Effects of a methyl-deficient diet on rat liver phosphatidylcholine biosynthesis

1981 ◽  
Vol 59 (7) ◽  
pp. 543-550 ◽  
Author(s):  
Dennis R. Hoffman ◽  
Judy A. Haning ◽  
W. E. Cornatzer
Keyword(s):  
Basal Diet ◽  
Female Rats ◽  
Deficient Diet ◽  
Acid Diet ◽  
Phosphatidylcholine Biosynthesis ◽  
Methionine Deficiency ◽  
Choline Phosphotransferase ◽  
Phosphatidylethanolamine Methyltransferase

To produce a severe choline–methionine deficiency, a synthetic L-amino acid diet, free of choline, methionine, vitamin B12, and folic acid and supplemented with guanidoacetic acid, a methyl group acceptor, was fed to female rats for 2 weeks. The in vitro activity of liver microsomal phosphatidylethanolamine methyltransferase was stimulated twofold when compared with basal diet controls. The activity of choline phosphotransferase was depressed by 86%; thus, the contribution of the methyltransferase in the overall synthesis of phosphatidylcholine apparently increased. However, measurement of the in vivo methylation of phosphatidylethanolamine by incorporation of [1,2-14C]ethanolamine into phosphatidylcholine indicates that the methylation pathway is markedly depressed in methyl deficiency. Hepatic concentrations of the methyltransferase substrate, S-adenosylmethionine, and the inhibitory metabolite, S-adenosylhomocysteine, were significantly altered such that an unfavorable environment for methylation was present in the deficient animal. The ratio of substrate to inhibitor was depressed from 5.2:1 in the controls to 1.7:1 in the livers of methyl-depleted rats. Control of transmethylation in accordance with the availability of substrates, phosphatidylethanolamine, or S-adenosylmethionine, and the level of S-adenosylhomocysteine is discussed.

Effects of in vivo gonadal hormone environment on in vitro hGRF-40-stimulated GH release

1985 ◽  
Vol 249 (3) ◽  
pp. E276-E280 ◽  
Author(s):  
W. S. Evans ◽  
R. J. Krieg ◽  
E. R. Limber ◽  
D. L. Kaiser ◽  
M. O. Thorner
Keyword(s):  
Female Rats ◽  
Male Rats ◽  
Gonadal Hormone ◽  
Base Line ◽  
Pituitary Cells ◽  
Intact Male ◽  
Castrate Male ◽  
Basal Release

The effects of gender and the gonadal hormone environment on basal and stimulated growth hormone (GH) release by dispersed and continuously perifused rat anterior pituitary cells were examined. Cells from intact male and diestrus day 2 female rats and from castrate male rats either untreated or treated with testosterone (T) or 17 beta-estradiol (E2) were used. Basal GH release (ng/min per 10(7) cells; mean +/- SE) by cells from diestrus day 2 female rats was less than by cells from castrate rats treated with T (4.3 +/- 0.6 vs. 11.4 +/- 2.7, respectively; P less than 0.025). No other differences in basal release were detected. Concentration-response relationships were documented between human GH-releasing factor 40 (hGRF-40; 0.03-100 nM given as 2.5-min pulses every 27.5 min) and GH release. Mean (+/- SE) overall GH release (ng/min per 10(7) cells) above base line was greater by cells from intact male rats (496 +/- 92) than by cells from castrate (203 +/- 37.3; P less than 0.0001), castrate and T-treated (348 +/- 52.8; P = 0.008), or castrate and E2-treated (58.1 +/- 6.8; P less than 0.001) male rats or by diestrus day 2 rats (68.6 +/- 9.5; P = 0.0001).(ABSTRACT TRUNCATED AT 250 WORDS)

scholarly journals Additional evidence for a proform to tropoelastin from chick aorta

1979 ◽  
Vol 177 (2) ◽  
pp. 559-567 ◽  
Author(s):  
C S Heng-Khoo ◽  
R B Rucker ◽  
K W Buckingham
Keyword(s):  
Basic Protein ◽  
Cross Linking ◽  
Protein Subunit ◽  
Deficient Diet ◽  
Culture In Vitro ◽  
One Step

Evidence is presented for the presence of precursor to tropoelastin in chick arterial extracts. The precursor is approx. 100 000 daltons in size. It is suggested to be a precursor to tropoelastin (72 000 daltons). This protein may be observed in culture in vitro if appropriate precautions are taken to inhibit proteolysis. Once synthesized, it appears to be converted into tropoelastin within 10–20 min. The protein may also be detected in vivo. When 1-day-old cockerels were fed on a copper-deficient diet (less than 1 p.p.m. to inhibit cross-linking) containing epsilon-aminohexanoic acid (0.2%) to retard proteolysis and then injected wiht [3H]valine, extraction of arterial proteins 12h after injection resulted in detection of two major peaks of [3H]valine-labelled protein with pI values of pH 7.0 and 5.0 respectively. The protein that focused at pH 7.0 was estimated to be about 100 000 daltons in size and could be shown to be converted into a more basic protein with the properties of tropoelastin. It is speculated that the protein with pI 5.0 may be yet another extension peptide. The data appear to be in keeping with similar observations by ourselves and others that a proform of tropoelastin exists, and, in at least one step before conversion into tropoelastin, exists as a 100 000-dalton protein subunit.

