bluuebunny/crossref_metadata_2025 huggingface dataset:
Histamine H1‐ and H2‐receptors in the central thermoregulatory pathways of the rat
Authors: Green M. D. , Cox B. , Lomax P.
Published: January 2005

The effects of phyrilamine and burimamide (histamine H1‐ and H2‐receptor blockers, respectively) on the hypothermic response to histidine loading have been studied in rats. The antagonists were injected into one of three sites in the brain: the preoptic/anterior hypothalamic nuclei, the lateral ventricle, or the third ventricle. Only injections of burimamide into the third ventricle blocked the hypothermic response to systemic injection of histidine. Behavioral studies revealed that, after histidine, the animals increased their time of exposure to a heat lamp, which suggests that efferent heat loss pathways had been activated. Previous studies have shown that H1‐receptor antagonists will block the hypothermic effect of histamine injected into the rostral hypothalamus. These data suggest that there are, at least, two sets of histaminergic receptors on the neuronal pathway through the hypothalamus: H1‐receptors in the rostral hypothalamus and H2‐receptor on neurons lying close to the wall of the third ventricle. Activation of this thermoregulatory pathway leads to increased heat loss and a fall in body temperature.
Nerve growth factor‐induced rapid activation of RNA labeling in dorsal root ganglionic dissociates from chick embryos
Authors: Horii Zen‐Ichiro , Varon Silvio
Published: January 2005

Dorsal root ganglionic cells, from 8‐day chick embryo, undergo anabolic declines when incubated in vitro without Nerve Growth Factor (NGF) or other supportive agents. To determine whether the decline could be opposed by delayed administration of the NGF, cells were incubated without the factor for varying times, then supplied with it and tested periodically with pulses of radiouridine or radioleucine. The decline in RNA labeling was actually reversed by a delayed addition of NGF, and the effect was fully elicited within less than 10 min from the treatment. With delays up to 6 hr, this rapid activation by NGF fully restored the incorporation rate exhibited by fresh cells or by cells continuously incubated with NGF. From the hour 8 on, the NGF‐induced activation of RNA labeling fell progressively shorter of restoring maximal performance until, by18 hr, it was no longer significant. The residual (irreversible) decline in RNA labeling, starting after 6 hr, developed with a time pattern coincidental with that of the irreversible decline in protein labeling also displayed by those untreated cells, and similar to the appearance of RNA degradation and the acceleration of protein degradation. All four such “degenerative” events were fully prevented by NGF when administered with delays shorter than 6 hr, and only interrupted (or delayed) by NGF delivered at later times. Additional experiments revealed that, over the first 6 hr, NGF also prevented or reversed a decline in TCA‐soluble radioactivity of the cells, an effect which was not blocked by actinomycin D. This rapid increase of soluble radio‐activity could be responsible for the rapid activation of RNA labeling and may also be involved in the prevention by NGF of the later developing degenerative events.
Bioelectric observations on adult and newborn hypothalamic dendrites
Authors: Torda Clara
Published: January 2005

Bioelectric activities of hypothalamic dendrites of newborn kittens and adult cats were recorded in vivo. Stimulation of various hypothalamic areas with electrical stimuli, or by injection of norepinephrine, generated propagated spikes in both new‐born and adult neurons. The morphologically immature hypothalamic dendrites were hypersensitive to stimuli and were able to generate propagated spikes not only of axon hillock (adults) but also of dendritic membrane origin. Some mechanisms responsible for the two types of spike formation (newborn and adult) have been identified.
Kinetics of interfacial ATP adsorption and anionic exchange with a synaptic membrane protein
Authors: Hoss Wayne , Abood Leo G.
Published: January 2005

A study was conducted on the adsorption of 14C‐ATP to a surface film of a hydrophobic protein derived from synaptic membranes isolated from bovine cerebellum. The adsorption of ATP to the protein film followed a rate law based on diffusion and an energy barrier to adsorption, the rate law being generally applicable to the adsorption of ions to a charged interface. Studies were also carried out on the displacement of ATP from the film by the injection of other nucleotides, inorganic phosphates, and other anions. The kinetics conformed to a rate law based on diffusion and displacement. The most important factor in the displacement of ATP was the magnitude of charge of the anion, while steric factors were relatively minor. However, from a consideration of the energy barrier to adsorption it appeared that steric factors play a greater role in the adsorption of ATP. The results are discussed in relationship to the configurational aspects of the surface film as well as their possible significance in synaptic function.
Molecular information structures in the brain
Authors: Conrad Michael
Published: January 2005

This paper presents a theory of memory and memory mediated learning based on the manipulation of macromolecular conformations. The main features of the theory are: (1) the brain contains primary and reference neurons; (2) inputs from the external environment produce particular patterns of primary firing; (3) the firing of a primary neuron sensitizes certain of its dendrites; (4) the sensitized primaries are loaded by the reference neuron active at the time and in such a way that they fire when called by this reference neuron, thus reconstructing the original pattern of primary activity. The reference neurons may also be loaded by primaries, thus making it possible for the reconstruction process to be initiated by some feature of the initial input. Each reference neuron loads and calls at most one primary pattern of activity, thereby preventing superposition of memories. If the primaries are loadable by sequences of impulses, this makes it possible to increase the connectivity among the various types of neurons by using party‐line organization. The loading and calling processes themselves are mediated by call molecules. These are allosteric enzymes, located in the dendrites of primary and reference neurons, whose states are set either by an impulse or sequence of impulses and which catalyze events leading to impulse formation whenever this input recurs. The call molecules are capable of duplicating their setting (or conformation) using either intra‐ or interneuronal potentials, thereby ensuring stability of the memory trace. The theory allows for general powers of memory manipulation (by rememorization), for the construction of time ordered, content ordered, and associative data structures, and for computation with global representations of the environment. It makes a large number of testable predictions, provides a natural interpretation for the structure of the cerebral cortex, and accounts for: resistance to cooling, differential effects of chemical agents on short and long term memory, distributed character of memory, accessibility of memories by stimulation of specific brain loci, and also the details of classical conditioning and instrumental learning.
Neurotransmission and glial cells: A functional relationship?
Authors: Henn Fritz A.
Published: January 2005

