bluuebunny/crossref_metadata_2025 huggingface dataset:
In vitro evidence of photoreception in the chick pineal gland and its interaction with the circadian clock controlling N‐acetyltransferase (NAT)
Authors: Kasal Charles A. , Perez‐Polo J. Regino
Published: January 2005

The response of the circadian rhythm in N‐acetyltransferase (NAT) activity to phase‐shifted light cycles was examined in vitro in explant cultures of chick (Gallus domesticus) pineal glands. Bisected portions of glands, obtained from birds housed in a light—dark cycle (LD 12:12), were explanted into culture and maintained under one of three light cycles (LD 12:12), the phase of which was either (1) similar to that of the birds' previous cycle, (2) seven hours phase‐delayed, or (3) six hours phase‐advanced. Following two to three days of exposure to the respective light cycles, cultures were placed into continuous darkness (DD). Sampling from cultures during exposure to DD revealed a circadian rhythm of NAT activity. In each case, the phase of the subsequent rhythm of enzyme activity in DD reflected that of the preceding in vitro light cycle. A distinct phase difference of approximately 180° was observed between cultures exposed to opposite lighting regimes. These results indicate entrainment of the circadian rhythm of NAT activity to the prevailing in vitro light cycle and suggest a direct interaction between pineal photoreception and the circadian “clock” controlling NAT.
Effects of low ammonia levels on NAD(P)H levels and glutamate secretion during calcium‐dependent depolarization of CNS slices
Authors: Cummins J. T. , Hamberger A. , NystróOum B.
Published: January 2005

Simultaneously with an evoked release of endogenous glutamate, redox changes in NAD(P)H levels occur as a response to electrical or chemical stimulation of the isolated CNS tissue. While electrical‐field stimulation induces a transient increase in tissue NAD(P)H, KCl stimulation produces a decrease in NAD(P)H. One possible interpretation for this difference is that elevated KCl induces glutamate release from larger cell populations, including glia, while electrical stimulation might have a more neuro‐specific action. In the present report, it is shown that the electrically or biochemically evoked release of endogenous glutamate is strongly inhibited by ammonium ions at 3–5 mM in the hippocampus and frontal cortex. At the same time, ammonium ions inverted the NAD(P)H response of the tissue during electrical stimulation, making both electrical and KCl depolarization induce a decrease in NAD(P)H. There was no effect of ammonium ions per se on the NAD(P)H levels, and to obtain the effects on both NAD(P)H and glutamate release, the tissue had to be exposed for 40–60 minutes to ammonium ions. The results are interpreted to indicate that ammonium ions influence regulatory control mechanisms in cell populations in the tissue slice that secretes glutamate in response to depolarization.
Effects of partial and complete vagal denervation on spontaneous ingestion and drinking induced with volemic and osmotic regulatory challenges
Authors: Martin James R.
Published: January 2005

The present study investigated the effects of unilateral right or left cervical vagotomy, selective subdiaphragmatic transection of the anterior vagal trunk, the posterior vagal trunk or the hepatic branch of the vagus, and the effects of total abdominal vagotomy with concomitant pyloroplasty on the regulation of spontaneous ingestive behavior and responsiveness to osmotic and volemic challenges. Total abdominal vagotomy with pyloroplasty somewhat reduced food intake, water consumption, and body weight measured ten weeks postsurgery. The other denervation procedures did not affect these parameters of spontaneous ingestive behavior. In additional tests given approximately two and four months postsurgery, rats that had undergone total abdominal vagotomy exhibited a significantly longer latency to drink and consumed less water than controls during the initial 0.5 hours after injection of hypertonic saline. These total abdominally vagotomized rats also exhibited significantly lower cumulative physiological saline intake in comparison to controls for 4, 8, and 16 hours after subcutaneous injection with polyethylene glycol, but not 2 or 24 hours postinjection. However, total abdominal vagotomy did not impair water drinking one, two, or four hours after injection with D,L‐isoproterenol (0.04–0.32 mg/kg body weight). The other denervation procedures did not alter drinking in response to isoproterenol or polyethylene glycol injections, and most of these groups exhibited normal latency and intake following injection of hypertonic saline. The hepatic vagotomy group, however, exhibited a shorter latency to drink in response to hypertonic saline injection than controls. The present results demonstrate that spontaneous food and water intake, body weight, and responsiveness to various volemic and osmotic regulatory challenges are clearly impaired only by the total abdominal vagotomy procedure.
Regional circadian variation of acetylcholine muscarinic receptors in the rat brain
Authors: Por Suzanne B. , Bondy Stephen C.
Published: January 2005

The level of binding of a labeled acetylcholine muscarinic antagonist (quinuclidinyl benzilate) to different cerebral membranes has been measured. Of the regions examined, circadian rhythmicity of binding could only be detected significantly in the hippocampus and the hypothalamus and not in the cerebral cortex, striatum, or cerebellum.
Noncoordinate regulation of myelinogenic parameters in primary cultures of dissociated fetal rat brain
Authors: Pfeiffer S. E. , Barbarese E. , Bhat S.
Published: January 2005

