Effects of cytidine-diphosphocholine on acetylcholine-mediated behaviors in the rat

Maternal Citicoline-Supplemented Diet Improves the Response of the Immature Hippocampus to Perinatal Asphyxia in Rats

BACKGROUND

Citicoline represents a dietary source of choline, an essential nutrient, and precursor of cell membrane components, highly required during development and post-injury recovery.

OBJECTIVES

We previously showed that perinatal asphyxia (PA) induces hippocampal neuroinflammation and injury that are subject to epigenetic change by maternal diet. The present study investigates maternal citicoline-supplemented diet (CSD) impact on offspring hippocampal response to PA.

METHODS

Six-day-old Wistar rats from mothers with standard-diet or CSD were exposed to PA. The hippocampal inflammation and injury were assessed by interleukin-1 beta (IL-1b), tumor necrosis factor-alpha (TNFα), and S-100B protein (S-100B), 24-48 h post-asphyxia. The microRNAs species miR124, miR132, miR134, miR146, and miR15a were measured from the hippocampus 24 h post-asphyxia, to investigate its epigenetic response to PA and maternal diet. At maturity, the offspring's behavior was analyzed using open field (OFT), T-maze (TMT), and forced swimming (FST) tests.

RESULTS

Our data show that the maternal CSD decreased IL-1b (p = 0.02), TNFα (p = 0.007), and S100B (p = 0.01) at 24 h postexposure, upregulated miR124 (p = 0.03), downregulated miR132 (p = 0.002) and miR134 (p = 0.001), shortened the immobility period in FST (p = 0.01), and increased the percentage of passed trials in TMT (p = 0.01) compared to standard-diet.

CONCLUSIONS

Maternal CSD reduces hippocampal inflammation and S100B level, triggers epigenetic changes related to homeostatic synaptic plasticity, memory formation, and neuronal tolerance to asphyxia, decreases the depressive-like behavior, and improves the lucrative memory in offspring subjected to PA. Thus, citicoline could be valuable as a maternal dietary strategy in improving the brain response to PA.

The Effect of Citicoline Supplementation on Motor Speed and Attention in Adolescent Males

OBJECTIVE

This study assessed the effects of citicoline, a nutraceutical, on attention, psychomotor function, and impulsivity in healthy adolescent males.

METHOD

Seventy-five healthy adolescent males were randomly assigned to either the citicoline group ( n = 51 with 250 or 500 mg citicoline) or placebo ( n = 24). Participants completed the Ruff 2&7 Selective Attention Test, Finger Tap Test, and the Computerized Performance Test, Second Edition (CPT-II) at baseline and after 28 days of supplementation.

RESULTS

Individuals receiving citicoline exhibited improved attention ( p = 0.02) and increased psychomotor speed ( p = 0.03) compared with those receiving placebo. Higher weight-adjusted dose significantly predicted increased accuracy on an attention task ( p = 0.01), improved signal detectability on a computerized attention task ( p = 0.03), and decreased impulsivity ( p = 0.01).

DISCUSSION

Adolescent males receiving 28 days of Cognizin® citicoline showed improved attention and psychomotor speed and reduced impulsivity compared to adolescent males who received placebo.

CDP-choline is not protective in the SOD1-G93A mouse model of ALS

Important pathogenic factors in ALS include excitotoxicity and oxidative stress. Cytidine 5-diphosphocholine (CDP-choline) has recently been reported to have neuroprotective effects in animal models for neurodegenerative diseases, attributable to its anti-glutamatergic, anti-excitotoxic, anti-apoptotic and membrane-preserving properties. In this study we administered either CDP-choline or vehicle to transgenic SOD1-G93A mice daily via intraperitoneal (i.p.) injection starting before disease onset (day 30). By monitoring of survival, motor function, weight and general condition we examined possible therapeutic effects. Additional animals were used for histological studies to determine the effect of CDP-choline on motor neuron survival, astrocytosis and myelination in the spinal cord. Results showed that CDP-choline treatment modified neither the deterioration of general condition nor the loss of body weight. Survival of CDP-choline treated animals was not prolonged compared to vehicle treated controls. None of the behavioural motor function tests revealed differences between groups and no differences in motor neuron survival, astrocytosis or myelination were detected by histological analyses. In conclusion, our data from the transgenic mouse model do not strongly support further clinical validation of CDP-choline for the treatment of ALS.

