scholarly journals Polyamine and amino acid content, and activity of polyamine-synthesizing decarboxylases, in liver of streptozotocin-induced diabetic and insulin-treated diabetic rats

1980 ◽  
Vol 190 (2) ◽  
pp. 395-403 ◽  
Author(s):  
Margaret E. Brosnan ◽  
Barbara V. Roebothan ◽  
Douglas E. Hall
Keyword(s):  
Amino Acids ◽  
Ornithine Decarboxylase ◽  
Insulin Treatment ◽  
Amino Acid Content ◽  
Diabetic Rats ◽  
Diabetic Rat ◽  
Decarboxylase Activity ◽  
Adenosylmethionine Decarboxylase ◽  
Ornithine Decarboxylase Activity ◽  
Total Dna

1. Concentrations of polyamines, amino acids, glycogen, nucleic acids and protein, and activities of ornithine decarboxylase and S-adenosylmethionine decarboxylase, were measured in livers from control, streptozotocin-diabetic and insulin-treated diabetic rats. 2. Total DNA per liver and protein per mg of DNA were unaffected by diabetes, whereas RNA per mg of DNA and glycogen per g of liver were decreased. Insulin treatment of diabetic rats induced both hypertrophy and hyperplasia, as indicated by an increase in all four of these constituents to or above control values. 3. Spermidine content was increased in the livers of diabetic rats, despite the decrease in RNA, but it was further increased by insulin treatment. Spermine content was decreased by diabetes, but was unchanged by insulin treatment. Thus the ratio spermidine/spermine in the adult diabetic rat was more typical of that seen in younger rats, whereas insulin treatment resulted in a ratio similar to that seen in rapidly growing tissues. 4. Ornithine decarboxylase activity was variable in the diabetic rat, showing a positive correlation with endogenous ornithine concentrations. This correlation was not seen in control or insulin-treated rats. Insulin caused a significant increase in ornithine decarboxylase activity relative to control or diabetic rats. 5. S-Adenosylmethionine decarboxylase activity was increased approx. 2-fold by diabetes and was not further affected by insulin. 6. Hepatic concentrations of the glucogenic amino acids, alanine, glutamine and glycine were decreased by diabetes. Their concentrations and that of glutamate were increased by injection of insulin. Concentrations of ornithine, proline, leucine, isoleucine and valine were increased in livers of diabetic rats and were decreased by insulin. Diabetes caused a decrease in hepatic concentration of serine, threonine, lysine and histidine. Insulin had no effect on serine, lysine and histidine, but caused a further fall in the concentration of threonine.

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.

Stimulation of rat ovarian ornithine decarboxylase in vitro by hCG, amino acids and bovine serum albumin

1980 ◽  
Vol 94 (4) ◽  
pp. 571-576 ◽  
Author(s):  
Kirsti Käpyaho
Keyword(s):  
Amino Acids ◽  
Bovine Serum Albumin ◽  
Cyclic Amp ◽  
Serum Albumin ◽  
Ornithine Decarboxylase ◽  
Bovine Serum ◽  
Defined Medium ◽  
Decarboxylase Activity ◽  
Ornithine Decarboxylase Activity

Abstract. Rat ovarian ornithine decarboxylase activity could be stimulated in vitro by a variety of factors, which apparently have different modes of action. Ovarian cells prepared from pre-pubertal rats by collagenase dispersion exhibited a low but detectable ornithine decarboxylase activity after a 6-h incubation in a defined medium. The enzyme activity was markedly enhanced in vitro by hCG, which also produced increased accumulation of cyclic AMP and stimulated the secretion of progesterone. In addition to the gonadotrophin, ovarian ornithine decarboxylase activity was strikingly stimulated by some non-essential amino acids, and especially by bovine serum albumin. While markedly enhancing ornithine decarboxylase activity, none of the latter additions increased the accumulation of cyclic AMP or enhanced the secretion of progesterone. Bovine serum albumin enhanced powerfully ornithine decarboxylase activity in vitro at very small concentrations (from 0.75 μm). The half-life of the enzyme remained unchanged (26—28 min) upon stimulation indicating that the stimulation mechanism did not involve any stabilization of the enzyme.

Sign in / Sign up

Export Citation Format

Share Document