The developmental regulation of sulfogalactosylceramide (sulfatide) synthesis, 2′,3′‐cyclic nucleotide‐3′‐phosphohydrolase activity (CNP), and myelin basic protein (MBP) accumulation, three markers characteristic of myelinogenesis, were observed in dispersed cultures of fetal rat brain in spite of the absence of the formation of compact, multilamellar myelin. Sulfatide synthetic rate and CNP activity began to increase by 8 days in vitro (DIV) (approximately comparable to days post‐natal) and reached their maxima by 20 DIV. MBP began to accumulate after 14 DIV and reached a maximum by 38 DIV. Thus, the temporal regulation of the onset of expression of these parameters, which is coordinate in vivo, has been dissociated into two sequential periods in vitro. Similarly, the regulatory mechanisms controlling the subsequent decline of the net expression of these three parameters were dissociated. Whereas, the increase in the net CNP activity ceased on schedule, the decline of sulfatide synthetic rate was delayed 20 days, and the accumulation of MBP underwent a net loss. These data suggest that there are multiple parallel but separate mechanisms of temporal regulation controlling myelinogenic gene expression, and that, among them, those factors that control MBP accumulation are more sensitive to disruption by the rigors of dissociated culture.
Alteration of metabolism of retinal taurine following prolonged light and dark adaptation: A quantitative comparison with gamma‐aminobutyric acid (GABA)
Authors: Ida Shuji , Nishimura Chihiro , Ueno Eiko , Kuriyama Kinya
Published: January 2005

Alteration of metabolism of taurine in prolonged light‐ and dark‐adapted frog retinae were studied in comparison with that of gamma‐aminobutyric acid (GABA) and the following results were obtained. (1) Statistically significant alterations in retinal taurine, an increase in dark‐adapted, and a decrease in light‐adapted states, respectively, occurred when frogs were adapted continuously to light or dark for more than 3 weeks. Under the same experimental conditions, no alteration in retinal GABA was noted. (2) At 3 weeks and thereafter, a significant increase of retinal cysteine sulfinic acid decarboxylase (CSD; EC 4.1.1.12) activity, an enzyme involved in the biosynthetic pathway of taurine, also occurred in the dark, whereas the activity in the light‐adapted retina was reduced. On the other hand, the retinal activity of L‐glutamate decarboxylase (GAD; EC 4.1.1.15), the rate‐limiting enzyme of GABA biosynthesis, was not altered in dark‐ as well as light‐adapted state. Similarly, retinal GABA‐transaminase (GABA‐T; EC 2.6.1.19)‐succinic semialdehyde dehydrogenase (SSADH; EC 1.2.1.16) was unaltered. (3) These alterations in retinal taurine were, however, unaccompanied by any changes in factors related to transmitter actions such as evoked release, high affinity uptake, and specific binding to synaptic membranes. The above results suggest that, different from GABA as a potent candidate for inhibitory neurotransmitter, retinal taurine may act as neuromodulator and/or may play an important role as a basic factor for maintaining cellular integrity under certain pathophysiological conditions.
Endogenous activation of guanylate cyclase in synaptosomal soluble fraction from rat brain
Authors: Yoshikawa Kazuaki , Kuriyama Kinya
Published: January 2005

Guanylate cyclase in crude mitochrondrial (P2) soluble fraction prepared from rat brain, obtained by a hypo‐osmotic treatment of P2, showed extremely higher activity than that in the same fraction from other organs. In addition the soluble fraction obtained from synaptosomes (P2‐B) contained the highest enzyme activity among other subfractions of the cerebral P2 examined. Guanylate cylase activity in the synaptosomal soluble fraction was, however, markedly suppressed by various compounds reacting with free radicals.

These results suggest that guanylate cyclase in the synaptosomal soluble fraction may be activated endogenously by a free radical and involved in the regulatory mechanisms for cyclic guanosine monophosphate (cyclic GMP) at presynaptic terminals.
Modification in messenger RNA population synthesized in rabbit cerebral cortex in the recovery period following convulsions
Authors: Cupello A. , Ferrillo F. , Rosadini G.
Published: January 2005

The labeling pattern of microsomal poly(A)‐associated messenger RNA was studied in rabbit cerebral cortex during the postconvulsive period. Labeled uridine was injected into the brain 2 hr after a single electroconvulsive shock and the animals sacrificed 1 hr later. Poly(A) RNA was then extracted from cerebral cortex microsomes, and fractionated by gel electrophoresis. The results indicate that the messenger RNA population synthesized in the cortex in the postconvulsive recovery period is clearly different from that synthesized in the normal controls.
Studies in neuronal ceroid lipofuscinosis: Enzymes of liver and brain tissues involved in the defense against oxidative damage
Authors: Garg Hari S. , Awasthi Yogesh C. , Neff William A. , Ansari Naseem H. , Srivastava Satish K.
Published: January 2005

The levels and the nature of peroxidase isozymes in the liver and brain tissues of a patient with Batten‐Spielmeyer‐Vogts (BSV) syndrome were found to be comparable to those of normal controls, indicating that peroxidase deficiency is probably not the basic genetic defect in Battens disease. The isoelectric focusing profile (four isozymes at pI 4.0, 4.5, 5.3, and 7.2) of liver peroxidases in the BSV patient was similar to that of normal control. Ion exchange chromatography revealed no noticeable difference in the liver peroxidase isozymes of the normal control and the BSV syndrome patient. The quantitative difference often observed in total peroxidase activity in normals and BSV syndrome patients can be attributed to different amounts of hemoglobin, which is known to express peroxidase activity. The levels of other enzymes known to be involved in the defense of tissues against oxidative damage, such as superoxide dismutase and glutathione peroxidase, and catalatic and peroxidatic activities of catalalase in the liver and brain tissues of the Battens patient, were comparable to the levels in the control subject. The brain peroxidase from both normal subjects and the Battens patient was completely inhibited by 5 mM sodium azide, whereas it did not affect the liver peroxidase activity.
Synaptosomes and mitochondria from rat brain cerebral cortex: In vivo interference on some enzymatic activities by SAMe and CDP‐choline
Authors: Villa R. F. , Curti D. , Polgatti M. , Benzi Gianni
Published: January 2005

