Monoamines in brain and urine of rats with hereditary hypothalamic diabetes insipidus

Summary Monoamine levels in brain and urine of homozygous and heterozygous diabetes insipidus (DI) rats (Brattleboro strain) were assessed. Homozygous DI rats had a higher whole brain content of serotonin than their heterozygous littermates. However, when corrected for differences in brain weight, homozygous DI also appeared to have higher brain concentrations of noradrenaline, tyrosine and GABA. The total 24 h excretion of all amines and their precursors was greater in the homozygous than in the heterozygous rats.The authors thankHerman Müller andIneke van de Veerdonk for their assistance with part of this study.     

‘Classical’ and ‘new’ diabetogens—comparison of their effects on isolated rat pancreatic islets in vitro

This study compares functional and morphological alterations caused by application of alloxan, streptozotocin, xanthine oxidase/hypoxanthine (generation of reactive oxygen species), or S-nitroso-N-acetyl-D,L-penicillamine (SNAP, liberation of nitric oxide) to isolated rat pancreatic islets in vitro. In perifusion experiments, membrane leakage—detected by non-stimulated insulin release—was found after application of all drugs, but showed a substance-specific time pattern. Twenty-four hours after application of the classical diabetogens (alloxan or streptozotocin), potassium chloride- and glucose-stimulated insulin secretion were markedly reduced, while a persistent reduction was observed neither after exposure to xanthine oxidase/hypoxanthine, nor to SNAP. Morphological analysis of the islets revealed that nearly all β-cells were destroyed following alloxan or streptozotocin treatment, while the majority of β-cells were configured regularly after application of xanthine oxidase/hypoxanthine or SNAP. Necrotic cells found after xanthine oxidase/hypoxanthine usually differed in morphology from those observed after application of the classical diabetogens. While the former cells were characterised by swollen nuclei, the latter had shrunken nuclei with irregular condensed chromatin. Apoptosis was found only following nitric oxide exposure. Due to these differences, it seems unlikely that alloxan, streptozotocin, xanthine oxidase/hypoxanthine, and nitric oxide have a common major feature in their toxic action. Received 16 September 1999; received after revision 15 November 1999; accepted 26 November 1999     

Hepatic and cerebral coenzyme a contents after intravenous injection of coenzyme a in rats

Summary Hepatic CoA concentrations and contents were significantly higher in rats having received i.v. CoA injections than in control rats. Maximum hepatic CoA concentrations were found 0.5–1 h after injection. In rat brain, no increase in CoA concentration was detected after i. v. injection of CoA.Acknowledgments. We thank MissV. Godly and MissA. M. Reber for excellent technical assistance. This work was supported by grants from F. Hoffmann-La Roche & Co., AG, Basel.     

Neurochemical correlates of alloxan diabetes: Protein and ribonucleic acid levels in the different regions of the rat brain

Summary The levels of protein and ribonucleic acid in the cerebrum, cerebellum, optic lobes and medulla oblongata of normal and alloxan-diabetic rats were measured. In general, the protein content and levels of ribonucleic acid in the broad compartments of the brain of rat decreased during diabetes.Acknowledgment. The authors thank Dr.A. R. Kasturi Bai, Head of the Department of Zoology, Bangalore University, for providing facilities during the study.     

Metabolism of the neuromodulator d-serine

Over the past years, accumulating evidence has indicated that d-serine is the endogenous ligand for the glycine-modulatory binding site on the NR1 subunit of N-methyl-d-aspartate receptors in various brain areas. d-Serine is synthesized in glial cells and neurons by the pyridoxal-5′ phosphate-dependent enzyme serine racemase, and it is released upon activation of glutamate receptors. The cellular concentration of this novel messenger is regulated by both serine racemase isomerization and elimination reactions, as well as by its selective degradation catalyzed by the flavin adenine dinucleotide-containing flavoenzyme d-amino acid oxidase. Here, we present an overview of the current knowledge of the metabolism of d-serine in human brain at the molecular and cellular levels, with a specific emphasis on the brain localization and regulatory pathways of d-serine, serine racemase, and d-amino acid oxidase. Furthermore, we discuss how d-serine is involved with specific pathological conditions related to N-methyl-d-aspartate receptors over- or down-regulation.     

Neurochemical correlates of alloxan diabetes: Gamma amino butyric acid of amphibian brain

Summary The levels of gamma aminobutyric acid decreased, while glutamic acid and aspartic acid levels increased in the forebrain, and decreased in the mid and hind brain regions of frog, Rana cyanophlictis during alloxan diabetes. Since glutamic acid and GABA are intimately involved in the central nervous system (CNS) functions, the alterations occurring in their levels during alloxan diabetes may be significant in bringing about a correlation between the diabetic state and the altered functional dynamics of the CNS.The authors thank Dr A. R. Kasturi Bai for the facilities to conduct the study.     

