Central Regulation of Adrenal Tyrosine Hydroxylase: Effect of Induction on Catecholamine Levels in the Adrenal Medulla and Plasma

The effect of induction of adrenal tyrosine hydroxylase (TH) by various centrally acting drugs on catecholamine levels in adrenal and plasma was investigated in rats. All the drugs tested, namely oxotremorine, Piribedil, B-HT 920, and HA-966, produced significant increases in adrenal dopamine content and plasma epinephrine level. Denervation of the adrenal abolished the increase in adrenal dopamine as it did the induction of tyrosine hydroxylase. The results suggest that the induced increase of adrenal TH activity, as mediated by certain drugs, results in an elevation of the plasma epinephrine level and that the adrenal dopamine content is a better indicator of the catecholamine-synthesizing capacity of the adrenal medulla than are the other catecholamines.     

Stimulation of Ornithine Decarboxylase Activity in Neural Cell Culture: Potential Role of Insulin

Abstract: Age-dependent decreases in the levels of ornithine decarboxylase activity were observed in the optic lobes, cerebral hemispheres, and midbrain-diencephalon of 6–17-day-old chick embryos. In dissociated cell cultures from chick embryonic brains a similar pattern of declining ornithine decarboxylase activity with time in culture was observed. Ornithine decarboxylase activity in the dissociated brain cell cultures was stimulated by changing the culture medium. The peak stimulatory effect was shown to occur 12 h after changing the medium. Although serum-free medium stimulated ornithine decarboxylase activity slightly, the presence of serum in the medium was the primary stimulatory factor. Both fetal calf serum and heat-inactivated fetal calf serum produced dose-dependent stimulation of ornithine decarboxylase activity. Dialyzed fetal calf sera stimulated ornithine decarboxylase, but to a lower level than that produced by nondialyzed sera. Insulin (0.5–10 μg/ml) stimulated ornithine decarboxylase activity in a dose-dependent manner in serum free medium. In addition, 10² M-L-asparagine stimulated ornithine decarboxylase activity in serum-free medium.     

Detection of Ornithine Decarboxylase Antizyme in Mouse Brain

Ornithine decarboxylase, the rate-limiting enzyme in polyamine synthesis, is known to be regulated by a macromolecular inhibitor, termed antizyme, in a number of cellular systems. The present results show that the antizyme is also a functional component of polyamine metabolism in the brain. It could be demonstrated both in normal randomly selected mice and in animals which had been subjected either to intracerebroventricular injection of saline, which is known to cause a transient activation of ornithine decarboxylase, or to 1,3-diamino-2-propanol, an antizyme-inducing agent. When compared to tissues or cell systems studied so far, the cytosol fraction from mouse brain homogenate appeared to contain an exceptionally high amount of antizyme, that was bound to some material other than active ornithine decarboxylase. This feature was seen in all the animal groups studied, being most prominent after saline injection, when the amount of dissociable antizyme exceeded 14-fold the corresponding released ornithine decarboxylase activity. In untreated animals the excess was about eightfold and after 1,3-diamino-2-propanol about fivefold.     

Transcription-Independent Activation of Ornithine Decarboxylase Activity by Heparin in Cloned Cerebral Endothelial Cells

Abstract: Heparin, a highly sulfated glycosaminoglycan, is known to be obligatory for long-term endothelial cell cultures; it potentiates the mitogenic activities of endothelial cell growth factors and prolongs the replicative life span of the cells. Here we have shown that besides its growth factor-supportive role, heparin exerts a specific action on cerebral capillary endothelial cells (cECs), unrelated to serum or growth factors, by increasing activity of ornithine decarboxylase (ODC; EC 4.1.1.17) in these cells. For our experiments we have used two different types of cloned cECs: type I cECs, grown in the presence of endothelial cell growth factor and heparin, and type II cECs, usually cultivated without growth factors. Heparin action on ODC activity was shown to be dose dependent within the range of 1–100 μg/ml. Increasing concentrations of or depletion of endothelial cell growth factor from type I cultures had no effect on ODC activity. The increase in enzyme activity was highest after 30 min to 1 h of heparin treatment. As evidenced by northern analysis, the heparin-mediated enhancement of ODC activity was not accompanied by changes of ODC mRNA levels. Studies of DNA replication revealed that in the absence of heparin-binding growth factors, heparin did not affect the proliferative activity of cloned cECs.     

