bluuebunny/crossref_metadata_2025 huggingface dataset:
Excitatory and inhibitory effects of acetylcholine on the anterior aorta muscle of Aplysia
Authors: Sawada M. , Hara N. , Ichinose M. , Maeno T.
Published: January 2005

The acetylcholine (ACh) responses of anterior aorta muscle cells of Aplysia kurodai were studied by intracellular recording and ACh iontophoresis. Three different types of membrane potential change were observed in response to ACh pulses: a rapid Na+‐mediated depolarizing response, a slow, mainly Cl−, in part K+‐mediated, hyperpolarizing response, and Na+ (for depolarizing component) and Cl− (for hyperpolarizing component)‐mediated biphasic response. The depolarizing response and the depolarizing component of the biphasic response were effectively blocked by hexamethonium or atropine. The hyperpolarizing response and the hyperpolarizing component of the biphasic response were completely blocked by tubocurarine. Low concentrations of ACh inhibited and relaxed the anterior aorta muscle; high concentrations of ACh excited the muscle and initiated contraction. The biphasic responses to ACh are likely due to the presence of more than one ACh receptor type on the same cell membrane of the anterior aorta muscle fiber.
Differential effects of early undernutrition in white and grey matter regions of rat brain
Authors: Rao K. V. Subba , Rao K. Subba
Published: January 2005

The effect of early postnatal undernutrition and subsequent rehabilitation on wet weight, DNA, RNA, protein, and the activities of acid and alkaline DNases in white and grey matter region of rat brain was studied. In respect to the various parameters studied, white matter was found to be markedly vulnerable to undernutrition, but the grey matter region was unaffected. It has also been observed that the earlier the initiation of nutritional rehabilitation (10th postnatal day) the better was the recovery of the white matter to a normal condition, and in some cases early nutritional rehabilitation resulted in better than normal biochemical composition of the region. The specific activity of acid DNase was unaffected by weanling undernutrition in both white and grey matter. The total activity of this enzyme, which was significantly reduced in white matter of undernourished animals, exhibited a remarkable recovery following rehabilitation, to more than normal levels at 150 days of age. Total activity of alkaline DNase was reduced only in 15‐day‐old white matter of deprived animals, and here also rehabilitation brought back this enzyme to significantly more than normal levels. It is concluded that the two DNases, whatever their actual physiological role might be, are synthesized in a preferential manner during the rehabilitation.
β‐Adrenergic receptor binding in different regions of rat brain after various intensities of electroshock: Relationship to postictal EEG
Authors: Perumal Authur S. , Barki Amiram I.
Published: January 2005

Relationships among different intensities of electroshock treatment (EST), EEG‐recordable primary after discharge (PAD), and β‐adrenergic binding in various brain regions were investigated in adult rats. Different intensities of EST (1–2, 6–8, 20–30 mamp) were applied through ear‐clip electrodes for 7 consecutive days. A Sigmoidal relationship was observed between the PAD and the applied currentintensity. 3H‐dihydroalprenolol (DHA) was used as a ligand to evaluate β‐adrenergic receptor binding in membrane preparation of the following brain regions: Cerebral cortex, cerebellum, pons‐medulla, and “midregion”–which consisted of the remainder tissue including thalamus, striatum, and midbrain. A significant decrease (28%) in binding was observed in cortex tissue after EST of 6–8 mamp but no changes were observed after either 1–2 mamp or 20–30 mamp. In “midregion,” a significant increase (40%) in binding was observed after EST with the subconvulsive intensity (1–2 mamp) whereas no changes were seen at higher intensites. The results suggest that in cortex, the function relating β‐adrenergic binding to current intensities may not be monotonic. The increase in binding seen in the “midregion” after subconvulsive EST may not be associated with changes related to the clinical efficacy of EST.
Toxic effects of ouabain and food and cosmetic dyes on nerve growth factor‐promoted differentiation of neurites in culture
Authors: Morris Stephen J. , Chronwall Bibie M.
Published: January 2005

The toxic effects of ouabain and various fluorescein analogs have been tested on nerve growth factor‐promoted (NGF‐promoted) outgrowth of neurites from embryonic chick sensory ganglia embedded in a matrix of native collagen. Ouabain inhibits outgrowth with an IC50 of approximately 5 μM. Erythrosin B (USFD&C Red 3) and other fluorescein derivative dyes brominated or iodinated on the xanthene ring also inhibit neurite outgrowth with IC50'S as low as 10 μm and promote early retraction of growing neurites. The effects of the dyes are due, at least in part, to photooxidation of the NGF, but they may also act directly on the cells. The culture system should prove useful as both a general and a specific in vitro assay for neurotoxicity.
Studies on metabolism of branched chain amino acids in brain and other tissues of rat with special reference to leucine
Authors: Rao T. Indira , Rao G. N. , Swamy M. , Sadasivudu B.
Published: January 2005

Leucine aminotransferase (EC 2.6.1.6) and 2‐oxoisocaproate dehydrogenase (EC 1.2.4.3) were studied in rat cerebral cortex, cerebellum, brain stem, liver, and muscle in normal and animals starved for 48 hours. In the brain, leucine aminotransferase, valine aminotransferase, and 2‐oxoisocaproate dehydrogenase showed a significant increase in starvation only in cerebellum while there was increase in 2‐oxoisocaproate dehydrogenase in cerebral cortex only. A significantly high increase in the activity of 2‐oxoisocaproate dehydrogenase was observed in muscle in starvation. A significant decrease in the activity of leucine aminotransferase was observed in liver in starvation. The increase in the activity of 2‐oxoisocaproate dehydrogenase in muscle and a decrease in the activity of leucine aminotransferase in liver in starvation indicate that the leucine is predominantly metabolized in extra hepatic tissues particularly in muscle.