Correlation between magnesium and potassium contents in muscle: role of Na(+)-K+ pump

1993 ◽  
Vol 264 (2) ◽  
pp. C457-C463 ◽  
Author(s):  
I. Dorup ◽  
T. Clausen
Keyword(s):  
Extensor Digitorum Longus ◽  
Extensor Digitorum ◽  
Deficient Diet ◽  
Young Rats ◽  
Wide Range ◽  
86Rb Influx

In young rats fed a Mg(2+)-deficient diet for 3 wk, Mg2+ and K+ contents in soleus and extensor digitorum longus muscles were significantly reduced and closely correlated. In isolated soleus muscles, Mg2+ depletion induced an even more pronounced loss of K+, and Mg2+ and K+ contents were correlated over a wide range (r = 0.95, P < 0.001). Extracellular Mg2+ (0-1.2 mM) caused no change in total or ouabain-suppressible 86Rb influx. After long-term incubation in Ca(2+)-Mg(2+)-free buffer with EDTA and EGTA, cellular Mg2+ and K+ contents were reduced by 35 and 15%, respectively, without any reduction in ATP and total or ouabain-suppressible 86Rb influx. In Mg(2+)-depleted muscles 42K efflux was increased by up to 42%, and repletion with Mg2+ produced a graded decrease. We conclude that Mg2+ and K+ contents are closely correlated in muscles Mg2+ depleted in vivo or in vitro and that neither extracellular nor moderate intracellular Mg2+ depletion affects total or Na(+)-K+ pump-mediated K+ influx. The reduced K+ content may rather be related to increased K+ efflux from the muscles.

scholarly journals HOXA5 Expression Is Elevated in Breast Cancer and Is Transcriptionally Regulated by Estradiol

2020 ◽  
Vol 11 ◽  
Author(s):  
Imran Hussain ◽  
Paromita Deb ◽  
Avisankar Chini ◽  
Monira Obaid ◽  
Arunoday Bhan ◽  
...  
Keyword(s):  
Breast Cancer ◽  
Cancer Cells ◽  
Breast Cancer Cells ◽  
Female Rats ◽  
Er Positive ◽  
Gene Regulatory ◽  
Cancer Tissues ◽  
Positive Breast Cancer

HOXA5 is a homeobox-containing gene associated with the development of the lung, gastrointestinal tract, and vertebrae. Here, we investigate potential roles and the gene regulatory mechanism in HOXA5 in breast cancer cells. Our studies demonstrate that HOXA5 expression is elevated in breast cancer tissues and in estrogen receptor (ER)-positive breast cancer cells. HOXA5 expression is critical for breast cancer cell viability. Biochemical studies show that estradiol (E2) regulates HOXA5 gene expression in cultured breast cancer cells in vitro. HOXA5 expression is also upregulated in vivo in the mammary tissues of ovariectomized female rats. E2-induced HOXA5 expression is coordinated by ERs. Knockdown of either ERα or ERβ downregulated E2-induced HOXA5 expression. Additionally, ER co-regulators, including CBP/p300 (histone acetylases) and MLL-histone methylases (MLL2, MLL3), histone acetylation-, and H3K4 trimethylation levels are enriched at the HOXA5 promoter in present E2. In summary, our studies demonstrate that HOXA5 is overexpressed in breast cancer and is transcriptionally regulated via estradiol in breast cancer cells.

scholarly journals Role of pyridoxal phosphate in mammalian polyamine biosynthesis. Lack of requirement for mammalian S-adenosylmethionine decarboxylase activity

1977 ◽  
Vol 166 (1) ◽  
pp. 81-88 ◽  
Author(s):  
A E Pegg
Keyword(s):  
Ornithine Decarboxylase ◽  
Pyridoxal Phosphate ◽  
Vitamin B ◽  
Decarboxylase Activity ◽  
Deficient Diet ◽  
Polyamine Biosynthesis ◽  
Adenosylmethionine Decarboxylase ◽  
Ornithine Decarboxylase Activity

