Caudate Nucleus Of Rat Brain Research Articles

Establishment of C6 brain glioma models through stereotactic technique for laser interstitial thermotherapy research.

Objective:To establish C6 brain glioma models using stereotactic technique, and to study effects of laser interstitial thermotherapy (LITT) in rat models of glioma.Methods:C6 glioma cells were cultured in dulbecco's minimum essential medium (DMEM) cell culture medium. The in vitro C6 cell cultures were stereotaxically implanted into the right caudate nucleus of rat brain. Presence of tumor was confirmed with Factor VIII R, hematoxylin–eosin stain, staining of glial fibrillary acid protein, and S-100 immunohistochemistry. After magnetic resonance (MR) scanning and correction of tumor location, the models were divided into groups according to the treating time and laser power (2–10 W). Semiconductor laser optical fibers were inserted in tumors for LITT. Cortex's temperature conducted from the center target was measured using infrared thermograph, and deep-tissue temperature around the target was measured using a thermocouple.Results:Rat C6 gliomas were inoculated with optimized stereotactic technique. These gliomas resembled human glioma in terms of histopathological features. Such models are more reliable and reproducible, with 100% yield of intracranial tumor and no extracranial growth extension. The difference between cortex temperature conducted from center target and deep-tissue temperature around target was not statistically significant.Conclusion:The rat C6 brain glioma model established in the study was a perfect model to study LITT of glioma. Infrared thermograph technique measured temperature conveniently and effectively. The technique is noninvasive, and the obtained data could be further processed using software used in LITT research. To measure deep-tissue temperature, combining thermocouple with infrared thermograph technique would present better results.

Paul Greengard: Signals underlying moods, addictions, and brain disorders

Although certain neurotransmitters had been identified more than 40 years ago, scientists knew relatively little about how these chemicals actually functioned. The basis for much of what neuroscientists know today about brain signaling was shaped by National Academy of Sciences member Paul Greengard's 1972 PNAS Classic paper, “Dopamine-sensitive Adenylate cyclase in caudate nucleus of rat brain, and its similarity to the ‘dopamine receptor’” (1).

Effect of morphine on the number and branching of astrocytes in various regions of rat brain.

We studied the effects of morphine in high doses on astrocytes in the nucleus accumbens, lateral septum, and caudate nucleus of rat brain. Activation of astrocytes in the nucleus accumbens and lateral septal nucleus was manifested in hyperplasia and elongation of astrocyte processes. In the caudate nucleus, the total length of astrocyte processes and branching of individual astrocytes decreased.

A novel thin-layer amperometric detector based on chemically modified ring-disc electrode and its application for simultaneous measurements of nitric oxide and nitrite in rat brain combined with in vivo microdialysis

A novel thin-layer amperometric detector (TLAD) based on chemically modified ring-disc electrode and its application for simultaneous measurements of nitric oxide (NO) and nitrite (NO2−) in rat brain were demonstrated in this work. The ring-disc electrode was simultaneously sensitive to nitric oxide (NO) and nitrite (NO2−) by modifying its inner disc with electropolymerized film of cobalt(II) tetraaminophthalocyanine (polyCoTAPc)/Nafion and its outer ring with poly(vinylpyridine) (PVP), respectively. The ring-disc electrode was used to constitute a novel TLAD in radial flow cell for simultaneous measurements of NO and NO2− in rat brain combined with techniques of high performance liquid chromatography (HPLC) and in vivo microdialysis. It was found that the basal concentration of NO in the caudate nucleus of rat brain is lower than 1.0×10−7 mol l−1, NO2− concentration is 5.0×10−7 mol l−1 and NO exists in brain maybe mainly in the form of its decomposed product.

Comparison of the autoradiographic binding distribution of [3H]-gabapentin with excitatory amino acid receptor and amino acid uptake site distributions in rat brain.

