Molecular forms of dopamine beta-hydroxylase in rat superior cervical ganglion and adrenal gland

Summary Dopamine beta-hydroxylase (DBH) enzyme activity was associated in rat superior cervical ganglion with tetrameric DBH-A (294,000 D) and dimeric DBH-B (147,000 D) and in rat adrenal gland with DBH-A and a novel molecular form of DBH, defined as DBH-C, with a molecular weight of 125,000 D. Pretreatment of the rats with cycloheximide markedly reduced DBH activity without altering the molecular heterogeneity.     

Dopamine-beta-hydroxylase activity in adrenal gland and spleen of rats after fasting and cold exposure

Fasting (48 h) results in dopamine-beta-hydroxylase (DBH) release both in adrenal gland and spleen, suggestive of an increase in the activity of these organs. Cold exposure (48 h) produces a dissociation of the sympathoadrenal response. When both stimuli are simultaneously employed, the DBH response suggests the preponderance of the response to fasting. Plasma DBH is decreased in all groups studied, this could be due to its half-life and the splenic DBH depletion.     

Dopamine-beta-hydroxylase activity in adrenal gland and spleen of rats after fasting and cold exposure

Summary Fasting (48 h) results in dopamine-beta-hydroxylase (DBH) release both in adrenal gland and spleen, suggestive of an increase in the activity of these organs. Cold exposure (48 h) produces a dissociation of the, sympathoadrenal response. When both stimuli are simultaneously employed, the DBH response suggests the preponderance of the response to fasting. Plasma DBH is decreased in all groups studied, this could be due to its half-life and the splenic DBH depletion.This work was supported by a grant of Fondo de Investigaciones Sanitarias de la Seguridad Social, No. 83/0905.     

Serum dopamine-beta-hydroxylase activity in a new strain of spontaneously hypertensive rats

Summary The serum dopamine--hydroxylase (DBH) activity is higher in 5-week-old rats of the Lyon Hypertensive strain than in rats of the Lyon Normotensive strain. This difference disappears in older animals when the hypertension is developed, while the DBH activity decreases in the both strains.This work was supported by grants from DGRST (77.7.1930), CNRS (RCP 080.469, ATP A651-3358), INSERM (15.75.38) and the Fondation pour la Recherche Médicale Française.     

Preparations of human dopamine beta hydroxylase subunits and antibodies against these subunits (author's transl)]

The present study deals with the dissociation of human dopamine beta hydroxylase (DBH) in subunits with a mol. wt of 79,500, and the preparation of specific antibodies in rabbits. No cross-reactivity was observed between human DBH and antibodies against human DBH subunits.     

Dopamine-beta-hydroxylase activity in stroke-prone spontaneously hypertensive rats

Dopamine-beta-hydroxylase (DBH) activity was higher in the serum, the mesenteric artery and the cerebral cortex of 4-week-old stroke-prone spontaneously hypertensive rats (SHRSP), and lower in the nucleus tractus solitarii than it was in spontaneously hypertensive rats (SHR).     

Specificity of action of phospholipases of rat intestinal mucosa]

The total homogenate of rat intestine is devoid of C or D phospholipase activity. At pH 6,5 in the presence of phosphatidylcholines, it exhibits a B phospholipase activity and in the presence of exogen lysophosphatidylcholines an A1 lysophospholipase activity. At pH 8,5 the intestinal mucous membrane of a rat shows an isolated A2 phospholipase activity.     

Thyroid hormones and cathepsin D activity in the rat liver,kidney and brain

Summary The effect of thyroidectomy and subsequent treatment with tri-iodothyronine (T₃), as well as that of thyrotoxicosis, was examined on cathepsin D activity in the rat liver, kidney and brain. Thyrotoxicosis resulted in a generalized increase in the enzyme activity in the 3 tissues; the effect of other thyroidal states was diverse and tissue-specific.     