Polyamines, Ornithine Decarboxylase, and Diamine Oxidase in the Substantia Nigra and Striatum of the Male Rat After Hemitransection

Partial hemitransection at the mesodiencephalic junction in the rat increased striatal and nigral putrescine concentrations on the lesioned side for at least 168 h, with maximal increases between 24 and 48 h. Spermidine and spermine levels declined at 24 h in the striatum, rising above control values at 48 h and further at 168 h. In the substantia nigra, they remained unchanged for the first 48 h and then increased by 168 h. Cadaverine in the striatum also increased at 48 h. On the intact side putrescine increased but to a much lesser extent (at 48 h in the striatum and at 24 and 48 h in the substantia nigra). Ornithine decarboxylase and diamine oxidase activities showed maximal increases at 24 h in the striatum of the lesioned side, whereas in the substantia nigra ornithine decarboxylase attained a very high value as early as 4 h after the operation and diamine oxidase activity peaked at 48 h. The enzyme activities returned toward the basal values at 168 h. On the intact side, ornithine decarboxylase showed a small increase starting at 4 h and diamine oxidase was enhanced at 48 h. These results indicate that the stimulation of biosynthetic and degradative enzymes of polyamine metabolism accompanied by marked and prolonged increases in putrescine may be essential events in the early phases of neuronal response to mechanical injury in the CNS.     

Ornithine Decarboxylase Activity in Brain Regulated by a Specific Macromolecul, the Antizyme

Mouse brain ornithine decarboxylase activity is about 70-fold higher at the time of birth compared with that of adult mice. Enzyme activity declines rapidly after birth and reaches the adult level by 3 weeks. Immunoreactive enzyme concentration parallels very closely the decrease of enzyme activity during the first postnatal week, remaining constant thereafter. The content of brain antizyme, the macromolecular inhibitor to ornithine decarboxylase, in turn is very low during the first 7 days and starts then to increase and at the age of 3 weeks it is about six times the level of that in newborn mice. This may explain the decrease in enzyme activity during brain maturation, and suggests the regulation of polyamine biosynthesis by an antizyme-mediated mechanism in adult brain.     

Involvement of an "Antizyme'' in the Inactivation of Ornithine Decarboxylase

DL-Allylglycine causes a marked increase in mouse brain ornithine decarboxylase (ODC) activity. The amount of immunoreactive enzyme protein increases concomitantly with the activity, but the enzyme protein decreases more slowly than that of the activity. The amount of immunoreactive ODC in brain is many hundred times that of the catalytically active enzyme. The fact that mouse brain cytosol contains high amounts of dissociable antizyme (an inactivating protein) indicates the existence of an inactive, immunoreactive ODC-antizyme pool. The total antizyme content does not change markedly, but instead there are significant changes in different antizyme pools. Putrescine concentrations start to increase 8 h after treatment with allylglycine and concomitantly with this increase, antizyme is released to inhibit enzyme activity. These results indicate the involvement of antizyme in the inactivation process of ODC.     

Ornithine Decarboxylase Activity During Development of Cerebellar Granule Neurons

Abstract: Ornithine decarboxylase (ODC), the key enzyme for polyamine biosynthesis, dramatically decreases in activity during normal cerebellar development, in parallel with the progressive differentiation of granule neurons. We have studied whether a similar pattern is displayed by cerebellar granule neurons during survival and differentiation in culture. We report that when granule cells were kept in vitro under trophic conditions (high K⁺ concentration), ODC activity progressively decreased in parallel with neuronal differentiation. Under nontrophic conditions (cultures kept in low K⁺ concentration), the enzymatic activity dropped quickly in parallel with an increased apoptotic elimination of cells. Cultures kept in high K⁺ but chronically exposed to 10 m M lithium showed both an increased rate of apoptotic cell death at 2 and 4 days in vitro and a quicker drop of ODC activity and immunocytochemical staining. A short chronic treatment of rat pups with lithium also resulted in transient decrease of cerebellar ODC activity and increased programmed cell death, as revealed by in situ detection of apoptotic granule neurons. The present data indicate that a sustained ODC activity is associated with the phase of survival and differentiation of granule neurons and that, conversely, conditions that favor their apoptotic elimination are accompanied by a down-regulation of the enzymatic activity.     

Ornithine Decarboxylase Activity and Edema Formation in Cerebral Ischemia of Conscious Gerbils

Abstract: General anesthetic agents often affect the biochemical and physiologic changes triggered by cerebral ischemia. This study examined the regional activities of ornithine decarboxylase (ODC) in gerbils subjected to 5 min of bilateral carotid occlusion without anesthesia. At 2, 4, and 6 h of reperfusion, significant ODC activity was observed in both the cortex and the hippocampus. Pretreatment with α-difluoromethylornithine (DFMO) significantly blocked the ODC activity at 2, 4, and 6 h. Significant edema formation was found at 2, 4, and 6 h. At 2 h, edema formation was unaffected by administration of DFMO. However, DFMO treatment reduced later edema formation at 4 and 6 h. These results demonstrate that ODC activity and edema formation are delayed in gerbils after the induction of transient ischemia even with the removal of anesthetic agents and their potentially protective effects. These findings suggest that ODC activity and its induction of delayed cerebral edema are specific to cerebral ischemia and not to an anesthetic effect. DFMO treatment reduced both the ODC activity and edema formation, indicating a role for polyamines in postischemic edema formation.     