1. Gabapentin is a novel anticonvulsant with an unknown mechanism of action. Recent homogenate binding studies with [3H]-gabapentin have suggested a structure-activity relationship similar to that shown for the amino acid transport system responsible for the uptake of large neutral amino acids (LNAA). 2. The autoradiographic binding distribution of [3H]-gabapentin in rat brain was compared with the distributions for excitatory amino acid receptor subtypes and the uptake sites for excitatory and large neutral amino acids in consecutive rat brain sections. 3. Densitometric measurement of the autoradiographic images followed by normalisation with respect to the hippocampus CA1 stratum radiatum, was carried out before comparison of each binding distribution with that of [3H]-gabapentin by linear regression analysis. The correlation coefficients observed showed no absolute correlation was observed between the binding distributions of [3H]-gabapentin and those of the excitatory amino acid receptor subtypes. The acidic and large neutral amino acid uptake site distributions demonstrated a much closer correlation to the [3H]-gabapentin binding site distribution. The correlation coefficients for D-[3H]-aspartate, L-[3H]-leucine and L-[3H]-isoleucine binding site distributions were 0.76, 0.90 and 0.88 respectively. 4. Concentration-dependent inhibition by unlabelled gabapentin of autoradiographic binding of L-[3H]-leucine and L-[3H]-isoleucine was observed, with non-specific binding levels being reached at concentrations between 10 and 100 microM. 5. Excitotoxic quinolinic acid lesion studies in rat brain caudate putamen and autoradiography were carried out for the amino acid uptake sites mentioned above. The resulting glial infiltration of the lesioned areas was visualized by autoradiography using the peripheral benzodiazepine receptor specific ligand [3H]-PK11195. A significant decrease in binding density in the lesioned area compared with sham-operated animals was observed for D-[3H]-aspartate, L-[3H]-leucine, L-[3H]-isoleucine and [3H]-gabapentin, whilst [3H]-PK11195 showed a significant increase in binding density indicative of glial infiltration into the lesioned area. These results suggest that the gabapentin binding site and the acidic and LNAA uptake site may be present on cell bodies of a neuronal population of cells. 6. From these studies it appears that [3H]-gabapentin, L-[3H]-leucine and L-[3H]-isoleucine bind to the same site in rat brain. The inhibition of [3H]-gabapentin binding by the LNAA uptake system-specific ligand, BCH, suggests that [3H]-gabapentin may label this uptake site, termed system-L. Conversely these ligands could be labelling a novel site that coincidentally has a similar structure-activity relationship to this uptake site. These results suggest a novel mechanistically relevant site of action for gabapentin and may enable further anti-epileptic agents of this type to be developed.

Quantitative in vivo measurements using microdialysis on-line with capillary zone electrophoresis

A system which couples microdialysis with capillary zone electrophoresis (CZE) on-line is used to monitor ascorbate and lactate in the caudate nucleus of rat brain. On-line interface of microdialysis probe and electrophoresis capillary, along with the high mass sensitivity of CZE, allows the probe to be operated at flow rates as low as 40 nl/min. Under these conditions, the relative recovery is nearly 100% and quantitative monitoring is possible. The microscale system also facilitates calibration by the low flow rate method. In spite of the low flow rate, temporal resolution in the 45–125 s range is possible for these compounds. The system is demonstrated by observing changes in ascorbate due to infusions of elevated K + through the dialysis probe and systemic injections of amphetamine and an anesthetic (ketamine/xylazine/acepromazine mixture). Lactate is monitored in response to elevated K + infusions.

On-line interface between microdialysis and capillary zone electrophoresis

A flow-gated, on-line interface between a microdialysis sampling probe and capillary zone electrophoresis with UV absorption detection was characterized and applied. Electrophoresis conditions were chosen so that ascorbic acid migrated in 42–100 s with 65000–120000 theoretical plates. These results were obtained using a 25 μm inner diameter capillary with an inlet to detector length of 15 cm and electric field strength of 400–600 V cm −1. Theoretical plates, migration times, and peak areas for ascorbic acid injected on-line from the interface were the same as those obtained for off-line injections. The system allowed step changes in ascorbic acid concentration to be followed with 85 s time resolution when the dialysis flow-rate was 79 nl min −1. The time resolution was improved to 65 s when the dialysis flow-rate was 155 ni min −1. The relative standard deviation for peak heights was 3.8% and a linear response over the physiologically relevant range for ascorbic acid was observed. At 79 nl min −1 the relative recovery of the probe was 98%. The high relative recoveries improved detection limits, simplified quantification, and resulted in decreased disturbance to the system being studied when compared to the more conventional dialysis flow-rates of 0.5-1 μl min −1. As a demonstration of the system, ascorbic acid in the caudate nucleus of rat brain was detected and monitored in response to systemic amphetamine injections and anaesthetic overdoses. This system is the first to demonstrate high relative recoveries and high time resolution simultaneously with microdialysis sampling.