Influence of gonadal hormones on the devleoping amphibian brain: Changes in ribonucleic acid,protein and activity levels of acetylcholinesterase on in vivo administration of progesterone

Summary The levels of RNA and protein and activity levels of acetylcholinesterase decreased in the brain of developing tadpoles of 13–15-day-oldBufo melanostictus on in vivo administration of progesterone (200 g/0.1 ml refined peanut oil). These changes suggest decelaration in the activity of the protein-synthetic machinery in progesterone administered animals.Acknowledgment: I am thankful to Dr.A. R. Kasturi Bai, Head of the Department of Zoology, Bangalore University for offering facilities to conduct the study.     

Effects of glycolytic metabolites on preservation of high energy phosphate level and synaptic transmission in the granule cells of guinea pig hippocampal slices

The present study was undertaken to investigate whether neural activity of hippocampal slices can be preserved after replacingd-glucose with glycolytic intermediate metabolites such as lactate, pyruvate and citrate or with other sugars such as fructose, mannose, maltose, glucosamine, sucrose and galactose. As an index of neural activity, population spikes (PS) were recorded in the granule cell layers after electrical stimulation to the perforant path of guinea pig hippocampal slices. In addition, we determined the levels of ATP and creatine phosphate (CrP) in each slice after the replacement ofd-glucose with these substrates, and correlated it with the neural activity. Substrates other thand-glucose could not maintain the PS for even 20 min although the slices perfused with medium containing lactate, pyruvate, galactose, fructose and maltose maintained similar levels of ATP and CrP as in slices incubated in thed-glucose-containing medium. These results indicate thatd-glucose is essential for the preservation of synaptic activity in addition to its main role as the substrate for energy production to maintain the levels of high energy phosphates.     

Quantitative Untersuchungen über den Nukleinsäureverlust des Gewebes bei Fixierung und Einbettung

Summary Quantitative chemical determination of nucleic acid shows that no loss of nucleic acid occurs on fixation with formalin andCarnoy's solution (24 or 2 h at room temperature) and after dehydration and embedding of the tissues. Small amounts of protein were shown in the fixative solution.

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Ausgeführt mit Mitteln der Deutschen Forschungsgemeinschaft.     

On the time course of thyrotropin suppression by high doses of thyroid hormones

Summary Basal and stimulated TSH decreased progressively. Basal TSH was suppressed below the detection limit of 0.4 U/ml after 74 h in 2 of the T₃ and all of the T₄ treated indiduals. At this time, in both groups 3 individuals could be significantly stimulated by TRH (about 5% of the pretreatment stimulation). There was no significant difference in the time course of suppression obtained by T₃ or T₄, though plasma T₃ levels in the T₄ treated group were considerably lower.Supported by the Deutsche ForschungsgemeinschaftThe excellent technical assistance of MissM. Knöpfle, MissU. Neun and Mr.G. Magin is gratefully acknowledged.     

d-Ribosylated Tau forms globular aggregates with high cytotoxicity

Although the glycation of Tau that is involved in paired helical filament formation in Alzheimer’s disease has been widely studied, little attention has been paid to the role of d-ribose in the glycation of Tau. Here, we show that Tau is rapidly glycated in the presence of d-ribose, resulting in oligomerization and polymerization. Glycated derivatives appeared after 24 h incubation. Western blotting indicated the formation of advanced glycation end-products (AGEs) during initial stages of glycation. Thioflavin T-positive (ThT-positive) aggregations that appeared from day 4 indicated the globular-like features. Atomic force microscopy revealed that the surface morphology of ribosylated Tau40 was globular-like. Kinetic studies suggested that d-ribosylated Tau is slowly oligomerized and rapidly polymerized with ThT-positive features. Moreover, d-ribosylated Tau aggregates were highly toxic to SHSY5Y cells and resulted in both apoptosis and necrosis. This work has demonstrated that d-ribose reacted with Tau protein rapidly, producing ThT-positive aggregations which had high cytotoxicity. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

High and low affinity transport ofL-arginine in rat brain synaptosomes

The uptake ofL-arginine into purified rat brain synaptosomes was investigated with respect to time and various concentrations ofL-[³H] arginine. Specific uptake was found to be linear with time for up to 5 min of incubation at 37°C. Electrolytes, including sodium chloride, potassium chloride, magnesium chloride and calcium chloride, inhibited uptake of 3 ML-arginine, and the inhibitory effect increased with increased electrolyte concentration under constant osmolarity. It was found thatL-arginine was transported into synaptosomes by two uptake components — a high affinity component (3.5 M) and a low affinity component (100 M). These two components were similar to the Ly⁺ system because of their extreme sensitivity to inhibition byL-lysine andL-ornithine but were distinguishable from each other by kinetic analysis of the uptake data and by their relative sensitivity to inhibition by several amino acids.     

Intraspezifische Unterschiede der relativen Hirngrösse beim Löwen (Panthera leo L.)

Summary Different stages of brain evolution expressed by the allometric relation of³ brain capacity and basal length of the skull are shown to be existent in the speciesPanthera leo. Whereas Asiatic lions obviously have the same level of brain size as leopards (Panthera pardus), African lions have higher brain capacities. A third level seems to be represented by the upper pleistocene American lion,Panthera leo atrox. These results permit us to reject some conceptions ofHerre andRöhrs ¹³ concerning the quantitative expression of mammalian brain evolution.     

