ON THE MODULATING EFFECTS OF OVARIES ON NEONATAL ANDROGEN PROGRAMMING OF RAT LIVER ENZYMES

1975 ◽  
Vol 78 (2) ◽  
pp. 294-301 ◽  
Author(s):  
Åke Stenberg
Keyword(s):  
Enzyme Activity ◽  
Rat Liver ◽  
Liver Enzymes ◽  
Testosterone Propionate ◽  
Reductase Activity ◽  
Female Rats ◽  
Time Of Death ◽  
Hepatic Enzyme ◽  
Enzyme Activity Pattern ◽  
Reversible Nature

ABSTRACT The metabolism of 4-[4-14C]androstene-3,17-dione in rat liver microsomal and cytosol fractions was investigated in adult female rats treated with 1.45 μmole of testosterone propionate at birth. The effects of ovariectomy at 14 and 43 days of age on neonatal testosterone imprinting of enzyme levels were studied. Animals spayed 14 days after birth showed a typical masculinized hepatic enzyme activity pattern with a decreased level of the 5α-reductase activity and increased levels of 5α-reductase, 16α-hydroxylase and 17α- and 3β-hydroxysteroid reductase levels. The pattern was essentially the same in testosterone propionate-treated rats spayed 43 days after birth – with the exception of a feminized 5α-reductase activity – whereas a completely feminized ("de-imprinted") pattern of enzyme activities was found in the rats with intact ovaries at the time of death. It is concluded that de-imprinting action of ovaries is mainly of a reversible nature.

scholarly journals Adrenal microsomal C19-steroid 5α-reductase activity in the Snell transplantable rat adrenocortical tumour 494 and the effect of oestradiol, testosterone propionate and adrenocorticotrophin in intact and gonadectomized rats

1973 ◽  
Vol 132 (2) ◽  
pp. 293-300 ◽  
Author(s):  
Paul V. Maynard ◽  
Euan H. D. Cameron
Keyword(s):  
Enzyme Activity ◽  
Steroid Hormones ◽  
Microsomal Fraction ◽  
Testosterone Propionate ◽  
Reductase Activity ◽  
Intact Control ◽  
Adrenal Tissue ◽  
Males And Females ◽  
Adrenocortical Tumour ◽  
Hormonal Treatments

The C19-steroid 5α-reductase activity in the microsomal fraction of rat adrenal tissue under various hormonal treatments was examined. In intact control rats the activity is similar in both males and females, and after gonadectomy it is markedly increased. Treatment with oestradiol (150μg/day per animal for 7 days) or testosterone propionate (2mg/day per animal for 7 days) lowered the activity of 5α-reductase in castrated animals to approximately the values for intact animals in both sexes, and in intact animals the activity was also decreased by these treatments. The enzyme activity was also decreased by adrenocorticotrophin treatment but to a lesser extent than by the steroid hormones. The activity of the 5α-reductase enzyme in the Snell adrenocortical tumour 494 is very low when incubated as a whole homogenate, but the activity in microsomal material of the tumour was measured and unexpectedly found to be similar to that in intact controls.

scholarly journals Different mechanisms of regulation of nuclear reduced nicotinamide–adenine dinucleotide phosphate-dependent 3-oxo steroid 5α-reductase activity in rat liver, kidney and prostate

1974 ◽  
Vol 142 (2) ◽  
pp. 273-277 ◽  
Author(s):  
Jan-Åke Gustafsson ◽  
Åke Pousette
Keyword(s):  
Testosterone Propionate ◽  
Reductase Activity ◽  
Nicotinamide Adenine Dinucleotide Phosphate ◽  
Female Rats ◽  
Male Rats ◽  
Regulatory Mechanisms ◽  
Oestradiol Benzoate ◽  
Liver And Kidney ◽  
Reduced Nicotinamide Adenine Dinucleotide ◽  
Hydroxy Steroid

The regulatory mechanisms involved in the control of the nuclear NADPH-dependent 3-ketosteroid 5α-reductase (5α-reductase) activity were studied in liver, kidney and prostate. The substrate used was [1,2-3H]androst-4-ene-3,17-dione (androstenedione) (for liver and kidney) or [4-14C]androstenedione (for prostate). The hepatic nuclear 5α-reductase activity was greater in female than in male rats, was greater in adult than in prepubertal female rats, increased after castration of male rats, but was not affected by treatment with testosterone propionate or oestradiol benzoate. These regulatory characteristics are in part different from those previously described for the hepatic microsomal 5α-reductase. The renal nuclear metabolism of androstenedione, i.e. 5α reduction and 17β-hydroxy steroid reduction, was relatively unaffected by sex, age, castration and treatment with testosterone propionate. However, treatment of castrated male rats with oestradiol benzoate led to a significant increase in the 5α-reductase activity and a significant decrease in the 17β-hydroxy steroid reductase activity. Finally, the nuclear 5α-reductase activity in prostate was androgen-dependent, decreasing after castration and increasing after treatment with testosterone propionate. In conclusion, the nuclear 5α-reductase activities in liver, kidney and prostate seem to be under the control of distinctly different regulatory mechanisms. The hypothesis is presented that whereas the prostatic nuclear 5α-reductase participates in the formation of a physiologically active androgen, 5α-dihydrotestosterone, this may not be the true function of the nuclear 5α-reductase in liver and kidney. These enzymes might rather serve to protect the androgen target sites in the chromatin from active androgens (e.g. testosterone) by transforming them into less active androgens (e.g. 5α-androstane-3,17-dione and/or 5α-dihydrotestosterone).