Coupling of adrenal medullary opioid receptors to islet-activating protein-sensitive GTP-binding proteins

Possible coupling of bovine adrenal medullary opioid receptors to islet-activating protein (IAP, pertussis toxin) -sensitive GTP-binding proteins was investigated by studying effects of guanyl-5′-y1 imidodiphosphate (Gpp(NH)p) and IAP treatment of membranes on opioid binding. Gpp(NH)p inhibited [ 3H]D-Ala 2-D-Leu 5 -enkephalin ([ 3H]DADLE) binding by increasing the dissociation constant of [ 3H]DADLE and membranes, and enhanced slightly [ 3H]diprenorphine binding. IAP treatment of membranes reduced [ 3H]DADLE binding and abolished almost completely the Gpp(NH)p inhibition of [ 3H]DADLE binding. Treatment of membranes with IAP and [ 32P]NAD resulted in radiolabeling of membrane proteins of approximately 39,000 dalton. DADLE inhibited adenylate cyclase activity in rat brain caudate nucleus. However, DADLE, β-endorphin, levorphanol and dynorphin A (1–13) did not show any significant inhibitory action on bovine adrenal medulary adenylate cyclase activity. These results suggest that bovine adrenal medullary opioid (DADLE) receptors are linked to IAP-sensitive GTP-binding proteins which are not directly coupled to adenylate cyclase.

Regional differences in resting extracellular potassium levels of rat brain

The extracellular potassium concentration in the cerebral cortex of the mammalian brain has been repeatedly reported to be approximately 3.0 mM. We have made detailed measurements with potassium-selective microelectrodes and have found significantly lower extracellular potassium concentrations in unstimulated rat brain caudate and thalamus (1.9–2.5 mM) when compared to cortex and cerebral spinal fluid (3.0–3.5 mM). These regional differences may be caused by variations in spontaneous activity of neurons, regional permeability differences in endothelial cells of brain capillaries to potassium, or caused by variations in uptake by glia.

Properties of a Ca 2+ and Mg 2+ stimulated ATPase in the rat caudate nucleus

Adenosine triphosphatase (ATPase) activity which could be stimulated maximally by either Ca 2+ or Mg 2+ was identified in a synaptosomal fraction from rat brain caudate nucleus. The thermodynamic properties of the Ca 2+ and Mg 2+ stimulated enzymes were similar to each other. Oligomycin, sodium azide and dinitrophenol had no significant inhibitory effects on stimulation by either cation. In vitro incubation of the ATPase with cis or trans-flupenthixol, chlorpromazine or trifluoperazine, but not with haloperidol, significantly inhibited stimulation by either cation. The DA receptor agonist 2-amino-6,7-dihydroxyl-1,2,3,4-tetrahydronaphthalene (ADTN) inhibited stimulation of the enzyme by either cation, while d-amphetamine, SKF 38393, pergolide and LY-171555 had no significant effects. Nomifensine at 10 −3M inhibited the cation stimulation by about 33%. In vivo administration of dopamine (DA) receptor antagonists (haloperidol, cis-and trans-flupenthixol, spiperone, chlorpromazine and trifluoperazine) and the agonist apomorphine neither inhibited nor stimulated ATPase activity. It appears from these data that the ATPase activity is not under DA receptor modulation. In addition, our tentative conclusion is that one enzyme is involved, because both Ca 2+ and Mg 2+ produced similar maximal stimulations, the activities as a function of temperature were similar, the enzyme could not be further stimulated with Ca 2+ after maximal stimulation by Mg 2+ (and vice versa), and the behaviour of the ATPase activity to all drugs tested was similar.

An iodinated ligand identifying the D-1 dopamine receptor

Iodination (with 125I) of SKF 83692 (2,3,4,5-tetrahydro-3-methyl-5-phenyl-1H-3-benzazepin-7-ol) produces a ligand of high specific activity. In the caudate nucleus of rat brain, this ligand binds to a site which discriminates between the active and inactive enantiomers of drugs selective for the D-1 receptor but which does not recognize drugs selective for the D-2 dopamine receptor or a serotonin receptor. Non-specific binding of this ligand is less than 5% of the total binding.

