bluuebunny/crossref_metadata_2025 huggingface dataset:
Hypotaurine uptake by the retina
Authors: Pasantes‐Morales H. , Morán J. , Fellman J. H.
Published: January 2005

A study of the transport of 3H‐hypotaurine by rat retina has been carried out. The process is markedly sodium and temperature dependent. Kinetic analysis of the data revealed two values for the affinity constant (K) of 4.91 μM and 1,071.3 μM. Some related and unrelated amino acids were examined as competitive inhibitors of 3H‐hypotaurine transport. Only GABA and β‐alanine exhibited appreciable inhibitory activity. Taurine, glycine, and guanidine ethane sulfonate were not inhibitors.

3H‐hypotaurine uptake was similarly distributed in the retinal subcellular fractions P1 and P2. The active uptake of 3H‐Hypotaurine by retinas of the rat and other species including chick and frog was studied and compared to cerebral cortex slices. The chick retina was similar to the rat in its capacity to transport hypotaurine whereas frog exhibited fourfold less activity. Slices of cerebral cortex from rat and chick exhibited hypotaurine uptake but again the magnitude of the transport was three to fourfold less than in the comparative retinas.
The synaptic form of acetylcholinesterase binds to cell‐surface heparan sulfate proteoglycans
Authors: Brandan E. , Inestrosa N. C.
Published: January 2005

We have previously communicated that heparan sulfate and heparin released 16S acetylcholinesterase (AChE) from cholinergic synapses. These experiments suggest that heparan‐like molecules are involved in the anchorage of AChE to the neuromuscular junction. In order to prove the in vivo interaction between the 16S AChE and heparan sulfate residues, the binding of exogenously added 16S enzyme to intact cells rich in cell‐surface heparan sulfate proteoglycans was examined; 16S AChE form was shown to bind to intact endothelial cells in a specific, time‐dependent, saturabel fashion. A single class of binding sites was involved and at saturation around 2.52 × 1011 molecules of 16S AChE/cm2 were bound. Fifty percent of the binding of the 16S AChE was blocked by heparan sulfate, heparin, or previous treatment of the cell with heparitinase. The binding was reversed by exogenous heparin, but not by chondroitin sulfate or hyaluronic acid. Our results demonstrate that the synaptic form of AChE binds to heparan sulfate proteoglycans on the surface of the cell.
Pharmacological identification of retinal cells releasing taurine by light stimulation
Authors: Salazar P. , Quesada O. , Campomanes M. A. , Morán J. , Pasantes‐Morales H.
Published: January 2005

The effect of drugs blocking synaptic activity at different retinal levels was examined in this study, in an attempt to identify the origin of the light‐stimulated release of 3H‐taurine from the chick retina. It was determined by autoradiography that the chick retina accumulates taurine in photoreceptors, in cells from the inner nuclear layer, and in processes of the inner plexiform layer. All these are possible sites for the release of taurine upon illumination. To discriminate among these possibilities, the effects of aspartate, tetrodotoxin, strychnine, picrotoxin, chlorpromazine, tubocurarine, atropine, glutamate diethyl esther, α‐amino adipate and 2‐amino‐4‐phosphonobutyrate were studied. Aspartate (10 mM), which is known to eliminate the light response of cells postsynaptic to photoreceptors, induced a marked increase of 150% in the resting efflux of 3H‐taurine but did not decrease significantly the light‐stimulated release. Tetrodotoxin, which blocks amacrine cell responses, decreased 3H‐taurine release stimulated by light by less than 20%. The efflux of taurine was unaffected by strychnine, pictrotoxin, tubocurarine, atropine, chlorpromazine, and 2‐amino‐4‐phosphonobutyrate, whereas it was increased by glutamate diethyl esther and α‐amino adipate. These results, all together, point to photoreceptors as the cells releasing 3H‐taurine in response to light.
Antigen‐specific adherence of antibody‐producing hybridoma cells: Application to neural and nonneural antigens
Authors: Najbauer J. , Tigyi G. J. , Nemeth P.
Published: January 2005

Antibody‐producing hybridoma cells specifically bind to microgram quantities of antigen molecules adsorbed onto the surface of plastic microtiter plates. The binding of hybridoma cells to nonantigen is optimally below 5%, similar binding of non‐antibody‐producing cells is 4–7%, compared to the binding of the hybridomas to their antigen. There is a difference in the kinetics of binding hybridomas to antigen compared to nonantigen. The number of bound cells depends on the amount, i.e., the surface density, of the antigen molecules and shows typical saturation effects.

Preincubation of hybridomas with excess free antigen and saturation of the antibody binding site on the surface with the hybridoma‐produced antibody reduces binding of the hybridoma cells to the antigen. Treatment of cells with trypsin reduces binding to antigen‐coated plastic surfaces. Drugs such as sodium azide, cytochalasin B, colchicine, vinpocetine, and vincristine sulfate reduce binding to the antigen. Hybridoma cells adhering to the antigen produce more antibody than nonadhering cells.