The investigations reported here demonstrate high affinity transport systems localized in glial cells which appear to be specific for amino acid neurotransmitter candidates. Data on uptake of γ‐aminobutyric acid (GABA), glutamate, glycine, and taurine, show transport systems with KT's in the range of 10−5M. In addition, the distribution of the glial transport system for glycine is shown to parallel the presumed distribution of glycine as an inhibitory neurotransmitter. Results of these studies also suggest that transport studies on brain homogenates or synaptosomal preparations do not serve to localize these functions to synaptic elements as is widely believed. This report shows that glia can form vesicles during homogenization which band with synaptosomes in density gradients, and retain transport activity. Glia also may contribute to the release of neurotransmitters via control of the extracellular to cause release of Ca++ by glia.
In vitro vs in situ development of Purkinje cells
Authors: Palacios‐Prü Ernesto , Palacios Laura , Mendoza Rosa V.
Published: January 2005

Analysis of in vitro vs in situ development of Purkinje cells was undertaken in order to compare the transitory morphology of Purkinje cells grown in situ with their differentiation in vitro. Purkinje cells in rotary cultures developed their basic morphological pattern only when the cultures were prepared from 16‐day chick embryos, indicating the existence of a critical period during their normal differentiation, which lasted approximately 24 hr between days 14 and 15 of embryonic development.
Failure to demonstrate alterations in gluconeogenesis in growth‐retarded weanling rats with dorsomedial hypothalamic lesions
Authors: Bernardis Lee L. , Goldman Jack K. , Bellinger Larry L.
Published: January 2005

Bilateral electrolytic lesions were placed in the dorsomedial hypothalamic nuclei (DMN) of weanling male Sprague‐Dawley rats. Sham‐operated rats served as controls. After 22 days on lab chow and tap water ad libitum, the animals were injected with U‐14 C‐alanine 0.167 μC/μ moles intraperitoneally (5 μC and 30 μ moles/100 gm body weight) and sacrificed 2 hr later. There was no significant difference, in the incorporation of the label into total lipid, free fatty acids, glycogen, or tissue protein of both liver and diaphragm, between the DMN‐lesioned and the sham‐operated rats. Similarly, there was no significant difference in the incorporation into the plasma glucose or protein. It is concluded that in spite of profound alterations in both ponderal and linear growth and food intake, there is no disruption of normal gluconeogenesis in the weanling rat with DMN lesions.
The relationship of afterhyperpolarizations of extraocular motoneurons to membrane potential
Authors: Barmack N. H.
Published: January 2005

The effect of membrane potential displacements caused by external current injection on the amplitudes of two antidromically evoked afterhyperpolarizations (AHP1 and AHP2) was measured in extraocular motoneurons. AHP1 had a reversal potential of –70m V and an average compensation for displacements from the reversal potential (“compensation gain”) of –0.36. AHP2 had a reversal potential of –80mV and a compensation gain of –0.08. Measurements of input resistance of these motoneurons demonstrate a 30–50% decrease at depolarized membrane potentials. This rectification could account for the apparent lack of summation of AHP2. The functional role of AHP1 and AHP2 in the regulation of discharge frequencies of extraocular motoneurons during normal eye movements is discussed.
Failure of hepatic infusion of amino acids and/or glucose to inhibit onset of feeding in the deprived dog
Authors: Bellinger L. L. , Birkhahn R. H. , Trietley G. J. , Bernardis L. L.
Published: January 2005

Nine mongrel dogs were fed for only 1 hour/day for 7–8 days and the time of onset of their eating and hourly intakes were recorded. At the end of this period, the hepatic portal vein was cannulated and the polyethylene cannula was exteriorized. Upon recovery to their preoperative food intake, the dogs were infused after a 23 hour fast over a 4 minute period with an amino acid (AA) mixture (FreAmine II, McGaw Laboratories) equal to 7.2% (37 trials), 14.4% (28 trials), or 21.6% (28 trials) of the dogs' daily AA requirements and presented with food 4 minutes later. In all 93 trials the dogs ate within 30 seconds of presentation of food and their hourly intakes were not significantly different from isotonic saline infusions. Six 23 hour deprived dogs were infused with 21.6% of their AA requirement and then presented with food 11 minutes later. Again, these dogs began eating within 30 seconds of presentation of food. Finally, 4 dogs were infused over a 4 minute period after a 23 hour fast (12 trials) with 7.2% of their daily AA requirements mixed with 6 g of glucose and presented with food 4 minutes later. The dogs began eating within 30 seconds in all 12 trials and their hourly intakes were not significantly depressed. These results question the existence or role of hepatic glucoammonium receptors involved in the control of feeding behavior.
Binding and immobilization of catecholamines by liposomes
Authors: Hoss Wayne , Smiley Constance
Published: January 2005