As a result of intraperitoneal administration of 2 ml of leucine (5 mM), a significant increase in 2‐oxoisocaproate dehydrogenase occurred in cerebral cortex, liver, and muscle while a profound increase in the activity of glutamate dehydrogenase (EC 1.4.1.2) was observed in all the brain regions and liver under these conditions. A significant increase in the content of glutamic acid, alanine, and GABA was observed in all the three regions of the brain after the administration of leucine. A significant increase in the content of glutamine was observed only in the cerebellum and cerebral cortex after leucine administration. These results indicate that leucine in brain might contribute to the formation of glutamate, not only by transmination, but also by promoting glutamate dehydrogenase activity. Thus, there is a change in the metabolism of glutamate family of amino acids and energy depletion. These results are discussed in relation to the brain function.
Isoniazid induced seizures and cerebral cortical and cerebellar energy metabolism
Authors: McCandless D. W. , Abel M. S. , Schwartzenburg F. C.
Published: January 2005

Isoniazid is a useful chemical convulsant in that metabolic events associated with the preseizure state can be easily examined. In the present study, net levels of glucose, glycogen, ATP, and phosphocreatine were measured using enzymatic techniques in control mice, and in those injected with isoniazid. Results from this study showed a differential effect of isoniazid on cells from the cerebral cortex and the cerebellum. In the preseizure stage, the high energy phosphates ATP and phosphocreatine were decreased in layer 1 and the pyramidal cell layer of the cerebral parietal cortex, but were unchanged in the cerebellum. At the onset of seizures, metabolites were decreased not only in cortical layers, but in the molecular layer and Purkinje cell rich layer of the cerebellum as well. The somewhat delayed response of the cerebellum emphasizes the differential nature of metabolism in various brain regions. Such a delay in cerebellar energy response to perturbation may be conducive to the seizure state. In another series of mice, either sodium valproate or clonazepam was administered prior to isoniazid, and metabolite studies repeated. Results showed that at a time when each anticonvulsant acted to eliminate overt seizure activity, the reduction in ATP and phosphocreatine was not as great as it was in seizing mice treated with isoniazid alone.
Effects of L‐glutamate and GABA on the response of expiratory neurons to mechanical loads
Authors: Toleikis J. R. , Frazier Donald T.
Published: January 2005

Expiratory neurons in the area of the nucleus retroambigualis were studied in anesthetized cats to determine their responsiveness to the iontophoretic application of the putative neurotransmiters, glutamate and gamma‐aminobutyric acid (GABA). Previous studies with glutamate and GABA revealed that these two substances were very effective in modulating the spontaneous activity of phasic medullary respiratory neurons. Mechanical loading of expiration, both resistive and elastic, was employed to test whether the presence of these transmitter substances altered the sensitivity of the expiratory cell to its volume related vagal input.

Expiratory unit activity analysis included: spikes/burst, burst duration, and average firing rate. Addition of mechanical loads on expiration caused consistent increases in all parameters monitored. Iontophoretically applied glutamate (x̄ = 65 nA) resulted in modest increases in all parameters. When mechanical loads were applied in the presence of a sustained level of glutamate the effects were additive. The general shape of the firing profile observed with loading remained essentially unchanged. Application of GABA (x̄ = 46 nA) resulted in a significant decrease in the parameters monitored. However, as long as phasic activity remained, loads applied in the presence of GABA produced approximately the same absolute change as they did during control. Some cells exposed to high concentrations of GABA lost their phasic activity.

This study suggests that either the synaptically activated receptors are not affected by glutamate or that these particular sites are not accessible via iontophoretic application. GABA depressed the activity of the cells in a graded fashion, but in modest concentrations did not interfere with the overall effectiveness of the vagally mediated input.
Lateral geniculate cells responses following blockade of the visual cortex in rats: A comparison with rabbits
Authors: Molotchnikoff S. , Tremblay F. , Baron G.
Published: January 2005

The functions of the visual cortex (VC) were interrupted in anesthetized and paralyzed hooded rats with KCl (3M Baker) applied topically and single unit recordings were performed on lateral geniculate cells. Responses of geniculate cells to diffuse 1 second flashes were tested prior to and following cortical inactivation. The results indicated: (1) a differential decline of “on” and “off” responses; (2) a shift of excitatory and inhibitory periods in some units; (3) a modification of spontaneous firing; and (4) the corticofugal influence in rats is comparable to rabbits, suggesting a similar organization in both species.
Bilateral secretory responses of the adrenal medulla during stimulation of hypothalamic or mesencephalic sites
Authors: Francke Paul F. , Culberson James L. , Carmichael Stephen W. , Robinson Robert L.
Published: January 2005

Bilateral secretion of epinephrine and/or norepinephrine from adrenal medullae occurred in 76% of cats studied following unilateral electrical stimulation of sites in the hypothalamus or rostral mesencephalon. Responses were generally greater on the ipsilateral side. In most experiments, epinephrine alone or both epinephrine and norepinephrine outputs were increased. In only two experiments norepinephrine output was increased. Stimulation of most hypothalamic sites that evoked bilateral secretion was accompanied by an increase in blood pressure. Stimulation of effective sites in the mesencephalon was not generally accompanied by blood pressure changes.
Pattern of acetylcholine receptor activity during regeneration of free muscle transplants of rats
Authors: Mong Franz S. F. , Farach Mary C. , Martinez‐Carrion Marino
Published: January 2005

