Citicoline (CDP-choline) increases Sirtuin1 expression concomitant to neuroprotection in experimental stroke

Unveiling citicoline's mechanisms and clinical relevance in the treatment of neuroinflammatory disorders

Citicoline, a compound produced naturally in small amounts in the human body, assumes a pivotal role in phosphatidylcholine synthesis, a dynamic constituent of membranes of neurons. Across diverse models of brain injury and neurodegeneration, citicoline has demonstrated its potential through neuroprotective and anti-inflammatory effects. This review aims to elucidate citicoline's anti-inflammatory mechanism and its clinical implications in conditions such as ischemic stroke, head trauma, glaucoma, and age-associated memory impairment. Citicoline's anti-inflammatory prowess is rooted in its ability to stabilize cellular membranes, thereby curbing the excessive release of glutamate-a pro-inflammatory neurotransmitter. Moreover, it actively diminishes free radicals and inflammatory cytokines productions, which could otherwise harm neurons and incite neuroinflammation. It also exhibits the potential to modulate microglia activity, the brain's resident immune cells, and hinder the activation of NF-κB, a transcription factor governing inflammatory genes. Clinical trials have subjected citicoline to rigorous scrutiny in patients grappling with acute ischemic stroke, head trauma, glaucoma, and age-related memory impairment. While findings from these trials are mixed, numerous studies suggest that citicoline could confer improvements in neurological function, disability reduction, expedited recovery, and cognitive decline prevention within these cohorts. Additionally, citicoline boasts a favorable safety profile and high tolerability. In summary, citicoline stands as a promising agent, wielding both neuroprotective and anti-inflammatory potential across a spectrum of neurological conditions. However, further research is imperative to delineate the optimal dosage, treatment duration, and underlying mechanisms. Moreover, identifying specific patient subgroups most likely to reap the benefits of citicoline as a new therapy remains a critical avenue for exploration.

Dysregulation of choline metabolism and therapeutic potential of citicoline in Huntington's disease

Huntington's disease (HD) is associated with dysregulated choline metabolism, but the underlying mechanisms remain unclear. This study investigated the expression of key enzymes in this pathway in R6/2 HD mice and human HD postmortem brain tissues. We further explored the therapeutic potential of modulating choline metabolism for HD. Both R6/2 mice and HD patients exhibited reduced expression of glycerophosphocholine phosphodiesterase 1 (GPCPD1), a key enzyme in choline metabolism, in the striatum and cortex. The striatum of R6/2 mice also showed decreased choline and phosphorylcholine, and increased glycerophosphocholine, suggesting disruption in choline metabolism due to GPCPD1 deficiency. Treatment with citicoline significantly improved motor performance, upregulated anti-apoptotic Bcl2 expression, and reduced oxidative stress marker malondialdehyde in both brain regions. Metabolomic analysis revealed partial restoration of disrupted metabolic patterns in the striatum and cortex following citicoline treatment. These findings strongly suggest the role of GPCPD1 deficiency in choline metabolism dysregulation in HD. The therapeutic potential of citicoline in R6/2 mice highlights the choline metabolic pathway as a promising target for future HD therapies.

Synthesis, antioxidant and neuroprotective analysis of diversely functionalized α-aryl-N-alkyl nitrones as potential agents for ischemic stroke therapy

Herein, we report the synthesis, antioxidant and biological evaluation of 32 monosubstituted α-arylnitrones derived from α-phenyl-tert-butyl nitrone (PBN) in the search for neuroprotective compounds for ischemic stroke therapy, trying to elucidate the structural patterns responsible for their neuroprotective activity. Not surprisingly, the N-tert-butyl moiety plays beneficious role in comparison to other differently N-substituted nitrone groups. It seems that electron donor substituents at the ortho position and electron withdrawing substituents at the meta position of the aryl ring induce good neuroprotective activity. As a result, (Z)-N-tert-butyl-1-(2-hydroxyphenyl)methanimine oxide (21a) and (Z)-N-tert-butyl-1-(2-(prop-2-yn-1-yloxy)phenyl)methanimine oxide (24a) showed a significant increase in neuronal viability in an experimental ischemia model in primary neuronal cultures, and induced neuroprotection and improved neurodeficit score in an in vivo model of transient cerebral ischemia. These results showed that nitrones 21a and 24a are new effective small and readily available antioxidants, and suitable candidates for further structure optimization in the search for new phenyl-derived nitrones for the treatment of ischemic stroke and related diseases.