The polarization of the native fluorescence of dopamine and noradrenaline has been used to measure their binding and immobilization by liposomes suspended in aqueous buffers. Whereas both catecholamines are significantly immobilized by brain phosphatidyl serine and yeast phosphatidyl inositol, phosphatidyl ethanolamine and phosphatidyl inositol from brain are ineffective. Dopamine is immobilized to a greater degree than noradrenaline. The dissociation constants determined from modified Scatchard plots of the polarization data are 1.7 × 10−4 and 9.6 × 10−5 M for dopamine with yeast phosphatidyl inositol and brain phosphatidyl serine, respectively. Apomorphine binds to a hydrophobic region of phosphatidyl serine liposomes with a KD value of 69 μM. It is suggested that a fraction of dopamine is complexed with membranous phosphatidyl serine in nerve terminals.
Bacterial lipopolysaccharide depresses spontaneous, evoked, and ionophore‐induced transmitter release at the neuromuscular junction
Authors: Person Robert James
Published: January 2005

The neurotoxicity of RNA‐free lipopolysaccharide (LPS) extracted from Salmonella Typhimurium (SR‐11) was tested at the frog neuromuscular junction using intracellular recording techniques. Spontaneous miniature endplate potential (MEPP) frequency was reduced to 45% of control after 60 minutes in the presence of 10 and 50 μg LPS/ml Ringer's solution. Elevation of extracellular [Ca] to 10 mM converted the MEPP frequency response to a biphasic pattern of early acceleration followed by late depression. Evoked endplate potentials (EPPs) were reduced in quantal content until phasic release of transmitter was abolished, while MEPP amplitude and endplate resting potential remained constant. Effects of the potent cation ionophore X537A on MEPP frequency were blocked by 45 minutes of pre‐exposure to LPS. Because of its extremely lipophilic character, LPS apparently alters the physical structure of the presynaptic terminal membrane, eventually reducing resting and phasic Ca influx, and isolating the presynaptic terminal from ionophore action.
Effects of the lateral septum and latent inhibition on successive discrimination learning
Authors: Toga Arthur W. , Burton Howard A.
Published: January 2005

Damage to the lateral nucleus of the septum in the rat resulted in atypical learning to a previously meaningless stimulus. Nonreinforced preexposure to a stimulus normally makes more difficult subsequent use of that stimulus for learning. The effect of this preexposure on learning is termed latent inhibition and was demonstrated in sham operated animals. Rats in which the lateral septum was damaged demonstrated a paradoxically smaller learning deficit in the presence of a conditioned stimulus that was previously presented without reinforcement, when compared to the performance of both septal lesioned rats not receiving nonreinforced preexposure and sham operates receiving preexposure. The interaction of nonreinforced preexposure and lateral septal lesions can be explained using a proposed sensitization hypothesis.
The interrelation between brain PO2 and NADH oxidation‐reduction state in the gerbil
Authors: Mayevsky A. , Lebourdais S. , Chance B.
Published: January 2005

The present investigation was aimed at studying the interrelation between hemodynamic, metabolic and oxygen tension in the brain of the gerbil exposed to various physiological and pathological conditions in the awake and anesthetized states. The hemodynamic and metabolic activities were evaluated by the DC fluorometer/reflectometer and were correlated to the pO2 values obtained by a surface electrode.

When the awake brain was exposed to spreading depression (SD), a typical oxidation cycle of the NADH was recorded concomitant with a decrease cycle of the pO2. Under anesthetic effect the same dip in pO2 response was found but the NADH showed a “reduction cycle.” The pO2 values were in a very good correlation with the changes in the reflectance trace, namely, the pO2 was a good indicator of the vasoconstriction‐vasodilatation responses under various conditions. The same model was used under hypoxic and ischemic conditions, as well as under the effects of anesthetics.
Glutamic acid transport in cortical synaptosomes from essential fatty acid deficient rats
Authors: Wheeler D. D. , Callihan C. S. , Wise W. C.
Published: January 2005

The sodium dependence of the high‐affinity transport of glutamic acid in rat brain synaptosomes has been studied in animals maintained on a diet deficient in essential fatty acids (EFAD), and the results compared to similar studies with animals on a normal diet. Although the data give best fit to the same kinetic model as for control data, there are differences in the constants that describe the model. Except at low sodium concentrations, uptake is lower for the EFAD group.

As a consequence of the differences in constants for the two groups, there are quantitative differences in the transport mechanism. The rate equation for the best fit model has been utilized to define certain functions in terms of dissociation and translocation constants, glutamate, sodium, and total carrier concentrations. These functions were calculated and utilized to compare the transport mechanism for the two groups. Although there are differences between these functions for control and EFAD animals, these differences are small and therefore of doubtful physiological significance.
Effect of methionine, glycine and serine on serine hydroxymethyltransferase activity in rat glioma and human neuroblastoma cells
Authors: Kohl Randall Lee , Perez‐Polo J. R. , Quay W. B.
Published: January 2005