The results reported in this paper show that antigen molecules adsorbed to include a plastic surface and hybridoma cells interact specifically. This system forms a suitable model to study the interaction of antigen with antigen‐specific cells and may be useful as a separation method for specific antibody‐producing cells.
Delayed phosphorylation of the largest neurofilament protein in rat optic nerve development
Authors: Dahl D. , Crosby C. J. , Gardner E. E. , Bignami A.
Published: January 2005

Monoclonal antibodies selectively reacting with the high molecular weight neurofilament proteins (NF 150K and NF 200K) on immunoblots of bovine spinal cord extracts were obtained upon immunization of mice with chicken brain antigen and with highly purified NF 150K or NF 200K isolated from bovine spinal cord by anion exchange chromatography. Antibodies reacting with NF 200K or with both NF 150K and NF 200K were selected for this study. The antibodies were screened on immunoblots for reactivity with phosphorylated epitopes by dilution of the supernatants in sodium potassium phosphate as well as by treatment of nitrocellulose transfers with alkaline phosphatase. Abolishment of staining under these conditions was taken as evidence of reactivity with phosphorylated epitopes. With phosphate/phosphatase‐sensitive antibodies, NF 200K immunoreactivity was a late event in rat optic nerve development. It was first observed at day 18 on immunoblots of sodium dodecyl sulfate extracts analyzed by gel electrophoresis. Conversely, with phosphate/phosphatase‐insensitive antibodies, NF 200K immunoreactivity was already present on day 10, the earliest age in this study. With one monoclonal reacting with phosphorylated NF 150K and NF 200K, NF 150K immunoreactivity was already present on day 10. It is proposed that NF 200K expression precedes NF 200K phosphorylation in development.
Cellular localization of proglucagon/glucagon‐like peptide I messenger RNAs in rat brain
Authors: Han V.K.M. , Hynes M.A. , Jin C. , Towle A.C. , Lauder J.M. , Lund P.K.
Published: January 2005

Techniques of in situ hybridization histochemistry, Northern blot hybridization, and immunocytochemistry were used to investigate the biosynthesis of glucagonlike immunoreactants (GLIs) in rat brain. Cells in the nucleus tractus solitarius of the medulla oblongata of adult rat brain hybridized to a synthetic oligonucleotide probe (GLP‐I oligomer) corresponding to nucleotide sequences in pancreatic proglucagon mRNA encoding glucagon‐like peptide I (GLP‐I), and stained with antisera specific for two antigenic determinants of pancreatic proglucagon, glucagon, and GLP‐I. These data suggest that there is de novo synthesis of proglucagon in cells of the nucleus tractus solitarius via expression of a proglucagon mRNA similar to that produced in pancreas. Previous studies have shown that cells in hypothalamus stain with GLP‐I antisera, but not with glucagon antisera. However, cells in the hypothalamus did not hybridize with the GLP‐I oligomer and may therefore produce a GLP‐I immunoreactant that is encoded by a mRNA different from the pancreatic proglucagon‐mRNA‐encoding glucagon and GLP‐I. Northern blot hybridizations with a cDNA probe encoding the entire pancreatic proglucagon sequence did not detect proglucagon/GLP‐I mRNAs in polyadenylated RNAs (Poly A RNA) from adult rat brainstem and hypothalamus, probably because of their low abundance. Poly A RNAs from fetal rat brain, however, contained two mRNAs that hybridized to the proglucagon cDNA probe. One mRNA of 1,300 bases is the same size as pancreatic proglucagon mRNA. The second mRNA of 1,500 bases may encode the GLP‐I immunoreactant detected in the hypothalamus of adult rat brain. The presence of neurons with glucagon and glucagon‐like peptides in the nucleus tractus solitarius suggests a role of these peptides in gustatory and/or cardiopulmonary control.
Expression of myelin proteolipid and basic protein mRNAS in cultured cells
Authors: Macklin W.B. , Weill C.L. , Deininger P.L.
Published: January 2005

Studies were undertaken to investigate the regulation of myelin‐specific mRNA expression in cultured cells. Three experimental systems were investigated: primary oligodendrocytes grown as enriched cell populations, primary oligodendrocytes grown in the presence of chick spinal cord neurons, and C6 cells. cDNA probes specific for the myelin proteolipid mRNA and the myelin basic protein mRNA were used to quantitate proteolipid and myelin basic protein mRNA levels in cells under different experimental conditions. C6 cells expressed less than 0.2% of the proteolipid mRNA that was expressed in primary oligodendrocytes. Primary oligodendrocytes expressed the myelin‐specific mRNAs for at least 104 days in culture, and the level of these mRNAs in cultures was elevated fourfold by coculturing rat oligodendrocytes with chick spinal cord neurons.
Long‐chain acyl‐coenzyme a synthetase in rat brain myelin
Authors: Vaswani K. K. , Ledeen R. W.
Published: January 2005

Long‐chain acyl‐CoA synthetase (EC 6.2.1.3), an enzyme(s) that activates fatty acids prior to incorporation into phospholipids and other substances, has been detected in highly purified myelin from rat brain stem. The high levels relative to microsomes (11% and 15% for oleate and arachidonate, respectively) tended to preclude contamination by the latter membrane as the source of activity. Additional evidence came from sequential purification and mixing experiments. Km values were not appreciably different for the two substrates with the two membranes, but Vmax values were approximately 2–4‐fold greater for arachidonate in both membranes. Triton X‐100 increased activity somewhat in myelin but not in microsomes; with arachidonate as substrate it reduced activity in the latter. Heat inactivation studies and pH profiles suggested the presence of two different enzymes, as previously shown for other tissues.
Translational regulation of myelin basic protein synthesis
Authors: Campagnoni A. T. , Hunkeler M. J. , Moskaitis J. E.
Published: January 2005