The interference of cytidine diphosphate choline (CDP‐choline) and of S‐adenosyl‐L‐methionine (SAMe) on several enzymatic activities related to energy transduction (citrate synthase, malate dehydrogenase, total NADH‐cytochrome c reductase, cytochrome oxidase) and cholinergic metabolism (acetylcholine esterase) was studied. These enzymatic activities were evaluated in the purified mitochondrial fraction and in the crude synaptosomal fraction of rat cerebral cortex, 30 or 60 minutes after the in vivo administration of a single dose of 40 and/or 80 and 320 mg.kg−1 by intraperitoneal injection. SAMe left the enzymatic pattern studied totally unmodified, while CDP‐choline increased the cytochrome oxidase, evaluated in the synaptosomal fraction. These findings are discussed with regard to SAMe compartmentation and CDP‐choline action.
Differences in the accumulation of lithium in human neuroblastoma and glioma cells in tissue culture
Authors: Saneto Russell P. , Perez‐Polo J. Regino
Published: January 2005

A human neuronal and a human glioma line were used to study lithium (Li) transport mechanisms and kinetics of influx. We demonstrated that, unlike the human erythrocyte or clonal neuroblastoma cell SY5Y, the cloned glioma cell line A1B1 had neither a ouabain or phloretin‐sensitive component of Li influx. Furthermore, glioma cells were shown to accumulate significantly more (4 fold) Li and at an apparently faster rate when compared to the neuroblastoma cell, SY5Y, over the same time period. Thus, these two clones may be better in vitro model system for the study of Li transport components native to the human central nervous system as compared to erythrocytes. This study also suggests that glial tissue may preferentially accumulate Li and in this way control the levels of extracellular Li surrounding some neurons.
Growth factor dependence of pheochromocytoma cells in chemically defined medium
Authors: Goodman Rosanne , Herschman H. R.
Published: January 2005

We have previously described the isolation of a clonal pheochromocytoma cell line (PC‐G2) which responds to nerve growth factor (NGF) [Goodman and Herschman, 1978] and epidermal growth factor (EGF) [Goodman et al, 1980] with increased specific activity of tyrosine hydroxylase (TH). This cell line thus can be used for studies of induction of a key enzyme in the biosynthesis of catecholamines using a homogeneous cell population under controlled environmental influences. However, the need for serum in the culture medium used to grow these cells still introduced a lack of total environmental control. Several laboratories have circumvented this problem by growing cells in chemically defined medium. In the present report we demonstrate that with a modification PC‐G2 cells can survive and grow in the chemically defined N3 medium devised by Bottenstein and Sato [1979]. While another pheochromocytoma cell line, PC‐12, was shown to grow in N3 medium without any supplement [Bottenstein et al, 1979], the PC‐G2 cells exhibit an absolute requirement for NGF or EGF in order to grow in this chemically defined medium. As was the case in the induction of TH in serum‐containing medium [Goodman and Herschman, 1978; Goodman et al, 1980], EGF was found to be 100 times more potent than NGF in the support of growth of the PC‐G2 cells. In the present report we demonstrate not only that either of these growth factors will support the growth of the PC‐G2 cells, but also that the relative potency of these two factors for support of the cell growth is similar to their relative potencies in the induction of tyrosine hydroxylase in serum‐containing medium.
Constancy of adult hypothalamic tyrosine hydroxylase after gonadal steroid treatment during development
Authors: Vaccari Andrea , Biassoni Roberto
Published: January 2005

Tyrosine hydroxylase (TH) was studied in the entire hypothalamus of 60‐day‐old male and female rats, and its activity was similar in both sexes. Administration of estrogen or androgen to male or female pups soon after birth and during development did not affect the kinetic parameters of TH. It is, thus, suggested that sexual dimorphism in the levels and turnover of catecholamines (CA) and their sensitivity to fluctuations in gonadal steroids during development do not depend on corresponding sex‐related or steroid‐sensitive differences in the synthesis of hypothalamic CA.
Human β‐nerve growth factor does not crossreact with antibodies to mouse β‐nerve growth factor in a two‐site radioimmunoassay
Authors: Beck Carol E. , Perez‐Polo J. Regino
Published: January 2005

The nerve growth factor protein (NGF) isolated from mouse submaxillary gland has been shown to be necessary to the development of vertebrate sensory and sympathetic ganglia. Also, wide ranging alterations in the levels of NGF in the peripheral circulation of humans suffering from a variety of neuropathies have been reported. Many of these reports relied on the use of antibodies directed to the mouse β‐NGF subunit for their quantitation of human NGF antigen. We report here on the lack of crossreaction between antibodies directed to mouse β‐NGF and its human counterpart isolated from placenta at term.
Nerve growth factor and cyclic AMP: Opposite effects on neuroblastoma‐substrate adhesion
Authors: Schulze I. , Perez‐Polo J. R.
Published: January 2005