Human neuroblastoma SK‐N‐SH‐SY5Y (5Y) and rat glioma (C6) cells were cultured with supplemental methionine, glycine, or serine for three to six days. Serine hydroxmethyltransferase (SHMT: L‐serine: tetrahydrofolate 5, 10‐hydroxymethyltransferase, EC 2.12.1) was assayed radiometrically in whole cell homogenates, crude supernatant fractions and crude particulate fractions. No significant changes in specific activity or cellular morphology were noted at methionine, glycine, or serine concentrations up to 16 mM. Serine concentrations of 20 and 40 mM led to significantly lower gliomal enzyme specific activities. This activity was unevenly distributed between soluble and particulate fractions, with 190 and 398 nmoles of HCHO formed per mg of protein per hour, respectively. Growth stage and time of incubation were major determinants of enzyme specific activity. C6 cells' specific activity rose slowly with increasing time in culture until cellular confluence. At this time there was a pronounced elevation in specific activity, occurring more rapidly in cells grown in 1.2 mM methionine. Intracellular amino acid analysis of C6 cells demonstrated a significant rise in methionine after four days in media containing 0.2 mM methionine. No appreciable diminution in the intracellular levels of glycine or serine occurred following incubation in excess methionine.

It is concluded that SHMT‐specific activity in C6 and 5Y cells is not regulated by glycine, serine, or methionine levels and that high concentrations of these amino acids (> 30 mM) are not detrimental to these cells derived from the CNS.
Studies on AMP deaminase and 5′‐nucleotidase in rat brain under different experimental conditions
Authors: Sadasivudu B. , Rao T. Indira , Murthy Ch. Radhakrishna
Published: January 2005

Adenosine monophosphate (AMP) deaminase and 5′‐nucleotidase, the two enzymes involved in the disposal of AMP, have been detected in different regions of normal rat brain and in animals subjected to heightened neuronal activity (leptazol‐induced convulsions) and to depression of the central nervous system (CNS) by the administration of barbiturates. They have also been estimated in the CNS of animals subjected to anoxia or treated with lithium and ammonium salts. The AMP deaminase activity was found to be highest in cerebellum and lowest in cerebral cortex, while the 5′‐nucleotidase activity was found to be highest in brain stem and lowest in cerebellum. The AMP deaminase activity was elevated in all the regions of brain during the preconvulsive and convulsive periods. The activity returned to normal during recovery. The activity of 5′‐nucleotidase was found to be depressed in the preconvulsive and post‐convulsive periods. The enzyme was also found to be depressed in all three regions after the administration of barbiturates. Administration of lithium or ammonium salts or induction of anoxic states resulted in an increase in the activity of AMP deaminase in all the three regions of brain. These results are discussed in relation to the probable production of cyclic AMP and cyclic guanosine monophosphate (GMP) which may have depressive and excitatory roles, respectively, in brain. It appears that increased AMP deaminase activity is associated with increased neuronal activity while depression of 5′‐nucleotidase activity is associated with conditions of decreased CNS excitability.
Simultaneous fluorescent retrograde axonal tracing and immunofluorescent characterization of neurons
Authors: Van Der Kooy Derek , Steinbusch Harry W. M.
Published: January 2005

A simple method is described for simultaneously double labeling single neurons with fluorescent retrograde axonal tracers and immunofluorescence using an antibody to serotonin. Caudate‐putamen injection of orange fluorescent propidium iodide, in particular, proved effective in retrogradely labeling dorsal raphe cell bodies. These same perikarya could be stained green with the indirect immunofluorescent method, using green fluorescent fluorescein isothiocynate (FITC) as the second antibody.
Axoplasmic transport with velocities induced by pargyline
Authors: Watson Danny F. , Donoso J. Alejandro , O'Neill Robert E. , Samson Fred E.
Published: January 2005

The axoplasmic transport of proteins in spinal motor neurons is altered by pargyline, a drug that causes increased release of monoamines. Two new peaks of transported protein were detected in the sciatic nerves of rats treated with pargyline (75 mg/kg/day ip for three days). These peaks moved with velocities of 595 mm/day (peak I) and 1,230 mm/day (peak II). The bulk of labeled protein was still transported at the control rate of 362 mm/day. Electrophoresis of transported polypeptides labeled with [35S] methionine showed that peak I material was qualitatively similar to material transported at the normal rate in controls, but peak II material contained fewer labeled polypeptides. Both peak I and peak II differed from controls in the relative intensity of labeling of various polypeptides. Fast axoplasmic transport in sensory neurons was unaffected by pargyline. Intraspinal injection of pargyline (50 μg/day for three days) caused changes in axoplasmic transport similar to those induced by intraperitoneal pargyline. These results show that transport of certain proteins along a peripheral nerve can be accelerated by a mechanism initiated in the region of the nerve cell bodies.
Inhibition of neurotransmitter receptor binding by ergot derivatives
Authors: Hruska Robert E. , Silbergeld Ellen K.
Published: January 2005

Bromocriptine, lergotrile, lisuride, metergoline, and the Sandoz ergot derivatives 25–397, 29–712, and 29–717 have been tested for their ability to inhibit the synaptic receptor binding of spiroperidol, 5‐hydroxytryptamine (5‐HT), d‐lysergic acid diethylamide (LSD), quinuclidinyl benzilate (QNB), WB.4101, and γ‐aminobutyric acid (GABA). Only GABA binding was not affected, and QNB binding was decreased only by lergotrile and metergoline at high concentrations. The most potent inhibitors of the other ligands were bromocriptine and lisuride for spiroperidol (1–2 nM), metergoline for 5‐HT (29 nM), lisuride for LSD (15 nM), and lergotrile for WB.4101 (17 nM). The direct receptor effects of the ergot derivatives in vitro may contribute to understanding their in vivo effects on behavior and in predicting their therapeutic potential in neurological and neuroendocrine disorders.
Specific enhancement of neuronal responses to catecholamine by p‐tyramine
Authors: Jones Roland S. G.
Published: January 2005

