. , Muskiet F. A. J. , Jeuring H. J. , Korf J.
Published: October 2006

Abstract— The effects of electrothermic destruction and electrical stimulation of the locus coeruleus on the brain levels of vanillylmandelic acid (VMA), 3‐methoxy‐4‐hydroxyphenylglycol (MOPEG) and noradrenaline (NA) were studied in the rat. Fourteen days after destruction of the locus coeruleus, the content of NA in the hippocampus and that of MOPEG in the rest of the brain were decreased by more than 70% and 50% respectively.

Stimulation of the locus coeruleus induced a decrease in hippocampal levels of NA of 38%, while MOPEG levels were found to be increased more than 3‐fold After intraventricular injection of 1 μg of adrenaline (A), the levels of MOPEG were Substantially increased In none of these experiments was any variation in VMA levels found, These results suggest that in the rat brain endogenous VMA is not a metabolite of either NA or A The formation of MOPEG from A as well as from NA appears to be possible.
GLYCINE SPECIFIC [3H]STRYCHNINE BINDING IN THE PIGEON CNS
Authors: LeFort D. , Henke H. , Cuéanod M.
Published: October 2006

Abstract— Glycine sensitive [3H]strychnine binding has been demonstrated in the pigeon CNS. The kinetic parameters in spinal cord, tectum, telencephalon and cerebellum in this order were: Kn, (nM) 5, 5, 2.3, 6 and Bmax (fmol/mg protein) 1000, 275, 92, 20. The effect of various amino acids and strychnine analogs on the binding was measured. Retinal ablation caused a 22% decrease in the glycine sensitive [3H]strychnine binding in the tectum while lesions destroying up to 80% of the nucleus Ipc had no effect.
STIMULATORY EFFECTS OF SUBSTANCE P ON NEURITE EXTENSION AND CYCLIC AMP LEVELS IN CULTURED NEUROBLASTOMA CELLS
Authors: Narumi Shigehiko , Maki Yoshitaka
Published: October 2006

Abstract— Synthetic substance P initially increased cyclic AMP levels and subsequently induced neurite extension in cultured neuroblastoma N 18 cells. The magnitude of these effects depended on the concentration of fetal calf serum (FCS) in the culture medium, being more evident in the presence of a lower (0.1%) concentration of FCS.

In Eagle's medium containing 0.1% FCS, low concentrations of substance P (10−7‐10−5 M) increased cyclic AMP levels and stimulated neurite extension.

In Eagle's medium containing 5%FCS, both substance P at concentrations of 10−5‐10−3M and dibutyryl cyclic AMP at concentrations of 10−4‐10−2M increased cyclic AMP levels and stimulated neurite extension. The activities of acetylcholinesterase, (Na++ K+)‐, HCO3− and Mg2+ ‐stimulated‐ATPase were also increased. Cell growth was inhibited.

Substance P at concentrations of 10‐7‐10−5M also stimulated the adenylate cyclase activity of a particulate fraction of N 18 in a concentration‐dependent manner.
NICOTINIC ACETYLCHOLINE RECEPTOR OF MAMMALIAN BRAIN: NAJA TOXIN BINDING TO SUBCELLULAR FRACTIONS OF RAT BRAIN1,2
Authors: Tindall Richard S. A. , Kent Matthew , Raskin Fred , Rosenberg Roger N.
Published: October 2006

Abstract— Subcellular fractions of rat brain cortex bound 6.8 ± 0.4 fmol of 125I‐labeled α‐naja toxin per milligram of protein. Toxin binding was saturable and specific e.g. nicotinic agonist and antagonist blockable. Regions in rat brain varied in saturable, specific toxin binding with hippocampus, olfactory area and corpus striatum displaying greatest toxin binding. We conclude that 125I‐α‐naja toxin is a suitable probe for nicotinic cholinergic receptor in brain.
DEVELOPMENT OF (Na+‐K+)‐ATPase IN RAT HINDBRAIN: INCREMENTS IN PARALLEL WITH Na+‐DEPENDENT PHOSPHORYLATION AND K+‐pNITROPHENYLPHOSPHATASE1
Authors: Bertoni John M. , Siegel George J.
Published: October 2006