Neuroprotective effects of citidine-5-diphosphocholine on impaired spatial memory in a rat model of cerebrovascular dementia

Citidine-5-diphosphocholine or citicoline (CDP-choline) is used as a neuroprotective and memory-enhancing drug in cerebral stroke, Alzheimer's disease, and other neurovascular diseases. Non-clinical studies have demonstrated the neuroprotective effects of CDP-choline in ischemic animal models. However, the relationship between the neuroprotective effect and the memory enhancing effect of CDP-choline is still unknown. No studies have demonstrated the ameliorative effect on impaired spatial memory and the suppressive effect on neuronal cell death of CDP-choline in the same model. In this study, we examined the effect of CDP-choline on impaired spatial memory and hippocampal CA1 neuronal death in rats subjected to repeated cerebral ischemia, and we compared the mechanism of CDP-choline to that of donepezil. Seven days post administration of CDP-choline (100, 300, 1000 mg/kg per day, p.o.) or donepezil increased correct choices and reduced error choices in an eight-arm radial maze task in a dose-dependent manner. Neuronal cell death of caspase-3 protein-positive neurons in the hippocampus were reduced by repeated administration of CDP-choline at the highest dose. These results suggest that CDP-choline has ameliorative effects on the impairment of spatial memory via hippocampal neuronal cell death in a rat model of cerebral ischemia.

Safety assessment of AGPC as a food ingredient

α-Glycerylphosphorylcholine (AGPC) is a semi-synthetic derivative of lecithin. Following oral administration, it is converted to phosphatidylcholine, a metabolically active form of choline that is able to reach cholinergic synaptic endings where it increases acetylcholine synthesis and release. A series of studies were conducted to demonstrate the safety of AGPC. The oral LD50 was equal to or greater than 10,000 mg/kg in rats and mice. Deaths were preceded by convulsions in some animals. Dosing of dogs with up to 3000 mg/kg AGPC resulted only in reduced activity. Sub-chronic and chronic oral toxicity studies in rats (up to 1000 mg/kg/day) and beagles (up to 300 mg/kg/day) produced symptomology primarily consisting of reduced activity; slight decreases in food consumption and body weight gain; and slight reduction in liver weight, paralleled by significant decreases in plasma triglycerides, bilirubin, and alkaline phosphatase. There were no histopathological correlates. The in vivo and in vitro assays clearly indicated that AGPC was devoid of mutagenic activity. Based on these results, AGPC is not genotoxic in vitro or in vivo, exhibits low acute oral toxicity and, has an oral NOAEL of 150 mg/kg bw/day following 26 weeks oral exposure.

Eight weeks of citicoline treatment does not perturb sleep/wake cycles in cocaine-dependent adults

BACKGROUND

Citicoline (cytidine-5'-diphosphate) is a mononucleotide composed of ribose, cytosine, pyrophosphate, and choline, and is involved in the biosynthesis of the structural phosopholipids of cell membranes. Treatment with citicoline, improves memory in patients with dementia, and reduces damage to the brain after traumatic brain injury or stroke. Recent research has been conducted to assess whether citicoline is an effective treatment for cocaine dependence. In cocaine-dependent individuals, withdrawal from cocaine is associated with disturbed sleep, which may contribute to the high rate of relapse to cocaine use. Therefore, it is important to know the impact of citicoline on the sleep/wake cycle in these individuals in order to rate its overall efficacy.

METHOD

In this double-blind, placebo-controlled trial, the effects of citicoline treatment on the sleep/wake cycles of cocaine dependent participants were assessed. The results of the current study are reported as part of a larger study, consisting of an eight-week treatment period to assess the efficacy of longer-term treatment with citicoline at decreasing cocaine consumption in cocaine-dependent polydrug using participants.

RESULTS

In this non-abstinent, cocaine-dependent population, citicoline had no effect on any of the sleep parameters measured including sleep efficiency, sleep latency, total sleep time, number of waking episodes, time awake per episode, amount of time in bed spent moving, number of sleep episodes, time asleep per episode, and amount of time in bed spent immobile.

CONCLUSIONS

These data suggest that eight weeks of citicoline administration does not disturb sleep/wake cycles of cocaine-dependent individuals.