Increased cellular adhesion has been postulated to be an early event required of neuroblasts undergoing neurite extension during differentiation. Nerve growth factor (NGF) induces neurite extension in a variety of cell types of neural crest origin. In the PC12 rat pheochromocytoma cell line, which has been proposed as a model for precursor cells to sympathetic neurons, NGF and dibutyryl cyclic AMP (dBcAMP) promote both neurite extension and an increased rate of cell‐substrate adhesion. Since dBcAMP can substitute for NGF in this enhancement of adhesion rate in the PC12 cell line, cAMP has been suggested as a second messenger for NGF. We have shown that in two nearly diploid adrenergic like human neuroblastoma clones, the KA and SY5Y cell lines, which also extend neurites in response to both NGF and dBcAMP, only NGF enhances cellular adhesion, as defined by an increase in the number of cells prelabeled with 35S‐methionine which attach to culture dishes at a given time. Incubation with monospecific antibodies directed against murine β‐NGF abolishes the NGF effect on adhesion. The NGF effect on human neuroblastoma is specific insofar as NGF does not facilitate adhesion of two glioma lines. Unlike the results obtained for PC12, in both SY5Y and KA lines, 1 mM dBcAMP decreases the rate of adhesion to levels significantly below those of controls. Adhesiveness of neuroblastoma cells treated with both NGF and dBcAMP is intermediate between that of cells treated with either agent alone. While theophylline mimics the dBcAMP effect, sodium butyrate has no such effect. At 22°C, the effect of NGF on neuroblastoma substrate adhesion is observable within 5 minutes and persists for 2 hours; treatment of the KA line with NGF at 37°C for 24 hours results in a more persistent enhancement of cell adhesion. Furthermore, both SY5Y and KA exhibit different morphologies when challenged with NGF, dBcAMP, or sodium butyrate. This study suggests that NGF and cyclic AMP do not share a common mechanism of action, but can in fact interest antagonistically in an adrenergic like neuroblastoma model system. Furthermore, the results suggest that increased cellular adhesiveness may not be an obligatory perequisite for neurite extension by neuroblasts in development.
Biochemical development of the human brain. III. Benzodiazepine receptors, free Y‐aminobutyrate (GABA) and other amino acids
Authors: Brooksbank B. W. L. , Atkinson D. J. , Balázs R.
Published: January 2005

Benzodiazepine receptor binding and the concentration of free tissue GABA, glutamate, glutamine, aspartate, and 13 other amino acids were estimated in specimens of cerebral cortex and cerebellum taken from normal foetuses and from perinatal and postnatal infants and adults postmortem.

Compared with the ontogenetic increase, previously reported, in [3H]muscimol binding, that of [3H]flunitrazepam binding developed more rapidly in the cerebellum and less rapidly in the cerebral cortex. The concentration of GABA in both brain parts increased with age more rapidly than did that of glutamate decarboxylase activity.

The overall pattern of developmental changes in the amino acid concentrations in the human brain showed many similarities with those reported in the brains of experimental animals. The concentration of the amino acids associated with the tricarboxylic acid cycle increased with age. Although the general downward trend in the levels of essential amino acids (with the exception of Met) was also evident in the human cerebral cortex, this was not the case in the cerebellum where the concentrations of most amino acids were relatively low in the foetus whereas the concentrations exceeded the cerebral cortical levels in the adult.
Ventromedial nucleus of the hypothalamus: Convergent excitatory and inhibitory responses to fimbria and stria terminalis stimulation
Authors: Marchand James E. , Defrance Jon F. , Stanley James C.
Published: January 2005

Field and extracellular unitary potentials were recorded in the ventromedial nucleus of the hypothalamus (VMH) of urethane‐anesthetized rabbits after stimulation of the fimbria and stria terminalis.

Stimulation of the lateral portion of the fimbria, which carries fibers from the ventral subiculum of the hippocampal formation, evoked a two‐component response. An early excitatory response, with an average latency of 10 msec, predominated along the lateral margins of the VMH. A later inhibitory potential with an average latency of 15 msec was seen predominantly within the central portions of the VMH. Stimulation of the dorsal component of the stria terminalis produced two similar response patterns: an early excitatory response with an average latency of 16 msec, followed by an inhibitory potential with an average latency of 25 msec. The topographical distribution of these two components of the response was nearly identical to that produced by lateral fimbria stimulation. In contrast, stimulation of the ventral component of the stria terminalis evoked a simple excitatory response with an average latency of 10 msec which was maximal within the core of the VMH.

Extracellular unitary recodings showed that the early negativity associated with stimulation of each of these three pathways reflects a monosynaptic excitation of VMH cells and that there was convergence of the three excitatory inputs at the single cell level.
Uptake, release, and binding of taurine in degenerated rat retinas
Authors: Salceda R. , Pasantes‐Morales H.
Published: January 2005

High‐affinity uptake, potassium‐stimulated release and receptor binding of γ‐aminobutyric acid (GABA) and taurine were studied in retinas of rats treated with monosodium glutamate (MSG) or iodoacetate‐malate (IAM). Such treatments produce a selective damage of the inner retinal layers (MSG) or of the photoreceptor layer (IAM).

MSG treatment decreased GABA uptake by more than 60%. Also, the potassium‐stimulated release of this amino acid was markedly diminished (90%) in retinas lesioned by MSG. MSG treatment decreased 3H‐GABA binding by 45%. Uptake, release or binding of GABA were unaffected by IAM‐treatment.

Taurine uptake was reduced by a similar degree by both MSG and IAM treatment, 57% and 38% respectively. Potassium‐stimulated release of taurine was unchanged by MSG and 50% reduced by IAM. Both treatments reduced the spontaneous release of endogenous taurine. Binding of taurine to receptors in retinal membranes was practically unaffected by any of the treatments utilized.