PRECOCIOUS 'FEMINIZATION' OF RAT LIVER ENZYMES IN THE PRESENCE OF ECTOPIC PITUITARY TISSUE

1978 ◽  
Vol 76 (2) ◽  
pp. 187-191 ◽  
Author(s):  
JAN-ÅKE GUSTAFSSON ◽  
PAUL SKETT
Keyword(s):  
Rat Liver ◽  
Liver Enzymes ◽  
Female Rats ◽  
Steroid Metabolism ◽  
Male And Female ◽  
Adult Rat ◽  
Female Type ◽  
Pituitary Tissue ◽  
Male And Female Rats

The presence of ectopic pituitary tissue (derived from an adult rat) in prepubertal male and female rats caused the immature, masculine-type hepatic steroid metabolism to develop into female-type metabolism. It is concluded that the hypothalamus–pituitary system controls the ontogenesis of sex-dependent steroid metabolism in rat liver.

Effect of adrenalectomy and hypophysectomy on responses of rat liver enzymes to high-protein diets

1968 ◽  
Vol 46 (10) ◽  
pp. 1253-1260 ◽  
Author(s):  
R. A. Freedland
Keyword(s):  
Enzyme Activity ◽  
Rat Liver ◽  
Liver Enzymes ◽  
High Protein Diet ◽  
High Protein ◽  
Protein Diet ◽  
Metabolic Function ◽  
Simple Pattern ◽  
High Protein Diets ◽  
Protein Diets

Although many enzymes are increased by either a high-protein diet or cortisol adminstration, there was no evidence of a glucocorticoid requirement for the high-protein mediated increases. This was particularly noticeable for enzymes markedly increased by feeding a high-protein diet. Neither adrenalectomy nor hypophysectomy prevented the diet-mediated increases, although in certain instances the responses were decreased. Many enzymes which were unaffected or decreased in the intact rat by feeding a high-protein diet had markedly different responses after endocrine removal. There did not appear to be a general or simple pattern of these altered responses. Therefore predictions on possible activity changes could not be made, except for those enzymes normally increased by a high-protein diet on the basis of metabolic function or hormonal effects. Possible hormonal controls of these changes in enzyme activity are discussed.

AN ANALYSIS OF AN APPARENT SEX DIFFERENCE IN THE DESOXYRIBONUCLEIC ACID CONTENT OF RAT LIVER

1975 ◽  
Vol 80 (2) ◽  
pp. 319-328
Author(s):  
R. S. Leeuwin ◽  
B. J. Visser ◽  
C. v. d. Meer
Keyword(s):  
Sex Difference ◽  
Rat Liver ◽  
Dna Content ◽  
Testosterone Propionate ◽  
Liver Extract ◽  
Extraction Procedure ◽  
Female Rats ◽  
Male Rats ◽  
Female Rat ◽  
Desoxyribonucleic Acid

ABSTRACT Using the extraction procedure of Schmidt & Thannhauser (1945) and the indole reaction for DNA according to Ceriotti (1952), the DNA content of female rat liver was about one and a half times that of male liver. Castration of male rats, with or without administration of testosterone propionate, had no effect on the liver DNA content. Spaying of female rats (5–6 weeks of age) caused a decrease of the liver DNA content. Substitution with oestradiol benzoate restored the amount of DNA. No significant sex difference was observed in the DNA content of either rat brain, kidney, spleen and thymus, or mouse liver. Dische's diphenylamine reaction showed no significant sex difference in the rat liver DNA content. It was concluded that rat liver may contain a substance which is controlled by oestrogens and which interferes with the indole reaction. The interfering factor is present in the protein fraction of the liver extract. The possible nature of this interfering substance is discussed.

scholarly journals Uridine kinase in embryonic rat liver. Modulation of enzyme activity by 5-azacytidine

1973 ◽  
Vol 133 (4) ◽  
pp. 609-613 ◽  
Author(s):  
J. Veselý ◽  
A. Čihák
Keyword(s):  
Enzyme Activity ◽  
Postnatal Development ◽  
Rat Liver ◽  
Kinase Activity ◽  
Liver Enzymes ◽  
Adult Rats ◽  
Uridine Kinase

Uridine kinase activity in rat liver decreases during embryonic and postnatal development. Administration of 5-azacytidine enhances liver uridine kinase activity in adult rats, but depresses it in embryos. The liver enzymes from the foetus and the adult are precipitated at different (NH4)2SO4 concentrations although they are eluted at about the same position on chromatography on a column of Sepharose 6B.

scholarly journals Steroid glucuronyltransferases of rat liver. Properties of oestrone and testosterone glucuronyltransferases and the effect of ovariectomy, castration and administration of steroids on the enzymes

