Effects of CDPcholine and CDPethanolamine on the alterations in rat brain lipid metabolism induced by global ischemia

Phospholipid and Lipid Derivatives as Potential Neuroprotective Compounds

The worldwide demographical trend is changing towards a more elderly population. In particular, this phenomenon is increasing the number of neurodegenerative disease cases (e.g., Alzheimer’s disease) in advanced countries. Therefore, there is a fertile field for neuroprotective approaches to address this problem. A useful strategy to protect the membrane integrity of cells and reduce inflammatory processes. In this context, the neurons represent particularly vulnerable cells. Thus, a protection strategy should include their membrane preservation and improved anti-inflammatory processes. The contribution of phospholipid derivatives to this issue is crucial and many articles evidence their role in both health and disease. On the other hand, some lipids containing choline actively participate to increase the choline levels in the nervous system. It is acknowledged that the cholinergic system plays a pivotal role both in the central and in the peripheral nervous system. Neurons cannot synthesize choline, which is provided by the diet. The reuptake of ACh and its hydrolysis represent the principal source of choline. Therefore, to cover choline needs, choline-containing lipids may be used. There are different works which demonstrate their neuroprotective features This review article analyzes phospholipid and lipid derivatives that through different mechanisms are involved in these protective processes, although, sometimes the same molecules may behave as neurotoxic elements, therefore, their protective machinery should be detailed better.

Citicoline in severe traumatic brain injury: indications for improved outcome : A retrospective matched pair analysis from 14 Austrian trauma centers

Goal-oriented management of traumatic brain injury (TBI) can save the lives and/or improve the long-term outcome of millions of affected patients worldwide. Additionally, enhancing quality of life will save enormous socio-economic costs; however, promising TBI treatment strategies with neuroprotective agents, such as citicoline (CDP-choline), lacked evidence or produced contradictory results in clinical trials. During a prehospital TBI project to optimize early TBI care within 14 Austrian trauma centers, data on 778 TBI patients were prospectively collected. As preceding evaluations suggested a beneficial outcome in TBI patients treated at the Wiener Neustadt Hospital (WNH), we aimed to investigate the potential role of citicoline administration, solely applied in WNH, in those patients. In a retrospective subgroup analysis we compared 67 patients from WNH with citicoline administration and 67 matched patients from other Austrian centers without citicoline use. Patients with Glasgow Coma Scale score <13 on site and/or Abbreviated Injury Scale of the region "head" >2 were included. Our analysis revealed significantly reduced rates of intensive care unit (ICU) mortality (5% vs. 24%, p < 0.01), in-hospital mortality (9% vs. 24%, p = 0.035) and 6‑month mortality (13% vs. 28%, p = 0.031), as well as of unfavorable outcome (34% vs. 57%, p = 0.015) and observed vs. expected ratio for mortality (0.42 vs. 0.84) in the WNH (citicoline receivers) group. Despite the limitations of a retrospective subgroup analysis our findings suggest a possible correlation between early and consequent citicoline administration and beneficial outcomes. Therefore, we aim to set up an initiative for a prospective, multicenter randomized controlled trial with citicoline in sTBI (severe TBI) patients.

Protective effect of CDP-choline on ischemia-reperfusion-induced myocardial tissue injury in rats

BACKGROUND

CDP-choline exerts tissue protective effect in several ischemic conditions. Recently we have reported that the drug prevents cardiac arrhythmias and improves survival rate in short-term myocardial ischemia reperfusion in rats.

AIM

In the current study, we determined the effect of intravenously administered CDP-choline on myocardial tissue injury induced by 30-min ischemia followed by 3-h reperfusion in anesthetized rats.

METHODS

Myocardial ischemia was produced by ligature of the left main coronary artery. CDP-choline (100-500 mg/kg) was intravenously injected in the middle of the ischemic period. Cardiovascular parameters were recorded through the experimental period. At the end of the reperfusion period, the hearts of the animals were removed and stained for the investigation of tissue necrosis and apoptosis. The infarct size was evaluated as the ratio of the infarct area to the risk area. Apoptotic activation was assessed by TUNEL assay. Also the blood samples of rats were collected for the measurement of M30-M65, ADMA, homocysteine, and lactate levels.

RESULTS

Ischemia/reperfusion caused serious injury in myocardium, increased blood ADMA and lactate levels without influencing other parameters. CDP-choline significantly reduced the infarct size and the number of apoptotic cells in the risk area. Blood pressure increased after CDP-choline injection; however, it returned back to the basal levels before the onset of reperfusion. CDP-choline failed to alter any other measured parameters.

CONCLUSION

The present results demonstrate that intravenously administered CDP-choline is able to protect myocardium from injury induced by long-term coronary occlusion-reperfusion in rats. The inhibition of apoptosis by the drug may contribute to its protective effect. But neither the increase in blood pressure in response to CDP-choline injection nor changes in plasma ADMA concentration appear to mediate the attenuation of the myocardial injury.

Metabolism of cytidine (5?)-diphosphocholine (cdp-choline) following oral and intravenous administration to the human and the rat

We examined the effects of cytidine (5?)-diphosphocholine (CDP-choline) on plasma levels of cytidine, choline, and unchanged CDP-choline among normal volunteers receiving the substance orally or intravenously, and rats receiving it intravenously. Two hours after a single oral dose (2g), plasma choline levels were increased by 48% and plasma cytidine by 136%. Among subjects receiving three doses (2g each) at two-hour intervals, plasma choline peaked (30% over baseline) 4 h after the initial CDP-choline dose, while plasma cytidine levels continued to increase for at lest 6 h, at which time they were five times basal levels (P < 0.01). Intravenously-administered CDP-choline was rapidly hydrolysed, in both the human and the rat. In humans given the CDP-choline by infusion over 30 min, plasma CDP-choline fell to undetectable levels almost immediately after the end of the infusion period; plasma choline and cytidine peaked at that time, but their concentrations remained significantly elevated for at least 6 h. In rats given a bolus injection of CDP-choline, five minutes earlier, the unchanged compound was also undetectable in plasma, while plasma cytidine levels increased markedly and remained elevated for at least 60 min. These observations show that CDP-choline is converted to at least two major circulating metabolites, choline and cytidine. Since both of these compounds are used in the biosynthesis of phosphatidylcholine, both may be involved in the long-term effects of the CDP-choline.

CDP-choline treatment induces brain plasticity markers expression in experimental animal stroke

We investigated the effect of CDP-choline on brain plasticity markers expression in the acute phase of cerebral infarct in an experimental animal model. Male Sprague-Dawley rats were subjected to permanent middle cerebral artery occlusion (pMCAO) and treated or not with CDP-choline (500 mg/kg) daily for 14 days starting 30 min after pMCAO. Functional status was evaluated with Roger's test; lesion volume with magnetic resonance imaging (MRI) and hematoxylin and eosin staining (H&E); cell death with TUNEL; cellular proliferation with BrdU immunohistochemistry; vascular endothelial growth factor (VEGF), synaptophysin, glial fibrillary acidic protein (GFAP) and low-density lipoprotein receptor-related protein (LRP) by immunofluorescence and Western-blot techniques. CDP-choline significantly improved functional recovery and decreased lesion volume on MRI, TUNEL-positive cell number and LRP levels at 14 days. In addition, CDP-choline significantly increased BrdU, VEGF and synaptophysin values and decreased GFAP levels in the peri-infarct zone compared with the infarct group. In conclusion, our data indicate that CDP-choline improved functional recovery after permanent middle cerebral artery occlusion in association with reductions in lesion volume, cell death and LRP expression. In fact, CDP-choline increased cell proliferation, vasculogenesis and synaptophysin levels and reduced GFAP levels in the peri-infarct area of the ischemic stroke.

Citicoline, use in cognitive decline: vascular and degenerative

CDP-choline has been widespread used in humans for decades as a treatment for many types of cognitive impairment. Despite this, its mechanism of action still remains unclear, but several experimental models in acute cerebral ischaemia suggest that it could have a brain repair action. Due to the lack of significant adverse effects and its high tolerability, there has been a growing interest for this molecule in recent years. In this article, a review of the most significant published clinical trials in cognitive decline has been made. A few Citicoline trials have studied its effects at medium and long-term on vascular cognitive impairment and Alzheimer's disease. Results show that Citicoline seems to have beneficial impact on several cognitive domains, but the methodological heterogeneity of the these studies makes it difficult to draw conclusions about these effects. New trials with a greater number of patients, uniform diagnostic criteria for inclusion and standardized neuropsychological assessment are needed to evidence with much more consistency Citicoline efficacy upon cognitive disorders. The use of new neuroimaging procedures in current trials could be of great interest.