The Combination of Citicoline and Nicotinamide Mononucleotide Induces Neurite Outgrowth and Mitigates Vascular Cognitive Impairment via SIRT1/CREB Pathway

Vascular dementia (VD) is characterized with vascular cognitive impairment (VCI), which currently has few effective therapies in clinic. Neuronal damage and white matter injury are involved in the pathogenesis of VCI. Citicoline has been demonstrated to exhibit neuroprotection and neurorepair to improve cognition in cerebrovascular diseases. Nicotinamide adenine dinucleotide (NAD+)-dependent sirtuin (SIRT) signaling pathway constitutes a strong intrinsic defense system against various stresses including neuroinflammation in VCI. Our hypothesis is that the combined use of citicoline and the precursor of NAD+, nicotinamide mononucleotide (NMN), could enhance action on cognitive function in VCI. We investigated the synergistic effect of these two drugs in the rat model of VCI by bilateral common carotid artery occlusion (BCCAO). Citicoline significantly enhanced neurite outgrowth in Neuro-2a cells, and the combination of citicoline and NMN remarkably induced neurite outgrowth in Neuro-2a cells and primary cortical neuronal cells with an optimal proportion of 4:1. In the rat model of BCCAO, when two drugs in combination of 160 mg/kg citicoline and 40 mg/kg NMN, this combination administrated at 7 days post-BCCAO significantly improved the cognitive impairment in BCCAO rats compared with vehicle group by the analysis of the Morris water maze and the novel object recognition test. This combination also decreased microglial activation and neuroinflammation, and protected white matter integrity indicated by the increased myelin basic protein (MBP) expression through activation of SIRT1/TORC1/CREB signaling pathway. Our results suggest that the combination of citicoline and NMN has a synergistic effect for the treatment of VD associated with VCI.

Role of Citicoline in Patients With Mild Cognitive Impairment

The term mild cognitive impairment (MCI) defines an intermediate state between normal aging and dementia. Vascular cognitive impairment refers to a decline in cognitive function that is caused by or associated with vascular disease and comprises all the spectrum of cognitive impairments, from MCI of vascular origin to vascular dementia. One of the available treatments for cognitive impairment is cytidine diphosphate-choline (CDP-Choline), or citicoline. The objective of the present manuscript is to provide complete evidence about the efficacy of citicoline for MCI, especially of vascular origin, but also due to other neurodegenerative disorders. Citicoline is a pharmaceutical product constituted by the combination of 2 natural molecules (cytidine and choline) and is marketed as a food supplement. It has been proposed to provide neuroprotective effects through diverse mechanisms of action. Taking into account the available literature, citicoline has shown a consistent improvement in cognitive function in patients with MCI, especially of vascular origin. Moreover, it provides beneficial effects on vascular, Alzheimer, and mixed dementias, stroke sequelae, intracerebral hemorrhages, traumatic brain injuries, and neurodegenerative diseases. Long-term treatment with citicoline has also been demonstrated to be well-tolerated and has not been associated with severe adverse events. Citicoline is a safe, well-tolerated, and promising agent with evidenced neuroprotective properties.