雄激素对人前列腺细胞中鸟氨酸脱羧酶基因表达的调节作用

 为探讨雄激素对人前列腺中鸟氨酸脱羧酶（ Ｏ Ｄ Ｃ）基因表达的调节作用,以研究雄激素诱导前列腺良性增生的分子机理,分离培养了人胎儿前列腺间质细胞,以 Ｍ Ｔ Ｔ 法测定不同浓度 Ｄ Ｈ Ｔ对细胞的促增殖作用;以最适浓度的 Ｄ Ｈ Ｔ（１ ０００ μｇ／ Ｌ）刺激该细胞,分别于 ０,３,６,１２,２４,３０ ｈ 提取总 Ｒ Ｎ Ａ,用斑点杂交及 Ｎｏｒｔｈｅｒｎ ｂｌｏｔ 法分析测定各组细胞中 Ｏ Ｄ Ｃ ｍ Ｒ Ｎ Ａ 的丰度,并对杂交膜进行薄层扫描定量．结果显示：（１） Ｄ Ｈ Ｔ 对前列腺间质细胞的增殖呈双相调节作用,即在低浓度时随着 Ｄ Ｈ Ｔ 浓度的增加,对该细胞的促增殖作用增强,１ ０００ μｇ／ Ｌ时刺激活性最强,高浓度 Ｄ Ｈ Ｔ 对该细胞的刺激作用降低．（２）斑点杂交显示,在 １ ０００ μｇ／ Ｌ Ｄ Ｈ Ｔ 刺激细胞后 ６ ｈ 时, Ｏ Ｄ Ｃ ｍ Ｒ Ｎ Ａ开始明显升高,２４ ｈ 达高峰（约为 ０ ｈ 的 ４８ 倍）,至 ３０ ｈ 有所降低．（３） Ｎｏｒｔｈｅｒｎ ｂｌｏｔ 结果显示,人胎儿前列腺间质细胞中有两种 Ｏ Ｄ Ｃ ｍ Ｒ Ｎ Ａ,分别为 ２０ ｋｂ 和 ２６ ｋｂ,经扫描定量结果显示：１ ０００μｇ／ Ｌ Ｄ Ｈ Ｔ 对两种 Ｏ Ｄ Ｃ ｍ Ｒ Ｎ Ａ     

Effects of Insulin on Cultured Rat Brain Cells: Stimulation of Ornithine Decarboxylase Activity

Abstract: Growth-promoting peptide hormones, including growth hormone and insulin, stimulate rat brain ornithine decarboxylase (ODC; EC 4.1.1.17) activity in vivo (Roger et al., 1974; Roger and Fellows, 1980). To determine if this is a result of a direct action on brain, we have investigated the effect of peptide hormones in primary cell cultures of brain from fetal rats of 20 days gestational age. Significant stimulation of ODC activity was observed 4 h after administration of porcine insulin and bovine growth hormone. On a molar basis, growth hormone was less potent than insulin. By contrast, glucagon, enkephalin, and angiotensin II did not stimulate ODC in this system. At 25 ng/ml, insulin stimulated ODC activity approximately threefold, with maximum stimulation of five- to sevenfold reached at 1 μg/ml. After a 1-h lag, insulin-stimulated ODC activity increased to a maximum between 5 h and 8 h and returned to basal levels by 24 h. The apparent K_m of ODC, 5.66 ± 1.16μM, was not significantly altered by insulin treatment, nor was any enzyme activator found in mediating insulin actions. Additional evidence suggests that insulin stimulation of ODC activity involves both de novo synthesis of the enzyme and a prolongation of ODC half-life by 50%. These findings, implicating insulin as a regulator of ODC activity in brain cells, suggest the possible involvement of insulin or an insulin-like peptide in the control of growth and development of the CNS.     