Determination of meta- and para-hydroxyphenylacetic acid levels in single caudate nuclei by selected metastable peak monitoring: a new sensitive gas chromatographic-mass spectrometric procedure

The levels of meta- and para-hydroxyphenylacetic acids in rat brain caudate nuclei have been determined by a new gas chromatography-mass spectrometric (GC-MS) procedure in which metastable transitions specific to the derivatized acids are observed. The method is more sensitive than previous procedures and allows determination of the acid concentrations using single caudate nuclei. The levels of the meta- and para-isomers were found to be 9.2 ± 1.5 and 43 ± 3.7 ng/g, respectively.

A sensitive and rapid fluorimetric assay for monoamine oxidase utilizing high pressure liquid chromatography

A rapid and sensitive assay for the measurement of monoamine oxidase (MAO) activity was developed. This method utilizes high pressure liquid chromatography with fluorescence excitation at 280 nm and detection at 330 nm at pH 5.0 of indoleacetic acid and 5-hydroxyindoleacetic acid, the deaminated products of two substrates for MAO, tryptamine, and serotonin, respectively. The assay allows for the complete separation of metabolites from either of the two substrates. The method has been used to determine MAO activity in the frontal cortex and caudate nucleus of rat brain using tryptamine and serotonin as substrates. The ease and rapidity of this assay make it suitable for use where routine enzyme determinations are required.

Transient Alterations in Neurotransmitter Activity in the Caudate Nucleus of Rat Brain after a High Dose of Ionizing Radiation

A single 10,000-rad dose of high-energy electrons induced an increase in dopaminergic and cholinergic activity in the caudate nucleus of the rat brain as assessed by K+-stimulated dopamine release in vitro and high-affinity choline uptake. These alterations occur during early transient incapacitation (ETI) and dissipate as the animal recovers behaviorally, in about 30 min after irradiation. Although the responses observed resemble those that result from blockade of dopamine receptors, no radiation-induced changes were found in dopamine-sensitive adenylate cyclase activity and [3H]haloperidol binding, two indices of dopaminergic receptor function. The data suggest that changes in dopaminergic and cholinergic activity are associated with the development of ETI and may play a role in the behavioral decrement observed under this condition.

Reversible inhibition of adenylate cyclase activity of rat brain caudate nucleus by oxidized glutathione

Basal and dopamine-stimulated adenylate cyclase (EC 4.6.1 1.) activities were strongly inhibited by GSSG, but not by GSH. Adenylate cyclase that had been inactivated by GSSG was reactivated by incubation with various sulfhydryl compounds including GSH. Formation of mixed disulfides by reaction between GSSG and protein-SH groups increased on incubation with GSSG and returned to the normal level on subsequent incubation with DTT.

Chemical lesion and drug induced supersentivity and subsensitivity of caudate dopamine receptors

In order to elucidate the mechanism of denervation supersensitivity, the effects of 6-hydroxydopamine lesion, placed in the substantia nigra, were examined on rat brain caudate adenylate cyclase and 3H-haloperidol binding to membrane dopamine receptors. In addition, the effects of chronic administration of L-DOPA, bromocriptine and piribedil were also investigated on 3H-haloperidol binding and dopamine, K + isoproterenol (IPNE) and 2-Cl-adenosine stimulated formation of cyclic AMP in caudate slices. 6-Hydroxydopamine lesions resulted in significantly greater stimulation of adenylate cyclase by dopamine at various concentrations tested. The haloperidol binding sites were increased by 28% on lesioned side caudate without changes in dissociation constants (K D). Three weeks after treatment with L-DOPA, bromocriptine or piribedil, the 3H-haloperidol binding sites were decreased by 40% with no change in K D. The stimulatory effect of dopamine on cyclic AMP formation was also abolished, although there was no change in IPNE, K +, or 2-Cl-adenosine stimulated cyclic AMP formation in caudate slices, suggesting a specific effect of dopamine agonists on dopamine receptors. The results of these studies suggest a close relationship between at least some populations of dopamine receptors and adenylate cyclase in the caudate nucleus.

