Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:4.1.1.17 (ornithine decarboxylase)
 6,351 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

TSH (1.0 U im) caused a 22-fold increase in thyroidal ornithine decarboxylase activity (ODC) 6 hours after administration in intact rats. Hypophysectomized rats treated with 1 U TSH showed a 5-fold increase in thyroid ODC activity. This stimulation appeared to be specific for TSH since hormones known to induce ODC activity in other target tissues, such as ACTH or LH, showed no significant stimulation. DIBUTYRYL CYCLIC AMP and aminopylline caused a 12-fold increase in ODC activity 5 hours after administration. Prostaglandins have also been implicated in the TSH-induced stimulation of cyclic AMP. Indomethacin (1.0 mg/100 g body wt, ip), an inhibitor of prostaglandin synthesis, was administered 3 hours before TSH with a resulting 30% diminution (P less than .001) in ODC activity compared with the administration of TSH alone. To rule out the possibility that the increase in ODC activity with TSH might be due to increased thyroid hormone secretion, ODC activity was evaluated 6 hours after triiodothyronine administration (60 mug/100 g body wt), and no significant increase in thyroid ODC activity was found. Stimulation of ODC activity was 90% inhibited by the intraperitoneal administration of actinomycin D (80 mug/100 g body wt) or cycloheximide (400 mug/100 g body wt) given simultaneously with TSH. These results indicated that TSH specifically stimulated thyroid ODC activity, which may be important for the growth-promoting action of the hormone on the thyroid gland. This action may be mediated by cAMP and prostaglandins and may require new protein synthesis.
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PMID:Thyroid-stimulating hormone regulation of ornithine decarboxylase activity in the thyroid. 17 Nov 42

The regulation of the activity of the renal enzyme ornithine decarboxylase (L-ornithine carboxy-lyase, EC 4.1.1.17) was examined in the rat. In the intact animal adapted to a light/dark cycle of 14 hours and 10 hours, respectively, the level of renal ornithine decarboxylase activity was rhythmical and paralleled the diurnal rhythm in plasma corticosteroid concentration. Renal ornithine decarboxylase activity and plasma corticosterone were highest during the early hours of darkness and lowest during the hours of light. Following hypophysectomy, the level of renal ornithine decarboxylase activity declined rapidly and remained low and without a demonstrable diurnal rhythm. When pituitary hormone levels were temporarily restored in the hypophysectomized rat by the injection of pituitary extract, renal ornithine decarboxylase activity increased rapidly, reached a peak within 8 hours, and returned toward pre-injection levels by 12 hours. Exogenous growth hormone, ACTH and cortisol each increased renal ornithine decarboxylase activity in the hypophysectomized rat, with the highest levels of activity being achieved with growth hormone. Other pituitary hormones (FSH, LH, TSH and prolactin) were ineffective. After bilateral adrenalectomy, renal ornithine decarboxylase activity retained a rhythmical pattern similar to that observed in the intact rat, but the levels were increased. Growth hormone and cortisol increased renal ornitine decarboxylase activity in the adrenalectomized-hypophysectomized animal to the same extent as in the hypophysectomized animal, but ACTH was almost totally ineffective. These data suggest that the pituitary plays a major role in the regulation of renal ornithine decarboxylase activity in the rat, primarily through the rhythmical secretion of growth hormone and ACTH.
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PMID:Hormonal regulation of renal ornithine decarboxylase activity in the rat. 17 86