Effects of citicoline used alone and in combination with mild hypothermia on apoptosis induced by focal cerebral ischemia in rats

The effects of citicoline used either alone or in combination with hypothermia on the suppression of apoptotic processes after transient focal cerebral ischemia were investigated. Middle cerebral artery occlusion (MCAo) was performed for 2 hours on Sprague-Dawley (SD) rats using intraluminal thread insertion. The treatment groups were as follows: Group 1, sham-operated; Group 2, saline; Group 3, citicoline (400mg/kg intraperitoneal.); Group 4, hypothermia (34+/-1 degrees C); Group 5, citicoline+hypothermia. All rats were reperfused for 24 hours, and after sacrifice and transcardiac perfusion, immunohistochemical studies were performed for markers of apoptosis. In Group 2, the Bcl-2 immunostaining score (mean+/-standard deviation, 0.71+/-0.75) was lower compared to Groups 3, 4 and 5 (2.33+/-0.81; 3.00+/-0.00; 2.20+/-0.83; p<0.05). There was higher expression of caspase-3 proteins in Group 2 (2.28+/-0.95) compared to Group 5 (1.50+/-0.83; p<0.05). Bax proteins were also increased in Group 2 (1.85+/-1.06) compared to Group 5 (0.40+/-0.54) and in Group 4 (2.00+/-0.00) compared to Group 5 (0.40+/-0.54; p<0.05). Significant differences in caspase-9 immunostaining scores were found in Group 2 (2.29+/-0.96) compared to Group 5 (0.20+/-0.44) (p<0.05); Group 3 (1.00+/-0.70) compared to Group 5 (0.20+/-0.44; p<0.05); and Group 4 (3.00+/-0.00; p<0.05) compared to Group 5 (0.40+/-0.54; p<0.05). Thus by suppressing apoptotic processes citicoline with hypothermia is more effective than either used alone in ameliorating cerebral damage after transient focal ischemia.

Citicoline improves functional recovery, promotes nerve regeneration, and reduces postoperative scarring after peripheral nerve surgery in rats

BACKGROUND

Citicoline has been shown to have beneficial effects in a variety of CNS injury models. The aim of this study was to test the effects of citicoline on nerve regeneration and scarring in a rat model of peripheral nerve surgery.

METHODS

Seventy adult Sprague-Dawley rats underwent a surgical procedure involving right sciatic nerve section and epineural suturing. Rats were assigned to the control or experiment groups to receive a topical application of 0.4 mL of saline or 0.4 mL (100 micromol/L) of citicoline, respectively. Macroscopic, histological, functional, and electromyographic assessments of nerves were performed 4 to 12 weeks after surgery.

RESULTS

In the control versus citicoline-treated rats, SFI was -90 +/- 1 versus -84 +/- 1 (P < .001), -76 +/- 4 versus -61 +/- 3 (P < .001), and -66 +/- 2 versus -46 +/- 3 (P < .001) at 4, 8, and 12 weeks after surgery, respectively. At 12 weeks after surgery, axon count and diameter were 16400 +/- 600 number/mm(2) and 5.47 +/- 0.25 microm versus 22250 +/- 660 number/mm(2) (P < .001) and 6.65 +/- 0.28 microm (P < .01) in the control and citicoline-treated groups, respectively. In citicoline-treated rats, histomorphological axonal organization score at the repair site was (3.4 +/- 0.1) significantly better than that in controls (2.6 +/- 0.3) (P < .001). Peripheral nerve regeneration evaluated by EMG at 12 weeks after surgery showed significantly better results in the citicoline group (P < .05). Nerves treated with citicoline demonstrated reduced scarring at the repair site (P < .001).

CONCLUSION

Our results demonstrate that citicoline promotes regeneration of peripheral nerves subjected to immediate section suturing type surgery and reduces postoperative scarring.

Delayed post-ischemic administration of CDP-choline increases EAAT2 association to lipid rafts and affords neuroprotection in experimental stroke

Glutamate transport is the only mechanism for maintaining extracellular glutamate concentrations below excitotoxic levels. Among glutamate transporters, EAAT2 is responsible for up to 90% of all glutamate transport and has been reported to be associated to lipid rafts. In this context, we have recently shown that CDP-choline induces EAAT2 translocation to the membrane. Since CDP-choline preserves membrane stability by recovering levels of sphingomyelin, a glycosphingolipid present in lipid rafts, we have decided to investigate whether CDP-choline increases association of EAAT2 transporter to lipid rafts. Flotillin-1 was used as a marker of lipid rafts due to its known association to these microdomains. After gradient centrifugation, we have found that flotillin-1 appears mainly in fractions 2 and 3 and that EAAT2 protein is predominantly found colocalised with flotillin-1 in fraction 2. We have also demonstrated that CDP-choline increased EAAT2 levels in fraction 2 at both times examined (3 and 6 h after 1 g/kg CDP-choline administration). In agreement with this, [(3)H] glutamate uptake was also increased in flotillin-associated vesicles obtained from brain homogenates of animals treated with CDP-choline. Exposure to middle cerebral artery occlusion also increased EAAT2 levels in lipid rafts, an effect which was further enhanced in those animals receiving 2 g/kg CDP-choline 4 h after the occlusion. Infarct volume measured at 48 h after ischemia showed a reduction in the group treated with CDP-choline 4 h after occlusion. In summary, we have demonstrated that CDP-choline redistributes EAAT2 to lipid raft microdomains and improves glutamate uptake. This effect is also found after experimental stroke, when CDP-choline is administered 4 h after the ischemic occlusion. Since we have also shown that this delayed post-ischemic administration of CDP-choline induces a potent neuroprotection, our data provides a novel target for neuroprotection in stroke.

Uridine and cytidine in the brain: their transport and utilization

The pyrimidines cytidine (as CTP) and uridine (which is converted to UTP and then CTP) contribute to brain phosphatidylcholine and phosphatidylethanolamine synthesis via the Kennedy pathway. Their uptake into brain from the circulation is initiated by nucleoside transporters located at the blood-brain barrier (BBB), and the rate at which uptake occurs is a major factor determining phosphatide synthesis. Two such transporters have been described: a low-affinity equilibrative system and a high-affinity concentrative system. It is unlikely that the low-affinity transporter contributes to brain uridine or cytidine uptake except when plasma concentrations of these compounds are increased several-fold experimentally. CNT2 proteins, the high-affinity transporters for purines like adenosine as well as for uridine, have been found in cells comprising the BBB of rats. However, to date, no comparable high-affinity carrier protein for cytidine, such as CNT1, has been detected at this location. Thus, uridine may be more available to brain than cytidine and may be the major precursor in brain for both the salvage pathway of pyrimidine nucleotides and the Kennedy pathway of phosphatide synthesis. This recognition may bear on the effects of cytidine or uridine sources in neurodegenerative diseases.

Omega-3 fatty acid deficiency in major depressive disorder is caused by the interaction between diet and a genetically determined abnormality in phospholipid metabolism

Omega-3 fatty acids are a type of polyunsaturated fatty acid (PUFA). A growing body of evidence suggests that this form PUFA is a useful and well tolerated treatment for major depressive disorder, a common and serious mental illness. The efficacy of omega-3 PUFA is routinely explained as being due to a deficiency caused by inadequate dietary intake of this class of fatty acid. The hypothesis considered states that low omega-3 PUFA abundance in patients with major depressive and related disorders is due to an underlying genetically determined abnormality. The hypothesis can explain why although a specific and consistent deficit in omega-3, but not omega-6, PUFA occurs in major depressive and related disorders, the literature does not consistently support the notion that this is due to deficient dietary intake. Specifically it is hypothesized that having genetically determined low activity of fatty acid CoA ligase 4 and/or Type IV phospholipase A(2) combined with the low dietary availability of omega-3 PUFA results in reduced cellular uptake of omega-3 PUFA and constitutes a risk factor for depression. The hypothesis also has important consequences for the pharmacological treatment of depression in that it predicts that administering agents which enhance phospholipid synthesis, particularly those containing ethanolamine such as CDP-ethanolamine, should be effective antidepressants especially when co-administered with omega-3 PUFA.