Reciprocal Regulation of Ornithine Decarboxylase and Choline Kinase Activities by Their Respective Reaction Products in the Developing Rat Cerebellar Cortex

Changes in the activity of choline kinase were measured in the cerebellum during development. Early transient increase was found in the enzyme activity just prior to and during birth. This period of increase did not coincide with the periods of transient elevation in ornithine decarboxylase and choline acetyltransferase previously observed in the developing cerebellum. The effects of the naturally occurring polyamines (putrescine, spermidine, and spermine) on choline kinase and choline acetyltransferase activities, and of phosphorylcholine (the product of the reaction catalyzed by choline kinase) on ornithine decarboxylase and choline acetyltransferase activities, were also examined. Choline acetyltransferase activity was not influenced by either polyamines or phosphorylcholine. However, choline kinase activity from 7-day-old, but not from adult, cerebellum was increased 25% in the presence of 4 mM spermine. In contrast, low spermidine concentrations (less than 2 mM) inhibited choline kinase activity selectively in 7-day-old cerebellum. Ornithine decarboxylase activity from 7-day-old cerebellum was inhibited in a concentration-dependent manner by phosphorylcholine. The present data together with other previous reports suggest that: (a) polyamines may play a role in choline utilization during development via their regulation of choline kinase activity, on the one hand, and of acetylcholinesterase activity on the other; and (b) during development, a reciprocal regulation of choline kinase and ornithine decarboxylase activities by their respective reaction products may exist, whereby choline kinase activity is regulated in a complex manner by polyamines and, in turn, ornithine decarboxylase is inhibited by phosphorylcholine.     

Ornithine Decarboxylase Induction by Glucocorticoids in Brain and Liver of Adrenalectomized Rats

Abstract: Ornithine decarboxylase (ODC), the rate-limiting enzyme in the biosynthesis of polyamines, was measured in the brain and the liver of adrenalectomized rats after an acute S.C. treatment with glucocorticoids. The effects of corticosterone and dexamethasone were compared in three brain areas, the cerebral cortex, hippocampus, and cerebellum. These structures have similar concentrations of cytosolic glucocorticoid receptor, as measured by an in vitro exchange assay using a specific glucocorticoid ligand, [³H]RU 26988, but contain different amounts of mineralocorticoid receptor. Corticosterone and dexamethasone increased ODC activity in the liver and brain areas in a dose dependent manner, dexamethasone being more active than corticosterone in all tissues. Moreover, estradiol, progesterone, and testosterone were inactive. Aldosterone, at high doses, increased brain ODC activity. Glucocorticoids, selected for their weak binding, or lack of binding to the mineralocorticoid receptor, were tested and found to be highly active in inducing brain and liver ODC, thus showing that ODC induction by steroids is specific for glucocorticoids. These results are among the first to suggest biochemically a central action of glucocorticoids following an acute treatment and confirm that the brain is a glucocorticoid target organ.     

A Developmental Study of Neuron-Specific Enolase in Rat Adrenal Medulla

Abstract: The levels of neuron-specific enolase (NSE) in rat adrenal medulla increase with age. A sharp increase was observed until the age of 15 days. At this time, the NSE level dropped slightly, followed by a gradual increase until the rats were 1 year old. The adrenal medullary NSE levels in males were higher than those observed in females. The difference was seen from 32 days of age, but was not statistically significant until 1 year. This study indicates that NSE can be used as a marker for differentiation in adrenal medulla, as it is used in the central nervous system and in neuroblastoma and pheochromocytoma cells.     

Induction of Ornithine Decarboxylase in Cerebral Cortex by Excitotoxin Lesion of Nucleus Basalis: Association with Postsynaptic Responsiveness and N-Methyl-d-Aspartate Receptor Activation

The major cholinergic innervation of the rat cerebral cortex arises from the nucleus basalis in the basal forebrain. Introduction of the excitotoxins kainate or ibotenate into the nucleus basalis by stereotaxic injection results in degeneration of the cholinergic cells. We have investigated the effect of this excitotoxic action on ornithine decarboxylase (ODC) activity and cholinergic responsiveness in the cerebral cortex. A massive and rapid induction of ODC activity was seen in ipsilateral cortex after injection of excitotoxin. A maximal increase in ODC activity of 268 times the control value was seen in ipsilateral cerebral cortex 8 h after lesioning. Thereafter, ODC activity declined but remained significantly greater than control levels for 32 h. Pretreatment of animals with the irreversible ODC inhibitor difluoromethylornithine prevented the induction of ODC by kainate. Tissue content of the ODC product putrescine showed a marked increase in cerebral cortex ipsilateral to the lesion, increasing sevenfold at 24 h, the maximal concentration reached. After 24 h, the level of putrescine decreased but remained significantly elevated above control values for 5 days. Levels of the polyamines spermidine and spermine were unaffected by lesioning. Increases on ODC activity of much smaller magnitude were also seen in brain regions not directly innervated from the ipsilateral nucleus basalis. However, the response in ipsilateral cortex was found to be dependent on an intact projection from nucleus basalis to cortex. The induction of ODC was shown to be prevented by treatment of rats with MK-801, a result indicating the involvement of N-methyl-D-aspartate (NMDA) receptors.(ABSTRACT TRUNCATED AT 250 WORDS)     