Abstract—

Rat hindbrain NaI‐enriched microsomal (Na+‐K+)‐ATPase activity, K+‐pNPPase activity, and Na+‐dependent steady‐state phosphorylation levels all increase approx 10‐fold relative to microsomal protein between 5 days prenatally and 60 days postnatally. These activities, as well as the mean wet weight of the hindbrain, are at half of their 60 day values shortly after the 10th postnatal day. For all ages, these hindbrain activities average over twice those found in the forebrain in a companion paper (Bertoni & Siegel, 1978). Increases during development in the amount of the related phosphorylatable polypeptide, estimated by densitometry of stained polyacrylamide gels containing fixed amounts of microsomal protein dissolved in SDS, are in agreement with increases in steady state levels of Na+‐dependent phosphorylation. The fraction of total phosphorylation that is Na+‐dependent rises steadily during development consistent with, but not obligatorily due to, a conversion of some of the previously Na+‐independent portion. Mg2+‐ATPase and Mg2+ ‐pNPPase activities and steady‐state Na+,‐independent phosphorylation levels do not increase in parallel during development. These observations add further support to the proposed partial reaction scheme for (Na+‐ K+)‐ATPase. The major increments in (Na +‐K+)‐ATPase occur simultaneously with the deposition of specialized plasma membranes, particularly in the molecular layer of the cerebellum, as described in previous studies of rat hind brain.
HISTAMINE AND MAST CELLS IN DEVELOPING RAT BRAIN
Authors: FERRER I. , PICATOSTE F. , Rodergas E. , Garcia A. , Sabria J. , BLANCO I.
Published: October 2006

Abstract—

The number and distribution of mast cells in rat brain were determined at different postnatal ages. The number of brain mast cells was found to change during ontogenic development following the same pattern as brain histamine (HA) levels. The calculated HA content of brain mast cells was close to the HA content of the crude nuclear fraction at every age studied. Since most of the brain HA in the newborn sediments with the crude nuclear fraction, these results suggest that the developmental pattern of brain HA reflects changes in the number of brain mast cells, that is, in the size of the mast cell HA pool. The HA content of the supernatant of the crude nuclear fraction corrected for mast cell HA contamination, on the other hand, follows a developmental pattern similar to that of other known neurotransmitters.
QUAKING MOUSE MYELIN: BIOCHEMICAL CHARACTERIZATION OF ZONAL GRADIENT SUBFRACTIONS
Authors: Waehneldt T. V. , Fagg G. E. , Matthieu J.‐M. , Baumann N. A. , Neuhoff V.
Published: October 2006

The brains of Quaking and littermate control mice were fractionated by differential and density gradient centrifugation into soluble, microsomal, myelin and related (SN 4) fractions. There were no apparent differences in protein composition between any Quaking and control fraction with the exception of myelin and SN 4. Analysis of CNP activity indicated that in Quaking animals a high proportion of the total activity was localized in microsomal fractions, while in controls a large percentage of activity was found in myelin and SN4; in contrast, there were no marhcd differences in the distribution of AChE activity between Quaking and control fractions.

The yield of myelin isolated from Quaking animals was 3.6%, of that from controls by electron microscopy myelin fractions from both Quaking and controls consisted of compact myelin whorls. Zonal centrifugation on continuous sucrose gradients demonstrated that both control and Quaking myelin was distributed in a bell‐shaped mode with peak densities at 0.66 0.68 and 0.71‐0.75 M‐sucrose, respectively. The specific activity of CNP was generally lower in mutant subfractions than in controls. Protein analysis revealed that there were similar qualitative trends between light and heay myelin subfractions from both mutant and control animals, although the levels of proteolipid and small basic proteins were substantially lower in all Quaking fractions. These results indicate that. although all mutant myelin subfractions are compositionally abnormal, the type of particle heterogeneity in Quaking myelin is similar to that observed in controls.
VULNERABILITY OF THE IMMATURE RAT BRAIN TO PHENYLACETATE INTOXICATION: POSTNATAL DEVELOPMENT OF THE DETOXICATION MECHANISM
Authors: Loo Y. H. , Fulton T. , Miller K. A. , Wisniewski H. M.
Published: October 2006

Phenylacetate is not excreted to any significant extent as the free acid in rat urine, but must be metabolized in the liver and kidney, first to phenylacetyl‐CoA, then to phenylacetylglycine. One hour after [14C]phenylacetate loading, the radioactivity in the liver and kidneys of the young rat could all be accounted for as unchanged phenylacetate (50‐5573, phenylacetylglycine (35–40%), and phenylacetyl‐CoA (5–8%). In the brain, the radioactivity was present mainly as phenylacetate (82–90%); only 10–18% was found as phenylacetyl‐CoA. The formation of phenylacetyl‐CoA appeared to be the rate limiting step in the clearance of phenylacetate.