Effects of citicoline on experimental spinal cord injury

OBJECTIVE

To investigate the effects of citicoline on experimental spinal cord injury (SCI).

BACKGROUND

Citicoline has been successfully used in clinical studies of head injury and cerebral infarction, but there is limited literature regarding its use in experimental SCI.

STUDY DESIGN

Twenty adult Wistar rats were divided into four groups: sham, trauma, vehicle, and citicoline-treated. SCI was produced using a weight drop technique. Citicoline 300 mg/kg was given intraperitoneally, 5 minutes after the induction of trauma. The animals were sacrificed and 1 cm long samples of injured spinal cord were obtained at 48 hours post-SCI. Lipid peroxidation was estimated by the thiobarbituric acid test. Neurological examinations were performed using a previously described grading scale.

RESULTS

Measures of lipid peroxidation and motor scores of the citicoline-treated group were significantly lower than those in the other injury groups.

CONCLUSIONS

Citicoline attenuated lipid peroxidation after SCI and improved the motor scores. Further investigations will be required to determine the long-term effects of this drug on spinal cord injury.

Neuroprotection afforded by prior citicoline administration in experimental brain ischemia: effects on glutamate transport

BACKGROUND AND PURPOSE

Cytidine-5'-diphosphocholine (citicoline or CDP-choline), an intermediate in the biosynthesis of phosphatidylcholine, has shown beneficial effects in a number of CNS injury models including cerebral ischemia. Citicoline is the only neuroprotectant that has proved efficacy in patients with moderate to severe stroke. However, the precise mechanism by which citicoline is neuroprotective is not fully known. The present study was designed to search for mechanisms of citicoline neuroprotective properties using in vivo and in vitro models of brain ischemia.

METHODS

Focal brain ischemia was produced in male adult Fischer rats by occluding both the common carotid and middle cerebral arteries. Brain glutamate levels were determined at fixed intervals after occlusion. Animals were then sacrificed, and infarct volume and brain ATP levels were measured. As in vitro model of ischemia, rat cultured cortical neurones or astrocytes, isolated or in co-culture, were exposed to oxygen-glucose deprivation (OGD) either in the absence or in the presence of citicoline (1-100 microM). Viability was studied by measuring LDH release. Glutamate release and uptake, and ATP levels were also determined.

RESULTS

Citicoline (0.5, 1 and 2 g/kg i.p. administered 1 h before the occlusion) produced a reduction of the infarct size measured at striatum (18, 27 and 42% inhibition, respectively, n = 8, P < 0.05 vs. ischemia), effect that correlated with the inhibition caused by citicoline on ischemia-induced increase in glutamate concentrations after the onset of the ischemia. Citicoline also inhibited ischemia-induced decrease in cortical and striatal ATP levels. Incubation of cultured rat cortical neurones with citicoline (10 and 100 microM) prevented OGD-induced LDH and glutamate release and caused a recovery in ATP levels after OGD, confirming our previous results. In addition, citicoline (100 microM) caused an increase in glutamate uptake and in EAAT2 glutamate transporter membrane expression in cultured rat astrocytes.

CONCLUSIONS

Our present findings show novel mechanisms for the neuroprotective effects of citicoline, which cooperate to decrease brain glutamate release after ischemia.

Cytidine-5'-diphosphocholine affects CTP-phosphocholine cytidylyltransferase and lyso-phosphatidylcholine after transient brain ischemia

Cytidine-5'-diphosphocholine (CDP-choline, also referred as citicoline), the key intermediate in phosphatidylcholine (PtdCho) synthesis, provided significant benefit in experimental central nervous system (CNS) injury including cerebral ischemia. CDP-choline is synthesized by CTP:phosphocholine cytidylyltransferase (CCT), the key rate-limiting enzyme in PtdCho synthesis. Phospholipase A(2) (PLA(2)) hydrolyzes PtdCho to produce free fatty acids and lyso-PtdCho, an inhibitor of CCT. We investigated the status of CCT and lyso-PtdCho after 10-min transient brain ischemia in gerbils with reperfusion up to 2 days. Ischemia with no reperfusion resulted in loss of CCT activity in cytosol (408 +/- 8 pmol/min/mg protein compared to sham 695 +/- 45; P < 0.01) and membrane (383 +/- 61 compared to sham 532 +/- 54; P < 0.05). CCT activity remained low over 24-hr reperfusion, and returned to sham levels at Day 2 in membrane but remained low in cytosol. CDP-choline significantly increased CCT activity in cytosol at 1 hr reperfusion (saline, 339 +/- 35 compared to CDP-choline, 430 +/- 70; P < 0.05) and in membrane at 6 hr (saline, 381 +/- 32 compared to CDP-choline, 489 +/- 50; P < 0.01) and 24 hr (saline, 417 +/- 24 compared to CDP-choline, 594 +/- 45; P < 0.01), but had no effect on CCT activity at Day 2. Lyso-PtdCho increased at 1-hr reperfusion (219 +/- 5 nmol/g tissue compared to sham, 92 +/- 8; P < 0.01), and remained elevated over 2 days. CDP-choline attenuated lyso-PtdCho levels at 1-hr reperfusion (162 +/- 21, P < 0.01 compared to saline). These data indicate that PtdCho synthesis is impaired after brain ischemia, and CDP-choline may increase PtdCho levels by attenuating the loss of CCT activity and lyso-PtdCho formation.

Lead-dependent effects on arachidonic acid accumulation and the proliferation of vascular smooth muscle

Lead (Pb(2+)) has been implicated in the development of hypertension and atherosclerosis. The proliferation of vascular smooth muscle cells (VSMC) is a central feature of both conditions and there is evidence that Pb(2+) potentiates serum-dependent cell growth. The aim of this work was to examine the role of phospholipase A(2) in mitogen-dependent VSMC proliferation and determine if Pb(2+) interacts with this system in order to potentiate mitotic events. It was observed that cell proliferation induced by angiotensin II, or fetal bovine serum, required the activation of a Ca(2+)-dependent cytosolic phospholipase A(2) and the subsequent release of unesterified arachidonic acid. This path was affected by Pb(2+) as the metal increased the amount of arachidonic acid accumulation induced by either mitogen. In addition, Pb(2+) potentiated mitogen-induced DNA synthesis when present at lower doses (0.02 or 0.2 mg%), but had no effect on DNA synthesis, or cell numbers, in unstimulated cells. However, a high dose (2 mg%) of Pb(2+) attenuated the DNA synthesis stimulated by angiotensin II, or serum, but induced the accumulation of unesterified arachidonic acid in unstimulated cells. A biphasic effect of Pb(2+) on cell numbers and viability was also observed as 0.02 or 0.2 mg% Pb(2+) did not affect cell numbers or trypan blue exclusion in unstimulated cells, while 2 mg% Pb(2+) reduced cell numbers and viability. It appeared, therefore, that the lower concentrations of Pb(2+) increased arachidonic acid release and DNA synthesis only in stimulated VSMC, perhaps due to further activation of a Ca(2+)-dependent processes. In contrast, the high dose of Pb(2+) reduced DNA synthesis in stimulated cells and reduced cell numbers and viability in unstimulated cells, which may relate to the noted increase in unesterified arachidonic acid.

Citicoline increases glutathione redox ratio and reduces caspase-3 activation and cell death in staurosporine-treated SH-SY5Y human neuroblastoma cells

Citicoline, or CDP-choline, is an essential endogenous intermediate in the biosynthesis of phosphatidylcholine that may act as a neuroprotector in several models of neurodegeneration. The present study analyses the effects of citicoline in the paradigm of staurosporine-induced cell death in human SH-SY5Y neuroblastoma cells. Citicoline reduces apoptosis induced by 100 nM staurosporine for 12 h in SH-SY5Y cells. This effect is higher with pre-treatment of 60 mM citicoline for 24 h after staurosporine challenge. Moreover, citicoline treatment restores glutathione redox ratio diminished after staurosporine challenge. Finally, citicoline also reduces the expression levels of active caspase-3 and specific PARP-cleaved products of 89 kDa resulting from staurosporine exposure when citicoline is added to the culture medium 24 h before staurosporine. These findings demonstrate that citicoline affects the staurosporine-induced apoptosis cell-signalling pathway by interacting with the glutathione system and by inhibiting caspase-3 in SH-SY5Y human neuroblastoma cells.