Acetylcholine receptor (AChR) activities were followed in regenerating muscle grafts of rats. The effects of prior nerve crush or treatment with Marcaine on α‐Bungarotoxin binding in graft muscle extracts were compared to nontreated controls. All treatment groups displayed a similar but characteristic pattern in which minor differences in the time course and absolute levels of AChR activities were observed. These results are interpreted in terms of possible alterations in AChR levels brought about by the changes in the degree of graft innervation.
Automatic control of potential and agonist‐induced current across the endplate membrane by drug electrophoresis
Authors: del Castillo J. , Specht P. , Auerbach A.
Published: January 2005

Two techniques are described that are designed to elicit long and constant postsynaptic depolarizations or agonist‐induced currents by the electrophoretic application of agonists to endplate membranes. In the first technique, which can be described as a “pharmacologic voltage clamp,” the current flowing through the agonist pipette is controlled by the potential across the endplate membrane. Sustained depolarizations of constant amplitude can be obtained in this manner, while the agonist current needed to produce and maintain the response is recorded. The second technique uses a signal proportional to the current flowing across a voltage‐clamped endplate membrane to control the delivery of agonist. This allows control of the intensity of the agonist‐induced current. The possible application of these techniques in studying receptor desensitization and obtaining samples of post‐synaptic current noise for spectral analysis is discussed.
Intracellular volume of osmotically regulated C‐6 glioma cells
Authors: Chan Pak Hoo , Kerlan Randi , Fishman Robert A.
Published: January 2005

The intracellular volume of neoplastic brain cells was investigated with regard to the effects of hypo‐osmolality and hyperosmolality utilizing double isotopic labeling with 3–0‐methyl‐D‐glucose or tritiated water to measure the total volume of the pellet and inulin or polyethyleneglycol to measure the extracellular volume of the pellet. The cellular pellets were rapidly separated from the incubation medium by centrifugation after addition of an oil mixture. After 60 minutes incubation in Hanks balanced salt medium, the intracellular volume was 7.50 ± 0.64, 8.48 ± 0.19, and 2.97 ± 0.18 ml H2O per 106 packed cells for C‐6 glioma cells, N18TG‐2 neuroblastoma cells, and NG108‐15 neuroblastoma X glioma hybrid cells, respectively. The extracellular trapped space of these cultured cells was about one third of the intracellular volume. The intracellular volume of C‐6 glioma cells was increased in hypotonic environment, whereas it was decreased with hyperosmolality. Both intracellular sodium and potassium were increased with increased osmolality of the incubation media. These data indicate iso‐osmotic regulation by tumor cells, i.e., there is a good correlation between the intracellular volume, intracellular cations and lactate levels of C‐6 glioma cells under various osmotic conditions.
Nerve growth factor, laminin, and fibronectin promote neurite growth in human fetal sensory ganglia cultures
Authors: Baron‐Van Evercooren Anne , Kleinman Hynda K. , Ohno Shinichi , Marangos Paul , Schwartz Joan P. , Dubois‐Dalcq Monique E.
Published: January 2005

The effect of mouse nerve growth factor (NGF) on cultured human fetal sensory neurons was assayed by measuring neurite length, density and rate of growth. Addition of NGF increased adhesion of dissociated sensory neurons cultured on collagen coated surfaces. Almost all neurons of 9 to 10 week old fetuses are postmitotic, contain neuron‐specific enolase, (an enzyme linked to differentiation), and require NGF for optimal neurite growth. Sensory ganglia re‐explanted on collagen showed maximal neurite length and density when treated with 1 ng/ml of NGF. Neurite density was reduced considerably in the absence of mouse NGF and was almost abolished by addition of antimouse NGF antibodies. Surfaces coated with the matrix glycoproteins laminin or fibronectin further stimulated neurite growth of ganglia in the presence of NGF. Increasing amounts of matrix proteins could partly compensate for the absence of mouse NGF or the inhibition of NGF activity by antibodies. Stimulation of neurite growth by matrix proteins was time‐dependent, and neurites showed maximum length at 10 days (2 to 3 mm). Neurite growth was more pronounced with laminin than with fibronectin and collagen, and antibodies to laminin suppressed all neurite growth. In the presence of a constant amount of NGF, mean neurite growth reached 26 μm/hr (at 1 day), and was 2.1 and 1.7 times faster on laminin and fibronectin (respectively) than on collagen. Thus, laminin, and to a lesser degree fibronectin, may enhance neurite growth of human sensory neurons in synergy with NGF.
Increase of a nerve growth factor‐like protein in the cerebellum of PCD mutant mice
Authors: Schwartz Joan P. , Ghetti Bernardino , Truex Lewis , Schmidt Michael J.
Published: January 2005

Several areas of mouse brain (cerebellum, brain stem, and hemispheres) contain levels of nerve growth factor (NGF) detectable by radioimmunoassay. However, this immunoactive NGF is not biologically active in the chick embryo sensory ganglia bioassay. Cerebellum from pcd mice, in which neuronal degeneration elicits a glial response, contains increased amounts of NGF immunoactivity. These results suggest that CNS glia may produce a NGF‐like protein for CNS neurons.
Insulin and somatemedin MSA promote nerve growth factor‐independent neurite formation by cultured chick dorsal root ganglionic sensory neurons
Authors: Bothwell Mark
Published: January 2005