Synthesis of the mouse myelin basic proteins (MBPs) was studied in reticulocyte lysates programmed with brain mRNA in the presence or absence of brain factors. Addition of brain factors to the lysates increased the incorporation of [35S] methionine into total TCA‐precipitable protein by a factor of 6–9, and the majority of this stimulation was found to be due to initiation factors. Although brain factors increased total protein synthesis, the percentage of MBP synthesis was reduced from 4.3% of the total counts incorporated (in the absence of brain factors) to 1.4% (in their presence). Increasing the concentration of brain mRNA in the lysates also reduced the relative levels of MBP synthesis. These results suggested the MBP mRNAs, as a group, were less efficiently initiated than most brain mRNAs. An analysis of the nucleotide sequence flanking the initiator codon of the MBP mRNAs indicates the presence of a second AUG codon 5 bases upstream, immediately followed by a termination codon, which may provide a structural explanation for the poorer initiation efficiency of the MBP mRNAs. Further analysis of the synthesis of the individual MBPs in the presence or absence of inhibitors of initiation (7‐methylguanosine triphosphate and aurintricarboxylic acid) and elongation (anisomycin and emetine) indicated that the 14‐kD MBP mRNA was less efficiently translated than the other MBP mRNAs. Synthesis of the 14‐kD MBP was more strongly inhibited by the initiation inhibitors than the other MBP mRNAs, and synthesis of the 14‐kD MBP was increased relative to the other MBPs in the presence of elongation inhibitors. These results are consistent with the notion that the 14‐kD MBP mRNA is initiated less efficiently than the other MBP mRNAs.
Transient increase in intracellular concentration of adenosine 3′:5′‐cyclic monophosphate results in morphological and biochemical differentiation of C6 glioma cells in culture
Authors: Sharma S. K. , Raj A. B. J.
Published: January 2005

Incubation of C6‐BU1 glioma cells in the presence of isoproterenol and Ro20‐1724—a potent cAMP phosphodiesterase inhibitor—results in a transient increase in intracellular cAMP levels, followed by a rapid efflux of cyclic AMP from the cells into the media. Two distinct types of morphological changes could be seen: (1) rounded cell bodies with multipolar processes and beadings after 30 minutes of incubation—this period coincides with a 70–80‐fold increase in intracellular cAMP levels, and (2) elongated cell bodies with extended bipolar processes after 24–48 hours. By this time the intracellular cAMP concentration drpped to a low level, which was only three‐ to four fold higher than that in control. The transient increase in intracellular cAMP concentration results in retardation of cell growth, diminished uptake of 3H‐2‐deoxyglucose, and abolition of enhanced synthesis of cyclic AMP by concanavalin A.
Monoclonal antibodies to a brain dopamine binding protein: Production, specificity, and immunohistochemistry
Authors: Hsu L. L. , Moroi K. , Lakchaura B. D. , Chan T. , Lin C.‐T. , Wu J.‐Y.
Published: January 2005

A dopamine binding protein (DABP) has been purified from the rat brain synaptic membrane to homogeneity by afinity chromatography and gel electrophoresis. The monoclonal antibodies against the DABP were produced by the mouse‐mouse hybridoma technique and characterized for their specificity to dopamine receptors by displacement of dopamine receptor binding. These monoclonal antibodies have been used to localize DABP in rat brain by immunohistochemistry. A specific linear structure of reaction product was seen in both caudate nucleus and cerebral cortex. This finding suggests that the DABP is present in the cerebral cortex and caudate nucleus as a membranous component of the neurons or their processes.
Serotonin turnover rate in raphe and cortex of mice infected with Venezuelan equine encephalomyelitis virus
Authors: Lima L. , Walder R. , Obregón F. , Drujan B.
Published: January 2005

The turnover of serotonin (5HT) was determined in the raphe area and cortex of mice infected with Pixuna, a strain of intermediate virulence of Venezuelan equine encephalomyelitis virus (VEEV). NMRI‐mice, 24 days old, were inoculated intracerebrally (ic) with 300 LDS0 of the virus. The animals were sacrificed 4, 7, 15, 21, 30, and 60 days postinoculation. 5HT and 5‐hydrodryindolacetic acid (SHIAA) in raphe and cortex were determined by high performance liquid chromatography (HPLC) with electrochemical detection. Turnover rate of 5HT was determined by the administration of pargyline, p‐chlorophenylalanine, and probenecid. The content of 5HT or SHIAA and 5HT/5HIAA ratios were not significantly different in infected compared with control mice. However, a decrease of 5HT turnover rate, determined after pargyline treatment, was observed in the raphe and not in the cortex of infected mice at 4 and 7 days after the inoculation. The turnover rate/(5HT)0 in raphe is decreased in infected mice with signs of illness, suggesting a lower density of 5HT innervation in this brain area. The administration of p‐chlorophenylalanine and probenecid showed that the cortex is also affected, but the synthesis is less modified than metabolism or elimination. Cell bodies of 5HT neurons seem to be more susceptible than projections to infection by Pixuna strain of VEEV.
Dopamine receptors on isolated membranes of rat lymphocytes
Authors: Ovadia H. , Abramsky O.
Published: January 2005

Using [3H]‐dopamine (DA) as the ligand of choice, we have shown that rat lymphocytes possess DA binding sites. The binding of [3H]‐DA was specific, saturable, and of high affinity. The specific binding in membranes obtained from Con A‐activated lymphoblasts was greater than the binding in respective unactivated lymphoid cells, and displaced by lower concentrations of unlabeled ligand. [3H]‐DA was displaced specifically by DA, norepinephrine, and apromorphine. The binding sites were insensitive to neuroleptic drugs such as sulpiride, bromocryptine, and haloperidol. On the basis of these findings, we have suggested that lymphocytes possess a receptor site for catecholamines and the receptor for DA might be a D‐3 receptor type.
Interleukin‐1‐like immunoreactiveity in pripheral tissues
Authors: Schultzberg M. , Svenson S. B. , Unden A. , Bartfai T.
Published: January 2005