Membrane stabilizer: citicoline

Brain ischaemia leads to a cascade of biochemical events, many of which ultimately cause cell membrane injury. Therefore, measures aimed at protecting neuronal membranes could be useful treatment strategies following stroke. Citicoline (cytidine-5-diphosphocholine; CDP-choline) is a naturally occurring nucleotide derivative that may reduce central nervous system (CNS) ischaemic injury by stabilizing cell membranes and reducing free radical generation. Several animal models of ischaemic stroke or hypoxia have shown beneficial effects of citicoline treatment. Randomized clinical stroke treatment trials performed outside of the United States (US) have shown promising results but several recent US trials have failed to support the use of citicoline following middle cerebral artery (MCA) stroke. It remains possible that more specific subgroups of patients may benefit from this well tolerated therapy, but these subgroups have yet to be determined. In addition, there remains the possibility that efficacy may be seen when citicoline is administered in combination with other neuroprotectants with complementary mechanisms of action.

Ischemic brain injury caused by interrupted versus uninterrupted occlusion in hypotensive rats with subarachnoid hemorrhage: neuroprotective effects of citicoline

This study investigated the neuroprotection provided by cytidine 5'-diphosphocholine (citicoline) during interrupted and uninterrupted occlusion of the basilar artery after subarachnoid hemorrhage (SAH) in 121 hypotensive rats. Animals were anesthetized and the basilar artery was exposed through a transclival approach. Baseline local cerebral blood flow (LCBF) values were recorded, and then the basilar artery was punctured, causing SAH. Blood was drawn to induce hypotension [60-70 mmHg mean arterial blood pressure (MABP)]. Control rats received intraperitoneal (i.p.) injections of 0.5 ml saline immediately after SAH before hypotension induction and after 60 min of occlusion. Experimental rats received 400-mg/kg citicoline i.p. at the same time points. Control group I and treatment group III were subjected to 60 min of interrupted occlusion (5 min of reperfusion after each 10 min of occlusion). Control group II and treatment group IV were subjected to 60 min of uninterrupted occlusion. MABP and LCBF were recorded every 5 minutes. Brain edema was evaluated in seven rats from each group at 24 hours after ischemic injury. At 3 days after occlusion, another set of 28 rats was killed and coronal brain slices were stained to assess infarct volume. The groups' physiological and edema findings were similar. In all groups, LCBF fell immediately after SAH and remained below baseline throughout the experiment. In the citicoline-treated rats, arterial pressure increased significantly after 30-40 min of occlusion, and brain slices showed significantly smaller infarct volumes compared to control slices (p < 0.05). Mortality was significantly lower in the citicoline-treated animals (p < 0.001). The results suggest that citicoline provides significant neuroprotection during cerebral ischemia, and that it significantly reduces mortality. Part of the neuroprotective effect may be mediated by recovery of arterial pressure.

Evaluation of combined fibroblast growth factor-2 and moderate hypothermia therapy in traumatically brain injured rats

Both the exogenous administration of fibroblast growth factor-2 (FGF-2) or the induction of moderate hypothermia have been shown to attenuate histopathology and improve functional outcome after traumatic brain injury (TBI). Since combined therapeutic strategies may be more beneficial than single therapies, we examined the potential synergistic effect of FGF-2 combined with moderate hypothermia treatment induced 10 min after TBI on functional and histological outcome following controlled cortical impact (CCI) injury. Fifty male Sprague-Dawley rats were randomized to one sham and four CCI treatment groups: Sham+vehicle (VEH); FGF-2 (45 microg/kg/h for 3 h i.v.)+Normothermia (37+/-0.5 degrees C); FGF-2+Hypothermia (32+/-0.5 degrees C for 3 h); VEH+Norm; VEH+Hypo. Vestibulomotor performance on the beam balance and beam-walk (BW) tasks on post-operative days 1-5 and spatial memory acquisition in the Morris water maze (MWM) on days 14-18 were assessed. After 4 weeks survival, histological evaluations (CA(1) and CA(3) cell counts and lesion volume) were performed. MWM performance improved in all treatment groups, but combined treatment was not more efficacious than either alone. The FGF-2+Hypo group performed significantly better than the other injured treatment groups in the BW task. Lastly, no significant group differences in beam balance or histological outcome were observed. These data suggest a suboptimal and incomplete synergy of combined FGF-2 and hypothermia treatment. These data may indicate that either our dose of FGF-2 or combination therapy was not optimized in our model.

Lipid alterations in transient forebrain ischemia: possible new mechanisms of CDP-choline neuroprotection

We have previously demonstrated that cytidine 5'-diphosphocholine (CDP-choline or citicoline) attenuated arachidonic acid (ArAc) release and provided significant protection for the vulnerable hippocampal CA(1) neurons of the cornu ammonis after transient forebrain ischemia of gerbil. ArAc is released by the activation of phospholipases and the alteration of phosphatidylcholine (PtdCho) synthesis. Released ArAc is metabolized by cyclooxygenases/lipoxygenases to form eicosanoids and reactive oxygen species (ROS). ROS contribute to neurotoxicity through generation of lipid peroxides and the cytotoxic byproducts 4-hydroxynonenal and acrolein. ArAc can also stimulate sphingomyelinase to produce ceramide, a potent pro-apoptotic agent. In the present study, we examined the changes and effect of CDP-choline on ceramide and phospholipids including PtdCho, phosphatidylethanolamine (PtdEtn), phosphatidylinositol (PtdIns), phosphatidylserine (PtdSer), sphingomyelin, and cardiolipin (an exclusive inner mitochondrial membrane lipid essential for electron transport) following ischemia/1-day reperfusion. Our studies indicated significant decreases in total PtdCho, PtdIns, PtdSer, sphingomyelin, and cardiolipin and loss of ArAc from PtdEtn in gerbil hippocampus after 10-min forebrain ischemia/1-day reperfusion. CDP-choline (500 mg/kg i.p. immediately after ischemia and at 3-h reperfusion) significantly restored the PtdCho, sphingomyelin, and cardiolipin levels as well as the ArAc content of PtdCho and PtdEtn but did not affect PtdIns and PtdSer. These data suggest multiple beneficial effects of CDP-choline: (1) stabilizing the cell membrane by restoring PtdCho and sphingomyelin (prominent components of outer cell membrane), (2) attenuating the release of ArAc and limiting its oxidative metabolism, and (3) restoring cardiolipin levels.

N-methyl bases of ethanolamine prevent apoptotic cell death induced by oxidative stress in cells of oligodendroglia origin

A major reason for brain tissue vulnerability to oxidative damage is the high content of polyunsaturated fatty acids (PUFAs). Oligodendroglia-like OLN 93 cells lack PUFAs and are relatively insensitive to oxidative stress. When grown in serum-free defined medium in the presence of 0.1 mM docosahexaenoic acid (DHA; 22:6 n-3) for 3 days, OLN 93 cells release in the medium 2.6-fold more thiobarbituric acid-reactive substances (TBARS) after a 30-min exposure to 0.1 mM H2O2 and 50 microM Fe2+. Release of TBARS was substantially decreased by approximately 20 and 30% on coincubation with either 1 mM N-monomethylethanolamine or N,N'-dimethylethanolamine (dEa), respectively. The protective effect of dEa was concentration- and time-dependent and was still visible after dEa removal, suggesting a long-lasting mechanism of protection. After 24 h following H2O2-induced stress, cell death monitored by cell sorting showed 16% of the cells in the sub-G1 area, indicative of apoptotic cell death. DHA-supplemented cultures showed 35% cell death, whereas cosupplements with dEa reduced cell death to 12%, indicating cell rescue. Although the exact mechanism for this protection is not known, the nature of the polar head group and the degree of unsaturation may determine the ultimate resistance of nerve cells to oxidative stress.

Neuroprotective effects of citicoline on brain edema and blood-brain barrier breakdown after traumatic brain injury

OBJECT

Cytidine 5'-diphosphocholine (CDPC), or citicoline, is a naturally occurring endogenous compound that has been reported to provide neuroprotective effects after experimental cerebral ischemia. However, in no study has such protection been shown after traumatic brain injury (TBI). In this study the authors examined the effect of CDPC on secondary injury factors, brain edema and blood-brain barrier (BBB) breakdown, after TBI.