Sensory neurons isolated from 8‐day chick embryo dorsal root ganglia are shown to be capable of surviving in tissue culture and extending neurites in the absence of nerve growth factor. Survival and formation of neurites by cells cultured in medium supplemented with 2% fetal calf serum is stimulated by insulin, proinsulin or somatemedin MSA. MSA is effective at much lower concentrations (50 ng/ml) than insulin or proinsulin and is suggested to be a physiological regulator of sensory neuronal development. It is demonstrated that at least part of the neuronal population is responsive to both nerve growth factor and insulin homologs.
Neurite outgrowth from cerebral cortical neurons is promoted by medium conditioned over heart cells
Authors: Kligman Douglas
Published: January 2005

Seven day chick embryo cerebral cortical neurons cultured at low density (10,000 cells/16 mm well) in serum‐free, defined medium in polylysine‐coated wells fail to extend neurites and assume a flattened phase‐dark morphology. Addition of serumfree, defined medium conditioned over chick embryo heart cells promotes neurite outgrowth and rounding of the cell body (which becomes phase bright). A sensitive bioassay, based on counting the number of phase‐bright neurons with processes at least equal to one cell body diameter after 20 hours in culture, was used to titrate neurite‐promoting activity in heart conditioned medium. This activity is completely destroyed by exposure to trypsin. As little as 2 μg/ml total conditioned medium protein elicits a half‐maximal response in this bioassay.
Nerve growth factor‐induced stimulation of α‐aminoisobutyric acid uptake in PC12 cells: Relationship to plasma membrane receptor occupancy
Authors: Kedes Dean H. , Gunning Peter W. , Shooter Eric M.
Published: January 2005

Nerve growth factor (NGF) stimulates the uptake rate of the nonmetabolized amino acid α‐aminoisobutyric acid (AIB) in the clonal PC12 pheochromocytoma cell line by 40–70%. This effect reaches a maximum after a 1‐hour incubation with the hormone and then drops over 50%, reaching a minimum after 4 hours of NGF administration. Longer exposure to the hormone leads to a gradual rise in stimulation, and by 24 hours, the cells regain about 80% of the original 1‐hour rate. Results of NGF‐binding studies indicate that stimulation of AIB uptake follows closely behind the amount of NGF bound to the low‐affinity NGF receptors. Dose‐response experiments indicate that full stimulation occurs biphasically. Within the NGF concentration range of 0.1 ng/ml to 1 ng/ml, the AIB uptake rate is 30% of the maximum 1‐hour response. At 2.5 ng/ml NGF, the stimulation jumps to about 75% maximal response while 100% response is reached between 5 ng/ml and 50 ng/ml NGF. We suggest that the two states of the NGF plasma membrane receptor on PC12 cells may both be involved in mediating NGF stimulation of AIB uptake.
Effect of thiamine deficiency and undernutrition on the lipid composition of rat spinal cord at 21 days of age
Authors: Reddy T. Sanjeeva , Ramakrishnan C. V.
Published: January 2005

Maternal thiamine deficiency and undernutrition are found to cause significant deficits in body and spinal cord weights of the offspring at 21 days of age. The concentration of different lipids is found to be decreased significantly in both experimental groups as compared to normal controls. However, these deficits do not seem to differ between the undernourished and the thiamine‐deficient groups. The results suggest a general effect of growth retardation rather than thiamine deficiency per se on the lipid composition of spinal cord.
Effect of undernutrition on some enzymes of purine metabolism in different regions of developing rat brain
Authors: Vanella A. , Barcellona M. L. , Avitabile M. , Avola R. , Ragusa N. , Serra I. , Giuffrida A. M.
Published: January 2005

The effect of undemutrition on the activity of some enzymes involved in purine metabolism, ie, adenosine aminohydrolase, adenylate aminohydrolase, and inosine phosphorylase in cerebral hemispheres, cerebellum, and brain stem of rats at different days of postnatal development was studied. Adenosine aminohydrolase, adenylate aminohydrolase, and inosine phosphorylase were assayed by radiochemical methods which involve the measurement of the radioactive products formed, ie, inosine, IMP, and hypoxanthine, respectively. The results obtained indicate that undemutrition affects the activity of the enzymes which control the concentration of purine nucleotides to a different degree in the three brain regions examined.
The principal projection pathway between the olfactory bulb and the prepyriform cortex in the cat
Authors: Willey T. J. , Maeda G. , Schultz R. L. , Seibly W. S. , Horowitz J. M.
Published: January 2005

