Development of Guanase and Xanthine Oxidase in Rat Liver

Silverstein, Emanuel; Zaklynsky, Orest; Horn, Toby M.

doi:10.3181/00379727-132-34155

Cited by 7 publications

(6 citation statements)

References 3 publications

(4 reference statements)

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“…Maturity in the male results in a twofold increase in enzyme activity (P < 0.005), whereas no significant difference is seen between immature and adult females. The insignificant prepubertal difference between sexes is similar to the data obtained in immature Wistar rats by Silverstein et a1 (12).…”

Section: Resultssupporting

confidence: 90%

Rat hepatic xanthine oxidase activity

Levinson

Chalker

1980

Arthritis & Rheumatism

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The effect of maturation, castration, and sex hormonal treatment on hepatic xanthine oxidase activity (XOA) was evaluated in Sprague-Dawley rats. In mature rats XOA was 59% greater in males than in females, whereas in the immature animal the differences between sexes were insignificant. Pubescence resulted in a twofold increase in activity in the male which was prevented by prepubertal orchiectomy. Conversely, prepubertal oophorectomy caused a twofold increase in XOA in females. Urinary uric acid excretion paralleled XOA in rats fed 1% oxonic acid. XOA was significantly elevated in females after postpubertal castration or testosterone treatment while orchiectomy or estradiol-17/? treatment in the mature male showed no effect. In summary, these data suggest that androgens are required during puberty for full expression of hepatic XOA, and furthermore, an ovarian suppressive effect is evident. In the adult rat only the female responds appreciably to hormonal manipulation.The influence of age and sex on the development of gout has been observed since ancient times (1). Population studies indicate that uric acid levels are lowest in childhood and diverge at puberty with female values about 1 mg/dl lower until menopause, at which time, the female values begin to approach male values (2-4). Wolfson et a1 attributed these variations to differences in the renal handling of uric acid, whereas more recent studies suggest either a permissive effect of androgens or an estrogen suppressive effect on blood urate values (5-In adult Wistar rats given short-term androgen or estrogen therapy, purine endproduct production was not significantly affected (1 1). Using prepubertal rats, Silverstein et a1 found age related increments in guanase and XOA although no sex differences were seen; moreover, adult enzyme activities were similar (1 2). No additional data are available regarding the effect of sex steroid hormones on uric acid production.A large body of information is available on the enzyme xanthine oxidase which catalyzes the conversion of hypoxanthine and xanthine to uric acid (13)(14)(15). Data on the induction of XOA by dietary protein manipulation in rats, allopurinol treatment of chicks, and enhanced urate precursor production by RNA and hypoxanthine feeding, and fructose infusion attest to the large number of potential factors controlling this particular enzyme.Because of the age and sex specific variations in urate concentration and the observed potential variability of XOA, we chose to reexamine the effects of gonadal tissue and exogenous sex steroid hormones on rat hepatic XOA. 10). MATERIALS AND METHODSExperimental design. Sprague-Dawley rats were housed at room temperature in a light-dark environment and maintained on Purina chow and water ad libitum. Groups of

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Section: Resultssupporting

confidence: 90%

Rat hepatic xanthine oxidase activity

Levinson

Chalker

1980

Arthritis & Rheumatism

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“…The development pattern of guanase activity which we observed in the rat liver is substantial ly superimposable on that reported by Silverstein et al (5). In agreement with Kumar et al (3) we found enzymatic activity in the brain at birth, but our data show a greater increase in activity with age.…”

Section: Referencessupporting

confidence: 78%

“…From the 3rd week on, it is possible to show an inhibitor of this enzy matic activity in the fraction of heavy mi tochondria (3). Silverstein et al (5) have shown a different pattern of postnatal development in the rat liver between guanase and xanthine oxi dase and suggest a different mechanism to regu late these two so closely connected enzymes in purine metabolism. Recently, Kumar et al (4) singled out, in rat and mouse tissues, two iso enzymes whose activity is regulated differently and suggest that in the same tissue one isoen…”

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confidence: 99%

Postnatal Behaviour of Guanase Activity in Rat Tissues

Nardiello¹,

Galanti²,

Russo³

et al. 1978

Enzyme

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The behaviour of guanase activity and the 8-azaguanine/guanine deamination ratio of rat tissues during postnatal development were studied. In the liver and brain, the enzymatic activity, present from birth, gradually increases up to the 4th week. In the kidney, guanase activity appears after the 1st week and reaches the level found in adult tissues after the 6th week. The value of the deamination ratio of tissues at birth is higher than that of adult animal tissues.

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“…From the beginning of pregnancy, DNA concentrations also rose. With involu The sensitivity of the present assay lends emphasis to the negative findings of undetect able guanase activity in fetal tissues and human (22) found that guanase appeared in rat liver only postnatally. This is now also found to be so for brain, lung and kidney, and for the fetal blood cells con tained in these fetal tissues, although all of these tissues in the adult stage contain substan tial guanase activities.…”

Section: 42mentioning

confidence: 99%

Guanase in Reticulocytes and Other Rat Tissues

Hb¹,

We²

1978

Enzyme

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A sensitive and precise assay of guanase was based on the conversion of 14C-guanine to uric acid in the presence of excess xanthine oxidase. The enzyme was entirely soluble in rat tissues and no inhibitors of it were detected. The most active tissues were red blood cells, lung and lactating mammary gland, with more than twice the activity of liver. The contained blood could account for the low activity in adult skeletal muscle and some other tissues. All fetal tissues examined were without activity. Activity in mammary gland rose fourfold during lactation and dropped precipitously during involution, with a secondary rise associated in time with the loss of cells from the gland. Reticulocytes present normally and after hemorrhagic anemia appeared to account for substantially all of the high guanase activity in red blood cells. The guanase level could be used to predict the degree of reticulocytosis in rats within confidence limits of ± 0.2%. The virtual absence of guanase in human red cells was confirmed, even in bloods containing elevated reticulocyte numbers.

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Development of Guanase and Xanthine Oxidase in Rat Liver

Cited by 7 publications

References 3 publications

Rat hepatic xanthine oxidase activity

Rat hepatic xanthine oxidase activity

Postnatal Behaviour of Guanase Activity in Rat Tissues

Guanase in Reticulocytes and Other Rat Tissues

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