METHODS

After anesthesia had been induced in Sprague-Dawley rats by using 1.5% halothane, an experimental TBI was created using a controlled cortical impact (CCI) device with a velocity of 3 m/second, resulting in a 2-mm deformation. Four sham-operated control animals used for brain edema and BBB breakdown studies underwent the same surgical procedure, but received no injury. Brain edema was evaluated using the wet-dry method 24 hours postinjury, and BBB breakdown was evaluated by measuring Evans blue dye (EBD) extravasation with fluorescein 6 hours after TBI. The animals received intraperitoneal injections of CDPC (50, 100, or 400 mg/kg two times after TBI [eight-10 animals in each group]) or saline (eight animals) after TBI. Traumatic brain injury induced an increase in the percentage of water content and in EBD extravasation in the injured cortex and the ipsilateral hippocampus. No significant benefit from CDPC treatment was observed at a dose of 50 mg/kg. Cytidine 5'-diphosphocholine at a dose of 100 mg/kg attenuated EBD extravasation in both regions, although it reduced brain edema only in the injured cortex. In both regions, 400 mg/ kg of CDPC significantly decreased brain edema and BBB breakdown.

CONCLUSIONS

This is the first report in which dose-dependent neuroprotective effects of CDPC have been demonstrated in the injured cortex as well as in the hippocampus, a brain region known to be vulnerable to injury, after experimental TBI. The results of this study suggest that CDPC is an effective neuroprotective agent on secondary injuries that appear following TBI.

A randomized efficacy trial of citicoline in patients with acute ischemic stroke

BACKGROUND AND PURPOSE

Citicoline (cytidine-5'-diphosphocholine; CDP-choline) may reduce central nervous system ischemic injury by stabilizing cell membranes and reducing free radical generation. A previous dose-comparison trial in patients with acute stroke found that 500 mg of citicoline appeared to improve neurological outcome with minimal side effects.

METHODS

The current trial was a 33-center, randomized, double-blind, efficacy trial in 394 patients comparing placebo (n=127) with citicoline (n=267) (500 mg po daily) for 6 weeks, with a 6-week posttreatment follow-up period. Patients with acute (24 hours) ischemic strokes clinically assessed to be in the middle cerebral artery territory with National Institutes of Health Stroke Scale (NIHSS) > or = 5 were enrolled.

RESULTS

Mean time to treatment was 12 hours, and mean age was 71 for placebo and 70 for citicoline. Although mean baseline NIHSS were similar for both groups, there was a higher percentage of placebo patients with NIHSS <8 (34% vs 22%; P<0.01). The incidence and type of side effects were similar between the groups. The planned primary analysis (logistic regression: 5 categories Barthel) failed the proportional odds assumption and was rendered unreliable. There were no between-group differences seen on the planned secondary assessment analyses at 90 days, including the Barthel Index > or = 95 at 12 weeks (last observation carried forward: placebo 40%; citicoline 40%) or mortality rate (placebo 18%; citicoline 17%). However, post hoc analyses in a subgroup of patients with baseline NIHSS > or = 8 found that citicoline-treated patients were more likely to have a full recovery (Barthel > or = 95): placebo 21%; citicoline 33%; P=0.05; whereas no difference was seen in patients with baseline NIHSS<8 (placebo 77%; citicoline 69%; P>0.1.

CONCLUSIONS

The results of this study indicate that citicoline was safe but ineffective in improving the outcome of patients with acute ischemic stroke who were enrolled in this trial. Post hoc analyses indicate that there may be a subgroup of patients with moderate to severe strokes who would benefit.

Ischemic cell death in brain neurons

This review is directed at understanding how neuronal death occurs in two distinct insults, global ischemia and focal ischemia. These are the two principal rodent models for human disease. Cell death occurs by a necrotic pathway characterized by either ischemic/homogenizing cell change or edematous cell change. Death also occurs via an apoptotic-like pathway that is characterized, minimally, by DNA laddering and a dependence on caspase activity and, optimally, by those properties, additional characteristic protein and phospholipid changes, and morphological attributes of apoptosis. Death may also occur by autophagocytosis. The cell death process has four major stages. The first, the induction stage, includes several changes initiated by ischemia and reperfusion that are very likely to play major roles in cell death. These include inhibition (and subsequent reactivation) of electron transport, decreased ATP, decreased pH, increased cell Ca(2+), release of glutamate, increased arachidonic acid, and also gene activation leading to cytokine synthesis, synthesis of enzymes involved in free radical production, and accumulation of leukocytes. These changes lead to the activation of five damaging events, termed perpetrators. These are the damaging actions of free radicals and their product peroxynitrite, the actions of the Ca(2+)-dependent protease calpain, the activity of phospholipases, the activity of poly-ADPribose polymerase (PARP), and the activation of the apoptotic pathway. The second stage of cell death involves the long-term changes in macromolecules or key metabolites that are caused by the perpetrators. The third stage of cell death involves long-term damaging effects of these macromolecular and metabolite changes, and of some of the induction processes, on critical cell functions and structures that lead to the defined end stages of cell damage. These targeted functions and structures include the plasmalemma, the mitochondria, the cytoskeleton, protein synthesis, and kinase activities. The fourth stage is the progression to the morphological and biochemical end stages of cell death. Of these four stages, the last two are the least well understood. Quite little is known of how the perpetrators affect the structures and functions and whether and how each of these changes contribute to cell death. According to this description, the key step in ischemic cell death is adequate activation of the perpetrators, and thus a major unifying thread of the review is a consideration of how the changes occurring during and after ischemia, including gene activation and synthesis of new proteins, conspire to produce damaging levels of free radicals and peroxynitrite, to activate calpain and other Ca(2+)-driven processes that are damaging, and to initiate the apoptotic process. Although it is not fully established for all cases, the major driving force for the necrotic cell death process, and very possibly the other processes, appears to be the generation of free radicals and peroxynitrite. Effects of a large number of damaging changes can be explained on the basis of their ability to generate free radicals in early or late stages of damage. Several important issues are defined for future study. These include determining the triggers for apoptosis and autophagocytosis and establishing greater confidence in most of the cellular changes that are hypothesized to be involved in cell death. A very important outstanding issue is identifying the critical functional and structural changes caused by the perpetrators of cell death. These changes are responsible for cell death, and their identity and mechanisms of action are almost completely unknown.

Enhancement of free fatty acid incorporation into phospholipids by choline plus cytidine

Cytidine and choline, present in cytidine 5'-diphosphate choline (CDP-choline), are major precursors of the phosphatidylcholine found in cell membranes and important regulatory elements in phosphatide biosynthesis. Administration of CDP-choline to rats increases blood and brain cytidine and choline levels; this enhances the production of endogenous CDP-choline which then combines with fatty acids (as diacylglycerol), to yield phosphatidylcholine. We examined the effect of providing cytidine and choline on incorporation of free fatty acids into phosphatidylcholine and other major phospholipids in PC12 cells. Addition of equimolar cytidine and choline (100-500 microM) to [3H]-arachidonic acid (50 microM, 0.2 microCi, bound to bovine serum albumin) dose-dependently increased the accumulations of [3H]-phosphatidylcholine (PtdCho), [3H]-phosphatidylinositol (PtdIno) and [3H]-phosphatidylethanolamine (PtdEtn) (by up to 27+/-3%, 16+/-3% and 11+/-3%, respectively, means+/-S.E.M.). This effect was seen with 8-18 h of incubation. The incorporation of [3H]-oleic acid into [3H]-PtdCho was even more enhanced (by up to 42+/-3%) as were the incorporations of [14C]-choline and [3H]-glycerol. The effects of choline and cytidine were enhanced by 12-O-tetradecanoylphorbol-13-acetate (TPA, 1 microM), which activates CTP:phosphocholine cytidylyltransferase (CT) and facilitates choline uptake. Replacing choline by ethanolamine also enhanced the incorporation of [3H]-arachidonic acid into [3H]-PtdEtn, [3H]-PtdIno and [3H]-PtdCho. Arachidonic acid (10-200 microM) alone failed to affect the incorporation of [14C]-choline into phosphatidylcholine. We suggest that the increases in phospholipid synthesis caused by concurrent cytidine and choline supplementation enhance the incorporation of arachidonic acid and certain other fatty acids into the major glycerophospholipids. Removing these fatty acids as source of potentially toxic oxidation products could contribute to the beneficial effects of CDP-choline in treating stroke or other brain damage.