Role of NAD+ and FAD in Ischemic Stroke Pathophysiology: An Epigenetic Nexus and Expanding Therapeutic Repertoire

The redox coenzymes viz., oxidized β-nicotinamide adenine dinucleotide (NAD⁺) and flavin adenine dinucleotide (FAD) by way of generation of optimal reducing power and cellular energy currency (ATP), control a staggering array of metabolic reactions. The prominent cellular contenders for NAD⁺ utilization, inter alia, are sirtuins (SIRTs) and poly(ADP-ribose) polymerase (PARP-1), which have been significantly implicated in ischemic stroke (IS) pathogenesis. NAD⁺ and FAD are also two crucial epigenetic enzyme-required metabolites mediating histone deacetylation and poly(ADP-ribosyl)ation through SIRTs and PARP-1 respectively, and demethylation through FAD-mediated lysine specific demethylase activity. These enzymes and post-translational modifications impinge on the components of neurovascular unit, primarily neurons, and elicit diverse functional upshots in an ischemic brain. These could be circumstantially linked with attendant cognitive deficits and behavioral outcomes in post-stroke epoch. Parsing out the contribution of NAD⁺/FAD-synthesizing and utilizing enzymes towards epigenetic remodeling in IS setting, together with their cognitive and behavioral associations, combined with possible therapeutic implications will form the crux of this review.

Deciphering therapeutic options for neurodegenerative diseases: insights from SIRT1

Silent information regulator 1 (SIRT1) is a nicotinamide adenine dinucleotide (NAD +)-dependent protein deacetylase that exerts biological effects through nucleoplasmic transfer. Recent studies have highlighted that SIRT1 deacetylates protein substrates to exert its neuroprotective effects, including decreased oxidative stress and inflammatory, increases autophagy, increases levels of nerve growth factors (correlated with behavioral changes), and maintains neural integrity (affects neuronal development and function) in aging or neurological disorder. In this review, we highlight the molecular mechanisms underlying the protective role of SIRT1 in modulating neurodegeneration, focusing on protein homeostasis, aging-related signaling pathways, neurogenesis, and synaptic plasticity. Meanwhile, the potential of targeting SIRT1 to block the occurrence and progression of neurodegenerative diseases is also discussed. Taken together, this review provides an up-to-date evaluation of our current understanding of the neuroprotective mechanisms of SIRT1 and also be involved in the potential therapeutic opportunities of AD and related neurodegenerative diseases.

Resveratrol has an Overall Neuroprotective Role in Ischemic Stroke: A Meta-Analysis in Rodents

Background: Resveratrol, a natural polyphenolic phytoalexin, is broadly presented in dietary sources. Previous research has suggested its potential neuroprotective effects on ischemic stroke animal models. However, these results have been disputable. Here, we conducted a meta-analysis to comprehensively evaluate the effect of resveratrol treatment in ischemic stroke rodent models.

Objective: To comprehensively evaluate the effect of resveratrol treatment in ischemic stroke rodent models.

Methods: A literature search of the databases Pubmed, Embase, and Web of science identified 564 studies that were subjected to pre-defined inclusion criteria. 54 studies were included and analyzed using a random-effects model to calculate the standardized mean difference (SMD) with corresponding confidence interval (CI).

Results: As compared with controls, resveratrol significantly decreased infarct volume (SMD −4.34; 95% CI −4.98 to −3.69; p < 0.001) and the neurobehavioral score (SMD −2.26; 95% CI −2.86 to −1.67; p < 0.001) in rodents with ischemic stroke. Quality assessment was performed using a 10-item checklist. Studies quality scores ranged from 3 to 8, with a mean value of 5.94. In the stratified analysis, a significant decrease of infarct volume and the neurobehavioral score was achieved in resveratrol sub-groups with a dosage of 20–50 mg/kg. In the meta-regression analysis, the impact of the delivery route on an outcome is the possible source of high heterogeneity.

Conclusion: Generally, resveratrol treatment presented neuroprotective effects in ischemic stroke models. Furthermore, this study can direct future preclinical and clinical trials, with important implications for human health.