Préparation des sous-unités de la dopamineβ hydroxylase humaine et des anticorps anti-sous-unités

Summary The present study deals with the dissociation of human dopamine hydroxylase (DBH) in subunits with a mol. wt of 79,500, and the preparation of specific antibodies in rabbits. No cross-reactivity was observed between human DBH and antibodies against human DBH subunits.

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Nous remercions Madame M. Le Maout pour son excellente aide technique.

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Ce travail a bénéficié de l'aide de l'INSERM (contrat no 75.4.161.2).     

Role of phospholipids in the binding activity of vasoactive intestinal peptide receptors

Phospholipase digestion of rat intestinal epithelial cell membranes was performed in order to study the influence of membrane phospholipids on the binding activity of VIP receptors. Phospholipases A2 and C strongly (ED50 congruent to 4 X 10(-2) and 4 X 10(-1) micrograms/ml, respectively) and rapidly reduced 125I-VIP binding to membranes whereas phospholipase D was ineffective. This suggests an important role of both hydrophobic and hydrophilic groups of phospholipids on VIP receptor binding activity.     

Comparison of lysine and tryptophan catabolizing enzymes in rat and bovine tissues

Summary Earlier studies indicate that -aminoadipate aminotransferase (AadAT) and kynurenine aminotransferase (KAT) activities from rat tissues are associated with a single protein. However, our recent studies indicate that AadAT activity from bovine liver and kidney is not associated with KAT activity. To test whether the lysine and tryptophan catabolism in bovine tissues differ from that in rat tissues, we compared the activities of enzymes involved in lysine and tryptophan pathways in rat and bovine tissues. The activities of lysine catabolizing enzymes such as AadAT, lysine -ketoglutarate reductase and saccharopine dehydrogenase in the bovine tissues were significantly lower than those found in rat tissues. The activities of tryptophan catabolizing enzymes such as KAT and kynurenine hydroxylase in the bovine tissues were negligible as compared to those in rat tissues. The results suggest that lysine is degraded via the saccharopine pathway in the livers and kidneys of both species but the metabolism of tryptophan in bovine tissues may be different from that in rat tissues.Acknowledgments. This work was supported by a grant from the Children's Hospital of Michigan and by a Research Career Development Award from the National Institutes of Health to D. R. Deshmukh.     

Wirkung von Actinomycin auf das Enzymmuster der Rattenniere während der Entwicklung

Summary Actinomycin D causes a marked increase of alkaline phosphatase activity in the zona subcorticalis of the developing rat kidney. The effect is more pronounced in female than in male animals. Acid phosphatase activity increases in males only.     

Dopamine-β-hydroxylase activity in stroke-prone spontaneously hypertensive rats

Summary Dopamine--hydroxylase (DBH) activity was higher in the serum, the mesenteric artery and the cerebral cortex of 4-week-old stroke-prone spontaneously hypertensive rats (SHRSP), and lower in the nucleus tractus solitarii than it was in spontaneously hypertensive rats (SHR).The authors wish to thank Prof. Masao Sano (Nagoya University) for his aid in dissecting the nucleus tractus solitarii and the locus coeruleus.     

Inhibitory effects of phenolic compounds on CCl4-induced microsomal lipid peroxidation

The antiperoxidative effects of 35 phenolic compounds, most of them belonging to the flavonoid class, were investigated using CCl4-induced peroxidation of rat liver microsomes. This system was rather insensitive to gallic acid, methyl gallate and ellagic acid. Nevertheless it was inhibited by flavonoids and structure/activity relationships were established. The most potent compounds were gardenin D, luteolin, apigenin (flavones), datiscetin, morin, galangin (flavonols), eriodictyol (flavanone), amentoflavone (biflavone) and the reference compound, (+)-catechin. The natural polymethoxyflavone gardenin D has shown a potency comparable to that of (+)-catechin and higher than that of silybin. Thus, it may be considered as a new type of natural antioxidant with potential therapeutical applications.     

Selective activation of noradrenergic neurons in the brainstem and spinal cord of young spontaneously hypertensive rats

Summary In young spontaneously hypertensive rats (SHR), dopamine -hydroxylase (DBH) and phenylethanolamine N-methyltransferase (PNMT) activities were examined in the brainstem nuclei. Activation of noradrenergic neurons in the locus coeruleus, A2 and spinal intermediolateral cell areas, resulting in enhanced sympathetic nervous activity in the periphery, initiates hypertension. Adrenergic neurons, unchanged in these and A1 cell areas of young SHR, are not involved in the development of hypertension in SHR.     

Changes in dopamineβ-hydroxylase activity of monkey plasma with age

Summary Plasma dopamine -hydroxylase activity of Japanese monkeys (Macaca fuscata fuscata) increased with age, and the developmental changes were similar to those of human beings. However, the adult level plasma DBH activity of various monkey species was much lower than that of human beings.We thank Dr.K. Nozawa, Dr.O. Takenaka and Mr.T. Shotake (Primate Research Institute, Kyoto University) for their help in collecting monkey blood samples.     

Inhibitory effects of phenolic compounds on CCl4-induced microsomal lipid peroxidation

Summary The antiperoxidative effects of 35 phenolic compounds, most of them belonging to the flavonoid class, were investigated using CCl₄-induced peroxidation of rat liver microsomes. This system was rather insensitive to gallic acid, methyl gallate and ellagic acid. Nevertheless it was inhibited by flavonoids and structure/activity relationships were established. The most potent compounds were gardenin D, luteolin, apigenin (flavones), datiscetin, morin, galangin (flavonols), eriodictyol (flavanone), amentoflavone (biflavone) and the reference compound, (+)-catechin. The natural polymethoxyflavone gardenin D has shown a potency comparable to that of (+)-catechin and higher than that of silybin. Thus, it may be considered as a new type of natural antioxidant with potential therapeutical applications.     

Glucose-evoked recovery of hepatic thyroxine 5'-deiodinase independent of de novo protein synthesis in fasted rat

The glucose-evoked recovery of Type I thyroxine 5'-deiodinase activity in the hepatic microsomes of fasted rat was not inhibited by either cycloheximide, puromycin or actinomycin D during 3 h after glucose feeding; however, [3H]-leucine uptake by the liver or the hepatic microsomal fraction was significantly inhibited by cycloheximide and puromycin but not by actinomycin D. These results indicate that the glucose-evoked recovery of deiodinase activity may be independent of de novo protein synthesis.     

Novel diterpenoid diacylglycerols from marine molluscs: potent morphogens and protein kinase C activators

Five novel 1,2-sn-diacylglycerols with diterpenoid acyl moieties in thesn-1 position were isolated and characterized, together with the corresponding 1,3-sn-diacylglycerols, from three species of dorid nudibranchs molluscs. Their potent activity as morphogens in vivo in theHydra tentacle regeneration assay and their parallel activity as activators of rat brain protein kinase C (PKC) in vitro are reported here. Our findings promote the use of these compounds as useful molecular probes for both in vivo and in vitro studies on the participation of PKC in cell development.     

Expression of the mutant gene for L-gulono-gamma-lactone oxidase in scurvy-prone rats

A mutant strain of Wistar rats with L-gulono-gamma-lactone oxidase deficiency has recently been established. To investigate this deficiency by DNA and RNA blot hybridization analyses, a fragment of a previously cloned cDNA encoding rat L-gulono-gamma-lactone oxidase was used as a probe. When genomic DNA of the mutant rat was digested with several restriction enzymes, the probe hybridized to fragments of the same sizes as those produced from DNA of normal rats. Poly(A)+RNA from the liver of the mutant rat was found to contain an L-gulono-gamma-lactone oxidase-specific mRNA of a normal size at a comparable level to that of normal rats. An in vitro translation experiment revealed that the mRNA programmed the synthesis of an enzyme protein which had the same molecular weight as that of the translational product of the normal mRNA, although the amount synthesized was markedly reduced as compared with that synthesized with the normal mRNA. In accordance with this observation, a very low but definite degree of L-gulono-gamma-lactone oxidase activity was detected in the microsomes of the mutant rat by a newly developed, highly sensitive method.