Citicoline treatment for experimental intracerebral hemorrhage in mice

BACKGROUND AND PURPOSE

Citicoline sodium (cytidine-5'-diphosphocholine) has been shown previously to reduce ischemic injury in focal central nervous system models. Intracerebral hemorrhage (ICH) appears to be associated with an area of edema and ischemic injury surrounding the hematoma that may be reduced by neuroprotective therapy. The present study was designed to test whether treatment with citicoline reduces ischemic injury and improves functional neurological outcome in an experimental model of ICH.

METHODS

In 68 Swiss albino mice (26 to 36 g), ICH was induced by collagenase injection into the caudate nucleus. Animals were randomized to receive either: citicoline 500 mg/kg or saline IP prior to collagenase and at 24 and 48 hours. Animals were rated on a 28-point neurological scale and sacrificed at 54 hours. The brains were sectioned, and the volume of hematoma, total lesion, and surrounding ischemic injury was determined.

RESULTS

In terms of functional outcome, animals treated with citicoline had improved neurological outcome scores compared with placebo-treated animals: 10.4+/-2.0 versus 12.1+/-2.4 (P<0.01). Regarding ischemic injury, although there was no difference in the underlying hematoma volumes, animals treated with citicoline had a smaller surrounding volume of ischemic injury than placebo-treated animals: citicoline, 13.8+/-5.8 mm3 (10.8+/-4.3% of hemisphere); placebo, 17.0+/-7.1 mm3 (13.3+/-5. 1%) (P<0.05).

CONCLUSIONS

In this animal model of ICH, treatment with citicoline significantly improved functional outcome and reduced the volume of ischemic injury surrounding the hematoma. This study supports a potential role for citicoline in clinical ICH treatment.

Regional changes of membrane phospholipid concentrations in rabbit spinal cord following brief repeated ischemic insults

Changes in the concentration of membrane-bound phospholipids following single (25-min) spinal cord ischemia and 3 h of reperfusion were determined. These were compared with the changes following brief repeated (8-, 8-, and 9-min) ischemia followed each time by reperfusion for 1 h, or the same periods of ischemia followed by 8 h, 8 h, and 24 h of reperfusion, respectively. Phosphatidylcholine (PC), phosphatidylethanolamine (PE), phosphatidylserine (PS), phosphatidylinositol (PI), and sphingomyelin (SM) were assayed in regions of the spinal cord of the rabbit, including gray matter, white matter, dorsal horns, intermediate zone, and ventral horns. The brief repeated ischemia with 1-h reperfusions produced more extensive degradation of phospholipids in almost all regions compared with the equivalent time of ischemia (25 min) in a single period. After a lengthy reperfusion after repeated ischemia, the phospholipids were resynthesized with the exception of the phosphatidylinositol in the gray matter. The resynthesis was most pronounced in the dorsal horns and in the white matter.

Lipid-dependent modulation of Ca2+ availability in isolated mossy fiber nerve endings

An enhancement of glutamate release from hippocampal neurons has been implicated in long-term potentiation, which is thought to be a cellular correlate of learning and memory. This phenomenom appears to be involved the activation of protein kinase C and lipid second messengers have been implicated in this process. The purpose of this study was to examine how lipid-derived second messengers, which are known to potentiate glutamate release, influence the accumulation of intraterminal free Ca2+, since exocytosis requires Ca2+ and a potentiation of Ca2+ accumulation may provide a molecular mechanism for enhancing glutamate release. The activation of protein kinase C with phorbol esters potentiates the depolarization-evoked release of glutamate from mossy fiber and other hippocampal nerve terminals. Here we show that the activation of protein kinase C also enhances evoked presynaptic Ca2+ accumulation and this effect is attenuated by the protein kinase C inhibitor staurosporine. In addition, the protein kinase C-dependent increase in evoked Ca2+ accumulation was reduced by inhibitors of phospholipase A2 and voltage-sensitive Ca2+ channels, as well as by a lipoxygenase product of arachidonic acid metabolism. That some of the effects of protein kinase C activation were mediated through phospholipase A2 was also indicated by the ability of staurosporine to reduce the Ca2+ accumulation induced by arachidonic acid or the phospholipase A2 activator melittin. Similarly, the synergistic facilitation of evoked Ca2+ accumulation induced by a combination of arachidonic acid and diacylglycerol analogs was attenuated by staurosporine. We suggest, therefore, that the protein kinase C-dependent potentiation of evoked glutamate release is reflected by increases in presynaptic Ca2+ and that the lipid second messengers play a central role in this enhancement of chemical transmission processes.

The effects of prolonged treatment with citicoline in temporary experimental focal ischemia

Potential therapeutic effects of cytidine 5-diphosphocholine (citicoline), a key intermediary in the biosynthesis of the membrane phospholipid, phosphatidylcholine, are presumably related to enhanced phospholipid synthesis in the ischemic brain. We evaluated prolonged citicoline treatment in a temporary focal ischemia model. Using the suture occlusion model, we induced 2 hours of temporary ischemia in 30 Sprague-Dawley rats. The rats were randomly and blindly assigned to receive intraperitoneally 500 mg/kg citicoline (HD), 100 mg/kg citicoline (LD) or physiologic saline as the control group once daily for 7 days (n = 10 per group) beginning at the time of reperfusion. Neurological scoring (0-5 scale) was performed daily. After elective sacrifice on day 7, or earlier if death occurred prematurely, the brains underwent 2,3,5-triphenyltetrazolium chloride (TTC) staining for calculation of corrected infarct and edema volume. The mean corrected infarct volume in the HD group was 125 +/- 45.2 mm3 (mean +/- SD), significantly smaller than controls, 243.5 +/- 88.6 mm3 (p < 0.01, Scheffe's-test). The LD group infarct volume was 200.2 +/- 62.8 mm3 (N.S.). The mean amount of brain edema in the HD group was 46.4 +/- 45.6 mm3 was smaller than the controls, 92.3 +/- 54.4 mm3 and the LD group, 84.9 +/- 71.7 mm3 (N.S.). Mortality before day 7 in the HD was 30% while it was 50% in the two other groups. The neurologic score on day 7 was 2.5 +/- 1.8 in the HD group, 3.3 +/- 1.8 in the LD group and 3.4 +/- 1.7 in controls (N.S.). These results demonstrate that extended high dose citicoline treatment significantly reduced infarct volume in this temporary focal ischemia model and that there was a trend toward reducing brain edema and mortality. These effects may be related to membrane stabilization and inhibition of free fatty acid release.

Altered lipid metabolism in the presence and absence of extracellular Ca2+ during combined oxygen-glucose deprivation in primary astrocyte cultures

The effect of combined oxygen-glucose deprivation (COGD) on lipid metabolism in primary rat cortical astrocyte cultures was studied in both the presence and absence of extracellular Ca2+. In this study, increases in intracellular Ca2+ from internal Ca2+ stores were not inhibited nor were internal Ca2+ levels buffered. Combined oxygen-glucose deprivation resulted in a quantitative reduction in phospholipid levels and an increase in free fatty acid and lysophospholipid levels. Four hours after the onset of COGD, ethanolamine- and choline glycerophospholipid levels were decreased by 40 and 46% from control levels in the presence of Ca2+, respectively. A similar decrease was found 6 hr after onset of COGD in the absence of Ca2+. These changes were accompanied by elevated levels of the corresponding lysophospholipids. However, the increases in lysophospholipid content did not account for the entire loss of ethanolamine- or choline glycerophospholipid. Phosphatidylserine was reduced in both the presence and absence of extracellular Ca2+ but phosphatidylinositol was only decreased in the absence of Ca2+. Statistically significant increases in total fatty acid (FA) and polyunsaturated fatty acid (PUFA) levels occurred at 30 min and 3 hr after the onset of COGD in the absence and presence of Ca2+, respectively. Arachidonic acid levels were increased in both groups by 1 hr. These increases in FA, PUFA, and specifically arachidonic acid were time-dependent and increased over the 12 hr of COGD. Collectively, these results indicate the activation of an acylhydrolase mechanism in the possible presence of an inhibited reacylation pathway.(ABSTRACT TRUNCATED AT 250 WORDS)

Metabolism and actions of CDP-choline as an endogenous compound and administered exogenously as citicoline

CDP-choline, supplied exogenously as citicoline, has beneficial physiological actions on cellular function that have been extensively studied and characterized in numerous model systems. As the product of the rate-limiting step in the synthesis of phosphatidylcholine from choline, CDP-choline and its hydrolysis products (cytidine and choline) play important roles in generation of phospholipids involved in membrane formation and repair. They also contribute to such critical metabolic functions as formation of nucleic acids, proteins, and acetylcholine. Orally-administered citicoline is hydrolyzed in the intestine, absorbed rapidly as choline and cytidine, resynthesized in liver and other tissues, and subsequently mobilized in CDP-choline synthetic pathways. Citicoline is efficiently utilized in brain cells for membrane lipid synthesis where it not only increases phospholipid synthesis but also inhibits phospholipid degradation. Exogenously administered citicoline prevents, reduces, or reverses effects of ischemia and/or hypoxia in most animal and cellular models studied, and acts in head trauma models to decrease and limit nerve cell membrane damage, restore intracellular regulatory enzyme sensitivity and function, and limit edema. Thus, considerable accumulated evidence supports use of citicoline to enhance membrane maintenance, membrane repair, and neuronal function in conditions such as ischemic and traumatic injuries. Beneficial effects of exogenous citicoline also have been postulated and/or reported in experimental models for dyskinesia, Parkinson's disease, cardiovascular disease, aging, Alzheimer's disease, learning and memory, and cholinergic stimulation.