1977 ◽  
Vol 162 (3) ◽  
pp. 545-556 ◽  
Author(s):  
G S Rao ◽  
G Haueter ◽  
M L Rao ◽  
H Breuer
Keyword(s):  
Enzyme Activity ◽  
Rat Liver ◽  
Specific Activity ◽  
Normal Activity ◽  
Competitive Inhibitor ◽  
Female Rats ◽  
Male Rats ◽  
Prolonged Treatment ◽  
Microsomal Preparation ◽  
Ionic Detergent

1. Microsomal preparations from rat liver, kidney and intestine were tested for UDP-glucuronyltransferase activity by using oestrone, oestradiol-17 beta, oestriol, testosterone, cortisol, cortisone, corticosterone, aldosterone, tetrahydrocortisol and tetrahydrocortisone as substrates. The microsomal preparation from the liver glucuronidated oestrone, oestradiol-17 beta and testosterone. 2. The specific activity of the enzyme was significantly higher in livers from female rats than in those from male rats. 3. Testosterone was actively glucuronidated by both sexes. Cortisol, cortisone, corticosterone, aldosterone, tetrahydrocortisol and tetrahydrocortisone were not glucuronidated by any of the three tissues. 4. The non-ionic detergent Lubrol WX activates liver microsomal UDP-glucuronyltransferase 2-3-fold with oestrone and testosterone as substrates. 5. Oestrone glucuronyltransferase was inhibited by oestradiol-17 beta, predominantly competitively and by testosterone non-competitively. Bilirubin was a non-competitive inhibitor of oestrone glucuronidation. p-Nitrophenol had no effect. 6. Oestrone glucuronyltransferase could not be stimulated by either acute or prolonged treatment of animals with phenobarbital, whereas a single dose of 3-methylcholanthrene led to a moderate stimulation. 7. Ovariectomy leads to a 56% decrease in oestrone glucuronyltransferase activity; administration of oestradiol-17 beta induces the enzyme to normal activity after 12 days, and after 15 days the activity is twice the control value. Actinomycin D and cycloheximide block the oestradiol-17 beta-induced increase in enzyme activity. 8. Castration has no effect on the activity of testosterone glucuronyltransferase, nor does administration of testosterone influence enzyme activity. The results provide strong evidence for the existence of multiple steroid glucuronyltransferases in the liver of the rat.

Effect of chlorophenoxyisobutyrate on rat liver non-saponifiables

1968 ◽  
Vol 46 (1) ◽  
pp. 81-84 ◽  
Author(s):  
W. E. J. Phillips ◽  
M. R. Lakshmanan ◽  
R. L. Brien
Keyword(s):  
Enzyme Activity ◽  
Vitamin A ◽  
Rat Liver ◽  
Serum Cholesterol ◽  
Reductase Activity ◽  
Liver Weight ◽  
Liver Cholesterol ◽  
Total Liver ◽  
Cholesterol Levels

Chlorophenoxyisobutyrate (CPIB) when fed in the diet at 0.2% for periods of from 3 to 25 days increased liver weight by 28% and increased total liver ubiquinones by 75%. This increase did not change succinate-neotetrazolium reductase activity. Although serum cholesterol levels were significantly reduced, no changes were observed in total liver cholesterol or vitamin A. The data suggest that this hypocholesterolemic agent, although it increases ubiquinone, does not adversely affect the above enzyme activity nor does it modify vitamin A utilization as determined from liver stores.

TESTOSTERONE Δ4-REDUCTASE ACTIVITY IN RAT LIVER: HORMONAL CONTROL IN VIVO

1974 ◽  
Vol 63 (1) ◽  
pp. 181-189 ◽  
Author(s):  
D. C. PATTERSON ◽  
A. F. CLARK ◽  
C. E. BIRD
Keyword(s):  
Rat Liver ◽  
Reductase Activity ◽  
Enzyme Level ◽  
Hormonal Control ◽  
Female Rats ◽  
Male Rats ◽  
Female Rat ◽  
Rate Limiting Step ◽  
Level Of Activity

SUMMARY The rate-limiting step in the metabolism of testosterone by the liver is reduction of the double bond in ring A. Using a spectrophotometric assay we have studied the effects of some hormonal manipulations on the levels (per mg protein) of testosterone Δ4-reductase activity in rat liver. While the levels of enzyme activity were higher for adult female rat liver than for adult male liver, there were no further changes in livers from female rats at day 15 of gestation. In male rats, castration increased, hypophysectomy decreased and adrenalectomy had no effect on the level of activity. Administration of oestradiol valerate increased the activity in intact and adrenalectomized animals and had no effect in the hypophysectomized or castrated groups. Administration of testosterone enanthate decreased the levels of activity in the castrated and adrenalectomized groups and had no effects in unoperated or hypophysectomized animals. When given together, the two hormones were antagonistic. Prolactin had no significant effects in either intact or hypophysectomized animals. Experiments with actinomycin D and cycloheximide indicated that the synthesis of new protein was involved in the effects of oestradiol in intact rats. All the changes reflected alterations in the microsomal enzyme level.

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