1. Polyamine concentrations were decreased in rats fed on a diet deficient in vitamin B-6. 2. Ornithine decarboxylase activity was decreased by vitamin B-6 deficiency when assayed in tissue extracts without addition of pyridoxal phosphate, but was greater than in control extracts when pyridoxal phosphate was present in saturating amounts. 3. In contrast, the activity of S-adenosylmethionine decarboxylase was not enhanced by pyridoxal phosphate addition even when dialysed extracts were prepared from tissues of young rats suckled by mothers fed on the vitamin B-6-deficient diet. 4. S-Adenosylmethionine decarboxylase activities were increased by administration of methylglyoxal bis(guanylhydrazone) (1,1′-[(methylethanediylidine)dinitrilo]diguanidine) to similar extents in both control and vitamin B-6-deficient animals. 5. The spectrum of highly purified liver S-adenosylmethionine decarboxylase did not indicate the presence of pyridoxal phosphate. After inactivation of the enzyme by reaction with NaB3H4, radioactivity was incorporated into the enzyme, but was not present as a reduced derivative of pyridoxal phosphate. 6. It is concluded that the decreased concentrations of polyamines in rats fed on a diet containing vitamin B-6 may be due to decreased activity or ornithine decarboxylase or may be caused by an unknown mechanism responding to growth retardation produced by the vitamin deficiency. In either case, measurements of S-adenosylmethionine decarboxylase and ornithine decarboxylase activity under optimum conditions in vitro do not correlate with the polyamine concentrations in vivo.

scholarly journals Amino acid regulation of synthesis of ribonucleic acid and protein in the liver of rats

1971 ◽  
Vol 124 (2) ◽  
pp. 385-392 ◽  
Author(s):  
R. W. Wannemacher ◽  
C. F. Wannemacher ◽  
M. B. Yatvin
Keyword(s):  
Amino Acids ◽  
Protein Synthesis ◽  
Free Amino Acids ◽  
Free Amino ◽  
Cellular Protein ◽  
Deficient Diet ◽  
Cellular Protein Content ◽  
Regulate Protein

Weanling (23-day-old) rats were fed on either a low-protein diet (6% casein) or a diet containing an adequate amount of protein (18% casein) for 28 days. Hepatic cells from animals fed on the deficient diet were characterized by markedly lower concentrations of protein and RNA in all cellular fractions as compared with cells from control rats. The bound rRNA fraction was decreased to the greatest degree, whereas the free ribosomal concentrations were only slightly less than in control animals. A good correlation was observed between the rate of hepatic protein synthesis in vivo and the cellular protein content of the liver. Rates of protein synthesis both in vivo and in vitro were directly correlated with the hepatic concentration of individual free amino acids that are essential for protein synthesis. The decreased protein-synthetic ability of the ribosomes from the liver of protein-deprived rats was related to a decrease in the number of active ribosomes and heavy polyribosomes. The lower ribosomal content of the hepatocytes was correlated with the decreased concentration of essential free amino acids. In the protein-deprived rats, the rate of accumulation of newly synthesized cytoplasmic rRNA was markedly decreased compared with control animals. From these results it was concluded that amino acids regulate protein synthesis (1) by affecting the number of ribosomes that actively synthesize protein and (2) by inhibiting the rate of synthesis of new ribosomes. Both of these processes may involve the synthesis of proteins with a rapid rate of turnover.

Rat renal 25-hydroxyvitamin D3 1- and 24-hydroxylases: their in vivo regulation

1984 ◽  
Vol 246 (2) ◽  
pp. E168-E173 ◽  
Author(s):  
Y. Tanaka ◽  
H. F. DeLuca
Keyword(s):  
Vitamin D ◽  
Inorganic Phosphorus ◽  
Hydroxylase Activity ◽  
Deficient Diet ◽  
Dihydroxyvitamin D3 ◽  
1,25 Dihydroxyvitamin D3 ◽  
Dietary Phosphorus ◽  
Low Calcium

The effects of thyroparathyroidectomy, parathyroid hormone, 1,25-dihydroxyvitamin D3, dietary calcium, dietary phosphorus, age, and sex on the renal 25-hydroxyvitamin D3 1- and 24-hydroxylases measured in vitro in rats have been studied. Thyroparathyroidectomy of vitamin D-deficient rats abolishes 25-hydroxyvitamin D3 1-hydroxylase activity, and administration of bovine parathyroid extract to the thyroparathyroidectomized rat restores diminished 1-hydroxylase activity. Both suppression and restoration of the enzyme activities require many hours (18-24 h) independent of rapid changes in serum calcium and inorganic phosphorus levels in response to these manipulations. Administration of 1,25-dihydroxyvitamin D3 to vitamin D-deficient rats suppresses 25-hydroxyvitamin D3 1-hydroxylase activity and stimulates 25-hydroxyvitamin D3 24-hydroxylase activity within 48 h. Rats maintained on a low-calcium or a low-phosphorus diet with a daily supplement of 20 IU vitamin D3 show high 25-hydroxyvitamin D3 1-hydroxylase activity and low 24-hydroxylase activity as compared with rats similarly treated but fed a diet containing adequate calcium or adequate phosphorus. When vitamin D-sufficient rats having suppressed renal 25-hydroxyvitamin D3 1-hydroxylase activity are placed on a low-calcium vitamin D-deficient diet for 7 days, the 1-hydroxylase activity is greatly stimulated in 6-wk-old rats but much less so in rats with advancing age.