The anatomy and neuroelectric properties of the lateral olfactory tract (LOT) were investigated in the cat. Electron micrographs were obtained from sampled areas across the rostro‐caudal projection of the pathway. Fiber diameters were estimated and axon spectra were obtained from three regions corresponding to penduncle, mid‐LOT, and caudal‐LOT. The mean inside diameter for all measured axons was 1.13 ± 0.53 μm. The greatest number was found in the peduncle (approximately 600,000 axons). Mid‐LOT and caudal‐LOT each contained approximately 250,000 axons. Unmyelinated processes were estimated to be more numerous than the myelinated axons. Synaptic structures were also observed in the LOT. Crosssectional area measurements of the LOT were obtained from tissue repared for light microscopy. The area decreased from about 0.3 to 0.2 mm2 across the projection from olfactory bulb to cortex. The anatomical data were used to predict the conduction properties of transmission over the LOT. The olfactory bulb mitral cells were stimulated electrically and conduction velocity and temporal dispersion were evaluated in the tract. The strength‐duration and stimulus‐response curves and the potential profile during stimulation were also obtained. The time constant for LOT axons was 0.3 msec. The stimulus‐response curve was sigmoidal in shape for both presynaptic and postsynaptic responses. The relationship between input (the action potentials) and output (cortical postsynaptic potentials) was linear up to 90 times threshold. Action potentials were conducted at 20 m/sec across the pathway over the peduncle and decreased to about 10 m/sec in caudal aspects. The potential profile for action potentials decayed exponentially into the depths of the cortex whereas the synaptic potential was a surface negative dipole field. The axon spectra were convolved with the electrophysiological properties of the LOT Yto mathematically reconstruct action potentials. The empirically derived monoand biphasic curves fitted reasonably well with experimentally derived data under various stimulus conditions.
Morphological changes in neuromuscular junctions during exercise
Authors: Palacios‐Prü Ernesto , Mendoza R. V. , Palacios L. , Colasante C.
Published: January 2005

Long lasting exercise produces several morphological changes in teleostean neuromuscular junctions (NJs), consisting of progressive synaptic vesicles (SVs) depletion and lamellar branching of the nerve endings. Exercised fishes kept swimming during 1 hr against a 3.51/min flow of oxygenated water in spite of the fact that the number of SVs was reduced in about 70% after 10 min of exercise. This observation indicates that the SVs formation fails to restore their original number and consequently, under such circumstances, the transmitter release may occur by a different mechanism.
Cross‐reactivities of monoclonal antibodies between select leech neuronal and epithelial tissues
Authors: Hogg N. , Flaster M. , Zipser Birgit
Published: January 2005

Three monoclonal antibodies, originally studied because of their neuron‐specific staining in the leech central nervous system, are characterized further here, both immunocytochemically and biochemically, with Western blot staining using the central nervous system and peripheral tissues. The three antibodies react both with neurons and select epithelial tissue in the central nervous system, gut, and penis. Antibody Lan3‐8 reacts with neurons in the nerve cord and gut but with epithelial cells in the penis; it binds to a 65K molecule in all three tissues. Lan3‐2 and Laz2‐369 are considered as a related pair because in the central nervous system the former stains all (four) and the latter generally only half (two) of the neurons in a standard midbody ganglion responding to nociceptive stimulation. In the gut, both antibodies label patches of epithelial cells and Laz2‐369 stains a previously unknown type of gut neuron. While a given antibody stains different bands in gut and central nervous system immunoblots, comparing the bands of both antibodies for the same tissue extract makes it apparent that there are similarities in the molecular species that both antibodies recognize.

For each monoclonal antibody, the histologically identified tissue antigens need to be correlated with proteins identified on Western blots. Of particular interest are the broad 130K bands to which Lan3‐2 and Laz2‐369 bind. The question is raised whether the molecular species in these bands represent a family of proteins that serve a specific nociceptive cell function.
Procedure for isolation of neuron‐ and astrocyte‐enriched fractions from chick brain of different ages
Authors: Rani B. Usha , Singh N. Indrapal , Ray A. , Rao K. Subba
Published: January 2005

A method for the isolation of ncurons and astrocytes from chick brain of different ages is described. In brief, the procedure involves incubation of the gray matter with trypsin, passage of the tissue successively through nylon/stainless steel screens of decreasing pore size, and further separation and purification of cell‐enriched fractions by centrifugation on Ficoll discontinuous gradient. Phase‐contrast microscopy revealed intact morphology of the cells. The cells were viable by trypan blue exclusion test.
Substrate specificity and developmental aspects of a presynaptic gaba receptor regulating glutamate release in the rat cerebellum
Authors: Aloisi F. , Gallo V. , Levi G.
Published: January 2005

In order to better characterize the presynaptic GABA receptors regulating glutamate release in the cerebellum [Levi and Gallo, 1981], a number of GABA agonists and GABA transport inhibitors were tested for their ability to potentiate the depolarization‐induced release of the glutamate analog D‐[3H]aspartate from superfused cerebellar synaptosomes. Of all the compounds tested, only those which are known to interact specifically with GABA receptors were effective when tested on synaptosomal preparations. The order of effectiveness found was the following: muscimol ≃ 3‐APS≥P4S > isoguvacine >THIP. GABA uptake inhibitors were unable to enhance D‐[3H]aspartate evoked release from synaptosomes, but were effective when tested in cerebellar slices; in the latter case, the activation of the GABA receptors may be achieved indirectly, through an increase of the extracellular GABA concentrations. The substrate specificity of the presynaptic GABA receptors regulating cerebellar acidic amino acid release appears to be similar to that reported for GABA receptors in radioligand binding studies and for GABA autoreceptors. Studies on synaptosomes from immature cerebella suggested that the presence of the potentiating effect on the acidic amino acid release by GABA agonists is correlated with the development of the parallel fiber terminals, which are believed to be the main site from which glutamate is released in the adult cerebellum.
Biologic and radioimmunologic activity of cholecystokinin in regions of mammalian brains
Authors: Simon‐Assmann P. M. , Yazigi R. , Greeley G. H. , Rayford P. L. , Thompson J. C.
Published: January 2005