These results are consistent with a neurotransmitter action of GABA at the inner retinal layers, while they do not support a major role for taurine as a synaptic transmitter in retina.
Effect of transganglionic degenerative atrophy on opiate receptors in the dorsal horn of the spinal cord
Authors: Csillik B. , Kiss J. , Knyihar‐Csillik Elizabeth , Lajtha A.
Published: January 2005

We investigated alterations in opiate‐binding sites in the upper dorsal horn after transection of the related peripheral sensory nerve in rats. The binding of (3H)diprenorphine was measured autoradiographically. The findings indicated a shift of the binding sites, rather than a degenerating disappearance, with a decrease in nerve fibers but an increase in nerve cells. This may be due to latent opiate‐binding sites becoming manifest.
Utilization of ketone bodies and glucose by established neural cell lines
Authors: Roeder Lois M. , Poduslo Shirley E. , Tildon J. Tyson
Published: January 2005

The rates of utilization of [3‐14C]‐acetoacetate, [3‐14C]‐3‐hydroxybutyrate, and [6‐14C]‐glucose were measured in four established cell lines from neuroblastoma of rat (B103) and mouse (N4TG1) and from rat astrocytoma (RGC6) and mouse oligodendroglia (G2620). The rates of incorporation of acetoacetate into lipid were 3–5 times higher than glucose in all cell lines. The incorporation of 3‐hydroxybutyrate was similar to that of glucose. Thin‐layer chromatography of the total lipid extracts showed the same relative rates of use of these substrates for synthesis of various phospholipids and neutral lipids. The rates of incorporation into neutral lipids and phosphatidylcholine were essentially linear for 12 hr; however, that into phosphatidylethanolamine was markedly higher in the second 6 hr interval than in the first. In all cases, the greatest percentage of label (35–50%) appeared in the phosphatidylcholine fraction. The distribution of label from each of the three substrates among the various lipids was similar in the glial cells, but there were marked differeneces in distribution of the two ketone bodies in the neuroblastoma lines. These cells also synthesized lipids that migrated to the same area on the chromatogram as cholesterol esters and free fatty acids. In three of the four cell lines the rates of oxidation were highest for glucose, intermediate for acetoacetate, and lowest for 3‐hydroxybutyrate. The ratios of the rate of incorporation to the rate of oxidation were higher for ketone bodies (3.32 for 3‐hydroxy‐butyrate and 5.29 for acetoacetate) than for glucose (0.41). This indicates that in these cells ketone bodies are directed toward lipid synthesis rather than oxidation, and glucose is preferentially used as an energy source.
[3H]spiperone binding sites in rat primary glial cultures, C6 glioma, and B104 neuroblastoma
Authors: Severson J. A. , de Vellis J. S. , Finch C. E.
Published: January 2005

Binding sites for [3H]spiperone were detected on membranes from primary glial cultures from neonatal rat cortex and striatum and from the C6 glioma cells. [3H]Spiperone binding was displacable by d‐butaclamol. However, competition studies suggest that [3H]spiperone binding to primary glial cultures was mainly to serotonergic sites, and binding to the C6 glioma was alpha‐adrenergic. No specific binding was detected to membranes from B104 neuroblastoma cells. Although [3H]spiperone binding to glial sites on whole striatum under generally used conditions is small (about 10%), the striatal glial hyperactivity that is often associated with neuronal degeneration could lead to an overestimation of presumed neuronal binding sites for dopaminergic ligands.
Taurine biosynthesis in frog retina: Effects of light and dark adaptations
Authors: Nishimura Chihiro , Ida Shuji , Kuriyama Kinya
Published: January 2005

The retinal uptake and metabolism of cysteine, a precursor for taurine biosynthesis, were analysed using the bull frog. The [14C] cysteine uptake into isolated retina had some specific properties: It was rather temperature independent, required Na ions, was inhibited by ouabain but not by dinitrophenol, and exhibited saturation kinetics composed of two components. When retinal homogenate was incubated with 12‐30 μM of L‐[U‐14C]cysteine, the accumulation of labeled alanine, cysteine sulfinic acid (CSA), cysteic acid (CA), hypotaurine, and taurine was detected. The metabolic conversions of [14C] cysteine to labeled alanine, hypotaurine, and taurine were linear over 90 minutes. Prolonged light adaptation (3 weeks) induced a significant reduction in the formation of labeled CA, CSA, hypotaurine, and taurine from [14C] cysteine. On the other hand, it was found that in dark‐adapted retinae, the formation of labeled taurine from [14C] cysteine increased significantly in spite of the reduction in the formation of labeled CA. These results indicate that biosynthetic pathways exist for taurine from cysteine in frog retina, and that these metabolic pathways are involved in the regulation of retinal taurine content under continuous visual adaptation.
Nerve growth factor and neural oncology
Authors: Vinores S. A. , Perez‐Polo J. R.
Published: January 2005

