摘要:

Abstract:The concentration of freemyo‐inositol in CSF was determined with a gas chromatographic‐mass spectrometric method using deuteratedmyo‐inositol as an internal standard after conversion to the hexa‐O‐acetyl derivative with acetic anhydride and pyridine. Twenty microliters of CSF is sufficient for the analysis which has a coefficient of variation of 9%. Identical analytical results were obtained on two different mass numbers. Schizophrenic patients were compared with healthy control persons. In addition, patients with rheumatoid arthritis or with neurological illnesses were studied. No consistent differences related to the illness could be found. The mean concentration ofmyo‐inositol was about 25 μg/ml. Treatment of schizophrenic patients with chlorpromazine or sulpiride had no significant effect on the concentration ofmyo‐i

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1985.tb03992.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

Abstract:The extracellular content of taurine, glutamate, and glycine was measured by the novel method of brain dialysis in the acute phases following an intrahippocampal injection of the excitotoxic convulsant brain metabolite quinolinic acid (QUIN). Using bilaterally depth electrodes physically combined with hollow fibers for dialysis, it was possible to collect continuously brain perfusates while simultaneously monitoring brain activity in the unanesthetized rat. In separate animals, hippocampal amino acid tissue levels were measured 2 h after an intracerebral injection of a convulsant dose (156 nmol) of QUIN. When compared with those in animal receiving the nonconvulsant decarboxylation product of QUIN, nicotinic acid, no differences in tissue levels were detected. In contrast, the same dose of QUIN caused a selective increase (2.24‐fold) in taurine levels in perfusates from the injected hippocampus. These changes were apparent prior to the onset of electrographic seizures and did not occur in the contralateral hippocampus where seizure activity was equally severe. Thus, increases in extracellular taurine, triggered by the presence of QUIN in the hippocampus, may reflect a selective tissue response to the neurotoxic (rather than the convulsant) effects of this excitotoxi

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1985.tb03993.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

Abstract:The present study was performed on retinas of chick embryos receiving at day 8 of incubation an intracerebral injection of 0.02 μg of corticosterone. We had previously shown with the use of [3H]quinuclidinylbenzilate ([3H]QNB) that such treatment induced the appearance of two muscarinic binding sites in the treated retinas, whereas only one was detectable in the controls. In the present study we investigated muscarinic cholinergic receptor subclasses with agonist and antagonist binding. Agonist binding was studied by varying the concentrations of carbachol and acetylcholine (10‐9M‐10‐5M) in the presence of a constant concentration (0.2 nM) of [3H]QNB. Two subpopulations of receptors were revealed, a high‐ and a low‐affinity receptor, in both treated and control retinas. However, in the hormonetreated retinas, the two subpopulations significantly differed from the controls in their affinity and in their relative percentage among the total receptor population. Moreover, using pirenzepine, an antagonist known to have the capacity to distinguish between muscarinic cholinergic subclasses, two receptor subpopulations were found to be present in the hormone‐treated retinas but a single one in the controls. It is suggested that hormone treatment can either induce the appearance of a new subclass of muscarinic cholinergic receptors or favor the maturation of a population of retinal cells having these receptors. Pirenzepine binding in retinas from intact embryos of 7, 9, and 11 days of incubation revealed one receptor subpopulation. Thus, these findings are more consistent with the hypothesis that corticosterone effects the target cells, either inducing changes in muscarinic receptor and/or modifying the receptor

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1985.tb03994.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

Abstract:Insulin‐induced hypoglycemia provokes polyribosome disaggregation and accumulation of monomeric ribosomes in the brain of rats with hypoglycemic paresis and coma. The extent of brain polyribosome disaggregation depends on the decrease of blood glucose concentration, and in comatose animals on the duration of hypoglycemia. Cycloheximide prevents the disaggregation of brain polyribosomes induced by hypoglycemia, indicating that hypoglycemia affects brain protein synthesis, decreasing the rate of initiation relative to the rate of elongation of polypeptide chain synthesi

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1985.tb03995.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

Abstract:Adenylate cyclase in homogenates ofDrosophila melanogasteris heterogeneous with respect to its affinity toward MgATP and its subcellular distribution.Kmvalues for MgATP range, under similar assay conditions, from ∼10−5Mto ∼10−3M, depending on the body region and on the subcellular localization of the enzyme. The majority of the enzyme in whole‐body preparations is particulate, but various body regions differ in the relative proportion of the soluble enzyme. The memory mutantrutabagalacks up to 35% of the total particulate activity. Even ligands that stimulate directly the catalytic subunit are incapable of bringing the activity of the mutant's enzyme to normal levels. The defect is differentially pronounced in various body parts and is associated with an altered responsiveness of the enzyme to Mg2+, to Ca2+, and to forskolin. It is suggested thatrutabagais lesioned in a subpopulation, or a functional state, of adenylate cyclase, which may play a role in memory

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1985.tb03996.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

Abstract:The effect of the glutamate antagonistα‐amino‐4‐phosphonobutyrate (APBA) on the release of endogenous amino acids from sensorimotor cortical synaptosomes of rats with a cortical cobalt focus and from nonepileptic rats was studied: (1) The release of endogenous glutamate, aspartate, and γ‐aminobutyric acid (GABA) from synaptosomal preparations of cobalt‐induced epileptogenic tissues was increased compared with the release from the contralateral (sensorimotor) region or the sensorimotor cortex of normal animals. The intrasynaptosomal content of these amino acids was reduced in proportion to the amount released. The levels of other amino acids were unaffected or showed much smaller changes. (2) APBA (0.5‐1 mM) decreased significantly the spontaneous release of aspartate and glutamate from the epileptic foci without affecting GABA or any other amino acid. (3) APBA produced no effect whatsoever on the release of any amino acid from synaptosomal preparations of nonep