scholarly journals Estrogen Protects Lenses against Cataract Induced by Transforming Growth Factor-β (TGFβ)

1997 ◽  
Vol 185 (2) ◽  
pp. 273-280 ◽  
Author(s):  
Angela M. Hales ◽  
Coral G. Chamberlain ◽  
Christopher R. Murphy ◽  
John W. McAvoy
Keyword(s):  
Growth Factor ◽  
Transforming Growth Factor ◽  
Hormone Replacement ◽  
Transforming Growth Factor Β ◽  
Epidemiological Studies ◽  
Female Rats ◽  
World Population ◽  
Damaging Effects

Cataract, already a major cause of visual impairment and blindness, is likely to become an increasing problem as the world population ages. In a previous study, we showed that transforming growth factor-β (TGFβ) induces rat lenses in culture to develop opacities and other changes that have many features of human subcapsular cataracts. Here we show that estrogen protects against cataract. Lenses from female rats are more resistant to TGFβ-induced cataract than those from males. Furthermore, lenses from ovariectomized females show increased sensitivity to the damaging effects of TGFβ and estrogen replacement in vivo, or exposure to estrogen in vitro, restores resistance. Sex-dependent and estrogen-related differences in susceptibility to cataract formation, consistent with a protective role for estrogen, have been noted in some epidemiological studies. The present study in the rat indicates that estrogen provides protection against cataract by countering the damaging effects of TGFβ. It also adds to an increasing body of evidence that hormone replacement therapy protects postmenopausal women against various diseases.

REGULATION OF THE METABOLISM OF PITUITARY NUCLEIC ACIDS IN FEMALE RATS

1980 ◽  
Vol 85 (1) ◽  
pp. 1-8 ◽  
Author(s):  
J. BÍRÓ
Keyword(s):  
Nucleic Acids ◽  
Intraperitoneal Injection ◽  
Anterior Pituitary ◽  
Rna Metabolism ◽  
Female Rats ◽  
Biphasic Effect ◽  
Lh Rh ◽  
Lh Releasing Hormone

SUMMARY Ovariectomy caused an increase in the metabolism of pituitary nucleic acids. This effect was reversed in vivo by a biphasic action of oestradiol-17β which first facilitated RNA metabolism after 8 h and then inhibited it 16 h after intraperitoneal injection. To analyse the origin of this biphasic effect the roles of LH releasing hormone (LH-RH) and hysterectomy were examined. Incorporation of uridine into the RNA of the anterior pituitary gland of female rats was inhibited both in vivo and in vitro by LH-RH. Hysterectomy augmented the increase in the RNA metabolism caused by ovariectomy whereas steroid-free uterine extracts inhibited the increase significantly. We have concluded that extrapituitary factors may be involved in the effects of oestrogen on the metabolism of pituitary nucleic acids.

DECREASED ALDOSTERONE PRODUCTION BY RAT ADRENAL TISSUE IN VITRO DUE TO TREATMENT WITH 9α-FLUOROCORTISOL, DEXAMETHASONE AND ADRENOCORTICOTROPHIN IN VIVO

1970 ◽  
Vol 63 (1) ◽  
pp. 1-10 ◽  
Author(s):  
Jürg Müller
Keyword(s):  
Sodium Intake ◽  
Sodium Balance ◽  
Potassium Ions ◽  
Aldosterone Secretion ◽  
Deficient Diet ◽  
Adrenal Tissue ◽  
Aldosterone Production ◽  
Unknown Control

ABSTRACT Quartered adrenal glands of rats treated with 9α-fluorocortisol, dexamethasone or adrenocorticotrophin (ACTH) for two weeks were found to produce 70–90% less aldosterone in vitro than the adrenal tissue of untreated animals. The same fractional decreases in aldosterone production were observed when the adrenal tissue was incubated under basal conditions or was stimulated by serotonin, potassium ions or ACTH. In rats kept on a sodium-deficient diet, treatment with dexamethasone and ACTH, respectively, impaired aldosterone production to the same extent as in rats on a normal sodium intake, whereas treatment with 9α-fluorocortisol was almost completely ineffective. These results indicate that inhibition of aldosterone secretion by an exogenous mineralocorticosteroid is mediated by changes in sodium balance. On the other hand, high levels of exogenous or endogenous glucocorticosteroids apparently decrease aldosterone production by a yet unknown control mechanism which is independent of sodium intake.

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