The precise role of the nerve growth factor protein (NGF) during the growth and development of the human nervous system is not determined. Although it appears to influence a number of neural functions, its mechanism of action is poorly understood. A number of researchers have proposed that NGF may be involved in several pathological conditions including cancer. It has been shown that NGF is secreted'by certain sarcoma (23), neuroblastoma (113), and glioma (7,102,136) cell lines and can bind to neuroblastoma and metastatic melanoma cell lines (42). Neuroblastoma (136,181) and pheochromocytoma (165) cells in vitro can be induced by NGF to differentiate toward a morphologically “more benign” state and appropriate NGF treatment of rats can reduce the number of chemically induced gliomas and neurinomas (174, 178). NGF can also reduce the growth of intracerebrally inoculated anaplastic glioma cells (172). Anti‐NGF treatment of rats (178) and mice (179) can alter the tumor distribution observed following ethylnitrosourea or benzo(a)pyrene treatment (10). In humans, it has been reported that serum levels of NGF are usually elevated in persons “at risk” for neurofibromatosis (156). The precise nature of the NGF role is not known in these instances. Further understanding of the action of NGF could be of clinical importance.
Cell surface and cytoskeletal antigens in cerebral cell cultures after chloroform‐methanol delipidation
Authors: Yavin E. , Yavin Z.
Published: January 2005

Fixation and in situ total delipidation of nerve cells in monolayer cultures have been used for immunofluorescence visualization of cellular antigens. Cells grown on poly‐L‐lysine‐coated coverslips are exposed to a chlorofordmethanol (2/1 by vol) solvent mixture for 15 min at −65°C. This step results in the fixation of cells and is accom‐panied by the complete extraction of cellular lipids. About 3.2% of the total 35S‐ methionine‐labeled trichloroacetic acid‐insoluble cellular material is extracted into the organic solvent mixture, demonstrating that aqueous soluble proteins are not signifi‐cantly extracted under these conditions. A total loss of tetanus toxin binding sites, presumably reflecting the removal of polysialogangliosides from the cell surface, is observed. The accessibility of antibodies against tubulin and against intermediate filaments after this treatment has been investigated. Visualization of these cytoskeletal elements by indirect immunofluorescence and by phase microscopy suggests that the removal of cellular lipids does not affect the apparent cytoarchitecture and that extraction with these organic solvents does not interfere with the staining of tubulin and intermediate filaments, the latter being exclusively present in nonneuronal cells. The advantage of this method of cell fixation and lipid extraction for immunofluorescence of cells in monolayer culture is discussed.
Viability, growth, and maturation of fetal brain and spinal cord in the siatic nerve of adult rat
Authors: Bernstein J. J.
Published: January 2005

The feasibility for growth, maturation, and differentiation of fetal nervous system implanted into adult mammalian peripheral nervous system was studied. Thirtyfive adult rats had the epineurium of the sciatic nerve crushed, perineurium minced, and fetal rat cortex or spinal cord implanted. Rats were utilized 7, 14, and 21 days, and 1, 2, 3, and 4 months later. A 1‐mm cube of cortex or a 1‐mm segment of spinal cord of 11‐, 12‐, or 15‐day gestation fetuses was placed into the epineurium. Age‐matched controls (7 DPI (days postimplantation) control for E15 implant was a 1‐day pup, 21 days' gestation) were utilized for comparison (two per time group). Five animals had sciatic crush and perineurial mince only, and the gait and toe‐spreading response were observed over 4 months. All implanted animals walked normally at 30 days. All implants were successful and survived the duration of the experiment. Cortical implants produced prominent bulges in the epineurium (21 days–4 months). Maximal neuronal and neurolgial cell division was observed at 7–21 days, decreased at 30 days, and stopped by 60 days. Most implanted cortical neurons had mature nuclei and immature dendritic patterns (apolar), and rarely had mature dendritic patterns. Neuroglia were abundant. The younger the cortical implant, the larger the cell mass produced (E11 > E15). The spinal cord implants survived, were viable, contained mainly neuroglia, and grew minimally. Host Schwann cells and nerve fibers were found in and around the implants. These data show that adult peripheral nervous system can act as an environment for growth and viability of fetal CNS implants.
Ultrastructural changes in the sensomotor cortex of the rabbit after complete 30‐min brain ischemia
Authors: Pluta R. , Gajkowska B.
Published: January 2005

Experiments were performed on rabbits in which complete 30‐min brain ischemia was induced. Electron‐microscopic studies revealed higher susceptibility to ischemia of the motor cortex than the sensory cortex, which was manifested by a higher number of damaged nerve cells in the former than in the latter. Ultrastructural abnormalities of motor cortex neurons, including the presence of numerous vesicular structures in the cell nuclei, swelling of mitochondria, and an increase in the number of intracytoplasmic fibrillary structures appeared 3 h after blood recirculation and became more intensive after 6 h.
Differential sensitivity of estrogen target tissues: Implications for estrogen regulation of serum luteinizing hormone
Authors: Kelner K. L. , Peck E. J.
Published: January 2005