Extracellular recording and iontophoresis techniques were used to study the interactions of the trace amine, p‐tyramine (p‐TA) with putative neurotransmitters on single neurones in the cerebral cortex and caudate nucleus of the rat. p‐TA, when applied with weak iontophoretic currents which did not result in any change in neuronal firing rate, caused a pronounced potentiation of depressant responses to iontophoretically applied dopamine (DA). Depressant responses of cortical neurones to noradrenaline were also markedly potentiated by weak background applications of p‐TA. This potentiating action of p‐TA was related to the amount of the trace amine applied and was apparently specific for catecholamines, since depressant responses to 5‐hydroxytryptamine and γ‐aminobutyric acid were unaffected. Excitatory responses to iontophoretically applied glutamate were also unaltered by weak applications of p‐TA. Excitatory responses of most neurones to acetylcholine (ACh) were also unaffected by p‐TA in the cortex and caudate nucleus. However, responses to ACh of a small number of cells in both brain areas were reduced in size during weak applications of p‐TA. It is suggested that p‐TA may act as a modulator of neurotransmission, particularly that mediated by DA in the central nervous system.
Horizontal cell processes in teleost retina
Authors: Parthe V.
Published: January 2005

Contacts between horizontal and bipolar cells are described in the retina of the teleost Eugerres plumieri. A single, long expansion observed in the external cone horizontal cells makes contact by means of a terminal button with the cell body of a bipolar. It represents the only contact between this class of horizontal cell and the bipolar soma. On the other hand, the medial and internal cone horizontal cells and the rod horizontal cells, which lack such a single, long expansion, display instead numerous short and fine expansions that terminate by means of a terminal knob on a bipolar cell body. The bipolar‐destined, short expansions of the rod horizontal cell make contact with large bipolar cell bodies, whereas corresponding short expansions of cone horizontal cells contact small bipolar cell bodies.

It is suggested that the ascending horizontal cell process forms presynaptic terminals in the photoreceptor triad complex, and that the single, long and the multiple, short bipolar‐destined expansions are postsynaptic to the bipolar cell body.
A new antigen common to the rat nervous and immune systems: I. Detection with a hybridoma
Authors: Akeson Richard , Graham Karen L.
Published: January 2005

An antibody secreting cell line has been obtained using the technology developed by Milstein, Kohler, and colleagues by fusion between ×63 myeloma cells and spleen cells from a mouse previously immunized with PC12 cultured rat pheochromocytoma cells. This antibody bound to particulate protein from adult rat brain and to a lesser extent spinal cord and retina but not adrenal. Lower levels of binding were observed also with spleen, bone marrow, and peritoneal exudate cells. Cells or particulate protein from seven nonneural, nonimmune tissues showed essentially no specific binding. Analysis of adherent and nonadherent peritoneal exudate cells indicated specific antibody binding to both populations. The specific antibody bound was greater in the non‐adherent fraction. The antigen has been provisionally named G5 after the antibody secreting clone. Like the Thy 1 antigen of rodents, it is expressed by subpopulation of cells from the nervous and immune systems. However the antigen could not be detected on the PC1 2 cell line used for immunization suggesting that Balb/C mice spontaneously produce antibody to this rat differentiation antigen.
Purification of dihydropteridine reductase from human platelets
Authors: Shen Rong‐Sen , Abell Creed W.
Published: January 2005

Dihydropteridine reductase was purified approximately 1,700‐fold from human outdated blood platelets. Two forms of the enzyme, A and B, were resolved. They have the same Km values for 2‐amino‐6,7,‐dimethyl‐4‐hydroxydihydropteridine (46 μml;M vs 49 μml;M), but the A form has a Km for NADH that is two times higher than that of the B form (20 μml;M vs 9 μml;M).
The effect of injections of dopaminergic agonists into the caudate nucleus on the electrocorticogram of the rat
Authors: Keane P. E. , Neal H.
Published: January 2005

Electrocortical activity was recorded in encéhale isolé rats during injection of various dopaminergic compounds into the caudate nucleus. Slow waves and spindles were observed following injection of compounds with different mechanisms of action in stimulating the dopamine receptor. Some arylalkylamine analogues also induced similar electrocortical changes, whereas others were inactive. The possible dopamine agonist activities of these compounds are discussed. The results support an involvement of dopamine in the production of electrocortical slow waves and spindles.
Reorganization and orientation of regenerating nerve fibres, perineurium, and epineurium in preformed mesothelial tubes – an experimental study on the sciatic nerve of rats
Authors: Lundborg Göran , Dahlin Lars Bertil , Danielsen Nils P. , Hansson Hans Arne , Larsson Karin
Published: January 2005