Rabbit antisera were raised against a synthetic peptide corresponding to the amino acid residues 169–194 in the murine interleukin‐1 sequences. Immunoreactive varicose fibers were observed in teh vas deferens, urinary bladder, gastrointestinal tract, and coeliacsuperior mesentric anglion complex of the rat. Fibers were also encountered around blood vessels in several organs including the thymus, spleen, lymph nodes, liver, and kidney.
Metabolism of cholesterol and triacylglycerol in cultured chick neuronal cells, glial cells, and fibroblasts: Accumulation of esterified cholesterol in serum‐free culture
Authors: Saito M. , Benson E. P. , Saito M. , Rosenberg A.
Published: January 2005

Metabolism of free and esterfied cholesterol and triacylglycerol was compard in cultured neuronal cells, glial cells, and fibroblasts grown from chick embryos. Cellular contents of free and esterified cholesterol were comparable in these cells and triactlglycerol content in the neuronal cells was about 40% of that in the other cell types. Cholesterol synthesis from [3H]acetate was high in all these cells and was not affected by fetal calf serum in the culture medium. Monensin, which has been shown to influence cholesterol metabolism through the inhibition of low‐density liporprotein receptor recycling in human fibroblasts, did not induce profound effects on cholesterol metabolism in these cells. Higher incorporation of [3H] oleic acid into esterified cholesterol was observed in the glial cells and fibroblasts when fetal calf serum was removed from the culture medium. Cellular content of the esterified cholesterol also increased in the glial cells under a serum‐free arrangement. 25‐Hydroxy‐cholesterol induced higher incorporation of both [3H]acetic acid and [3H]oleic acid into esterified cholesterol in all of these cells. The results indicate that the active metabolism of cholesterol found in cultured chick neural cells and fibroblasts may not be regulated by and LDL receptor‐mediated system and some factors in fetal calf serum inhibit cellular accumulation of esterified cholesterol.
Angiotensin‐converting enzyme associated with Torpedo californica electric organ membranes
Authors: Altstein M. , Dudai Y. , Vogel Z.
Published: January 2005

Torpedo electric organ contains high concentrations of angiotensin converting enzyme (ACE) like activity, cleaving [Leu5]enkephalin at the Gly3‐Phe4 peptide bond. Most of the activity cosediments with the cell membranes. The enzymatic preparation from membranes is inhibited by low concentrations of the ACE inhibitors, AQ 14225 and SQ 20881 (IC50 of 0.6 and 15 nM, respectively), and is weakly inhibited by the neutral endopeptidase inhibitors, phosphoramidon and thiorphan (IC50 of 30 μM and ca. 70 nM, respectively). The enzyme degrades hippuryl‐His‐Leu and is activated by NaCl. Hippuryl‐His‐Leu and [Leu5]enkephalin are degraded with Km of 93 and 41 μM, and Vmax of 21 and 10 nmol/mg protein/min, respectively. The specific activity of the ACE‐like activity in homogenates of Torpedo electric organ is relatively high (6.3 nmol hippuryl‐His‐Leu/mg protein/min); this value is similar to that obtained for rat lung and rat striatum.
Effects of Ca2+ entry blockers on kainate‐induced changes in extracellular amino acids and Ca2+ in vivo
Authors: Lazarewicz J. W. , Lehmann A. , Hamberger A.
Published: January 2005

The effect of organic Ca2+ channel blockers and Co2+ on kainate‐induced in 45Ca2+ efflux and amino acid release was studied in the rabbit hippocampus with the dialysis‐perfusion technique. Administration of 1 mM kainate caused a transient, 50% drop of extracellular Ca2+. This effect was insensitive to 100 μM flunarizine or verapamil, 10 μM nimodipine, and 6 mM CoCl2. The organic Ca2+ entry blockers did not significantly influence kainate‐induced changes in extracellular amino acid, whereas Ca2+ affected both basal and kainic acid stimulated release of amino acids. These results indicate that kainate‐regulated Ca2+ ionophores differ from Ca2+ channels in peripheral tissues in terms of sensitivity to Ca2+ entry inhibitors.
Quisqualate‐sensitive, chloride‐dependent transport of glutamate into rat brain synaptosomes
Authors: Zaczek R. , Balm M. , Arlis S. , Drucker H. , Coyle J. T.
Published: January 2005

A chloride‐dependent transport process for glutamate has been identified in partially purified rat brain synaptosomes. This process shares many characteristics with the chloride‐dependent sequestration process for glutamate in brain sonicates, which was previously thought to represent a quisqualate receptor, such as sensitivity to specific inhibitors and regulation by anions. Increases the concentrations of chloride led to and increase in the apparent Vmax without affecting the KT. Synaptosomes preincubated with [3H]‐L‐glutamate exhibit an efflux of the radiolabel, which was stimulated by a substrate for the carrier in the incubating medium, indicating the bidirectional nature of the transport. The chloride‐dependent transfer process is restricted to the brain, and regional and developmental profiles clearly distinguish it from the sodium‐dependent high‐affinity uptake process for glutamate. Nevertheless, the effects of excitotoxic lesions strongly suggest a neuronal localization of the chloride‐dependent transport.
Spinal cord interneuron degenerative atrophy caused by peripheral nerve lesions is prevented by serotonin depletion
Authors: di Giulio A. M. , Tenconi B. , Mannavola A. , Mantegazza P. , Schiavinato A. , Gorio A.
Published: January 2005