Zur zellulären Aminosäure-Inkorporation im in- und exkretorischen Pankreas unter experimentellen Bedingungen

Summary After glucagon and tolbutamide administration, the protein synthesis in the nucleus increases, especially in the B- but to a lesser extent also in the A-cells. Similar effects are noted in the cytoplasma of B-cells. Already 2 h following alloxan premedication, there is no activity in the nucleus and cytoplasm of B-cells, whereas in the A-cells they are markedly labelled.     

Zur Feinstruktur früher Veränderungen an Rattenhirngewebe nach Injektion von Methylnitrosoharnstoff

Summary Focal proliferations of adventitial cells of small blood vessels in the rat brain were found within 6 weeks after i.p. injection of methyl-nitroso-urea. The results of electron microscopic examination suggest the preneoplastic nature of the changes.

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FrauK. Wiegand danken wir für wertvolle technische Mitarbeit.     

Comportamento dell allossanain vivo

Summary The author describes a microprocedure, based on the o-phenylenediamine reaction, for the determination of alloxan in blood and tissuesin vivo. With this method he has been able to determine alloxan in blood, liver, kidney, muscle, and pancreas of rats treated with diabetogenous doses of alloxan. This substance has been found in the blood and tissues during an hour and a half after the injection and in the urine collected directly from the ureter a quarter of an hour after the injection.     

Microsomal glutathione S-transferases: selective up-regulation of leukotriene C4 synthase during lipopolysaccharide-induced pyresis

Cysteinyl-leukotrienes (cys-LTs) are potent smooth muscle contracting agents, which play key roles in inflammatory and allergic diseases. The committed step in cys-LT biosynthesis is catalyzed by leukotriene C₄ synthase (LTC4S) as well as microsomal glutathione S-transferase type 2 (MGST2) and type 3 (MGST3). Here we report that intraperitoneal injections of lipopolysaccharide in rats lead to a strong increase of LTC4S messenger RNA (mRNA) levels after approximately 1 h, particularly in the heart, brain, adrenal glands and liver, without any significant effect on MGST2 and MGST3 mRNA levels. After 6 h, LTC4S mRNA returns to basal levels, concomitant with a 4.9-, 4.0-, 2.9- and 2.3-fold induction of LTC4S protein in brain, heart, liver and adrenal gland, respectively. Hence, challenge with lipopolysaccharide in vivo causes an organ-selective, local priming for leukotriene C₄ synthesis. Moreover, these data suggest that LTC4S and cys-LTs may be involved in acute systemic inflammatory responses such as fever and tachycardia.Received 12 August 2004; received after revision 27 October 2004; accepted 1 November 2004     

A simple method for blood exchange in mice

Summary Ease of transfusion and high long-term survival rate were obtained when whole blood was administered via the corpus cavernosum of the penis and removed from the orbital sinus of male C57Bl mice. When 2 volumes of blood are replaced approximately 14% of pre-transfusion red cells remain after hematocrit corrections are made. The posttransfusion hematocrit levels dropped 19%, probably the result of leakage, which is difficult to avoid.Supported in part by NIH Grant No. CA08318 and NIH Center Grant No. CA14520.I acknowledge with thanks the technical assistance of Mrs.Joan Mitchen and Ms.Irene Uebersetzig. I am grateful to Mr.Randy Jirtle for providing the labelled red cells and for his interest in these studies.     

Changes in adenylate cyclase and 5′-nucleotidase activities in liver membranes from alloxan diabetic rats

Summary Liver membrane adenylate cyclase activity was significantly higher and 5-nucleotidase activity significantly lower in alloxan diabetic rats compared with normal rats.     

盐酸戊乙奎醚对大鼠感染性脑水肿AQP4表达的影响

目的：研究盐酸戊乙奎醚对感染性脑水肿保护作用的机制。方法：采用左颈内动脉注射脂多糖复制大鼠感染性脑水肿模型,将84只雄性SD大鼠随机分为对照组（C组）、水肿组（I组）、盐酸戊乙奎醚治疗组（P组）。检测6h、12h、24h、48h时各组大鼠脑组织含水量、病理形态;脑组织SOD活性、MDA含量;免疫组化法及RT—PCR法检测AQP4蛋白分布与AQP4mRNA含量。结果：（1）与C组相比,I组、P组脑含水量、MDA含量均升高,同时SOD活性、AQP4蛋白、AQP4mRNA表达均减少（P〈0．01）。与对应时间点P组相比,I组脑含水量、MDA含量均升高,同时SOD活性、AQP4蛋白、AQP4mRNA表达均减少,于24h达高峰,48h仍在较高水平（P〈0．01）。（2）脑组织光镜检查：I组大鼠脑组织损伤严重,P组损伤明显减轻。结论：盐酸戊乙奎醚能在一定程度上可减轻感染所致的脑组织损伤,上调AQP4表达,对脑水肿有一定治疗作用,其机制可能与抗氧化作用有关。