Changes in brain striatum dopamine and acetylcholine receptors induced by chronic CDP-choline treatment of aging mice

1. Spiroperidol binding (dopamine D2 receptors) and quinuclidinyl benzilate binding (muscarinic receptors) in striata of 19-month old mice was analyzed for animals that had received chronic administration of cytidine 5'-diphosphocholine (CDP-choline) incorporated into the chow consumed (100 or 500 mg kg-1 added per day) for the 7 months before they were killed. 2. Treated animals displayed an increase in the dopamine receptor densities of 11% for those receiving 100 mg kg-1 and 18% for those receiving 500 mg kg-1 as compared to the control aged animals that had received no CDP-choline. Control animals showed, from 2 months to 19 months of life, a 28% decrease in the receptor density. No change in the affinity of the receptors for spiroperidol was found in the treated or untreated animals. 3. Muscarinic acetylcholine receptor densities were also partially recovered by the same treatment in aged animals that showed a 14% decrease of these receptors in this case. The muscarinic receptor density increased 6% for the animals that received 100 mg kg-1 and 17% for the animals that received 500 mg kg-1 without any change in the affinity of the receptor for quinuclidinyl benzilate. 4. Aged animals displayed a slight increase in brain membrane fluidity as indicated by a decrease in the polarization value of the non-polar fluorophore 1,6-diphenyl-1,3,5-hexatriene. Interestingly, in the treated animals a greater increase in membrane fluidity was determined and found to be very similar for the two doses.5. It is concluded that chronic administration of CDP-choline to aged animals promoted a partial recovery of the striatum dopamine and acetylcholine receptor function normally reduced with aging, which might be explicable in terms of mechanisms involving fluidity of the brain neuronal membrane.

Arachidonic acid metabolism in gerbil cerebra: effects of ischemia and pentobarbital

Pentobarbital pretreatment may be used to predict biochemical events involved in ischemic brain damage following bilateral carotid artery ligations in the gerbil, since it reduces the subsequent edema and mortality. The effects of this anesthetic on the ischemia-induced modifications of cerebral arachidonic acid metabolism were investigated, in order to correlate observed alterations with tissue damage. Cerebral lipids were radiolabeled in vivo with [3H]arachidonic acid prior to 10 min of cerebral ischemia and 0-120 min of perfusion. Ischemia stimulated a 97.3% increase in unesterified [3H]arachidonate, which was due to the loss of label from choline, inositol, and ethanolamine glycerophospholipids. Tissue reperfusion stimulated further reductions in [3H]choline and [3H]inositol glycerophospholipids, while ethanolamine glycerophospholipid and triglyceride labeling increased. Inositol glycerophospholipid, but not choline glycerophospholipid, labeling returned to control level by 60 min of reperfusion. Pentobarbital pretreatment reduced the accumulation of [3H]arachidonate by 56.2% during ischemia. It increased the recovery of [3H]ethanolamine glycerophospholipids during the ischemic period and [3H]choline glycerophospholipids during the first 5 min of reperfusion. These effects accounted for the reduction of unesterified [3H]arachidonate observed during ischemia and reperfusion.

Effect of partial ischemia on phospholipids and postischemic lipid peroxidation in rabbit spinal cord

Rabbit spinal cord, subjected to severe partial ischemia induced by abdominal aorta ligation tightly below the renal arteries, was analyzed for phospholipid composition and levels of lipid peroxidation products after 10, 20, and 40 min of the insult. Under conditions when spinal cord blood flow was decreased below 5% of control, concentrations of inositol and ethanolamine phospholipids were decreased by 30% and 10%, respectively. Phosphatidic acid concentration was also altered during ischemia. No accumulation of thiobarbituric acid reactive substances (TBA-RS), conjugated dienes and fluorescent lipid soluble material was found throughout the ischemic period. Pattern of TBA-RS, conjugated diene, and fluorophore formation during postischemic in vitro incubation without and with a peroxidation couple (Fe2+, ascorbic acid) showed increased susceptibility to postischemic lipid peroxidation in tissues after 20 and 40 min of ischemia.

Kinetic and biochemical properties of CTP:choline-phosphate cytidylyltransferase from the rat brain

In order to investigate the mechanisms involved in some brain disorders at the membrane level, we studied the kinetics and biochemical properties of brain CTP:choline-phosphate cytidylyltransferase (EC 2.7.7.15), the rate-limiting enzyme of the two-step biosynthesis of phosphatidylcholine. This enzyme catalyzes the biosynthesis of CDPcholine from choline phosphate and CTP. We found that its subcellular localization (mainly in microsomal and cytosolic fractions) was different from that of phosphatidylethanolamine N-methyltransferase (EC 2.1.1.17), the enzyme of the alternative pathway for phosphatidylcholine synthesis. CTP:choline-phosphate cytidylyltransferase showed a Km of 10 mM for CTP and 0.3 mM for choline phosphate and exhibited a random mechanism. CDPcholine, the reaction product, was a competitive inhibitor of choline phosphate and CTP utilization and had a Ki of 0.090 mM. Both particulate and soluble enzymes required Mg2+ and exhibited an optimal pH at about 7. Cytosolic activity was enhanced by addition of unsaturated fatty acids or phospholipids extracted from brain membranes. Such an enhancement was increased with the centrifugation time used for preparing the soluble enzyme.

[3H]arachidonic acid metabolism in rat brain minces: effects of nucleotide triphosphates, CDPcholine and CMP

Rat brain minces were used to investigate the effects of nucleotides on the metabolism of arachidonic acid in nerve tissue. Brain free fatty acids, neutral lipids and phospholipids, were radiolabeled in vivo following intracerebral injection of [3H]arachidonic acid. Minces were prepared from the radiolabeled cerebra and were incubated in a modified Krebs-Ringer buffer with and without various nucleotides. The incubation-induced accumulation of unesterified [3H]arachidonate was reduced in the presence of CDPcholine, ATP, CTP, GTP, and UTP. These nucleotides inhibited choline and inositol glycerophospholipid hydrolysis. They also reduced the amount of labeled diglycerides. However, CDPethanolamine had no effect on arachidonic acid metabolism in the mince preparation and CMP appeared to stimulate further hydrolysis of choline glycerophopholipids, resulting in increased accumulation of [3H]arachidonic acid and labeled diglycerides. We suggest that the production of unesterified [3H]arachidonate and labeled diglycerides is due to the involvement of more than one catabolic reaction, since the high energy nucleotides had similar effects on fatty acid accumulation, but different effects on phospholipid labeling.