Peripheral nerve section causes a degenerative atrophy of substance P sensory input and of met‐enkephalin interneurons in the dorsal horn of the spinal cord. Radioimmunoassay of both peptides indicates that the decrease in peptide levels ranges from 30 to 50%, that it occurs several days after lesioning, and that it is simultaneous for the two peptides. Quantitative immunocytochemistry performed by computer‐assisted analysis of met‐enkephalin‐positive boutons shows that following sciatic nerve lesions there is a decresed density of immunoreactive boutons per unit area in densit of immunoreactive boutons per unit area in the substantia gelatinosa of the dorsal horn in the lumbar cord ipsilateral to the lesion. Within 24 h of nerve injury there is a significant and transient enhancement of serotonin turnover, as indicated by the increased levels of 5‐hydroxyindolacetic acid in the lumber cord, without any change in serotonin concentrations. The restoration of normal serotonin metabolism at d 10 postlesioning coincides with the peptidergic loss. However, if, prior to nerve resection, serotonin stores are depleted by p‐chlorophenylalanine treatment, the damage to met‐enkephalin interneurons in fully prevented, while substance P loss does still occur. These results suggest that signals caused by the section of a peripheral nerve are directly responsible for substance P loss in the spinal cord and are, presumably, rapidly transported into the CNS, causing an activation of the serotoninergic raphe neurons projecting to spinal cord. The activation of this system is likely responsible for the degenerative atrophy of the met‐enkephalin interneurons. These results further confirm our previus suggestion (Di Giulio et al: Peptides 6:24–256, 1985; Brain Res 342:405–408, 1985) that the peptidergic loss induced by perpheral nerve section may be intraspinally regulated, and that pain sensations which develop after nerve lesions may be related to intraspinal alterations, such as the atrophy of met‐enkephalin‐containing interneurons, rather than to the formation of a large neuroma by the injured axons. As a matter of fact the increased serotonin turnover is triggered within 24 h, while neuroma formation requires several days following nerve lesion.
Glycolipid sialosyltransferase activity in synaptosomes exhibits a product specificity for (2–8)disialosy lactosyl ceramide (ganglioside GD3)
Authors: Durrie R. , Saito M. , Rosenberg A.
Published: January 2005

Intact synaptosomes prepared from 28‐day‐old rat brains were incubated with CMP‐N‐acetyl‐(14C) neuraminic acid in Krebs‐Henseleit buffer in an atmosphere of 95% O2: 5% CO2, at 37°C. The activity of CMP‐NANA: ganglioside sialosyltransferase using endogenous acceptors was 0.84 pmoles NANA transferred/mg synaptosomal protein/hr. Analysis of the distribution of labeled sialic acid revealed that GD3 ganglioside (α2→8 disialosyl, α2→3 galactosyl, β1→4 glucosyl, β1→1‐ ceramide) was the major product in the membrane carrying 32% of the total lipid bound label. Treatment of the reaction products with Clostridium neuraminidase liberated labeled sialic acid from GD3 and yielded labeled GM3, then unlabeled lactosyl ceramide. Lac‐cer and GM3 are present in small amounts in synaptosomes, and GD3 repressents less than 2% of the total ganglioside. Our findings indicate that the sialosyltransferse activity of synaptosomes exhibits a preferential product specificity for the small pool of synaptosomal membrane GD3 ganglioside that may be formed in situ, via sialosylation of its precursor (GM3 or lactosyl ceramide) which pre‐exists in the synaptosomal plasma membrane. The second major labeleld product quantitatively was GD1a whose precursor substrate, GM1, is quite abundant in the membrane, so that the conversion rat of GM1 to GD1a was low in comaprison with GD3 formation. Sialosylation of other synaptosomal membrane gangliosides was negligible.
Alterations in the adenylate cyclase‐cAMP‐phosphodiesterase system in the locus coeruleus during the development of spontaneous hypertension of the rat
Authors: Bahner U. , Schmid G. , Geiger H. , Heidland A. , Palkovits M.
Published: January 2005

The quantitatively most important noradrenergic cell group of the brain is the locus coreruleus. Significantly increased cAMP concentration could be measured in spontaneously hypertensive rats in comparison to normotensive Wistar‐Kyoto control rats at every stage investigated. Furthermore, both the basal activity and maximal stimulation of Ca++‐and GTP‐dependent adenylate cyclase as well as phosphodiesterase activity were significantly decreased in the spontaneously hypertensive rats at 14 weeks of age. The possible role of the locus coeruleus in spontaneous hypertension is presumed in counterrgulatory mechanisms against rising blood pressure.
Effect of acute ethanol administration on brain levels of tetrahydropapaveroline in L‐dopa‐treated rats
Authors: Cashaw J. L. , Geraghty C. A. , McLaughlin B. R. , Davis V. E.
Published: January 2005

The effect of ethanol on the concentration of the aberrant dopemine metabolite, tetrahydropapaveroline (THP), in brains of L‐dopa‐treated rats has been evaluated. THP was isolated from rat brain extract by a newly developed multiple stage separation technique that is highly specific for the alkaloid. THP, dopa, and dopamine were assayed by high‐performance liquid chromatography with electrochemical detection. THP was not found in brains of untreated animals. However, levels of 0.42 pmol THP per g brain were observed in animals that received L‐dopa (200 mg/kg) by intraperitoneal injection (IP) 90 min before decapitation. Administration of ethanol (3g/kg) IP to L‐dopa‐treated animals at time intervals ranging from 60 to 240 min before decapitation resulted in significant increase in brain levels of THP as compared to L‐dopa‐treated animals. Maximum levels of THP (4.02 to 4.82 pmol/g brain) were observed when ethnol was given at time intervals ranging from 80 to 180 min before the animals were killed. Administration of ethnol and L‐dopa, as compared to the administration of L‐dopa only, markedly increased brain levels of dopa and dopamine. Maximum brain levels of THP, dopa, and dopamine in animals administered ethanol plus L‐dopa as compared with L‐dopa‐treated animals repressented a 1048%, 325%, and 84% increase, respectively. These results strongly support the concept that the concentration of THP in the brain of intact animals can be enhanced by ethanol administration.
Some characteristics of muscle‐conditioned media with excitatory and inhibitory influences of neurite outgrowth from early neural tube explants
Authors: Heaten M. B.
Published: January 2005