Regeneration of severed peripheral nerves is unfortunately often incomplete, due to loss of nerve fibers and neuroma formation. A new approach is presented with the intention of improving the conditions for nerve repair. In the first of the two stages, a pseudosynovial tube is formed around a silicone rubber rod, surrounded by a stainless steel spiral, which was placed in the backs of rats. This tube, in the second stage, is used as a free “tube graft” to bridge gaps of about 10–12‐mm lengths in the severed sciatic nerve. The tube was kept open by the metal spiral. Regenerating nerve fibers with their sprouts grew into the initially open space in the tube. A new nerve trunk was formed, comprised of closely packed myelinated and unmyelinated axons, organized into fascicles. Demonstration by electron microscopy and by EMG recording of reinnervation of foot muscles supported successful long‐term results. The fascicles were delimited by perineurial and epineurial sheaths and, furthermore, showed signs of maturation. It was also demonstrated that the nerve‐fiber regeneration ceased after a few weeks if there was no distal nerve inserted into the tube. The importance of optimizing the interaction between local factors and regenerating nerve fibers for reestablishment of functionally valuable motor units is discussed.
Effects of neurotransmitters on calcium efflux from cultured glioma cells
Authors: Lazarewicz Jerzy W. , Kanje Martin
Published: January 2005

The effects of various neurotransmitters and cyclic nucleotides on 45Ca2+ efflux in cultured human glioma cells were investigated. Glutamate and glycine, but not GABA, stimulated 45Ca2+ release from the cells.

Stimulation of beta‐adrenergic receptors but not alpha‐adrenergic receptors also increased 45Ca2+ efflux. Cholinergic receptor stimulation by carbachol had the same effect. The stimulatory effect of carbachol was abolished in the presence of either atropine or hexamethonium.

C‐AMP and c‐GMP increased the 45Ca2+ efflux, suggesting that these agents are involved in the transmitter‐stimulated release of 45Ca2+ from the cells.

Kinetic analysis of the efflux revealed four calcium compartments. The carbachol‐stimulated efflux represented a net release of calcium and could be ascribed to the slowest compartment.

The physiological role of the transmitter‐stimulated calcium release is discussed in terms of calcium‐regulated stimulus‐response coupling in glial‐neural interaction during excitation.
Synthesis of gangliosides by cultured oligodendrocytes
Authors: Mack Stephen R. , Szuchet Sara , Dawson Glyn
Published: January 2005

Gangliosides are enriched in the nervous system compared to other tissues. The synthesis of gangliosides by monolayer cultures of isolated oligodendrocytes has not previously been investigated. Cells were labeled with [3H]galactose at preselected times and gangliosides isolated by phase partition, purified, and identified by chromatography. Cultured oligodendrocytes showed selectivity in their synthesis of gangliosides, which was expressed in the type of ganglioside synthesized as well as in the change of incorporation over time in culture. For the first ten days, there was very little incorporation of [3H]galactose in gangliosides, but this was followed by a stimulation of uptake for GM3, GM1/GD3, and GD1 gangliosides, reaching a maximum after approximately 25–30 days in vitro. There was little incorporation into GM2 or trisialogangliosides throughout the life of the cultures. Since oligodendrocytes synthesize extensive membranes during this period, one may speculate that the de novo‐synthesized gangliosides are used for membranes.
Effect of hypoxia on the incorporation of [2‐3H]glycerol and [1‐14C]‐palmitate into lipids of various brain regions
Authors: Alberghina M. , Giuffrida A. M.
Published: January 2005

The lipid metabolism in guinea pig brain after intermittent hypoxia, prolonged for 80 hrs, was markedly impaired. The in vivo incorporation of [2‐3H]glycerol and [1‐14C]palmitate into lipids of microsomes, mitochondria, myelin, and synaptosomes, purified from cerebral hemispheres, was significantly lower in the hypoxic animals than in the controls. The same effect was observed on the incorporation of labeled precursors into lipids of mitochondria purified from cerebellum and brainstem. In particular, the labeling of the major phospholipids present – ie, phosphatidylcholine (PC) and phosphatidylethanolamine (PE) – in the mitochondria of the three brain regions examined decreased after hypoxic treatment.
Effect of taurine on seizures induced by 4‐aminopyridine
Authors: Pasantes‐Morales H. , Arzate M. E.
Published: January 2005

The effect of intraperitoneally injected taurine against the convulsive activity induced by 4‐aminopyridine (4‐AP) was studied in 12‐ to 15‐day‐old mice. At a dose of 2.6 mg/kg, taurine increased the latency of clonic seizures from 7 to 20 minutes, reduced the incidence of tonic seizures from 92% to 30% and the postconvulsive mortality from 80% to 31%. The injection of EDTA prior to the administration of taurine prevented the protective effect of the amino acid. GABA and glycine at the same doses did not protect against 4‐AP‐induced seizures. 4‐AP caused a small increase (19%) in 45Ca accumulation by mice brain synaptosomes incubated in a Krebs‐HEPES medium containing low CaCl2 (0.1 mM) and also slightly potentiated the veratrine and potassium‐induced increase in calcium accumulation. 4‐AP at concentrations of 1–2 mM caused a marked increase (100%–500%) of 45Ca acculation by synaptosomes incubated in a Krebs‐bicarbonate medium containing 2.5 mM CaCl2. This increase was completely antagonized by taurine but not by GABA or glycine. The present observations suggest that the anticonvulsant effect of taurine might be mediated by 4‐AP‐calcium‐taurine interactions.
Taurine binding to membranes from rat brain regions
Authors: Löpez‐Colomé A. M. , Pasantes‐Morales H.
Published: January 2005

