Glutamate decarboxylase and γ-Aminobutyrate transaminase in developing rat brain

Résumé Le décarboxylase de glutamate (GAD) et le transaminase -aminobutyro--cétoglutarique (GABAT) ont été étudiés dans le cerveau du rat pendant le développement postnatal. Le résultat le plus frappant de cette recherche a été de montrer que le rapport de ces deux enzymes est à peu près constant au cours du développement. Ce rapport (GABAT/GAD) est de 2,5 à 3,7.     

Increase in rabbit hypothalamic histidine decarboxylase activity after oophorectomy and thyroidectomy

Zusammenfassung Die Histidin-Decarboxylase-(HD)-Aktivität im Hypothalamus des Kaninchens wurde nach Oophorectomie und Thyroidectomie gemessen. Die Resultate zeigten, dass die HD-Aktivität sich 20 Tage nach der Oophorectomie und der Thyroidectomie verdoppelt. 20 Tage nach kombinierter Oophorectomie und Thyroidectomie stieg die HD-Aktivität ungefär 4mal, verglichen mit der Aktivität des Kontrollmatrials. Sham-operierte Kontrollen zeigten keine Veränderungen der HD-Aktivität im Hypothalamus.     

The effect of continuously cooling the hypothalamic preoptic area on antibody titre in the rat

Summary Continuous cooling of the hypothalamic preoptic area for 5 days, as well as sublethal infection withSalmonella enteritidis, increased the titre of antibodies against sheep erythrocytes, suggesting that the febrile response stimulates the humoral immune response.We thank Dr W. Mannheim from the Institute of Hygiene for kindly supplying the cultures ofS. enteritidis. This work was supported by the Schwerpunktprogramm Temperaturregulation und-adaptation of the Deutsche Forschungsgemeinschaft.     

Glutamate decarboxylase activity in brain regions of differentially-housed mice; a difference in the olfactory bulb

Summary Glutamate decarboxylase (GAD) activities were determined in homogenates of 8 brain regions of mice that had been differentially housed (isolated vs grouped) for 4–9 weeks. GAD activity was lower in whole forebrains and in olfactory bulbs of isolated mice, changes which might be associated with their increased aggressiveness.     

Serotonin and 5-hydroxyindoleacetic acid concentrations in individual hypothalamic nuclei and other brain areas of rat

Summary Serotonin and 5-hydroxyindoleacetic acid (5-HIAA) were measured in individual nuclei of rat hypothalamus and other brain areas using HPLC with electrochemical detection. 5-HIAA levels were first demonstrated in hypothalamic and some discrete brain areas. The 5-HIAA/5-HT ratio was highest in the n. caudatus putamen, high in the n. ventromedialis and lowest in the n. suprachiasmaticus.     

Histidine decarboxylase and DOPA decarboxylase in the stomach of the developing rat

Zusammenfassung Im Magen der fötalen Ratte erreicht die Dopadecarboxylase-Aktivität 19 Tage nach der Paarung Werte, die den Aktivitätswerten des erwachsenen Tieres entsprechen. Die Aktivität bleibt auch während der weiteren Entwicklung hoch. Die Histidindecarboxylase des fötalen Rattenmagens ist während der embryonalen Entwicklung hoch, aber die Aktivitätswerte fallen bei der Geburt zu nicht messbaren Werten ab. Ungefähr 8 Tage post partum steigt die Histidindecarboxylase des Magens wieder an und erreicht einen Monat nach der Geburt Werte, die den Aktivitätswerten des erwachsenen Tieres entsprechen. In der jungen Ratte wird die Magenhistidindecarboxylase weder durch Gastrininjektion noch durch Hungern beeinträchtigt. Vom 18. Tag nach der Geburt an kann die Enzymaktivität durch Hungern verringert und durch Gastrin wieder erhöht werden.     

Glutamate and GABA levels and glutamate decarboxylase activity in brain regions of rats after prolonged treatment with alkali cations

Resume L'administration chronique des cations des métaux alcalins (Na⁺, Rb⁺, Cs⁺) à les rats a provoqué la croissance des niveaux de glutamate et GABA dans certaines régions du cerveau. On n'a remarqué aucun changement en activité GAD de ces régions.     

Influence of castration and testosterone replacement on hypothalamic tyrosine hydroxylase activity in the rat

Summary Hypothalamic tyrosine hydroxylase (TH) activity of castrate rats is modulated by testosterone propionate (TP) in vivo. Kinetic studies revealed that bothV _max andK _m were virtually unaltered for substrate tyrosine in the presence of an excess of DMPH₄ cofactor. TP replacement to castrate rats increased theK _m for added DMPH₄ cofactor, whileV _max decreased. These results suggest that TP decreases TH activity of castrate rats by inhibiting the enzymereduced pteridine cofactor complex.     

Influence of castration and testosterone replacement on hypothalamic tyrosine hydroxylase activity in the rat.

Hypothalamic tyrosine hydroxylase (TH) activity of castrate rats is modulated by testosterone propionate (TP) in vivo. Kinetic studies revealed that both Vmax and Km were virtually unaltered for substrate tyrosine in the presence of an excess of DMPH4 cofactor. TP replacement to castrate rats increased the Km for added DMPH4 cofactor, while Vmax decreased. These results suggest that TP decreases TH activity of castrate rats by inhibiting the enzyme-reduced pteridine cofactor complex.     

Is the basal activity of rat stomach histidine decarboxylase affected by antrectomy?

The serum gastrin concentration and the gastric histidine decarboxylase activity are high in freely fed, unoperated rats but low in antrectomized rats. Following food deprivation the serum gastrin level and the enzyme activity are reduced simultaneously in the unoperated rats. After fasting for 36-48 h - but not before - the enzyme activity drops to the same low levels as in antrectomized rats.     

Histidine decarboxylase in the bone marrow of the rat

Résumé Dans l'étude ci-dessus la formation d'histamine dans la moelle osseuse du rat adulte a été attribuée à une enzyme identique ou semblable à la décarboxylase d'histidine du rat foetal. Par conséquence, l'enzyme de la moelle osseuse diffère de l'enzyme qui, étant présente dans l'écorce rénale des animaux adultes, forme l'histamine.     

Glutamate decarboxylase in barley aleurone and its relationship toα-amylase development during germination

Résumé L'enzyme glutamate décarboxylase se trouve dans les extraits d'eau de l'aleurone de l'orge. Au début de la germination, l'activité de cette enzyme augmente, mais après, quand apparait l'enzyme -amylase, elle diminue. Quoiqu'au dessous d'une concentration de 2×10^–6 M l'acide -amino butyrique (GABA) n'affecte pas l'activité de l'-amylase in vitro, la GABA à 5×10^–6 M peut provoquer une inhibition de 25% qui n'est pas modifiée par des concentrations de GABA comprises entre 5×10^–6 M et 10^–3 M.