In the rat, it is generally accepted that the primary site of estrogen's stimulatory (positive) effects on serum LH is the preoptic area‐anterior hypothalamus (POA/AH). In contrast, the primary site of estrogen's inhibitory (negative) effects on serum LH levels has not been conclusively identified. There is evidence to suggest both a medial basal hypothalamic (MBH) and an anterior pituitary site of action. The present studies utilized a unique characteristic of these estrogen effects to investigate their putative loci. Extensive dose‐response curves of estrogen's induction of positive and negative feedback indicated that the negative feedback response was activated at a lower concentration of serum estradiol than the positive feedback response. The differential sensitivities of these two responses suggested that the tissues mediating them might also be differentially sensitive to estradiol. In a previous paper, we showed that receptor translocation is an index of estrogen sensitivity. We measured receptor translocation in response to a series of estradiol doses in the POA/AH, the MBH, and the pituitary. Dose‐response curves for estrogen's effect on receptor translocation showed that the pituitary receptor translocation mechanism is activated at significantly lower levels of serum estradiol than that of either the POA/AH or the MBH. These results are consistent with the POA/AH as a site of estrogen's positive feedback effects. In addition, they suggest that negative feedback in the rat may be mediated via estrogen's action at the anterior pituitary. Estrogen's negative feedback effect on serum LH occurs at a serum level of estrogen at which no receptor is translocated in the MBH. Therefore, the pituitary, which does possess nuclear receptors at these estradiol dose levels, is more likely to be the primary mediator of estrogen's negative feedback effects. In another experiment, pituitary, but not hypothalamic, receptor was translocated to the nuclear fraction with an injection of 100 μg clomiphere (Clomid). Under these conditions serum LH is depressed, thus strengthening the hypothesis that, in the rat, estrogen action on the pituitary can cause suppression of serum LH independently of the hormone's action in the hypothalamus.
Essential fatty acid deficiency: A suggestion concerning experimental design
Authors: Levine S. , Ivasauskas E. Y. , Sowinski R. , Kikkawa Y.
Published: January 2005

In experiments on essential fatty acid deficiency, various strategems have been used to balance the deficient and control groups for all nutrients except essential fatty acids. We suggest the use of a single fat‐free diet for both groups, with essential fatty acids administered parenterally to the control (nondeficient) group once each week.
Antagonistic effects of taurine and 4‐aminopyridine on guinea pig ileum
Authors: Arzate M. E. , Ponce H. , Pasantes‐Morales Herminia
Published: January 2005

The effects of 4‐aminopyridine (4‐AP) and of taurine on the guinea pig ileum were examined. Four‐AP increases the basal activity from 1.3 to 6.45 cm2/min. This effect is atropine‐sensitive and calcium‐dependent. Taurine counteracts the effects of 4‐AP on muscle contracture in a concentration‐dependent manner. In muscles preincubated with 20 mM taurine, the effect of 4‐AP decreased about 65%. Taurine added at the time of maximal effect of 4‐AP reduced the muscle contracture induced by the drug to the basal levels. Glycine and β‐alanine did not influence the contracture induced by 4‐AP, whereas 25 mM γ‐aminobutyric acid (GABA) reduced it by 30%. Taurine reduced the basal muscle activity by 50% but did not affect the contracture induced by exogenously applied acetylcholine.
Ultrastructure of fetal spinal cord and cortex implants into adult rat spinal cord
Authors: Bernstein J. J. , Patel U. , Kelemen M. , Jefferson M. , Turtil S.
Published: January 2005

The ultrastructure of cortex and spinal cord from 11‐, 12‐, and 15‐day‐old fetuses implanted into the spinal cord of adult rats was studied over 3 months. Under deep Chloropent anesthesia, a 0.5 × 1.0‐mm square of fetal cortex or a 1.0‐mm segment of fetal spinal cord was implanted subpially between the left dorsal column and the dorsal horn of 70 adult rats. Implants grew toward gray matter, usually interfacing with the host at the isthmus between the horns of the spinal cord. However, implants were observed that occupied the entire left dorsal and ventral horns of the left half of the host spinal cord. Implants had concentric zones: A central zone with basal lamina lined joined channels and subjacent neuroglia; a zone of differentiating implant nervous system; a zone with basal lamina lined implant with overlying pial cells on the dorsal and lateral surfaces of the implant; a zone that interfaced with the host with overlapping neuropil on the lateral and ventral surfaces of the implant. Neuron types were typical for cortical or spinal implants. Implants survived for 3 months and reached stages of neuronal and neuroglial maturation similar to controls. Both fetal spinal cord and brain were successful as implants, had delayed differentiation, and formed complex neuropils. The zone of overlapping interface of the donor and host is an anatomical indication of physiological and functional integration.
Biosynthesis of phospholipids and sphingolipids from acetoacetate and glucose in different regions of developing brain in vivo
Authors: Yeh Y.‐Y.
Published: January 2005

The incorporation of 14C‐label from subcutaneously injected [3‐14C]acetoacetate and [U‐14C]glucose into phospholipids and sphingolipids in different regions of developing rat brain was determined. In all regions, phosphatidylcholine was the lipid synthesized most readily from either substrate. The percentages of radioactivity in other phospholipids and most sphingolipids remained relatively constant throughout postnatal development. An exceptional increase in the percentage of radioactivity incorporated into cerebroside, coinciding with a decrease of incorporation into phosphatidylcholine, was first noted on day 12 and continued until a maximal level was reached between days 18 and 20 of postnatal age. These developmental changes in preferential synthesis of lipids were associated with increased demands for phospholipids and cerebroside during the early and late postnatal stages, respectively. There was no difference in accumulation of radioactivity from acetoacetate, expressed as dpm of [14C]acetoacetate recovered in phospholipids plus sphingolipids per g of tissue, among all brain regions during the first 5 days of life. During active myelination (12 to 20 days of age); however, the amount of 14C‐label was highest in brain stem, ranging from 1.9‐ to 2.3‐fold greater than values for cerebrum and thalamus. The region with the next highest accumulation was cerebellum, followed by midbrain. During the same period, brain stem was likewise the most active site of accumulation of radioactivity from 14C‐labeled glucose. Higher amounts of [14C]acetoacetate label accumulated in lipids of brain stem and cerebellum, relative to midbrain, thalamus, and cerebrum, coincide with evidence that active myelination begins in the hindbrain and proceeds rostrally toward the forebrain. Ketone bodies could therefore serve as a potential source of phospholipids and sphingolipids for brain growth and maturation.
Fetal calf serum‐mediated inhibition of neurite growth from ciliary ganglion neurons in vitro
Authors: Davis G. E. , Skaper S. D. , Manthorpe M. , Moonen G. , Varon S.
Published: January 2005