The distribution and heterogeneity of cholecystokinin (CCK) in different regions of the central nervous system (CNS) of 12 adult rats and six cows was determined by means of specific radioimmunoassays. In addition, the biologic activity of immunoreactive material was evaluated in a bioassay that used a rabbit gallbladder‐strip preparation. High amounts of immunochemically detectable CCK‐8 (20.2 ± 1.5 pmol/g) and CCK‐33 (33.7 ± 3.3 pmol/g) and of biologically active CCK were found in the telencephalon, although concentrations decreased progressively from the rostral to the caudal portions of the brain. The distribution and biologic activity of CCK was similar in rat and cow brain. Ratios of biologic to immunologic activity ranged from 1.0 to 8.0 and were higher for CCK‐8 than for CCK‐33. The results indicate that (1) CCK‐8 and CCK‐33 immunoreactivity are widely distributed throughout the CNS in a unique and differential manner; (2) CCK is biologically active in all the regions of the brain, with a pattern of distribution similar to that found with radioimmunoassay; (3) measurable bioactivity was equal to or greater than measurable immunoreactivity in all areas of the brain in rat and cow; and (4) CCK is present in tissues without significant species differences between rat and cow.
Activities of arginase, transamidinase, and ornithine aminotransferase in glia, neurons, and synaptosomes
Authors: Swamy M. , Shrivastaw K. P. , Prasad M. S. K. , Sadasivudu B.
Published: January 2005

The regional, cellular, and subcellular distribution of some enzymes of the urea cycle in brain is not clearly known. Glia, neurons, and synaptosomes have been prepared from rat cerebral cortex and arginase (EC 3.5.3.1), transamidinase (EC 2.1.4.1), and ornithine aminotransferase (EC 2.6.1.13) have been estimated in order to understand the metabolic and functional role of these enzymes. It has been observed that arginase is predominantly localized in synaptosomes and neurons. The ornithine aminotransferase was found to be high in glial cells and very high in synaptosomes (higher than arginase). Transamidinase was mostly localized in glial cells. The implication of these results has been discussed in relation to a possible role of ornithine acting as a precursor of glutamate in glutametargic nerve endings and its possible participation in the glutamate‐glutamine cycle.
In bovine brain extracts, RNAs are active factors that stimulate the proliferation of chick neuroblasts in culture
Authors: Barakat I. , Sensenbrenner M. , Labourdette G.
Published: January 2005

Extract was prepared from bovine brain by treatment with chloroform‐methanol, drying of the precipitate, and successive extractions of the powder with Tris buffer. Influence of this extract on neuroblast proliferation in culture was tested. Neuroblast cultures were prepared from brain hemispheres of 6‐day‐old chick embryos. Cell proliferation was quantified by incorporation of 3‐thymidine. The brain extract was able to stimulate the proliferation of the neuroblasts in culture. In order to purify the factor responsible of this effect, the brain extract was subjected to diethylaminoethyl (ENAE)‐cellulose chromatography and gel filtrations. By UV spectrography and destruction of the activity with RNAase and KOH, it was shown that in the extract RNAs are responsible for at least a part of the effect on the proliferation of neuroblasts in culture. Brain RNA is not specific for this effect, since mouse ribosomal RNA was also active. The effect could be actually elicited by some nucleotides.
A comparative study of L[3H]‐glutamate and L[3H]‐cysteine sulfinate binding sites in subcellular fractions of rat brain
Authors: Recasens M. , Saadoun F. , Baudry M. , Maitre M. , Lynch G.
Published: January 2005

A comparative study of the binding of L‐cysteine sulfinic acid (CSA) and L‐glutamic acid (GLU) to various subcellular fractions of membranes from rat brain was made. Kinetic parameters were determined in all fractions for both types of binding. The effects of membrane preincubation, freezing, and thawing were also examined. The GLU and CSA specific binding levels increased in medium‐density (C) and high‐density (D) synaptic membranes as compared to the crude mitochondrial/synaptosomal membranes (wP2). Freezing and thawing reduced CSA binding in all tested subcellular fractions. GLU binding is reduced in wP2, C, and D. Binding to the “light” synaptic membranes (B) was not significantly affected, suggesting the presence of two GLU sites. Kinetics of the GLU binding indicated that the temperature‐sensitive and ‐insensitive sites have Kd of 600 nM and 1,100/nM, respectively. Preincubation of fresh membranes conversely affected CSA and GLU binding to the various subcellular fractions, increasing CSA binding in wP2, B, C and decreasing it in D suggesting the existence of distinct sites for GLU and CSA. Preincubation of previously frozen membranes similarly modified CSA and GLU binding except in B fractions. CSA and GLU binding exhibited different pH sensitivities in both fresh and frozen membranes. These results indicate that multiple acid amino acid binding sites exist in membranes and that they can be differentiated according to their sensitivity to temperature. They also suggest the existence of distinct sites for CSA and GLU in fresh membranes, giving further support to the hypothesis that CSA may also serve a neurotransmitter role in the rat central nervous system.
Effects of lithium on [3H](–)quinuclidinyl benzilate ([3H](–)QNB) binding to rat brain muscarinic cholinergic receptors
Authors: Hruska R. E. , Ludmer L. M. , Pert A. , Bunney W. E.
Published: January 2005