[3H]‐taurine binding to membranes from different regions from rat brain was studied. Binding to membranes from cerebral cortex and its subcellular fractions, hypothalamus, olfactory bulb and cerebellum was measured. Binding to membranes from dorsal root ganglion was also determined. Na+‐dependent taurine binding was consistently observed in all the membranes except those from dorsal root ganglion. A KD = 4.06 μM was obtained for binding to membranes from cerebral cortex. Na+‐dependent taurine binding was displaced by 20 μM strychnine or bicuculline. Na+‐independent taurine binding with properties corresponding to a postsynaptic interaction could not be detected in any of the regions studied. The possibility of Na+‐dependent taurine binding, representing binding to uptake sites or to postsynaptic receptors for GABA and glycine, is discussed.
3H‐muscimol binding in synaptosomal fractions from bovine and developing rabbit retinas
Authors: Redburn Dianna A. , Mitchell Cheryl K.
Published: January 2005

Bovine and rabbit retina synaptosomal fractions bind the potent and specific GABA agonist, [3H]‐muscimol with high affinity and limited capacity. The high degree of pharmacological specificity and the subcellular distribution of these binidng sites are similar to those reported for [3H]‐GABA binding sites. These observations suggest that these sites represent the recongition sites for GABA receptors. The specific binding of [3H]‐muscimol in retinal homogenates from different aged rabbits reveal a distinct developmental profile with a fivefold to six fold increase in binding between days 5 and 13. Thus, it appears that GABA receptor development continues after eye opening in rabbits (day 9–10) and that receptor maturation is delayed by at least two to three days with respect to published reports of GABA uptake and evoked release.
Bouton renewal patterns in rat hindlimb cortex after thoracic dorsal funicular lesions
Authors: Ganchrow Donald , Bernstein Jerald J.
Published: January 2005

The transneuronal effect of bilateral, dorsal funicular lesions (T 12) on the frequency of boutons on cells in layer IV of hindlimb cortex was studies. Adult rats were utilized 1, 2, 3, 7, 14, 30, 45, 60, 90, or 120 days postoperative (DPO), and tissue was processed for the light microscopic visualization of silver‐impregnated boutons (Rasmussen method). Bouton counts were taken on soma, or along 5‐ and 10‐μm segments of proximal dendrite branching from soma. The soma diameter also was measured on those neurons chosen for bouton counts on the circumference of the soma. Statistically significant, increased afferentation on soma and proximal dendrite occurred during the first postlesion week relative to longer survival times; bouton counts on the proximal dendrite showed a trend (not statistically significant) toward increases above normal. These data mirror similar, consistent increases in bouton counts reported in thalamic ventroposterolateral nucleus of these same cases. At 14 DPO, bouton counts on the soma decreased below normal (P<0.005) and, except at 60 DPO, remained so through 120 DPO (P<0.025). Bouton counts on the proximal dendrite also decreased below normal at 14 DPO (P<0.005), thereafter exhibiting either periodic (along 5‐7μm) or extended (along 10‐7mu;m) periods in significant decreases from normal. Correlations in lesioned cases between the number of boutons on the soma and either bouton counts on proximal dendrite or soma diameter were positive and statistically significant (P<0.005 in all correlations). Possible anterograde (via the dorsal column‐medial lemniscal system) and/or retrograde (via the corticospinal tract) transneuronal mediation of these effects in hindlimb cortex is discussed.
On the presence of met 5‐enkephalin receptors on the plasma membrane of deiters'neurons and their modulation of GABA transport
Authors: Cupello Aroldo , Hydén Holger
Published: January 2005

Met 5‐enkephalin blocks the active transport of GABA across plasma membranes of rabbit Deiters' neurons prepared by microdissection. Such an effect is receptor‐mediated, being reversed by the antagonist Naloxone.

This result shows that Deiters' neurons bear enkephalin receptors, and suggests a hypothesis on the mechanism of enkephalin‐mediated neuronal inhibition.
Flow of glucose carbon into cholesterol and phospholipids in various regions of the adult rat brain: Enhanced incorporation into hypothalamic phospholipids
Authors: Barkai Amiram I.
Published: January 2005

The contribution of glucose carbon to the biosynthesis of cholesterol and phospholipids in distinct brain regions was studied quantitatively in the adult male rat. Rates of flow of glucose carbon into the lipids in vivo were calculated from two measurements: the curve representing the decrease in plasma 14C‐glucose with time and the specific activity of the cerebral lipid 180 minutes after a rapid intravenous injection of a tracer dose of D–U 14C‐glucose. The following brain regions were studied: cerebral cortex, hypothalamus, medulla, and corpus callosum and cerebellum. The values for carbon flow into phospholipids were significantly higher in the hypothalamus than in the whole brain, whereas small, but insignificant, regional differences were found for carbon flow into cholesterol. The conversion of U‐14C‐glucose to individual phospholipids of both hypothalamus and cerebral cortex was further investigated in vitro in order to establish whether the higher rate of carbon flow into hypothalamic phospholipids resulted from enhanced synthesis of a particular phospholipid. In agreement with the results obtained in vivo, the rate of incorporation of 14C into total phospholipids was 60% higher in hypothalamic tissue. The results indicate that the higher rate of carbon flow into hypothalamic phospholipids might be attributed to enhanced incorporation of glucose carbon to phosphatidyl‐choline and phosphatidyl‐ethanolamine following a faster conversion of glucose to glycerol in this brain region.
Influence of triiodothyronine on the amino acid uptake of brain and spinal cord in normal and spinal hemisected adult rats
Authors: Wells Michael R. , Lofton S. A. , Bernstein Jerald J.
Published: January 2005