Embryonic chick ciliary ganglion (CG) neurons cultured in fetal calf serum‐containing medium have been previously reported to extend neurites on polyornithine (PORN) substrata precoated with a neurite‐promoting factor (PNPF) from rat schwannoma‐conditioned medium. On PORN substrata alone, however, no neuritic growth occured. This was interpreted as evidence that PORN was an incompetent substratum for ciliary neuritic growth. In this study, we now find that an untreated PORN substratum allows neuritic growth in serum‐free defined medium. When PNPF was added to PORN, a more rapid and extensive neuritic response occured. After 5 hr of culture, a 60% neuritic response occurred on PNPF/PORN, whereas no neurons initiated neurites until 10–12 hr on PORN. The inhibitory effect of fetal calf serum noted above on PORN could be obtained in part by pretreating the substratum with serum for 1 hr. Maximal inhibitory effects in the PORN pretreatment were achieved after 30 min and were not further improved by treatments up to 4 hr. Bovine serum albumin was also found to inhibit neurite growth on PORN to about 60% of the inhibition obtained by an equivalent amount of serum protein. Fetal calf serum was shown to cause a 15% reduction in the percentage of neurons bearing neurites after its addition to 18‐hr serum‐free PORN cultures and to cause statistically significant reductions in neurite lengths measured 2 hr later.
Biology of gangliosides: Neuritogenic and neuronotrophic properties
Authors: Ledeen R. W.
Published: January 2005

Research on the biologic function of gangliosides has accelerated in recent years following discovery of their pronounced effects when administered exogenously to neurons in culture and in vivo. These effects are of two principal types: (1) neuronotrophic, concerned primarily with survival and maintenance of the neuron, and (2) neuritogenic, involving significant increase in the number, length, and/or branching of neuronal processes. Such neurite‐promoting activity has been observed in primary cultures of neurons from brain and ganglia as well as transformed lines of neuronal origin. These phenomena may be related to the remarkable growth of aberrant secondary neurites, often accompanied by synaptogenesis, observed in the gangliosidoses. Several in vivo studies have shown exogenously administered gangliosides to aid nervous system repair in both the CNS and PNS, although it is not clear in some cases whether the observed effects should be attributed to neuronotrophic or neuritogenic effects (or both). This article attempts to briefly review the principal developments that have occurred in this area of ganglioside research over the past several years. It also presents for consideration some of the tentative hypotheses put forward concerning mechanism of action.
Antibodies to gangliosides inhibit goldfish optic nerve regeneration in vivo
Authors: Sparrow J. R. , McGuinness C. , Schwartz M. , Grafstein B.
Published: January 2005

Intraocular injection of antiserum to mixed ganglioside or to GM1 inhibited the regeneration of goldfish optic axons following an optic nerve crush. For example, injections of antiserum on 5 consecutive days beginning the day before the crush resulted in a decrease of about 40% in the axonal outgrowth distance measured at 10 days after the crush. The inhibition was observed even when the treatment was begun a few days after the lesion, and greater degrees of inhibition were observed when the treatment was given later in regeneration. This indicates that the antiganglioside serum interfered with axonal elongation more than with the initial sprout formation. The antiganglioside treatment did not impair the enlargement of the cell bodies and nucleoli that accompanies regeneration, nor did it affect fast axonal transport of protein, glycoprotein, or glycolipid in regenerating nerves. Thus inhibition of outgrowth by antiganglioside treatment was not mediated by a gross change in the metabolism of the regenerating neurons. Treatment of normal neurons with the antiserum produced a 20–30% increase in the amount of 3H‐glucosamine‐labeled glycoproteins and glycolipids conveyed by fast axonal transport. These results suggest that membrane gangliosides may normally influence the supply of axonally transported glycosylated macromolecules. However, the effect of antiganglioside on axonal transport of glycosylated molecules and on axonal outgrowth are not necessarily related to each other.
The functional recovery of damaged brain: The effect of GM1 monosialoganglioside
Authors: Toffano G. , Savoini G. , Aporti F. , Calzolari S. , Consolazione A. , Maura G. , Marchi M. , Raiteri M. , Agnati L. F.
Published: January 2005

In the present study the topology and the biochemical mechanisms underlying the functional recovery of the dopaminergic nigrostriatal system is further analyzed. Rats with unilateral hemitransection were treated with 30 mg/kg GM1 monosialoganglioside or with its internal ester derivative for different periods of time. GM1 enhances 3H‐dopamine uptake in striatal synaptosomes of the lesioned side, and the enhancement of dopamine uptake precedes that of striatal tyrosine hydroxylase activity. The above biochemical effects are accompanied by changes in behavioral‐and electrophysiological‐related parameters. The effect of GM1 on striatal tyrosine hydroxylase of the lesioned side disappears when the ascending dopaminergic fibers are extensively lesioned. This suggests that the source of regrowing dopaminergic nerve terminals in the striatum of partially lesioned rats resides mainly in the intact axons remaining in the ipsilateral side. When GM1 is injected into partially lesioned rats kept in darkness, no effect on tyrosine hydroxylase activity is observed. This indicates that the mechanism through which GM1 acts involves a normal light‐dark cycle.