Addition of lithium in vitro inhibited the binding of [3H](–)QNB to muscarinic cholinergic receptors of homogenates of tissue prepared from the striatum, cortex, and hippocampus of rat brain. Chronic in vivo exposure of rats to lithium in their food produced serum levels of lithium comparable to therapeutic levels. After in vivo exposure, the tissue homogenates prepared from these rats had an apparent decrease in receptor density in the three brain areas. However, if the tissue homogenates were washed twice, before addition to the assays, no differences in binding were detectable. Similar effects on unwashed and washed tissue homogenates can be demonstrated after in vivo exposure to lithium. Therefore, the apparent decrease in binding after in vivo lithium treatment is probably due to lithium retained in the tissue. No permanent alterations in the muscarinic receptor characteristics were measurable after the removal of the lithium. Nevertheless, in vivo interactions at muscarinic receptors may be important under conditions when therapeutic levels of lithium are present.
Effect of guanidinoethane sulfonate on taurine uptake by rat retina
Authors: Quesada O. , Huxtable R. J. , Pasantes‐Morales H.
Published: January 2005

Guanidinoethane sulfonate (GES) markedly decreased 3H‐taurine accumulated in the retina by the high‐affinity uptake process. The effect of GES was dosedependent. Analysis of the kinetics of GES effect revealed that it is a competitive inhibitor. The uptake of taurine by GES was less affected in rat cerebral cortex slices, where the inhibition by 1 mM GES was only 28%. Taurine accumulation by tissues of rats treated with GES (0.1% and 1% in the drinking water) was found to be particularly decreased in the retina, although accumulation by heart and liver was also affected by the higher dose. Taurine uptake by cerebellum and cerebral cortex slices was unaffected by GES. Treatment of rats with GES is known to produce an alteration in the structure and function of the retina, but apparently not in other organs. We discuss whether the marked effect of GES on taurine transport by the retina is related to the deleterious effect of the inhibitor in this organ.
Taurine‐ and penicillin‐induced epileptic activity
Authors: Alvarez A. , de Cotte D. Marcano , Pérez J. R. , Requena M. A. , Vallecalle E. , Drujan B. D.
Published: January 2005

The present study has been performed to investigate the effect of i.v. administration of taurine on the electrical activity of the epileptogenic focus induced by penicillin applied to the right sensory motor cortex of adult rats. Taurine (100 mg/kg body weight) was administered 15, 30, 60, and 120 min before the application of penicillin. The EEG was unipolarly recorded by means of electrodes applied to the pia. Taurine caused a decrease of the frequency as well as the spike amplitude of epileptic discharge. The spread of epileptogenic foci to the opposite hemisphere was retarded when compared to that of control animals. The maximal antiepileptic effect of taurine was observed when the amino acid was administered 30–60 min previous to penicillin. It is suggested that high concentrations of taurine in the brain might be necessary to inhibit the epileptic activity.
Investigations on myelinogenesis in vitro: Regulation of 5′‐nucleotidase activity by thyroid hormone in cultures of dissociated cells from embryonic mouse brain
Authors: Shanker G. , Rao G. S. , Pieringer R. A.
Published: January 2005

The developmental pattern of the myelin‐associated 5′‐nucleotidase and its regulation by L‐3,3′,5,‐triiodothyronine (T3) have been demonstrated in a culture system of cells dissociated from embryonic mouse brain. Hypothyroid calf serum containing low levels of T3 (31 ng/100 ml), and thyroxine, T4 (< 1 μg/ml), was used in the culture medium in place of normal calf serum (T3, 103 ng/100ml; T4, 5.7 μg/ml) to render the cultures responsive to exogenously added T3. By means of T3 supplementation, the lower levels of enzyme activity observed in the cultures grown in the presence of hypothyroid calf‐serum containing medium could be restored to a considerable extent although not completely to normal values. Halfmaximal stimulatory effect was obtained at 3.9 × 10−8 M T3 concentration. Among the various substrates tested, 5′‐AMP, 5′‐UMP and 5′‐CMP were equally good, while 5′‐GMP yielded approximately half the activity.
Fatty acid and long‐chain base composition of gangliosides isolated from adult human brain
Authors: Ando S. , Yu R. K.
Published: January 2005

A series of major and minor ganglioside species were isolated from a single human adult brain and analyzed for their lipophlic composition. Hematosides, GM3 and GD3, each showing double bands on thin‐layer chromatograms, were separated into the upper band and lower band fractions to be analyzed for the heterogeneity of their ceramide moieties. The upper band fractions of GM3 and GD3 were found to contain relatively high amounts of longer‐chain fatty acids (C20C26), whereas the lower band fractions contained high amounts of shorterchain fatty acids (C16C18). Compared to other gangliosides which contain hexosamine, the two hematosides contained a smaller proportion of stearic acid. The proportion of 4‐eicosasphingenine was found to increase with increasing sialic acid content in gangliosides. These findings suggest that, in the biosynthesis of various gangliosides, N‐acetylhexosamine is preferentially transferred to hematosides rich in stearic acid, and sialic acid residues are preferentially transfered to 4‐eicosasphingenine‐containing species.
Studies on bioactive gangliosides: II. Requirement of ganglioside GD1a for prolonged GQ1b‐driven nerve growth promotion in neuroblastoma cell lines
Authors: Arita M. , Tsuji S. , Omatsu M. , Nagai Y.
Published: January 2005