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1985.tb03997.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

Abstract:Clonic seizures were induced in Swiss or DBA/2 mice by methyl‐6‐7‐dimethoxy‐4‐ethyl‐β‐carboline‐3‐carboxylate (DMCM), 0.048 mmol/kg i.p., or by methyl‐β‐carboline‐3‐carboxylate (β‐CCM), 0.044 mmol/kg i.p. Measurement of regional brain (cortex, hippocampus, striatum, and cerebellum) amino acid levels after 15 min of seizure activity showed increases in γ‐aminobutyric acid (GABA) (in all regions after β‐CCM, and in cortex and hippocampus after DMCM), and an increase in glycine in the striatum after β‐CCM. Aspartate levels fell (in cortex and hippocampus) after DMCM, but were unchanged in all regions after β‐CCM. Glutamate levels fell in cortex after β‐CCM and in striatum after DMCM. Pretreatment with the excitatory amino acid receptor antagonist, 2‐amino‐7‐phosphonoheptanoic acid, 0.5 mmol/kg i.p., 45 min prior to the β‐carboline, significantly increased the ED50for DMCM‐induced clonic seizures (4.68 μmol/kg vs. 9.39 μmol/kg). Similar pretreatment did not significantly alter the ED50for β‐CCM (4.22 μmol/kg vs. 6.6 μmol/kg). Pretreatment with 2‐amino‐7‐phosphonoheptanoic acid, 1.0 mmol/kg, blocked the increase in GABA content produced by DMCM but not the fall in cortical aspartate content. Potassium‐induced release of preloaded D‐[3H]aspartate from rat cortical or hippocampal minislices was enhanced in the presence of DMCM (100 μM). In contrast, stimulated release of D‐[3H]aspartate (from cortex or hippocampus) was not altered in the presence of β‐CCM (100 μM). Although DMCM and β‐CCM are both considered to induce convulsion by acting at the GABA‐benzodiazepine receptor complex, the convulsions differ in several pharmacological and biochemical respects. It is suggested that enhanced release of excitatory

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1985.tb03998.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

Abstract:The molecular forms and membrane association of acetylcholinesterase (acetylcholine hydrolase, EC 3.1.1.7) and pseudocholinesterase (acylcholine acylhydrolase, EC 3.1.1.8) were determined in the presence of protease inhibitors in dissected regions of developing human fetal brain, as compared with parallel areas from mature brain. All areas contained substantial cholinesterase activities, of which acetylcholinesterase accounted for almost all the activity. Two major forms of acetylcholinesterase activity, sedimenting at 10–11S and 4–5S, respectively, were detected on sucrose gradients and possessed similar catalytic properties, as judged by their individualKmvalues toward [3H]acetylcholine (ca. 4 × 10−4M). The ratio between these forms varied by up to four‐ to fivefold, both between different areas and within particular areas at various developmental stages, but reached similar values (about 5:2) in all areas of mature brain. Acetylcholinesterase activity was ca. 35–50% lowsalt‐soluble and 45–65% detergent‐soluble in various developmental stages and brain areas, with an increase during development of the detergent‐soluble fraction of the light form. In contrast, pseudocholinesterase activity was mostly low‐salt‐soluble and sedimented as one component of 10–11S in all areas and developmental stages. Our findings suggest noncoordinate regulation of brain acetylcholinesterase and pseudocholinesterase, and indicate that the expression of acetylcholinesterase forms within embryonic brain areas depends both on cell type compos

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1985.tb03999.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

Abstract:Receptors for thyrotropin‐releasing hormone (TRH) in the rat brain and the pituitary are heterogenous. The receptors were classified into four types according to the dissociation constant (KD). High‐affinity receptors (KD<3 nM) are present in the pituitary, hypothalamus, amygdala, and limbic forebrain which contains the nucleus accumbens and the septum. Intermediate‐affinity receptors (KD, 5–16 nM) are evidently present in the frontal cortex, hippocampus, striatum, thalamus, and the brainstem, but may also be present in other regions. Lowaffinity TRH receptors (KD, 50–80 nM) are seen in the limbic forebrain, amygdala, and the hypothalamus. Verylow‐affinity receptors (KD, 215 nM) exist in the pituitary. Experiments using DN‐1417 (γ‐butyrolactone‐γ‐carbonyl‐histidyl‐prolinamide citrate), a synthetic TRH analogue with a more potent central activity, indicated the presence of TRH receptors having a high affinity to DN‐1417 at least in the limbic forebrain but not in the pituitary. This type of receptor is not labeled by [3H](3methyl‐histidine2)‐TRH. Density of the TRH receptor is the highest in the pituitary a

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1985.tb04000.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

Abstract:Three distinct vesicle fractions enriched 40–60 times in the neuropeptides substance P, somatostatin, and vasoactive intestinal peptide (VIP) were prepared from the myenteric plexus of guinea pig ileum by density gradient centrifugation in a small zonal rotor. Mean densities (in g · ml−1) and diameters (in nm) of the three classes of vesicles were: substance P, 1.123, 65; somatostatin, 1.138, 37; VIP, 1.148, 110; standard deviations were about 5%. These peaks were distinct from the peak of acetylcholine‐containing vesicles of density 1.066 g · ml−1and diameter 61 nm. When a relatively mild method of homogenization was used a second peak of acetylcholine appeared in the same region of the gradient as VIP and the VIP was larger. This may represent a class of vesicles containing both acetylcholine and VIP, though cosedimentation of two classes of vesicles of almost the same density and similar fragility, one containing VIP and the other acetylcholine, cannot be entirely excluded on present

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1985.tb04001.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY