Age-related response of citrate synthase to hydrocortisone in the liver and brain of male rats

Summary The activity of citrate synthase of the liver and brain of rats shows a gradual increase as a function of age. Adrenalectomy causes no significant change in the activity of citrate synthase in either of these tissues in young, adult or old rats. Administration of hydrocortisone to adrenalectomized rats depresses the activity of this enzyme maximally in the liver and brain of young rats. Administration of actinomycin D tends to normalize, the depressed level of this enzyme.Acknowledgments. The authors are indebted to Professor M.S. Kanungo of the Department of Zoology of Banaras Hindu University for helpful advice and facilities. A part of this project was presented at the 12th International Congress of Biochemistry, Australia, 1982.     

Age-related adrenocortical response to short-term starvation in young rats

Summary In a study of the response to short-term starvation in 4-week-old and 7-week-old male rats, it was found that in the younger rats corticosterone levels rose earlier and reached higher levels; they fell after refeeding to a greater extent. Body weight loss followed the same pattern. Younger rats seem to adapt better to fasting and refeeding.     

Pituitary response to gonadotropin-releasing hormone in diabetic male rats

Summary The rise in serum luteinizing hormone concentration after treatment with gonadotropin-releasing hormone was less in diabetic castrated male rats than control castrates. In intact male rats, gonadotropin-releasing hormone treatment resulted in higher serum luteinizing hormone concentrations in diabetic than in control rats.Acknowledgments. This work was supported in part by a grant from the Medical Research Council of Canada. The authors are grateful to Dr G.D. Niswender, Dr L.E. Reichert, Jr. and the National Institute of Arthritis, Metabolism and Digestive Diseases, Rat Pituitary Hormone Program for providing radioimmunoassay materials. The streptozotocin was kindly provided by Dr W.E. Dulin, The Upjohn Company. D.B. Beaton and J. Brunka provided excellent technical assistance.     

Regulatory properties of the citrate synthase fromRhodospirillum rubrum

Summary Citrate synthase, purified 600-fold fromRhodospirillum rubrum, is activated by KCl and inhibited by ATP and NADH; the effect of the latter inhibitor is completely counteracted by AMP and partially counteracted by KCl.This work was supported by grants from the Consejo Nacional de Investigaciones Cientificas y Técnicas de la República Argentina and the Consejo de Investigaciones de la Universidad Nacional de Rosario. JJC, and EM and AIH, are members of the Carrera del Investigador Cientifico of the former and the latter institutions, respectively.     

Effect of age on the activity and citrate inhibition of malate dehydrogenase of the brain and heart of rats

Zusammenfassung Es wurde die cytoplasmatische und mitochondrische Malate Dehydrogenase im Gehirn und Herz junger und alter Ratten spektrophotometrisch untersucht und signifikante Aktivitätsunterschiede gemessen.     

Regulatory properties of the citrate synthase from Rhodospirillum rubrum.

Citrate synthase, purified 600-fold from Rhodospirillum rubrum, is activated by KCl and inhibited by ATP and NADH; the effect of the latter inhibitor is completely counteracted by AMP and partially counteracted by KCl.     

The response of male and female rats with hypothalamic lesions to low and high environmental temperatures

Zusammenfassung Es wird gezeigt, dass normale weibliche Ratten weniger kälteresistent sind als gleichaltrige männliche Ratten desselben Stammes. Dies gilt auch für weibliche Tiere mit elektrolytischen Läsionen in verschiedenen Loci des Hypothalamus. Am 25. Tag in den Nuclei supraoptici lädierte Ratten zeigen eine ausgeprägte Unfähigkeit, Hitze zu ertragen. Dies steht in Übereinstimmung mit der gegenwärtigen Auffassung, dass der vordere Hypothalamus bei der Beseitigung der Überhitzung eine Rolle spielt.

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This investigation was supported by grants from the Medical Research Council of Canada and the National Science Foundation, U.S.A.

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In part taken from a thesis submitted to the faculty of graduate studies, Univ. of Western Ontario, London (Canada) and in partial fulfillment of the requirements for the degree of Doctor of Philosophy (1961).     

Corticoadrenal and behavioral response to open field in pairs of male rats either familiar or non-familiar to each other

The effect of the presence either of a familiar or non-familiar conspecific animal on serum corticosterone and some behavioral responses in the open field was studied in male Sprague-Dawley rats. Animals tested in presence of a familiar animal showed a higher corticosterone response and a higher defecation rate. It suggests that rats experienced more emotional reactivity in presence of a familiar animal than in presence of a non-familiar one. Time spent in social interaction was higher in non-familiar pairs; however, ambulation and rearing were lower, suggesting competition between social investigation and novel environment exploration.     

Effects of progesterone and estradiol benzoate on superoxide dismutase activity in the brain of male rats

The activities of mitochondrial, manganese-containing superoxide dismutase (MnSOD) and cytoplasmic, copper-zinc-containing superoxide dismutase (CuZnSOD) were measured in subcellular fractions of whole brain homogenates prepared from intact and gonadectomized (GDX) male rats, untreated or treated subcutaneously (sc) with a single dose of 2 mg progesterone (P) and/or 5 g estradiol benzoate (EB). Neither MnSOD nor CuZnSOD was affected by the removal of the testes. Similarly, CuZnSOD activity was steady following systemic administration of P and/or EB to intact and GDX animals 2 h or 24 h prior to sacrifice. On the other hand, both P and EB suppressed MnSOD in the brain of either intact or GDX rats. These results suggest involvement of P and EB in the control of MnSOD activity in the brain of male rats.     

Biochemical changes of brain and liver in neonatal offspring of rats fed monosodium-l-glutamate

Zusammenfassung Nachweis, dass die Ernährung von Ratten mit Monosodiuml-Glutamat (MSG) im Laufe der ersten 21 Tage nach der Geburt keinen Einfluss auf die Entwicklung sowie auf das Körper-, Gehirn- und Lebergewicht hatte. Diätetisches MSG hatte ausserdem keinen Effekt auf Protein, Aspartat und Glutamat im Gehirn.     

Effects of constant light exposure and blindness on the oxidative metabolism of selected brain areas in male rats

Summary Male rats were housed in continous illumination or blinded when 21 day-old and killed 69 days later. The continuous illumination exposure increased the weights of testes and sex accessory organs and reduced the pineal gland weight. Blindness decreased weights of testes, sex accessory organs and anterior pituitary. The oxygen consumption rate of the hypothalamus was higher in the blinded animals than in the controls and lower in the continuously illuminated rats. No one of such groups showed significant changes in the oxygen consumption by either the amygdata or the hippocampus.     

The effect of X-irradiation on the citrate content in mouse liver

Zusammenfassung Nach einer Bestrahlung mit 690 R beruhen Veränderungen des Citratgehaltes in der Leber gefütterter Mäuse auf unregelmässiger Nahrungsaufnahme, während in 24 h hungernden Mäusen der Citratgehalt nach 690 R über 11 Tage fast unverändert bleibt und erst vom 12.–15. Tag nach der Bestrahlung ansteigt. Die Ergebnisse werden diskutiert im Hinblick auf Phosphofruktokinase — und Acetyl-CoA-Carboxylase-Aktivität.     

Inhibition of DNA synthesis in regenerating rat liver by hydrocortisone

Résumé Dans le foie du rat en voie de régénération, la biosynthèse de DNA est inhibée au maximum par le hydrocortisone 17–19 h après l'opération. C'est pourquoi le foie en régénération est le plus sensible au hydrocortisone s'il est injecté pendant la période de la synthèse maximale de DNA.     

Pyruvate kinase activity in brain,liver and brown adipose tissue and the effect of cortisone in suckling rats

Zusammenfassung Die Pyruvatkinaseaktivität wurde im Gehirn und in den Muskeln von Ratten während der Entwicklung bestimmt. Die Aktivität war in Feten höher als in säugenden Jungen und stieg dann wieder an. Kortisonacetat (5 mg · 100 g/Tag, 3 Tage) erhöht die Pyruvatkinaseaktivität am 10. Tag im braunen Fettgewebe und erniedrigt sie in der Leber. Eine hohe Fettdiät, vom 14. Tag an gefüttert, hat denselben Effekt am 30. Tag. Das Muskel- und Gehirnenzym kann man durch hohe Fettdiät oder Kortison nicht verändern.     

The effect of neonatal administration of testosterone and oestradiol on the liver nuclear volume of male and female rats

Zusammenfassung Wirkung von Testosteron oder Östradiol auf die Grösse bzw. das Kernvolumen der Leberzellen von neugeborenen männlichen und weiblichen Ratten. Testosteron verursachte vor allem bei weiblichen Tieren eine erhebliche Volumenzunahme der Leberzellenkerne, während Kastration eine Verminderung der Polyploidie zur Folge hatte.

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The work was done during the tenure of the Widnes Cancer Research Fellowship. The author wishes to thank Dr.J. C. Davis for the helpful discussion and the North West Cancer Research Fund for the financial support.