Citicoline for Supporting Memory in Aging Humans

Citicoline is the generic name of CDP-choline, a natural metabolite present in all living cells. Used in medicine as a drug since the 1980-s, citicoline was recently pronounced a food ingredient. When ingested, citicoline breaks down to cytidine and choline, which become incorporated into their respective normal metabolic pathways. Choline is a precursor of acetylcholine and phospholipids; these is a neurotransmitter pivotal for learning and memory and important constituents of neuronal membranes and myelin sheaths, respectively. Cytidine in humans is readily converted to uridine, which exerts a positive effect on synaptic function and supports the formation of synaptic membranes. Choline deficiency has been found to be correlated with memory dysfunction. Magnetic resonance spectroscopy studies showed that citicoline intake improves brain uptake of choline in older persons, suggestive of that it shall help in reversing early age-related cognitive changes. In randomized, placebo-controlled trials of cognitively normal middle-aged and elderly persons, positive effects of citicoline on memory efficacy were found. Similar effects of citicoline on memory indices were also found in patients suffering from mild cognitive impairment and some other neurological diseases. Altogether, the aforementioned data provide complex and unambiguous evidence supporting the claim that oral citicoline intake positively influences memory function in humans who encounter age-related memory impairment also in the absence of any detectable neurological or psychiatric disease.

Sleep, Sirtuin 1 and Alzheimer's disease: A review

Sleep plays a major role in brain health, and cognition. Disrupted sleep is a well-described symptom of Alzheimer's disease (AD). However, accumulating evidence suggests suboptimal sleep also increases AD risk. The deacetylase Sirtuin 1 (Sirt 1), encoded by the SIRT1 gene, impacts sleep via its relationship to wake-sleep neurotransmitters and somnogens. Evidence from animal and human studies supports a significant and complex relationship between sleep, Sirt 1/ SIRT1 and AD. Numerous hypotheses attempt to explain the critical impact of Sirt 1/ SIRT1 on wake- and sleep- promoting neurons, their related mechanisms and neurotransmitters. However, there is a paucity of studies assessing the interaction between sleep and Sirt 1/ SIRT1, as a principal component of sleep regulation, on AD pathology. In this review, we explore the potential association between Sirt 1/ SIRT1, sleep, and AD aetiology. Given sleep is a likely modifiable risk factor for AD, and recent studies suggest Sirt 1/ SIRT1 activation can be modulated by lifestyle or dietary approaches, further research in this area is required to explore its potential as a target for AD prevention and treatment.

Citicoline and COVID-19-Related Cognitive and Other Neurologic Complications

With growing concerns about COVID-19’s hyperinflammatory condition and its potentially damaging impact on the neurovascular system, there is a need to consider potential treatment options for managing short- and long-term effects on neurological complications, especially cognitive function. While maintaining adequate structure and function of phospholipid in brain cells, citicoline, identical to the natural metabolite phospholipid phosphatidylcholine precursor, can contribute to a variety of neurological diseases and hypothetically toward post-COVID-19 cognitive effects. In this review, we comprehensively describe in detail the potential citicoline mechanisms as adjunctive therapy and prevention of COVID-19-related cognitive decline and other neurologic complications through citicoline properties of anti-inflammation, anti-viral, neuroprotection, neurorestorative, and acetylcholine neurotransmitter synthesis, and provide a recommendation for future clinical trials.

Histone Deacetylases and Their Isoform-Specific Inhibitors in Ischemic Stroke

Cerebral ischemia is the second leading cause of death in the world and multimodal stroke therapy is needed. The ischemic stroke generally reduces the gene expression due to suppression of acetylation of histones H3 and H4. Histone deacetylases inhibitors have been shown to be effective in protecting the brain from ischemic damage. Histone deacetylases inhibitors induce neurogenesis and angiogenesis in damaged brain areas promoting functional recovery after cerebral ischemia. However, the role of different histone deacetylases isoforms in the survival and death of brain cells after stroke is still controversial. This review aims to analyze the data on the neuroprotective activity of nonspecific and selective histone deacetylase inhibitors in ischemic stroke.