This study examined the growth of basal plate explants from 40‐hr chick embryos containing the trigeminal motor nucleus in the presence of target muscle‐conditioned medium (MCM) from day‐4, day‐10, and day‐18 embroys. We had previously found that MCM derived from the 4‐day target tissue enhanced neurite outgrowth from explants, while target MCM from 10‐ and 18‐day embryos inhibited it. For the present study, target MCM was treated with trypsin to assess the nature of the active fractions, or pre‐incubated in polyornithine‐coated dishes to determine the possible in polyornithine‐coated dishes to determine the possible presence and relative contributions of substrate‐binding vs. soluble components. Both trypsinization and pre‐incubation ablished the outgrowth‐enhancing potential of the 4‐day MCM, indicating a protein or polypeptide substeate‐binding active fraction, with no appreciable active souluble component. When the 10‐day target MCM were trypsinized, the inhibitory indluence was reversedm and neurite outgrowth was enhanced. Similarly, when the MCM from these embryos was preincinated over polyornithinem the inhibitory influence was lost and was replaced by a stimulatory one. These results suggest that the 10‐ and 18‐day MCM contain an active inhibitory fraction that is a protein or polypeptide, and which binds to a positively charged substate. When this inhibitory fraction is inactivated or depleted, an excitatory soluble fraction is revealed. Such a dual nature in MCM has not been seen previously and may be expressed only when the media are assayed with very early neural tissue.
Localization of the pool of G4 acetylcholinesterase characterizing fast muscles and its alteration in murine muscular dystrophy
Authors: Gisiger V. , Stephens H. R.
Published: January 2005

The distributions of acetylcholinesterase and its molecular forms within muscles of normal and dystrophic 129/ReJ mice were established by a concomitant cytochemical and biochemical study performed on 1‐mm serial sections of three predominantly fas muscles, i.e., anterior tibialis, extensor digitorum longus, and sternomastoid, as well as the slow‐twitch soleus. This comparative study showed the following main finding.(1)In every muscle of bothe normal and dystrophic mice (a) the three asymmetric forms were confined to the motor zone where they systematically codistributed with the endplates, and (b) all globular forms, including G4, were concentrated at the motro zone from which they extended over the entrie muscle length along a concentration gradient. (2) In the normal muscles, the perijunctional sarcoplasmic cytochemical reaction exhibited by individual fibers was grouped into a well‐defined conjunctional acetylcholinesterase compartment in which the endplates were embedded. The overall intensity of the cojunctinal cytochemical reaction was either high or low according to whether the muscle was predominantly fast or slow. (3) This conjuncitonal acetylcholinesterase compartment varied in close parallelism with G4 and thus appeared as the cytochemical correlate of the G4 molecules concentrated around the endplates. In particular, as the shape of the motor zone progressively increased in complexity along with the intricacy of the muscle fiber organization, from sternomastoid to extensor digitorum longus to anterior tibialis, so did both the relative volume occupied by the cojunctional acetylcholinesterase compartment and the proportion of G4. (4) The motor zone of the normal fast‐twitch muscles characteristically differed from that of the soleus by the presence of a G4‐rich enviornment around the endplates, which was cooperatively provided by the the surrounding fibers. (5) In dystrophic muscles, this cojunctinal G4‐rich compartment was lost: the cytochemical compartment was no longer discernable, while G4 was reduced to a minimal low level similar to that characteristic of the normal soleus.
Immune response products alter CNS acitivity: Interferon modulates central opioid function
Authors: Dafny N. , Lee J. R. , Dougherty P. M.
Published: January 2005

The presents report provides evidence to support the hypothesis that peptides released during an immune response alter CNS activity and thus may provide a means for the immune system to transmit afferent single into the brain. Specifically, it is demonstrated that recombinant interferon‐alpha (rIFN‐α), a peptide associated with the immune response to viral infection, can alter opiate withdrawal severity in a dose‐dependent manner upon direct injection into brain areas essential for this phenomenon. These results are compared and contrasted with the effect of systemically injected rIEN‐α upon opiate withdrawal. In addition, an electrophysiological investigation into the basis of the interaction of opioids and rIFN‐α in brain structures essential for the expression of opioid activities is also presented. Finallu, the effects of rIFN‐α upon the functions of both the CNS and other systems is discussed in terms of the effects reported for other peptides associated with immune responses.
Neuropeptide Y in the rat nucleus accumbens: Ultrastructural localization in aspiny neurons receiving synaptic input from GABAergic terminals
Authors: Massari V. J. , Chan J. , Chronwall B. M. , O'Donohue T. L. , Oertel W. H. , Pickel V. M.
Published: January 2005