The thyroid hormones triiodothyronine (T3) and L‐thyroxine appear to enhance regeneration in the peripheral and central nervous system (CNS). The following experiments examine possible metabolic substrates for the action of T3 on the adult rat CNS after spinal hemisection. The protein incorporation of (3H)lysine after a left spinal hemisection (T2) or control operations was examined 1, 3, 7, and 14 days postoperation. Triiodothyronine (1 μg/kg body weight in a bicarbonate buffer) was injected daily for the postoperation or equivalent time period. One hour prior to decapitation, animals were given a subcutaneous injection of 200 μCi of (3H)lysine. Samples of brain and spinal cord were dissolved, and the radioactivity of acid‐precipitable protein and acid‐soluble fractions were determined by scintillation counting. T3 treatment influenced the general levels of incorporation of all treated groups over all days postoperation. Specific effects were observed in spinal hemisected T3‐treated animals. A significant hemispheric (P<0.05) asymmetry was present at 3 days postoperation with the right somatomotor cortex higher in protein radioactivity than the left. In spinal cord, the area of the lesion and areas just caudal to the lesion were higher in (3H)lysine incorporation in T3‐treated rats relative to controls. T3 effects appear to involve an increased sensitivity of the cells of the injured nervous system to the hormone.
α1 and α2 Adrenergic receptors in mouse brain astrocytes from primary cultures
Authors: Ebersolt C. , Perez M. , Bockaert J.
Published: January 2005

Mouse brain astrocytes from primary cultures were found to contain both α1 and α2 adrenergic receptors. 3H WB 4101 labeled one category of binding site (KD=1.5±0.39 nM, Bmax =64±7.9 fmoles/mg protein) with typical α1 adrenergic specificity (WB 4101 >prazosin>yohimbine). The density of α1 adrenergic receptors was 2–3 times higher in mouse cerebral cortex than in glial cells.

Like rat brain [U'Pritchard et al, 1979; Rouot et al, 1980], mouse glial cells were found to contain two categories of 3H clonidine binding sites: high affinity sites, which were identical to the high but not to the low affinity sites found in rat brain, since (1) they displayed the same affinity for 3H clonidine (KD=1.2±0.13 nM, n=4) and the same typical α2 adrenergic specificity (yohimbine>WB 4101 > prazosin); (2) the dissociation rate constant for clonidine binding was equal to 0.06 min−1, a value close to that found previously for the high affinity 3H clonidine binding sites in rat brain (0.05 min−1); and (3) divalent cations augmented and guanyl nucleotides reduced 3H clonidine binding as in rat brain. Na+ decreased 3H clonidine binding in a complex manner.

The number of high affinity sites in glial cells (52 ±9.4 fmoles/mg protein, n=4) was half the number found in mouse cerebral cortex (98 fmoles/mg protein). Low affinity 3H clonidine binding sites (KD=81±18 nM, Bmax=96±5.8 fmoles/mg protein, n=3) were not fully characterized.

In conclusion, glial cells contained the same α adrenergic receptors as those described in brain, but their physiological function is not yet known.
The vimentin‐GFA protein transition in rat neuroglia cytoskeleton occurs at the time of myelination
Authors: Dahl Doris
Published: January 2005

Extraction with Triton, a nonionic detergent, is a common procedure to prepare intermediate filament enriched fractions from cells maintained in culture. The Triton‐Insoluble fraction is called a cytoskeletal preparation. Using this procedure, we previously demonstrated that vimentin and glial fibrillary acidic protein (GFA) are major cytoskeletal proteins of neuroglia, in newborn and adult rat brain, respectively. In the present communication we report that the vimentin‐GFA transition in rat brain occurs during the 2nd‐3rd week, ie, at the time of rapid myelination when dividing glioblasts in white matter differentiate into oligodendroglia and interfascicular astrocytes.
Reversible dissociation of a bovine cardiac factor that supports survival of avian ciliary ganglionic neurones
Authors: Bonyhady Rae E. , Hendry Ian A. , Hill Caryl E.
Published: January 2005

The relationships has been sttudied between a high and a low molecular weight form of a bovine cardiac factor that supports the survival of avian ciliary ganglionic neurones in culture. Reversible dissociation of the high molecular weight from into identical or similarly sized subunits of apparent molecular weight in the range 15,000–30,000 has been demonstrated. In addition, other inactive high molecular weight components of cardiac extract were found to interact synergistically with both active forms of the factor.
Changes in enzyme activities of glycerolipid metabolism of guinea‐pig cerebral hemispheres during experimental hypoxia
Authors: Alberghina Mario , Viola M. , Giuffrida A. M.
Published: January 2005

Hypoxic treatment causes changes of some enzymatic activities involved in the glycerolipid metabolism in subcellular fractions of guinea pig cerebral hemispheres. The activity of lysophosphatidylcholine acyltransferase, choline phosphotransferase, glycerol‐3‐phosphate acyltransferase(s), as well as the activity of triacylglycerol lipase significantly decreased in the microsomes of cerebral hemispheres of animals intermittently exposed to hypoxic treatment for eighty hours. At the same time, a marked activation of microsomal and mitochondrial phospholipase A2 occurred. The changes of the above‐mentioned enzymatic activities after the hypoxic treatment correlated well with the increase in the level of brain and blood free fatty acids. The changes also correlated with the decrease of labeled lipid precursors incorporated into lipids of the cerebral hemispheres, observed during oxygen insufficiency.