Effects of Electroconvulsive Shock on Tetrahydrobiopterin and GTP-Cyclohydrolase Activity in the Brain and Adrenal Gland of the Rat

The effects of a single and repeated electroconvulsive shock (ECS) (300 mA, 0.2 s) on tetrahydrobiopterin (BH4) levels and GTP-cyclohydrolase activity in the brain and adrenal glands of rats were examined. Twenty-four hours after the last ECS treatment (one/day for 7 days), biopterin levels were significantly elevated in the locus coeruleus, hippocampus, frontal cortex, hypothalamus, ventral tegmental area, and adrenal gland. There were no changes in biopterin levels after a single application of ECS. GTP-cyclohydrolase activity was significantly increased in the locus coeruleus, frontal cortex, hippocampus, hypothalamus, and adrenal gland 24 h after repeated ECS and remained elevated in certain tissues up to 8 days after the last treatment. Kinetic analysis of adrenal and locus coeruleus GTP-cyclohydrolase 1 day after 7 days of ECS showed significant changes in both Km and Vmax values. These data suggest that the long-term increases in BH4 levels and GTP-cyclohydrolase activity after repeated ECS may play a part in the mediation of the antidepressant effects of ECS.     

Effects of Denervation and Axotomy on Nervous System-Specific Protein, Ornithine Decarboxylase, and Other Enzyme Activities in the Superior Cervical Sympathetic Ganglion of the Rat

The time courses of changes of three enolase isozymes (alpha alpha, alpha gamma, and gamma gamma), S-100 protein, 2',3'-cyclic nucleotide 3'-phosphodiesterase (CNPase), ornithine decarboxylase (ODC), beta-galactosidase, and glucose-6-phosphate dehydrogenase (G6PDH) were examined from 1 to 14 days after cutting of the preganglionic nerve (denervation) or the postganglionic nerve (axotomy) of the superior cervical sympathetic ganglion (SCG) of the rat. The wet weight and protein content in the axotomized SCG increased continuously, to nearly twice those of the denervated SCG for 1-2 weeks after the operations. Among enolase isozymes in the SCG, neuron-specific gamma gamma-enolase decreased rapidly after denervation and stayed at a low level for 2 weeks, whereas the isozyme remained almost unchanged after axotomy. On the contrary, ganglionic alpha alpha-enolase and the alpha gamma-hybrid form increased remarkably to reach a maximum at the second day after axotomy, and remained above control for 1 to 2 weeks; these two enolase isozymes showed little change after denervation. Denervation caused a much larger increase than did axotomy in the ganglionic S-100 protein, an astrocyte-specific protein, during the first week after the operation, while the protein content decreased after 2 weeks of either denervation or axotomy. CNPase, a myelin-associated enzyme, rose suddenly 2 days after axotomy, and remained at a rather high level compared with the denervated ganglion, which showed little variation.(ABSTRACT TRUNCATED AT 250 WORDS)     

Ornithine Decarboxylase in Human Brain: Influence of Aging, Regional Distribution, and Alzheimer's Disease

Abstract: Although experimental animal data have implicated ornithine decarboxylase, a key regulatory enzyme of polyamine biosynthesis, in brain development and function, little information is available on this enzyme in normal or abnormal human brain. We examined the influence, in autopsied human brain, of postnatal development and aging, regional distribution, and Alzheimer's disease on the activity of ornithine decarboxylase. Consistent with animal data, human brain ornithine decarboxylase activity was highest in the perinatal period, declining sharply (by ∼60%) during the first year of life to values that remained generally unchanged up to senescence. In adult brain, a moderately heterogeneous regional distribution of enzyme activity was observed, with high levels in the thalamus and occipital cortex and low levels in cerebellar cortex and putamen. In the Alzheimer's disease group, mean ornithine decarboxylase activity was significantly increased in the temporal cortex (+76%), reduced in occipital cortex (−70%), and unchanged in hippocampus and putamen. In contrast, brain enzyme activity was normal in patients with the neurodegenerative disorder spinocerebellar ataxia type I. Our demonstration of ornithine decarboxylase activity in neonatal and adult human brain suggests roles for ornithine decarboxylase in both developing and mature brain function, and we provide further evidence for the involvement of abnormal polyamine system activity in Alzheimer's disease.