In the urine at least 95% of the radioactivity was present as phenylacetylglycine, less than 1% as phenylacetate, and 3–4% as phenylacetyl‐CoA. The concentration of phenylacetylglycine in the urine was therefore used as a measure of the in vivo rate of phenylacetatc clearance. This detoxication process was found to develop postnatally. The formation of phenylacetylglycine was barely detecrabie in the newborn rat and remained relatively slow for about 2 weeks. During the third week a large increase in enzymatic activity, approx 40% occurred. Adult level of activity was reached in the 40 day old rat.

The extremely slow rate of detoxication in the newborn animal was reflected in the persistence of high concentrations of phenylacetate in the tissues. The relevance of our findings to human phenyl‐ketonuria is discussed
THE TURNOVER AND SUBCELLULAR LOCALIZATION OF THE CHICK FOREBRAIN SMALL NUCLEAR RNAs
Authors: Gunning P. W. , Austin L. , Jeffrey P. L.
Published: October 2006

Analysis of 2 day old chick forebrain RNA on polyacrylamide gels revealed the presence of the 29S, 18S, 5.5s and 5s rRNAs, 4S tRNA and the small mol wt nuclear RNA (snRNA) species K, L, C, DD and G. The turnover of these molecules was studied following the intracerebral injection of [3H]uridine into 2 day old animals. The specific activities of these molecules declined over a 23 day time course and all displayed first‐order decay kinetics. Apparent half‐lives (in days) for 29S (7). 18S (S), L (24), C (6.5), DD′ (8.5), 5.5S (7), 5S (13), G (6) and 4S (7) were obtained.

The subcellular localization of the snRNAs was studied in 5 day old chick forebrain. The snRNAs accounted for almost 17% of nuclear RNA, in contrast to their low levels in whole forebrain (1.2%). This was due to an approx 20‐fold nuclear enrichment of C, DD′, G′ and H. Relatively low levels of K and L were present within the nuclear fraction. However, K and L, and to a lesser extent C and DD, were readily detected within the post‐microsomal supernatant. Production of a pH 5 enzyme fraction from this supernatant resulted in a 2‐3‐fold enrichment of K, L, C and DD′ with respect to tRNA. The polysome containing fractions also displayed significant levels of L with about 1 mol of L per 30 of 5S rRNA.

A new method for the determination of the subcellular distribution of the snRNAs is described. It depends upon the purity of the nuclear, microsomal and cell sap subfractions rather than upon total recoveries from such fractions.

Utilizing the relative amounts of these RNA species within whole forebrain and the major subfractions, distributions (as a percentage within each fraction) were obtained. The observation of significant levels of K, L, C and DD within the cytoplasmic fractions raises some doubts about previous suggestions of an exclusively nuclear role for these molecules. It is proposed that the snRNAs may be involved in a multistage interaction within the process of eukaryotic gene expression.
THE DIRECT MEASUREMENT OF THE AXOPLASMIC TRANSPORT OF INDIVIDUAL RNA SPECIES: TRANSFER BUT NOT RIBOSOMAL RNA IS TRANSPORTED
Authors: Gunning P. W. , Por S. B. , Langford C. J. , Scheffer J. , Austin L. , Jeffrey P. L.
Published: October 2006

Analysis of chick retinal and tectal RNA revealed that in addition to the major cytoplasmic RNAs (rRNA and tRNA), a number of the small mol wt nuclear RNAs (snRNAs) can also be detected. Subfractionation data indicated that one of these molecules, DD′, is of at least 95% nuclear location within the retina. Thus, very little, if any, of the retinal DD′ is available for axoplasmic transport from the retina into the optic nerve and tectum.