The activities of ornithine and S-adenosyl-L-methionine decarboxylase were assayed in the thymuses of adult rats killed at 7-day intervals up to 6 wk after either pinealectomy or sham pinealectomy. The absence of the pineal gland markedly influenced the ornithine decarboxylase activity in the thymus, in which the level of the enzyme was decreased permanently by the 4th wk after the operation (P less than 0.05). The time course of the changes in S-adenosyl-L-methionine decarboxylase activity in the thymus during the entire period investigated was also significantly (P less than 0.05) modified by pinealectomy but did not show any stable trend. Adrenalectomy significantly raised (P less than 0.001) for ornithine decarboxylase; P less than 0.01 for S-adenosyl-L-methionine decarboxylase) the basal levels of the thymic biosynthetic polyamine decarboxylases. A pharmacological dose of corticosterone or cortisol produced a rapid and significant decrease in ornithine and S-adenosyl-L-methionine decarboxylase activities (P less than 0.02) in the thymus, whereas the injection of either D-aldosterone or ACTH was ineffective. Therefore, the thymic biosynthetic polyamine decarboxylases that in this organ are known to be located only in the lymphocytes appear to be regulated in opposing ways by the pineal gland and by the adrenal cortex.
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PMID:Endocrine regulation of thymic biosynthetic polyamine decarboxylases in adult rat. 22 48

Adrenalectomy as well as single or multiple hydrocortisone and ACTH administration have been studied for their effect on putrescine, spermidine and spermine contents, ornithine decarboxylase and S-adenosyl-+methionine decarboxylase activities in the rat hypothalamic and hippocampal tissues and fraction of nervous endings. The data obtained prove complicated character of changes in polyamine metabolism in the studied structures when glucocorticoid level is disturbed. Hormone action is characterized by regional and intracellular specificity and depends upon the ratio of administration and the initial hormonal background of the organism. The significance of these changes for feedback regulation of ACTH secretion and metabolism of GABA is discussed.
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PMID:[Polyamines in the hypothalamus and hippocampus after the changes in corticosteroid levels in rats]. 164 33

We have reported previously that expression of the human apolipoprotein E (apoE) gene in mouse Y1 adrenocortical cells suppresses basal and adrenocorticotropin (ACTH)-stimulated steroidogenesis. To understand the mechanism of this suppression, we have examined the integrity of cAMP regulated events required for adrenal steroidogenesis. Both acute and chronic responses to ACTH or cAMP are suppressed in Y1 cells which express apoE (Y1-E cells) as compared with parental Y1 cells. Acute morphologic changes in response to cAMP and acute induction of steroidogenesis by cAMP are suppressed in the Y1-E cell lines. Constitutive expression of P450-cholesterol side chain cleavage enzyme mRNA, the rate-limiting enzyme in steroid hormone synthesis, is reduced up to 11-fold in the Y1-E cell lines. The level of mRNA encoding P450-cholesterol side chain cleavage correlates directly with the reduction in basal steroid production observed in the individual Y1-E cell lines. Expression of P450-11 beta-hydroxylase mRNA, although readily detectable in Y1 parent cells, is absent or reduced in the Y1-E cell lines. Inhibition of cAMP-regulated gene expression is not restricted to genes required for steroid synthesis, since cAMP induction of ornithine decarboxylase mRNA is also inhibited in the Y1-E cell lines. These data indicate that suppression of steroidogenesis in Y1-E cells is due, at least in part, to inhibition of cAMP-regulated gene expression. These effects are not due to a defective cAMP-dependent protein kinase, since kinase activity in vitro and activation in vivo are unaltered in the Y1-E cell lines. These results suggest that expression of apoE in Y1 cells blocks cAMP-mediated signal transduction at a point distal to activation of cAMP-dependent protein kinase.
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PMID:Suppression of cAMP-mediated signal transduction in mouse adrenocortical cells which express apolipoprotein E. 165 49

It has been shown that single or multiple hydrocortisone and ACTH administrations to intact rats increased GABA content and its synthesis from glutamate and putrescine in synaptosomes of hypothalamus. The letter content was increased by single hormonal administration while multiple hormonal administration and adrenalectomy decreased it. Ornithine decarboxylase activity was increased by single hydrocortisone administration to intact animals, following adrenalectomy, and it was decreased by single hormonal administration to adrenalectomized rats. GABA synthesis in synaptosomes of hippocampus from putrescine was increased by single hydrocortisone and multiple hormonal administrations. GABA content was increased by multiple administration of both hormones and was decreased by adrenalectomy. Putrescine level was decreased by multiple hydrocortisone administration to intact and single administration to adrenalectomized rats; ornithine decarboxylase activity was decreased by multiple administration of both hormones.
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PMID:[Formation of gamma-aminobutyric acid from glutamate and putrescine in rat hypothalamic and hippocampal synaptosomes and regulation of these processes by glucocorticoids]. 168 16