The novel effects of gangliosides from human brain on the number of nuclei of nerve cells and neurite outgrowth were studied in cultures of human neuroblastoma cell lines GOTO and NB‐1. Ganglioside GQ1b at a nanomolar level stimulated cell proliferation and neurite outgrowth during culture for 24 hours, as reported previously [J Biochem 94: 303–306, 1983]. Although the neurite promoting activity of GQ1b was similar to those of total human brain gangliosides (GS) and nerve growth factor (NGF), its activity on cell proliferation did not persist on longer culture; that is, the number of GQ1b‐treated cells rapidly decreased to the control level during culture for 48 or 72 hours. In contrast, on treatment with GS or NGF, the number of cell nuclei increased continuously during prolonged culture. These results showed that either some other molecular species of ganglioside(s) than GQlb or other substances such as proteins present in the GS fraction were responsible for the long‐term activity. Studies on the GS fraction after its treatment with proteases and neuraminidases revealed that ganglioside GDla (20 ng/ml) had the ability to prolong the activity of GQlb. Namely, GQlb and GDla gangliosides cooperated in maintaining the number of nuclei in long‐term cultures of neuroblastoma cell lines.
Interaction of GM1 ganglioside with PC12 pheochromocytoma cells: Serum‐ and NGF‐dependent effects on neuritic growth (and proliferation)
Authors: Katoh‐Semba R. , Skaper S. D. , Varon S.
Published: January 2005

The effects of ganglioside GM1 on proliferation and neuritic growth of PC12 pheochromocytoma cells were studied in the presence and absence of nerve growth factor (NGF). In the absence of NGF, but not in its presence, a decrease in the total number of PC12 cells was first observed after 4–6 days of culture with 10−6 M GM1 in 0.1% fetal calf serum, and with 10−3 M GM1 on 10% serum. NGF, with or without GM1, limits cell growth to the first 4–6 days. GM1 enhanced neuritic recruitment with serum concentrations of 0.3% or more. Optimal neurite response varied from 10−6 M GM1 with 0.3% serum to 10−4 M GM1 with 10% serum. The influence of GM1 on neurites became more pronounced with increasing serum concentrations, becoming maximal with 1% or greater serum. Serum exhibited a concentration‐dependent inhibitory influence (lag) on NGF‐induced neuritic recruitment, which was abolished by GM1. Rates of neuritic recruitment following the lag were unaffected by GM1, while showing an inverse correlation with serum concentrations of 0.1–0.5%. Serum may delay the NGF‐induced neuritic recruitment of PC12 cells by two independent mechanisms. These results suggest that GM1, in some manner, prevents the serum‐induced delay in the onset of neuritic recruitment, rather than stimulating the rate at which it precedes.
Does the interstitial nucleus of Cajal project to the hypoglossal nucleus in the rat?
Authors: Aldes L. D. , Boone T. B.
Published: January 2005

The present study sought to determine whether or not the hypoglossal nucleus receives direct afferent projections from the interstitial nucleus of Cajal. Results from anterograde and retrograde labeling experiments in the rat indicated that while projections from the interstitial nucleus of Cajal do not terminate within the hypoglossal nucleus, they do so among a small group of neurons located ventrolateral to the hypoglossal nucleus, the nucleus of Roller. These findings are discussed in relation to orolingual motor behavior.
Kinetics of GTP‐modulation of adenylate cyclase in gerbil cerebral cortex after bilateral ischemia
Authors: Taylor M. D. , Palmer G. C. , Callahan A. S.
Published: January 2005

Changes in the sensitivity of adenylate cyclase and steady‐state levels of cyclic AMP (adenosine 3′,5′‐monophosphate) occur in mammalian brain during ischemic episodes. In our previous investigation with the gerbil model of bilateral ischemia there was an indication that ischemic conditions produced an enhancement of GTP sensitivity of adenylate cyclase within the cerebral cortex. The present study employed a kinetic analysis to evaluate further the role of this GTP modulation of adenylate cyclase in the gerbil frontal cortex during periods of bilateral ischemia and recirculation. In general, after either 15‐min (with or without 15‐min reflow) or 60‐min ischemia the Vmax to GTP (alone or with dopamine and norepinephrine) was increased. Under these conditions the ED50 for half‐maximal enzyme activation was decreased, indicating a greater affinity of the transducer site for GTP during ischemia. However, if irreversible 60‐min ischemia was followed by 15‐min reflow the enzyme responses to GTP were now absent. An unexpected observation showed that the ED50 for GTP activation of cortical adenylate cyclase was likewise attenuated when sham‐operated animals were compared to normal gerbils.
A quantitative study of growth cone filopodial extension
Authors: Argiro V. , Bunge M.B. , Johnson M.I.
Published: January 2005

The extension of filopodia from growth cones of regenerating neurites from rat superior cervical ganglion neurons in tissue culture was studied. Cultures were grown on a thin layer of fibrous collagen and maintained in a medium containing serum and nerve growth factor. Time‐lapse cinematography and computer‐assisted morphometry were used to observe and measure the kinetics of extension of individual filopodia. Filopodia extended from the growth cone margin, trailing neurite, or from each other. Frequently, extension was preceded by the appearance at the cone margin of a nodule of cytoplasm which appeared dense in phasecontrast optics. Branch points between adjacent extending filopodia remained fixed with respect to the growth cone while the filopodia lengthened. The rate of extension was maximum just after initiation (0.12 ± 0.4 μm/sec; mean ± SD; n = 36) and declined thereafter until the filopodium collapsed. This initial rate of extension was directly correlated with the eventual length of the filopodium (r = 0.67). Filopodia of growth cones arising from embryonic neurons exhibited higher initial extension rates (range: 0.07 to 0.20 μm/sec; mean = 0.13 μm/sec) than those of postnatal neurons (range: 0.01 to 0.13 μm/sec; mean = 0.09 μm/sec). These data are discussed in relation to a model proposed by Tilney and Inoue [1982] for the extension, by distal addition of G‐actin to growing filaments, of another type of elongating process filled with microfilaments, the acrosomal process of Thyone sperm.