Effects of CDP-choline on neurologic deficits and cerebral glucose metabolism in a rat model of cerebral ischemia

The effects of cytidine 5'-diphosphocholine (CDP-choline) on neurologic deficits and cerebral glucose metabolism were studied in a rat model of transient cerebral ischemia. Cerebral ischemia was induced by occluding both common carotid arteries for 20 or 30 minutes 24 hours after the vertebral arteries were permanently occluded by electrocautery. CDP-choline was administered intraperitoneally twice daily for 4 days after reestablishing carotid blood flow. CDP-choline at two dosages (50 and 250 mg/kg) shortened the time required for recovery of spontaneous motor activity in a dose-related manner; recovery time was measured early after reperfusion. Neurologic signs were observed for 10 days. High-dose CDP-choline improved neurologic signs in the rats within 20-30 minutes of ischemia. When cerebral glucose metabolism was assessed on Day 4, increases in the levels of glucose and pyruvate were accompanied by decreases in the synthesis of labeled acetylcholine from uniformly labeled [14C]glucose measured in the cerebral cortex of rats with 30 minutes of ischemia. High-dose CDP-choline also attenuated changes in these variables. CDP-[1,2-14C]choline injected intravenously 10 minutes after reperfusion was used for membrane lipid biosynthesis. These results indicate that CDP-choline has beneficial effects on brain dysfunction induced by cerebral ischemia, which may be due in part to the restorative effects of CDP-choline on disturbed cerebral glucose metabolism, probably by stimulating phospholipid biosynthesis.

Treatment of acute cerebral infarction with a choline precursor in a multicenter double-blind placebo-controlled study

A multicenter double-blind placebo-controlled study of cytidine 5'-diphosphocholine (CDP-choline) was conducted to evaluate possible clinical benefits of the drug in patients with acute, moderate to severe cerebral infarction. The patients included also suffered from moderate to mild disturbances of consciousness, and all were admitted within 14 days of the ictus. Patients were allocated randomly to treatment with either CDP-choline (1,000 mg/day i.v. once daily for 14 days) or with placebo (physiological saline). One hundred thirty-three patients received CDP-choline treatment, and 139 received placebo. The group treated with CDP-choline showed significant improvements in level of consciousness compared with the placebo-treated group, and CDP-choline was an entirely safe treatment.

Effects of CDP-choline on phospholipase A2 and cholinephosphotransferase activities following a cryogenic brain injury in the rabbit

Within the tissue surrounding the necrotic lesion, following a cryogenic injury of the brain, there is a definite activation of phospholipase A2 (at 2 and 4 hr post lesion) that accounts, at least in part, for the phospholipid breakdown. There is also an activation of cholinephosphotransferase (at 2 hr post lesion) that may correspond to an early process of phospholipid resynthesis. Oral CDP-choline in this model is able to completely inhibit the activation of phospholipase A2, but has no detectable effect on cholinephosphotransferase activity. The beneficial effect of CDP-choline might be explained by a prevention of destruction rather than by an enhancement of reconstruction of phospholipids.

Accurate evaluation of 1,2-diacylglycerol in gerbil forebrain using HPLC and in situ freezing technique

Gerbil forebrains were frozen in situ to inactivate the tissues, and 1,2-diacylglycerols were first measured quantitatively by HPLC. Although 1,2-diacylglycerols were completely recovered from the HPLC column, the control amount of 1,2-diacylglycerol in gerbil forebrain was only 79.6 nmol/g wet weight, which is about one-fourth of that previously reported for gerbil brain inactivated by liquid N2 after decapitation instead of in situ freezing. The fatty acid composition of 1,2-diacylglycerols in gerbil forebrain was first reported and the control 1,2-diacylglycerols were richer in palmitic acid than in stearic acid or arachidonic acid, which is rather different from the data previously reported for mouse or rat brain obtained by decapitation and analyzed by traditional TLC methods. The amount of 1,2-diacylglycerol increased by 82.9% in gerbil forebrain during 5 min of ischemia induced by bilateral carotid ligation. Arachidonic acid and stearic acid were abundant in the 1,2-diacylglycerols produced by 5 min of ischemia. Thus we were able to obtain accurate values of the amount and the fatty acid composition of 1,2-diacylglycerols in gerbil forebrains using HPLC and in situ freezing technique.

Effect of CDP-choline on hypocapnic neurons in culture

Neuronal cultures from chick embryo cerebral hemispheres were protected against a hypocapnic injury by adding to their growth medium 10(-6)M CDP-choline before or after the injury. The protection obtained with CDP-choline was analyzed by a morphometric analysis and showed that pretreatment of neuronal cultures with CDP-choline maintained the number of cell aggregates and of primary neuronal processes at control values after hypocapnic shock. Various experiments showed that the intact molecule was responsible for the protective action, since pretreatment with different concentrations of various nucleosides and nucleotides (up to 10(-5) M), choline, and phosphorylcholine was without protective effect. The addition of CDP-choline after the hypocapnic injury resulted in a protection of the cultures as shown by morphological observation. Incubation of neurons with radioactive choline showed that hypocapnia increased the incorporation of the label into phospholipids whereas the presence of CDP-choline reduced it. The de novo synthesis of choline was affected by neither hypocapnia nor CDP-choline treatment. The results indicate that CDP-choline may have the capacity to protect neurons under conditions of basic pH and that cellular proliferation may be stimulated by the compound.

Mechanical damage to murine neuronal-enriched cultures during harvesting: effects on free fatty acids, diglycerides, Na+,K+-ATPase, and lipid peroxidation

The most commonly used procedure to harvest cultured cells from petri dishes is to scrape the cells off the plates with a rubber or Teflon policeman. However, the results reported herein demonstrate that this technique, with its associated mechanical trauma, significantly perturbed cell membranes in neuronal-enriched cultures derived from the ventral half of fetal murine spinal cords. This is evidenced by liberation of free fatty acids and diglycerides, partial inhibition of Na+,K+-ATPase activity, and increased malondialdehyde production. Harvesting the cells by freezing, either on liquid nitrogen or dry ice, significantly attenuated these effects. This important observation indicates that mechanical manipulation of cultured cells during harvesting significantly affects subsequent biochemical analyses, particularly those associated with the cell membrane (e.g., membrane lipid metabolism and assay of intrinsic membrane enzymes).

Membrane lipid changes in laminectomized and traumatized cat spinal cord

Free fatty acid (FFA), diacylglycerol (acyl2Gro), icosanoid, phospholipid, and cholesterol levels were measured in samples of cat spinal cord (L2) that were frozen in situ with vertebrae intact, at various times after laminectomy, and at various times after laminectomy with compression trauma to the spinal cord. Tissue samples either were grossly dissected into gray and white portions prior to FFA and acyl2Gro analysis or were used whole for the other lipid types. Gray matter total FFA and acyl2Gro values were abnormally high in samples frozen with vertebrae intact and in those frozen 10 min after laminectomy. This indicates that the surgical procedures resulted in some perturbation of spinal cord lipid metabolism. If the experimental animals were allowed to recover for 90 min after laminectomy, the gray matter FFA and acyl2Gro levels were greatly reduced. Compression of the spinal cord with a 170-g weight for 1, 3, or 5 min (following 90 min of recovery after laminectomy) caused significant elevations of total FFA, acyl2Gro, icosanoids, and phosphatidic acid and significant decreases in ethanolamine plasmalogens and cholesterol. Among the total FFA, arachidonic acid was found to have the largest relative increase. Comparisons of gray and white matter demonstrate that, in general, changes in white matter FFA and acyl2Gro were similar to those seen in gray matter. However, the increases in white matter levels of FFA and acyl2Gro were delayed, occurring after the elevations in gray matter. For some FFA (e.g., arachidonate), the rise in white matter occurred as gray matter levels were decreasing. This suggests that the initial alteration in spinal cord lipid metabolism after trauma was in gray matter but, with time, spread radially into white matter.

The effect of CMP on the release of free fatty acids of rat brain in vitro

With CMP, phosphatidylcholine can be converted to diacylglycerols and CDPcholine by reversal of the cholinephosphotransferase that is normally used for synthesis. Incubation of homogenates of rat brains at pH 8 with 20 mM MgCl2 increased the free fatty acid (FFA) levels 30 to 117%. The FFA levels increased 62 to 212% when 4 mM CMP was included. Diacylglycerols were also produced. Hydrolysis of the diacylglycerols to FFA was markedly inhibited by inclusion of 3 mM diisopropylphosphofluoridate in the incubation mixture. The composition of the fatty acids released by CMP resembles that of phosphatidylcholine except for some polyunsaturated fatty acids. These may have been released from the ethanolamine glycerophospholipids. Most of the CMP-stimulated release of FFA was blocked by inclusion of 1 mM CDPcholine in the incubation mixture. Rat brains were labeled by intracerebral injection of [3H]oleic acid. The labeled oleic acid was released primarily from phosphatidylcholine. Thus, measurements of both mass and radioactivity confirm that the reversal of cholinephosphotransferase followed by diacylglycerol lipase can be an important pathway for the liberation of FFA from phosphatidylcholine.