Adrenal ornithine decarboxylase (ODC) is greatly elevated in rats dosed once with one of several insecticides; chlordecone, p,p'DDT or permethrin. An abrupt rise in the dose-response curve was apparent between 25 and 50 mg chlordecone/kg body wt, corresponding to the range where major behavioral changes occur. The latter dose of chlordecone resulted in a persistent elevation of adrenal ODC for at least 4 days, longer than that caused by the other insecticides examined. No equivalent changes were found in levels of hypothalamic or hippocampal ODC after chlordecone treatment. Hypophysectomy did not reduce the response of adrenal ODC to chlordecone, after the diminished size of the adrenal gland in operated animals was taken into account. Isolated adrenal cortical cells of a mouse tumor line (Y-1), when incubated in media containing 10(-5) M chlordecone, responded with increased ODC activity. These data suggest that the mechanism of adrenal activation by chlordecone may possess a direct component, in addition to the well-characterized stimulation of pituitary ACTH secretion caused by chlordecone acting on the hypothalamo-hypophyseal system.
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PMID:Modulation of adrenal ornithine decarboxylase by chlordecone, p,p'DDT and permethrin. 243 15

The implication of polyamines in cellular growth and differentiation processes and the existence of a polyamine-mediated protein phosphorylation system in adrenocortical cells suggest that polyamines may be examined as potential intracellular messengers in the pleiotypic action of ACTH. Bovine adrenocortical cells in culture exhibit a specific, energy-dependent, partly sodium-supported, inward polyamine transport system, independent of the A, L, and N aminoacid uptake systems. Steroidogenic concentrations of ACTH (10(-12) to 10(-9)M) induced a rapid activation of the polyamine uptake, resulting in a 2- to 3-fold increase in intracellular polyamine content, over 1 h. The ACTH dose-response curves for steroidogenic activity and for polyamine uptake were similar. Other adrenocortical effectors such as angiotensin II, acetylcholine, and the phorbol ester 12-O-tetradecanoylphorbol-13-acetate (TPA) activated polyamine uptake with a pattern parallel to their steroidogenic potency (i.e. ACTH greater than angiotensin II greater than acetylcholine, TPA). Steroidogenic concentrations of 8-bromo-cAMP displayed no effect on the adrenocortical polyamine uptake, suggesting that cAMP does not mediate this action of ACTH. On the other hand, ACTH induced a large increase in ornithine decarboxylase (ODC) activity in bovine adrenocortical cells, after a 6- to 8-h lag period, resulting in an average 2-fold increase in cell putrescine, spermidine, and spermine content. However, when the cells were previously polyamine loaded, ACTH-dependent ODC induction was suppressed. Adrenocortical cell polyamine content thus appears to be under hormonal control. ACTH may act through two possible pathways: 1) the rapid activation of the cell polyamine accumulation from an extracellular source and 2) the delayed increase in polyamine biosynthesis secondary to induction of ODC activity, when the cells are relatively depleted of the polyamines. These observations suggest that polyamines may function as intracellular messengers for some of the ACTH effects in bovine adrenocortical cells.
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PMID:Hormonal control of polyamine levels in bovine adrenocortical cells. 300 91