A Retrospective Study on the Benefits of Combined Citicoline, Memantine, and Acetylcholinesterase Inhibitor Treatments in Older Patients Affected with Alzheimer's Disease

BACKGROUND

Background: Citicoline has been proven to have beneficial effects in patients with cognitive impairment. In previous studies, combined treatment with memantine and acetylcholinesterase inhibitors (AChEIs) maintained cognitive function in patients with Alzheimer's disease (AD) better than memantine or AChEIs alone.

OBJECTIVE

To evaluate the effectiveness and safety of a combination therapy of oral citicoline, memantine, and an AChEI in AD when compared with memantine and an AChEI without citicoline.

METHODS

This was a retrospective multi-centric case-control study, conducted in Italian Centers for Cognitive Impairment and Dementia. Overall, 170 patients were recruited (34.11%of men, mean age 76,81±4.93 years): 48.8%treated with memantine and donepezil; 48.2%with memantine and rivastigmine; 2.9%with memantine and galantamine. 89 patients (control-group) were treated with memantine and an AChEI, whereas 81 patients (case-group) were treated with oral citicoline 1000 mg/day added to memantine and an AChEI given orally. Cognitive functions, activities of daily living, instrumental activities of daily living, comorbidities, mood and behavioral disturbances were assessed at baseline, month 6, and month 12.

RESULTS

In the case group, MMSE score had a statistically significant increasing trend between T0 and T2 (14.88±2.95 versus 15.09±3.00; p = 0.040), whereas in the control group, MMSE score showed a statistically significant decrease trend (14.37±2.63 versus 14.03±2.92 p = 0.024).

CONCLUSION

In older patients with AD, a triple therapy with citicoline, memantine, and AChEI was more effective than memantine and AChEI without citicoline in maintaining the MMSE total score after 12 months.

[Molecular and clinical aspects of the effect of cytidyndiphosphocholine on cognitive functions]

OBJECTIVE

Systematization of the array of publications on cytidyldiphosphocholine (CDP-choline).

MATERIAL AND METHODS

Systematic computer analysis of all currently available publications on CDP-choline (1750 publications in PUBMED) using the topological theory of big data analysis.

RESULTS

CDP-choline is essential for acetylcholine biosynthesis, phospholipid metabolism, and DNA methylation. The article describes the effects of CDP-choline on acetylcholinergic and other types of neurotransmission, anti-inflammatory, neuroprotective and neurotrophic effects of CDP-choline. Also, the paper presents the effects of the molecule on lipid metabolism and gene expression within the post-genomic paradigm (in particular, an increase in the expression of nicotinic and muscarinic acetylcholine receptors). The results of fundamental and clinical studies of CDP-choline in the treatment of cognitive impairments associated with cerebral ischemia and neurodegeneration are presented.

CONCLUSION

The pharmacological effects of CDP-choline are mediated through multiple molecular mechanisms that contribute to the nootropic action of this molecule.

Personalizing the Care and Treatment of Alzheimer's Disease: An Overview

Alzheimer's disease (AD) is a progressive, complex, and multifactorial neurodegenerative disorder, still without effective and stable therapeutic strategies. Currently, available medications for AD are based on symptomatic therapy, which include acetylcholinesterase (AChE) inhibitors and N-methyl-D-aspartate (NMDA) receptor antagonist. Additionally, medications such as antipsychotic drugs, antidepressants, sedative, and hypnotic agents, and mood stabilizers are used for the management of behavioral and psychological symptoms of dementia (BPSD). Clinical research has been extensively investigated treatments focusing on the hallmark pathology of AD, including the amyloid deposition, tau hyperphosphorylation, neuroinflammation, and vascular changes; however, so far without success, as all new potential drugs failed to show significant clinical benefit. The underlying heterogeneous etiology and diverse symptoms of AD suggest that a precision medicine strategy is required, which would take into account the complex genetic, epigenetic, and environmental landscape of each AD patient. The article provides a comprehensive overview of the literature on AD, the current and potential therapy of both cognitive symptoms as well as BPSD, with a special focus on gut microbiota and epigenetic modifications as new emerging drug targets. Their specific patterns could represent the basis for novel individually tailored approaches aimed to optimize precision medicine strategies for AD prevention and treatment. However, the successful application of precision medicine to AD demands a further extensive research of underlying pathological processes, as well as clinical and biological complexity of this multifactorial neurodegenerative disorder.