Following intraocular injection of [3H]uridine, considerable incorporation of isotope into DD′ was observed within the optic tectum after 4, 8 and 16 days. This result indicates the presence of considerable local (i.e. tectal) synthesis. The specific activities of 29S, 18S and 5S rRNA and 4s tRNA relative to that of DD′ were measured in the optic tectum 8 and 16 days after the intraocular introduction of [3H]uridine. The same measurements were also made in intracranially injected animals. While the 29S/DD′, 18S/DD′ and 5S/DD′ specific activity ratios obtained were independent of the injection route, the 4S/DD′ ratio obtained from intraocularly injected animals was significantly greater (at least 2‐fold) than that obtained from intracranially injected animals. Similar analysis was also performed with the optic nerve complex at 16 days post‐injection with identical results.

These results demonstrate that tRNA, but not rRNA, is transported from the retina into the optic nerve and tectum in the 2‐day‐old chicken.
CHARACTERIZATION OF THE Ca2+‐INDUCED PROTEOLYTIC ACTIVATION OF TRYPTOPHAN HYDROXYLASE FROM THE RAT BRAIN STEM
Authors: Hamon Michel , Bourgoin Sylvie
Published: October 2006

The incubation of the 35,000 g supernatant of a rat brain stem homogenate in the presence of 7.5 mM‐CaC12 for 10 min at 25°C resulted in a more than 2‐fold increase in its tryptophan hydroxylase activity. This activation was irreversible and involved a reduction in the molecular weight of the enzyme, from 220,000 to 160,000. The partially proteolysed tryptophan hydroxylase, in contrast to the native enzyme, could not be activated by trypsin, sodium dodecyl sulphate, phosphatidylserine or phosphorylating conditions; dithiothreitol and Fe2+ were the only compounds whose stimulating effect on the enzymatic activity was not prevented by the Ca2+ ‐induced proteolysis of tryptophan hydroxylase.

These findings suggest that the mol. wt. 60,000 fragment removed by the Ca2+ dependent neutral proteinase plays a critical role in the regulatory properties of tryptophan hydroxylase.
A COMPARATIVE STUDY OF PINEAL ACETYL‐CoA HYDROLASE AND N‐ACETYLTRANSFERASE ACTIVITIES
Authors: Namboodiri M. A. A. , Namboodiri Mini A. , Weller Joan L. , Klein D. C.
Published: October 2006

pineal acetyl‐CoA hydrolase is measurable at 4 days before birth. It increases rapidly to a maximum of 0.37 nmol/min/0.1 mg protein during the first week after birth, thereafter gradually decreasing and stabilizing at adult levels (0.27 nmol/min/0.1 mg protein) 3‐4 weeks after birth. Unlike A/‐acetyltransferase, the activity of acetyl‐CoA hydrolase does not increase following treatment with isoproterenol, does not exhibit a circadian rhythm and is not inactivated on exposure of the animals to light at night. In addition, denervation of the pineal gland does not alter acetyl‐CoA hydrolase activity.
PROTEIN PROFILES OF RAT EMBRYO CEREBRAL CELLS DURING DIFFERENTIATION IN CULTURE
Authors: Richter‐Landsberg C. , Yavin E.
Published: October 2006

The protein composition of the particulate fraction of dissociated foetal rat cerebral cells during maturation in culture was investigated. SDS polyacrylamide gel electrophoresis showed a general decrease in the histonal components and significant changes in composition of a group of polypeptides with molecular weights ranging from 42 to 60 K. Two of these polypeptides coelectrophoresed with tubulin and actin whereas a 48 K polypeptide comigrated with the major component of the Wolfgram myelin protein. Its relative quantity appeared to approach a plateau after 8 days in culture. The myelin basic and proteolipid proteins were below detection levels in cultured cells at any time point investigated. A group of polypeptides with estimated molecular weights of 47, 51 and 52 K possibly representing synaptic proteins increased with time in culture. The appearance of a prominent band (60 K) in brain cultures and in other cells of divergent origin was demonstrated. This protein may be related to the process of cell adaptation to culture conditions. The developmental changes in the protein profile are discussed in the context of an in vitro myelinogenesis and synaptogenesis and compared with whole brain particulate and subcellular fractions.
PROTEIN and RNA SYNTHESES and PRECURSOR UPTAKE WITH ISOLATED NERVE and GLIAL CELLS
Authors: Yanagihara T.
Published: October 2006