The activity of S-adenosylmethionine decarboxylase (SAM-DC) has been measured in the adrenal gland of rats given treatments that are known to result in increased activity of ornithine decarboxylase in this organ. In contrast to the effects of the dopamine agonists piribedil and apomorphine on the latter enzyme, the administration of these drugs caused decreases of SAM-DC in both parts of the gland. After piribedil the activity decreased rapidly to a minimum at 2-4 h, with recovery by 6 h. The stress of immobilization or the administration of insulin or 2-deoxyglucose (2-DG) also decreased adrenal SAM-DC activity. The results contrast with those observed in other rat tissues where SAM-DC is generally induced by treatments that induce ornithine decarboxylase. Denervation of the adrenal gland did not clearly affect the reduction in adrenomedullary SAM-DC after 2-DG. Hypophysectomy resulted in reduced SAM-DC activity in both adrenal medulla and cortex; the activity could be restored by giving the animals 2 IU ACTH daily for 4 days. These changes in activity were parallelled by changes in immunoreactive protein. 2-DG did not decrease SAM-DC in hypophysectomized rats receiving maintenance ACTH dosage. This indicates the presence of hormonal control over the activity of SAM-DC in the adrenal medulla and cortex. Acute administration of an additional 10 IU ACTH to hypophysectomized rats on maintenance dosage of ACTH resulted in decreased SAM-DC activity in both adrenal medulla and cortex. These decreases were not abolished by inhibition of corticosteroid synthesis with metopirone. PRL and GH had no significant effect on adrenal SAM-DC activity of hypophysectomized rats. The reduction of SAM-DC activity in both parts of the gland of hypophysectomized rats with administration of (Bu)2cAMP suggests that cAMP may mediate the decreases in SAM-DC caused by the above treatments.
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PMID:Decreased activity of adrenal S-adenosylmethionine decarboxylase in rats subjected to dopamine agonists, metabolic stress, or bodily immobilization. 303 Jun 95

Adrenal ornithine decarboxylase activity was stimulated in a dose-related manner after administration of ACTH or dibutyryl ((6)N-2'-O-dibutyryl) cyclic AMP to hypophysectomized rats. Little effect was observed for 2 h, but striking increases in enzyme activity were observed 4 h after administration of these substances. Effects of ACTH and dibutyryl cyclic AMP were not secondary to stimulation of steroidogenesis, since hydrocortisone had no effect on adrenal ornithine decarboxylase although it did stimulate activity of the enzyme in the liver and kidney.ACTH, given subcutaneously to hypophysectomized rats, induced striking increases in adrenal cyclic AMP levels within 15-30 min with a fall towards the base line in 1 h. Increases in ornithine decarboxylase activity lag several hours after this endogenous cyclic AMP peak, in contrast to the stimulatin of steroidogenesis by the nucleotide that requires only 2-3 min. After graded doses of ACTH, increases in adrenal cyclic AMP levels at 30 min were paralleled by proportional increases in adrenal ornithine decarboxylase activity 4 h after hormone treatment. Whereas maximal levels of adrenal steroidogenesis have been observed at tissue cyclic AMP levels of 6 nmol/g. ACTH is capable of inducing increases in nucleotide levels up to 200 nmol/g or more. These high tissue levels of cyclic AMP, although unneccessary for maximal steroidogenesis, appear to stimulate adrenal ornithine decarboxylase activity. Several results in addition to the time lag in the stimulation of ornithine decarboxylase activity suggest a mechanism involving accumulation of the enzyme or some factor needed for its activity rather than direct activation of the enzyme by cyclic AMP. Thus, the addition of cyclic AMP directly to the ornithine decarboxylase assay mixture in vitro was without stimulatory effect. In addition, actinomycin D or cycloheximide in doses sufficient to block adrenal RNA and protein synthesis, respectively inhibited the stimulation of ornithine decarboxylase activity by ACTH in vivo. An adrenocortical cancer was found to maintain ornithine decarboxylase activity at very high levels, but did so at much lower cyclic AMP levels than those of ACTH-stimulated adrenals. It is concluded that ACTH stimulates adrenal ornithine decarboxylase activity and that this effect may be mediated by cyclic AMP. However, cyclic AMP be mediated by appear to be a determinant of the high level of enzyme activity found in adrenocortical cancer.
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PMID:Regulation of adrenal ornithine decarboxylase by adrenocorticotropic hormone and cyclic AMP. 435 78


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