Effects of Citicoline as an Adjunct Treatment for Alzheimer's Disease: A Systematic Review

BACKGROUND

A critical strategy in the management of Alzheimer's disease (AD) is optimizing the effects of currently available pharmacologic therapies such as citicoline (CC).

OBJECTIVE

The purpose of this study was to determine the effects of CC as adjunct therapy to cholinesterase inhibitors (AChEI) in the treatment of AD.

METHODS

We identified relevant studies by electronic search until April 2020. We considered studies with a comparator group that enrolled elderly patients with a diagnosis of AD and employed CC as an adjunct therapy to AChEIs compared to AChEI monotherapy or comparisons of different AChEIs combined with CC. Methodological quality assessment was done using the Newcastle-Ottawa Scale.

RESULTS

Out of 149 articles identified, two retrospective cohort studies involving 563 elderly patients affected with AD were included. After 3 months and 9 months, better Mini-Mental Status Examination scores were observed in the "AChEIs + CC" group versus "AChEIs alone" group. CC combined with donepezil may be better in improving cognition than when combined with rivastigmine. No significant difference was noted in terms of activities of daily living (ADL) and instrumental-ADL. Neuropsychiatric Inventory and Geriatric Depression Scale-short form scores appeared to be lower in the combination treatment versus monotherapy. The adverse events of combined treatment were self-limiting and included occasional excitability, gastric intolerance, and headache.

CONCLUSION

Limited evidence from pooled data of two observational studies suggests that CC used in adjunct with AChEIs in the treatment of AD was well-tolerated and showed improvement in cognition, mood, and behavioral symptoms compared to treating with AChEIs alone.

Citicoline in Ophthalmological Neurodegenerative Disease: A Comprehensive Review

Cytidine 5'-diphosphocholine has been widely studied in systemic neurodegenerative diseases, like Alzheimer's disease, Parkinson's disease, and brain ischemia. The rationale for the use of citicoline in ophthalmological neurodegenerative diseases, including glaucoma, anterior ischemic optic neuropathy, and diabetic retinopathy, is founded on its multifactorial mechanism of action and the involvement in several metabolic pathways, including phospholipid homeostasis, mitochondrial dynamics, as well as cholinergic and dopaminergic transmission, all being involved in the complexity of the visual transmission. This narrative review is aimed at reporting both pre-clinical data regarding the involvement of citicoline in such metabolic pathways (including new insights about its role in the intracellular proteostasis through an interaction with the proteasome) and its effects on clinical psychophysical, electrophysiological, and morphological outcomes following its use in ophthalmological neurodegenerative diseases (including the results of the most recent prospective randomized clinical trials).

Citicoline Improves Human Vigilance and Visual Working Memory: The Role of Neuronal Activation and Oxidative Stress

Introduction:

Psychomotor performance task is used to assess the arousal and cognitive functions of the central nervous system. Alternatively, human visual working memory reflects the capability of the individual’s short-term memory. Psycho-mental stimuli are linked to the stimulation of Malondialdehyde (MDA) formations. Citicoline is a nootropic nucleotide agent with a favorable effect on the augmentation of human memory and cognitive function. Thus, the purpose of this study was to determine the effect of citicoline on human vigilance, visual working memory, and oxidative stress using healthy volunteers.

Methods:

40 healthy volunteers were enrolled and divided into two groups: group A: 20 volunteers received 500mg/day starch capsule for two weeks and group B: 20 volunteers received 500mg/day citicoline capsule for two weeks. Human vigilance, visual working memory, and oxidative stress markers of each volunteer were assessed before and after citicoline and placebo intake. The obtained data were analyzed by SPSS regarding P<0.05 as statistically significant.