Protein and RNA syntheses were investigated with bulk isolated nerve and glial cells from rabbit brain. For polypeptide synthesis, ‘intact’ cells were incubated with [3H]leucine under various conditions and the results were compared with those of polyribosomal polypeptide synthesis. For RNA synthesis ‘intact’ cells were incubated with [3H]uridine or [3H]guanosine and the results were compared with those of DNA‐dependent RNA polymerase assay. The bulk isolated ‘intact’ nerve cells were more active in protein synthesis than the ‘intact’ glial cells, while the latter synthesized RNA more actively than the former, although both polyribosomal polypeptide synthesis and DNA‐dependent RNA polymerase activity were higher with the nerve cells, indicating a higher potential for the nerve cells. The observed discrepancy of RNA synthesis was explained by the significantly less active uptake of nucleosides with the nerve cells. Both protein and RNA syntheses with ‘intact’ cells were sensitive to hypoxic or glucose‐deficient conditions. While both the nerve and glial cells were sensitive to hypoxia to a similar extent, the nerve cells were more sensitive to glucose deficiency. It was suggested that the bulk isolated nerve and glial cells still retain certain integral cell functions as viable cells, and can be utilized for various physiological and pharmacological investigations provided caution is exercised in their application and in the interpretation of the results.
CORRELATIONS BETWEEN A FLUORIMETRIC and MASS FRAGMENTOGRAPHIC METHOD FOR THE DETERMINATION OF 3‐METHOXY‐4‐ HYDROXYPHENYLACETIC ACID and TWO MASS FRAGMENTOGRAPHIC METHODS FOR THE DETERMINATION OF 3‐METHOXY‐4‐ HYDROXYPHENYLETHYLENE GLYCOL IN CEREBROSPINAL FLUID
Authors: Muskiet F. A. J. , Jeuring H. J. , Korf J. , Sedvall G. , Westerink B. H. C. , Teelken A. W. , Wolthers B. G.
Published: October 2006

One‐hundred and twenty‐two lumbar cerebrospinal fluid (CSF) samples were assayed for 3‐methoxy‐4‐hydroxyphenylacetic acid (HVA) by both a fluorimetric and mass fragmentographic method. The correlation coefficient (cc) and residual standard deviation (Syx) of the results were calculated as 0.966 and 23.3 ng/ml, respectively. If only samples containing less than 100ng/ml of HVA were considered, somewhat different values for cc and Syx were found (0.854 and 10.0 ng/ml, respectively). The data obtained by the fluorimetric method were consistently 17% lower than those obtained by the mass fragmentographic method. Spiking experiments resulted in 96.5 ± 7.8% recovery for the fluorimetric method, whereas the use of a deuterated internal standard was found to compensate completely for losses in the mass fragmentographic method. In addition the correlation between two different mass fragmentographic methods for the simultaneous determination of HVA and 3‐methoxy‐4‐hyd‐roxyphenylethylene glycol (MOPEG) in CSF was studied. The measurements were performed in different laboratories and resulted in correlation coefficients of 0.941 and 0.940 and residual standard deviations of 7.6 and 1.0 ng/ml for HVA and MOPEG, respectively. From all data we conclude that mass fragmentographic methods for the determination of catecholamine metabolites in CSF are superior to fluorimetric methods because of their selectivity, reproducibility and accuracy.
CHARACTERIZATION OF THE BINDING OF [3H]MUSCIMOL, A POTENT γ‐AMINOBUTYRIC ACID AGONIST, TO RAT BRAIN SYNAPTOSOMAL MEMBRANES USING A FILTRATION ASSAY
Authors: Williams Michael , Risley Edwin A.
Published: October 2006

Abstract— The binding of [3H]muscimol, a potent GABA agonist, to crude synaptic membranes prepared from rat brain was studied using a filtration method to isolate membrane‐bound ligand. Specific binding was found to be saturable and occurred to two binding sites of Kd5 5 and 30 nm. Binding was Na+‐independent and enhanced by both freezing and Triton treatment. Regional and subcellular distribution studies and pharmacological characterization of specific [3H]muscimol binding are consistent with binding to the synaptic GABA receptor.
TAURINE IN DEVELOPING RAT BRAIN: CHANGES IN BLOOD‐BRAIN BARRIER
Authors: Sturman J. A.
Published: October 2006