Chronic administration of UMP ameliorates the impairment of hippocampal-dependent memory in impoverished rats

We have previously shown that chronic, but not acute, dietary supplementation with CDP-choline prevents the hippocampal-dependent memory deficits manifested by aged rats and by rats reared under impoverished environmental conditions. In rats, dietary CDP-choline is rapidly metabolized into cytidine and choline; the cytidine is then readily converted to uridine, which enters the brain and, via conversion to UTP and CTP, increases brain levels of membrane phosphatides. Hence, we have assessed whether administering a uridine source (UMP) instead of CDP-choline can also ameliorate the memory deficits in rats reared under impoverished environmental conditions. At weaning, 32 male Sprague-Dawley rats were exposed to either enriched (EC) or impoverished (IC) conditions for 3 mo. Concurrently, IC and EC rats were given access to either a control diet or a diet supplemented with 0.1% UMP. Rats were then assessed for learning and memory skills using 2 versions of the Morris water maze, the hidden platform version that assesses hippocampal-dependent cognitive memory processing, and the visible platform version that assesses striatal-dependent habit memory. As expected, exposure to the impoverished environment impaired hippocampal-dependent, but not striatal-dependent learning and memory. Supplementation with UMP prevented this cognitive dysfunction, as had been observed with supplemental CDP-choline. These results suggest that IC rats do not use and/or remember their spatial strategies for task solving as well as EC rats, and that long-term dietary supplementation with UMP alleviates this dysfunction.

Functional Development of Oligodendrocytes and Open-field Behavior in Developing Rats: An Approach Using Monoclonal Antibody to Immature Oligodendrocytes

To examine the relation between functional development of oligodendrocytes and open-field behavior during the postnatal period, a mouse monoclonal antibody termed 14F7, which predominantly labels stage-specific immature oligodendrocytes, was employed. Antibody 14F7 was administered intraperitoneally into male pups on day 3 and 4 after birth. The open-field test was performed on days 12 and 18 of the postnatal period. Horizontal activity increased remarkably with the growth of pups. On day 18, horizontal activity in the group with 14F7 was significantly higher than the control, while there was no significant difference between treatments on day 12. In contrast to the horizontal activity, the frequency of hind leg rearing, vertical activity, in the group with 14F7 was significantly lower than that in the control. On day 12, choline acetyltransferase (ChAT) and acetylcholinesterase (AChE) activities in the cerebral cortex were similar between the groups. These activities increased with the growth of pups in both groups. In the 14F7 group on day 18, ChAT activity was the same as the control, whereas AChE activity was significantly lower compared with the control. These results suggest that neonatal exposure to 14F7 induces abnormal neurotransmission by reducing the degradation of acetylcholine and alters the spontaneous activities in developing rats.

Effect of CDP-choline on brain acetylcholinesterase and Na(+), K(+)-ATPase in adult rats

OBJECTIVE

The aim of this work was to investigate the effect of different cytidine-5'-diphosphocholine (CDP-choline) concentrations (0.1-1 mM) on acetylcholinesterase (AChE), (Na(+),K(+))-ATPase and Mg(2+)-ATPase activities in homogenates of adult rat whole brain and in pure (nonmembrane bound) enzymes.

DESIGN AND METHODS

Tissues were homogenized, centrifuged at 1000 xg for 10 min, and in the supernatant AChE activity and Na(+),K(+)-ATPase, Mg(2+)-ATPase activities were determined according to Ellman's method and Bowler's and Tirri's, respectively.

RESULTS

After a 1-3 h CDP-choline preincubation, this substance induced a maximal stimulation of 20%-25% (p < 0.001) for AChE and 50-55% (p < 0.001) for Na(+), K(+)-ATPase, but it did not influence Mg(2+)-ATPase activity. One mM acetylcholine (ACh) resulted in an approximately 18% (p < 0.001) AChE inhibition by excess substrate in the brain homogenate, while 0. 01 mM noradrenaline did not influence Na(+),K(+)-ATPase activity.

CONCLUSIONS

CDP-choline can stimulate brain AChE and Na(+), K(+)-ATPase independently of ACh and noradrenaline. This enzymatic stimulation may be due to the transformation of CDP-choline to membrane phophatidylcholine. The above data could explain in part the clinical effects of this substance in some neuronal disturbances.

Facilitatory effects of chronically administered citicoline on learning and memory processes in the dog

1. Citicoline (cytidine (5') diphosphocholine) has been shown to reverse aging-induced memory deficits, scopolamine-induced amnesia and nucleus basalis magnocellularis lesion-induced learning impairment. 2. This study aimed to evaluate the effects of citicoline on learning and retrieval processes in a complex differential reinforcement of response duration schedule in normal dogs. 3. The effects of citicoline on a stabilized performance were also measured in order to be able to differentiate specific memory effects from non specific influences on the motor, neuro-vegetative and motivational systems. 4. The results demonstrate that citicoline can exert facilitatory effects on learning and memory but also on retrieval processes. The complete absence of effects on the stabilized performance and on the motor, neuro-vegetative and motivational systems constitutes arguments in favour of a selectivity of action on the memory processes.

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.