The effect of spermine and spermidine on the hydrolysis of acetylthiocholine in the presence of rat caudate nucleus homogenate or acetylcholinesterase from Electrophorus electricus.

Abstract— The effects of spermine and spermidine tetrahydrochloride on female Agus rat brain caudate nucleus homogenates, soluble acetylcholinesterase from the electric organ of Electrophorus electricus and acetylthiocholine iodide were studied. Measurements were made using an autoanalytical spectrophotometric method which measured the initial rate of reaction rapidly and accurately. Both polyamines interacted with the substrate, acetylthiocholine, causing an increase in the rate of its non‐enzymatic hydrolysis. Slight inhibitory effects on acetylcholinesterase were also observed. Combined effect of the polyamine on the substrate and the enzyme showed an inhibition at low and activation at high (above 1 mm) substrate concentrations.

Decarboxylation of newly formed DOPA by caudate nucleus synaptosomal particles

The present study compares dopamine formation from two different sources of DOPA: preformed and added to the medium and that newly formed by the hydroxylations of phenylalanine or tyrosine. Synaptosomal preparations from rat brain caudate nucleus were incubated with 3H-labeled DOPA mixed as cosubstrate with either [14C]phenylalanine or [14C]tyrosine. Following the incubation, DOPA and dopamine were separated and their isotope ratios (isotope in phenylalanine (tyrosine) X 100/isotope in DOPA cosubstrate) were determined and compared. The results show that the ratio in dopamine was not only different from that in DOPA but was in fact 8.3-15.0 times higher. Although the absolute values of the isotope ratios were affected by any changes of the cosubstrate concentrations, the ratio in dopamine was found to be higher than in DOPA at all the substrate concentrations tested. When the synaptosomes were separated post-incubation from the medium and analyzed, the ratio in dopamine was also found to be higher than that in DOPA. Also, the large difference between the intrasynaptosomal ratios persisted throughout the incubation period ranging from 10 to 45 min. The results suggest that the DOPA which is newly formed by the hydroxylations, (a) may not be freely exchangeable with added DOPA because of compartmentation and (b) may be preferentially decarboxylated to dopamine.

CHARACTERIZATION OF A DOPAMINE‐SENSITIVE ADENYLATE CYCLASE IN THE RAT CAUDATE NUCLEUS

Abstract— An adenylate cyclase present in the caudate nucleus of rat brain, which is selectively stimulated by low concentrations of dopamine, and which is believed to mediate dopaminergic synaptic transmission, has been characterized with respect to several properties. The parameters studied included temperature, pH, ATP concentration, Mg/ATP ratio, and metal ion specificity. The effects of other compounds, including EGTA, NaF and several guanosine nucleotides, were also tested on the dopa‐mine‐sensitive adenylate cyclase. In addition, the subcellular distribution of the enzyme was studied. The highest specific activity was found in subcellular fractions enriched in nerve endings. A half‐maximal increase in the activity of the enzyme in a subcellular fraction occurred in the presence of 4 × 10−6 M dopamine. Fluphenazine, a dopamine antagonist, competitively inhibited the activity of the enzyme in this fraction, with a calculated inhibition constant (Ki) of 8 × 10−9M.

Dopamine-sensitive adenylate cyclase in caudate nucleus of rat brain, and its similarity to the "dopamine receptor".

An adenylate cyclase that is activated specifically by low concentrations of dopamine has been demonstrated in homogenates of caudate nucleus of rat brain. A half-maximal increase in the activity of the enzyme occurred in the presence of 4 muM dopamine. Concentrations of dopamine as low as 0.3 muM stimulated the activity of the enzyme. The adenylate cyclase activity of the homogenates was also stimulated by low concentrations of apomorphine, a substance known to mimic the physiological and pharmacological effects of dopamine. The stimulatory effect of dopamine was blocked by low concentrations of either haloperidol or chlorpromazine, agents known to block the actions of dopamine in mammalian brain. The results suggest that dopamine-sensitive adenylate cyclase may be the receptor for dopamine in mammalian brain. The isolation of this enzyme from caudate nucleus should facilitate the search for new therapeutic agents useful in the treatment of extrapyramidal diseases.