Abstract— The fate of [35S]taurine injected intraperitoneally or intracranially has been compared in rats throughout neonatal development. The amount of [35S]taurine present in the whole rat pup 24 h after intraperitoneal injection increases during development to a maximum 15 days after birth, and declines thereafter, whereas the amount of [35S]taurine reaching the brain 24 h after intraperitoneal injection was greatest in the first 5 days after birth. The amount of [35S]taurine remaining in the brain 24 h after intracranial injection does not vary throughout the period of neonatal development. These results suggest that the ‘blood‐brain’ barrier is more accessible to taurine in the first few days after birth than later in neonatal development, and that factors other than simple exchange are involved.
THE CHARACTERIZATION OF SPHINGOLIPIDS OF OLIGODENDROGLIA FROM CALF BRAIN
Authors: Abe Toshiaki , Norton William T.
Published: October 2006

Abstract— Purified oligodendroglia isolated from bovine brain white matter were found to contain, in addition to galactosylceramide, sulfatide and sphingomyelin, significant quantities of glucosylcerai‐mide, dihexosylceramide and esterified galactosylceramide. These sphingolipids were isolated and quan‐titated and their fatty acid and long chain base patterns compared with those from sphingolipids isolated from bovine myelin, white matter and gray matter.

The minor glycosphingolipids, glucosylceramide, dihexosylceramide and esterified galactosylceramide, constituted a higher percentage of glial lipids than of myelin lipids. Glucosylceramide accounted for 12% of the total glial monohexosylceramide fraction and 0.8% of total lipids; dihexosylceramide was 0.9% of total glial lipids. Both of these lipids had small quantities of α‐hydroxy fatty acids. The unsubstituted fatty acids of glucosylceramide were mostly short chain (16 and 18 carbons) and were different from those of the dihexosylceramides which were a mixture of short and long chain. The hydroxy acids of each of these lipids were, however, similar and resembled those of galactosylceramide.

The fatty acid patterns of galactosylceramide, sulfatide and sphingomyelin from glial cells resembled those of the corresponding lipids from myelin and white matter. The amide‐linked acids of esterified galactosylceramide contained both unsubstituted and α‐hydroxy chains. Their patterns were not identical to those of galactosylceramide, but were similar in all brain fractions.

With the exception of sphingomyelin and dihexosylceramide, which contained small amounts of C20‐sphingosine, all sphingolipids analyzed contained mostly sphingosine and dihydrosphingosine.

We conclude that the distribution of sphingolipids in the oligodendroglia is characteristic, but the lipophilic residues of these lipids are not cell‐specific.
THE INCORPORATION OF [1‐14C]LINOLENATE INTO LIPIDS OF DEVELOPING RAT BRAIN DURING ESSENTIAL FATTY ACID DEPRIVATION
Authors: Dwyer Barney , Bernsohn Joseph
Published: October 2006

Abstract— Twenty‐one‐day old essential fatty acid (EFA) deprived rats incorporated about twice the radioactivity from [1‐14C]linolenate into brain lipid fractions as did controls. At 5 min after injection, 2/3 of the radioactivity was associated with the less polar lipid fraction of both control and EFA deprived animals. By 30 min after injection, 70% of the radioactivity was in the phospholipid fraction. This value increased to 90% at later time points.

The specific activity of brain phospholipids from EFA deprived rats was always greater than that of controls. This held true for the individual phosphatide fractions also. In general, phosphatidylcholine (PC) was labeled most rapidly. With increasing time intervals, radioactivity was transferred to phospha‐tidylethanolamine (PE) and phosphatidylserine + phosphatidylinositol (PS + PI).

The transfer of fatty acid radioactivity into phospholipid and the distribution of radioactivity among individual phosphatides did not appear to be affected by the dietary state. However, the total amount of radioactivity incorporated was related to the amount initially retained by brain after injection. Our data suggest that one or more components of the less polar lipid fraction may act as a ‘trap’ or reservoir for fatty acids which are required for phospholipid synthesis.