Persistence of the circadian variation and altered response to hepatectomy of hepatic ornithine decarboxylase activity with malignant tumor burden

Tumour effect on arginine/ornithine metabolic relationship in hypertrophic mouse kidney

The presence of a tumour significantly changes nitrogen metabolism, including that of amino acids and polyamines, in host animals. In this study, we examine whether developing tumours affect the metabolic relationship of arginine and ornithine, precursors of polyamines, in the testosterone-induced hypertrophic mouse kidney model. Androgen-induced changes in the activity of enzymes involved with ornithine biosynthesis (arginase), its consumption (ornithine aminotransferase, OAT and ornithine decarboxylase, ODC) and the hypertrophy of host mouse kidney were not affected by the presence of an ascitic tumour (EAC) and only slightly by a mammary carcinoma (MaCa). The HPLC determined renal level of arginine and ornithine showed a striking homeostasis and was disturbed neither by testosterone nor EAC. The effect of MaCa and testosterone on the levels of both amino acids, although significant, was not very pronounced. Developing tumours, especially ascitic, altered the renal activity of OAT and ODC, but not of arginase, in testosterone-untreated mice. All examined tumours, EAC, L 1210 and MaCa actively metabolized arginine and ornithine. the tumour content of arginine which coincided with the activity of arginase, resulted in a marked increase of the ornithine/arginine ratio in tumours, when compared with kidneys. These results indicate that the androgen-induced anabolic response in mouse kidney is preserved, in spite of tumour requirements for essential metabolites.

Effects of Freund's complete adjuvant on the diurnal rhythms of neuroendocrine processes and ornithine decarboxylase activity in various tissues of male rats

The aim of this study was to investigate the effects of Freund's complete adjuvant (FCA) on the diurnal rhythms of hormonal parameters in serum and ornithine decarboxylase (ODC) activity in various tissues of male rats. On days 1-2 after FCA, increase of ODC activity (used to evaluate the level of activation) was observed in the hypothalamus, pituitary gland, adrenal medulla, adrenal cortex, liver and lymphoid tissues, while the ODC activity in the kidney was reduced. This was accompanied by an increase in serum corticosterone. On days 3-4 after FCA, ODC activity remained elevated in the pituitary gland, liver and lymphoid tissues, while the ODC activity in the testes and pancreas was reduced; kidney ODC activity returned to baseline. This was associated with increased serum levels of prolactin (Prl) and luteinizing hormone, but decreased growth hormone, testosterone and insulin. The increase in ODC activity in the thymus, as well as the reduced ODC activity in the testes and kidney, can be obtained with paraffin. Furthermore, bromocryptine microcapsules (CBLA) reduced the FCA-induced increase of ODC activity in the pituitary gland, liver and lymphoid tissues (days 3-4) but did not affect the changes in other tissues. The increase in ODC activity in the pituitary gland, liver and lymphoid tissues is specific for FCA. A role for Prl in the induction of ODC in liver and lymphoid tissues is suggested by the fact that CBLA suppresses this enhancement.