The ultrastructure, afferent input, and sites of termination of neurons containing neuropeptide Y‐like immunoreactivity (NPY‐LI) were examined in the adult rat nucleus accumbens by using the peroxidase‐anti‐peroxidase (PAP) method. The NPY‐LI was seen in sparsely distributed, spindle‐shaped perikarya having cross‐sectional diameters of 15–20 μm. These perikarya exhibited highly invaginated nuclear membranes and thin rims of cytoplasm containing Golgilamellae, dense‐core vesicles, and other organelles. A few large, principally aspiny, dendrites also showed NPY‐LI. The dendrites received synaptic input from unlabeled terminals forming both symmetric and asymmetric junctions. Immunolabeling for NPY was evident in other processes that were not clearly differentiated as dendrites or axons. These were seen primarily near glial processes and the basal laminae of blood vessels. A few myelinated and many unmyelinated axons and axons terminals also were labeled for NPY. These terminals contained numerous, small (40–60 nm), clear and one or more large (80–100 nm) dense core vesicles. Forty‐seven percent (27 out of 57) of the terminals containing NPY‐LI formed symmetric junctions with unlabeled dendrites or dendritic spines. The remainder lacked recognizable densities within single planes of section. The neurons exhibiting NPY‐LI in the nucleus accumbens were characterized further with respect to their afferent input from terminals labeled for the GABA‐synthesizing enzyme, glutamic acid decarboxylase (GAD). Immunogold labeling of a rabbit antiserum against NPY and PAP labeling for a sheep antiserum to GAD were sequentially applied to the same sections. The GAD‐labeled terminals formed symmetric junctions primarily with the more numerous unlabeled dendrites. However, a few synaptic junctions also were detected between the GAD‐labeled terminals and dendrites showing immunogold labeling for NPY. We conclude (1) that in the rat nucleus accumbens, NPY‐LI is found principally in neurons of the aspiny type and (2) that the output from these presumably intrinsic neurons to other neighboring neurons or blood vessels is at least partially modulated by GABA.
Protective action of calcium channel blockers on Na+, K+ –ATPase in gerbil cerebral cortex following ischemia
Authors: Palmer G. C. , Palmer S. J. , Christie‐Pope B. C.
Published: January 2005

The present study was initiated to determine whether pretreatment of gerbils with calcium channel blockers, flunarizine and verapamil would prevent injury to cerebral ATPases following secondary ischemia consisting of 60‐min bilateral clamping of the carotids followed by 40 min of reperfusion. The sequence of ischemia produced a deficit in Na+, K+ ‐ATPase activity without influencing Ca++, Mg++ ‐or Mn++ ‐sensitive ATPases. Pretreatment with flunarizine significantly prevented the damage to Na+, K+ ‐ATPase while the effect of verapamil was marginal. Verapamil, along with dimethylsulfoxide (DMSO), reduced the mortality rate of gerbils subjected to the paradigm of ischemia. When added directly to the cerebral fractions in vitro the two calcium channel blockers inhibited Na+, K+ ‐ATPase alone. Flunarizine was more potent in vitro than verapamil.
Insulin and insulinlike growth factor receptors regulating neurite formation in cultured human neuroblastoma cells
Authors: Recio‐Pinto E. , Ishii D. N.
Published: January 2005

The functional role of brain insulin and insulinlike growth factor (IGF) receptors is being sought. Recently it has been found that these ligands are members of a newly identified family of neuritogenic polypeptides. We studied the relationship between125I‐insulin and125I‐IGF binding and their capacity to enhance neurite formation in cultured human neuroblastoma SH‐SY5Y cells. The binding of125I‐insulin was temperature‐dependent and heterogeneous. The Scatchard plot and dissociation rate were both consistent with the presence of two types of sites. There appeared to be about 900 high affinity sites per cell with a Kd of about 3 nM. This compared favorably with the half‐maximal concentration of 4 nM for enhancement of neurite formation. The type I IGF sites were also present. Physiology concentrations of insulin clearly enhanced neurite formation through the insulin sites, whereas physiology concentrations of IGF‐I and IGF‐II enhanced through the IGF sites. Cross‐occupancy of sites was observed at supraphysiologic concentrations, providing a reasonable explanation for the broad dose‐response curves for these ligands. These results support the suggestion that one function of insulin and IGF receptors in neural tissues may be to modulate neurite formation.
The complete nuleotide sequence and structure of the gene encoding bovine phenylethanolamine N‐methyltransferase
Authors: Batter D. K. , D'Mello S. R. , Turzai L. M. , Hughes H. B. , Gioio A. E. , Kaplan B. B.
Published: January 2005

A cDNA clone for bovine adrenal phenylethanolamine N‐methyltransferase (PNMT) was used to screen a Charon 28 genomic library. One phage was identified, designated λP1, which included the entire PNMT gene. Construction of a restriction map, with subsequent Southern bloty analysis, allowed the identification of exon‐containing fragments. Dideoxy sequence analysis of these fragments, and several more further upstream, indicates that the bovine PNMT gene is 1,594 base pairs in length, consisting of three exons and two introns. The transcription initiation site was identified by two independent methods and is located iapproximately 12 base pirs upstream ffrom the ATG translation start site. The 3′ untranslted region is 88 base pairs in length and contains the expected poly‐adenylation signal (AATAAA). A putative promoter sequence (TATA box) is located about 25 base pairs upstream from the transcription initiation site. Computer comparison of the nucleotide sequence data with the consensus sequences of known regulatory elements revealed potential binding sites for glucocorticoid receptors and the Sp1 regulatory protein in the 5′ flanking region of the gene. Additionally, comparison of the sequence of the exons of the PNMT gene with cDNA sequences for other enzymes involved in biogenic amine synthesis revealed no significant homology, indicating that PNMT is not a member of a multigene family of catecholamine biosnthetic enzymes.
Localization of corticotropin‐releasing factor, somatostatin, and vasoactive intestinal polypeptide in the parabrachial nuclei of the human brain
Authors: Pammer Csilla , Fodor M. , Palkovits M.
Published: January 2005