Results:

Placebo had no significant effect on human vigilance and visual working memory after two weeks of therapy (P>0.05), whereas citicoline improved most variables of psychomotor performances and working memory (P<0.01). Placebo significantly increased serum MDA levels from 19.44±2.11 to 29.66±3.28 nmol/mL (P=0.0001), while citicoline significantly decreased MDA serum levels from 19.11±2.66 to 15.63±1.33 nmol/mL (P=0.0001).

Conclusion:

Citicoline improves human psychomotor vigilance, arousal, and visual working memory with significant amelioration of oxidative stress compared with placebo.

The Importance of Citicoline in Combined Treatment in Dementia: What did the Citimem Study Teach us?

BACKGROUND

Citicoline is a drug used both in degenerative and in vascular cognitive decline; memantine is a drug used for the treatment of mild to moderate Alzheimer's disease (AD). Our hypothesis is that their combined use could have enhanced action in patients having AD and mixed dementia (MD). We report the main tips from a recent study on the use of these drugs, the CITIMEM study.

METHODS

The study was retrospective and was performed on 126 patients aged 65 years old or older affected with AD or MD (mean age 80.7 ± 5.2 years old) who had been visited between 2015 and 2017 in four different centers for dementia all over Italy. Neuropsychological and functional tests were administered at baseline (T0), after 6 (T1), and 12 months (T2). The effects of combined treatment versus memantine alone on cognitive functions assessed by Mini-Mental State Examination (MMSE) and the possible onset of side effects or adverse events, as well as the influence on daily life functions and behavioral symptoms, were investigated.

RESULTS

Patients undergoing combined treatment showed a significant increase in MMSE vs. memantine alone, both at T1 (p=0.003) and T2 (p =0.000).

CONCLUSION

The CITIMEM study confirms our hypothesis that the combined administration of memantine plus citicoline is safe and more effective than memantine alone on cognition in patients suffering from AD or MD.

Application of Citicoline in Neurological Disorders: A Systematic Review

Citicoline is a chemical compound involved in the synthesis of cell membranes. It also has other, not yet explained functions. Research on the use of citicoline is conducted in neurology, ophthalmology, and psychiatry. Citicoline is widely available as a dietary supplement. It is often used to enhance cognitive functions. In our article, accessible databases were searched for articles regarding citicoline use in neurological diseases. This article has a systemic review form. After rejecting non-eligible reports, 47 remaining articles were reviewed. The review found that citicoline has been proven to be a useful compound in preventing dementia progression. It also enhances cognitive functions among healthy individuals and improves prognosis after stroke. In an animal model of nerve damage and neuropathy, citicoline stimulated regeneration and lessened pain. Among patients who underwent brain trauma, citicoline has an unclear clinical effect. Citicoline has a wide range of effects and could be an essential substance in the treatment of many neurological diseases. Its positive impact on learning and cognitive functions among the healthy population is also worth noting.

The Beneficial Roles of SIRT1 in Neuroinflammation-Related Diseases

Sirtuins are the class III of histone deacetylases whose deacetylate of histones is dependent on nicotinamide adenine dinucleotide (NAD+). Among seven sirtuins, SIRT1 plays a critical role in modulating a wide range of physiological processes, including apoptosis, DNA repair, inflammatory response, metabolism, cancer, and stress. Neuroinflammation is associated with many neurological diseases, including ischemic stroke, bacterial infections, traumatic brain injury, Alzheimer's disease (AD), and Parkinson's disease (PD). Recently, numerous studies indicate the protective effects of SIRT1 in neuroinflammation-related diseases. Here, we review the latest progress regarding the anti-inflammatory and neuroprotective effects of SIRT1. First, we introduce the structure, catalytic mechanism, and functions of SIRT1. Next, we discuss the molecular mechanisms of SIRT1 in the regulation of neuroinflammation. Finally, we analyze the mechanisms and effects of SIRT1 in several common neuroinflammation-associated diseases, such as cerebral ischemia, traumatic brain injury, spinal cord injury, AD, and PD. Taken together, this information implies that SIRT1 may serve as a promising therapeutic target for the treatment of neuroinflammation-associated disorders.