The immunocytochemical localizations of corticotropin‐releasing factor (CRF), somatostatin (SRIF), and vasoactive intestinal polypeptide (VIP) were studied in the human parabrachial nuclei (PBN) using the avidin‐biotin complex (ABC) technique. The brains were obtained from seven adult male human subjects of 38–74 years. In three cases, the brains were fixed within 2 hr, in four cases within 5 hr, postmortem. All of these peptides were detected in fibers through the orocaudal extent of the lateral PBN, whereas the medial nucleus contained only CRF immunoreactive fibers. Immunoreactive fibers were distributed unevenly within the lateral nucleus with the highest density in the dorsal and much fewer in the ventral part of the lateral subdivision. The highest to lowest density of immunostained processes were detected using CRF, SRIF, and VIP antisera, respectively. Since NPB is known as an important relay nucleus for the central autonomic pathway, the presence of the above noted neuropeptides in nerve fibers in this area may suggest a neurotransmitter or neuromodulatory role of CRF, somatostatin, and VIP in certain autonomic nervous mechanism of the human brain.
Effects of inhibitors of glycoprotein processing on oligodendroglial differentiation in primary cultures of embryonic rat brain cells
Authors: Bhat Narayan R.
Published: January 2005

The effects of N‐linked oligosaccharide processing inhibitors on oligodendroglial differentiation were examined in cultures of embryonic rat brain cells. The glucosidase inhibitors, 1‐deoxynojirimycin (dNM) and castanospermine, were found to have marked inhibitory effects on the developmental expression of oligodendroglial properties, i.e., sulfogalactolipid synthesis and 2′3′‐cyclic nucleotide 3′‐phosphohydrolase (CNP). On the other hand, the mannosidase inhibitors, 1‐deoxymannojirimycin (dMM) and swainsonine, had relatively little effects. Since both classes of inhibitors block the formation of complex‐type oligosaccharide chains as revealed by concanavalin A‐Sepharose affinity chromatography of the glycopeptides, complex oligosaccharides oligosaccharides do not seem to play a role in oligodendroglial differentiation. The results indicate instead that the early trimming reactions involving the removal of glucose residues by processing glucosidases may be critical for the functioning of specific glycoprotein(s) essential to oligodendroglial differentiation.
Glycerol oxidation in discrete areas of rat brain from young, adolescent, and adult rats
Authors: McKenna Mary C. , Tildon J. Tyson , Bezold L. I.
Published: January 2005

We have reported previously that the oxidation rate of [1,3‐14C] glycerol to 14CO2 is lower in whole brain homogenates from neonatal rats and increases about 30% during the suckling period to adult levels. To determine whether there are developmental changes in glycerol oxidation in discrete regions of brain, we examined the oxidation of glycerol by homogenates of hypothalamus, cerebellum, brain stem, hippocampus, and cerebral cortex of young (4–6 days) and older (18–20 days) pups and adult (>90 day) rats. The oxidation was measured at both low (0.2 mM) and high (2.0 mM) concentrations of glycerol, since the oxidation of glycerol by brain tissue has been shown to exhibit biphasic kinetics. At each age, and with both concentrations of glycerol, there were significant differences among the discrete brain regions. Although the rate of glycerol oxidation increased with age in most areas of brain, each brain region had a distinct developmental profile. In the hypothalamus, the oxidation of glycerol increased significantly between 4–6 days and adult levels at 18–20 days. The oxidation of glycerol was essentially the same in homogenates of cortex from young and older pups, but it was significantly increased in adults. In contrast with other brain regions, the oxidation of glycerol by brain stem was highest at 4–6 days and significantly decreased with age. The developmental profile of glycerol oxidation in hippocampus and cerebellum was particularly complex, since it increased with age at low, but not at high, concentrations of glycerol. This developmental pattern in hippocampus and cerebellum could be related to changes in the biphasic kinetics of glycerol oxidation and suggests that glycerol metabolism is different in these two areas of brain compared with other areas of brain.
GABAA and GABAB sites in bovine adrenal medulla membranes
Authors: Castro E. , Oset‐Gasque M. J. , Cañadas S. , Gimenez G. , González M. P.
Published: January 2005

The effect of several ligands and Ca2+ ions on [3H]GABA binding to bovine adrenal medulla membranes was investigated. Without any blockade, the [3H]GABA binding showed two components, one of low affinity (Kd = 139 ± 22 nM and Bmax = 3.2 ± 0.4 pmol/mg protein) and the other of high affinity (Kd = 41 ± 6 nM and Bmax = 0.35 ± 0.26 pmol/mg protein). Muscimol specifically blocked low‐affinity sites, and ( – )baclofen blocked high‐affinity components. Ca2+ ions were strictly necessary for maximum binding to high‐affinity sites, whereas they did not significantly affect sites of the lower affinity. These results show that the bovine adrenal medulla has a GABAA receptor population of low affinity together with a GABAB receptor of high affinity.
Light‐dependent subcellular movement of photoreceptor proteins
Authors: Whelan J. P. , McGinnis J. F.
Published: January 2005

The intracellular localization of photoreceptor‐specific proteins 33 kd, beta‐transducin, and 48 kd, as determined by immunocytochemistry, is transient and dependent on the lighting environment to which the retina is exposed. Western analysis of the proteins in isolated rod outer segments from mouse retina demonstrates that beta‐transducin actually moves from the outer segment to the inner segement in response to light and that 48 kd moves simultaneously in the opposite direction. The light‐induced movements appear to be initiated by the absorption of light by rhodopsin because red light, which does not bleach rhodopsin, does not produce this redistribution of phototoreceptor proteins. Time course analysis of these movements suggests that the light‐induced shift is detectable at the earliest time examined (30 seconds). The bidirectional movement suggests that the photoreceptor cells have at least two distinct dyneinlike or kinesin‐like translocator molecules that act as microtubule‐based motors. This movement appears to be a basic mechanism by which photoreceptor cells rapidly and radically alter the subcellular concentrations of photoreceptor‐specific proteins, which in turn may affect the rapid changes in membrane potential that occur during phototransduction.