Anti-inflammatory and Neuroprotective Agents in Clinical Trials for CNS Disease and Injury: Where Do We Go From Here?

Neurological disorders are major contributors to death and disability worldwide. The pathology of injuries and disease processes includes a cascade of events that often involve molecular and cellular components of the immune system and their interaction with cells and structures within the central nervous system. Because of this, there has been great interest in developing neuroprotective therapeutic approaches that target neuroinflammatory pathways. Several neuroprotective anti-inflammatory agents have been investigated in clinical trials for a variety of neurological diseases and injuries, but to date the results from the great majority of these trials has been disappointing. There nevertheless remains great interest in the development of neuroprotective strategies in this arena. With this in mind, the complement system is being increasingly discussed as an attractive therapeutic target for treating brain injury and neurodegenerative conditions, due to emerging data supporting a pivotal role for complement in promoting multiple downstream activities that promote neuroinflammation and degeneration. As we move forward in testing additional neuroprotective and immune-modulating agents, we believe it will be useful to review past trials and discuss potential factors that may have contributed to failure, which will assist with future agent selection and trial design, including for complement inhibitors. In this context, we also discuss inhibition of the complement system as a potential neuroprotective strategy for neuropathologies of the central nervous system.

Citicoline Protects Auditory Hair Cells Against Neomycin-Induced Damage

Aminoglycoside-induced hair cell (HC) loss is one of the most important causes of hearing loss. After entering the inner ear, aminoglycosides induce the production of high levels of reactive oxygen species (ROS) that subsequently activate apoptosis in HCs. Citicoline, a nucleoside derivative, plays a therapeutic role in central nervous system injury and in neurodegenerative disease models, including addictive disorders, stroke, head trauma, and cognitive impairment in the elderly, and has been widely used in the clinic as an FDA approved drug. However, its effect on auditory HCs remains unknown. Here, we used HC-like HEI-OC-1 cells and whole organ explant cultured mouse cochleae to explore the effect of citicoline on aminoglycoside-induced HC damage. Consistent with previous reports, both ROS levels and apoptosis were significantly increased in neomycin-induced cochlear HCs and HEI-OC-1 cells compared to undamaged controls. Interestingly, we found that co-treatment with citicoline significantly protected against neomycin-induced HC loss in both HEI-OC-1 cells and whole organ explant cultured cochleae. Furthermore, we demonstrated that citicoline could significantly reduce neomycin-induced mitochondrial dysfunction and inhibit neomycin-induced ROS accumulation and subsequent apoptosis. Thus, we conclude that citicoline can protect against neomycin-induced HC loss by inhibiting ROS aggregation and thus preventing apoptosis in HCs, and this suggests that citicoline might serve as a potential therapeutic drug in the clinic to protect HCs.

Posible involvement of nitric oxide in anticonvulsant effects of citicoline on pentylenetetrazole and electroshock induced seizures in mice

Cerebroneurovascular trauma is recognized as an important risk factor in the development of seizure and epilepsy. Administration of citicoline in these situations is a conventional therapeutic strategy, which combines neurovascular protection and repair effects. The aim of the present study is clarifying the effect of acute and sub-chronic citicoline administration on pentylenetetrazole (PTZ) and electroshock induced seizures in mice. Besides we examined the probable role of NO and its interaction with citicoline in seizure experiments.

Male mice were received acute and sub-chronic regimens of different doses of citicoline (62.5, 125, 250 and 500 mg/kg) before the intravenous or intraperitoneal PTZ-induced seizures or electroshock. To clarify the probable role of NO, 7-nitroindazole (7-NI) (60 mg/kg) or aminoguanidine (AG) (100 mg/kg) were injected 5 min before citicoline in separate groups.

The results revealed that neither acute nor sub-chronic treatment with citicoline could affect the seizures induced by intravenous or intraperitoneal PTZ, but in electroshock model, citicoline showed anti-epileptic properties. Co-administration of citicoline and selective nitric oxide synthase (NOS) inhibitors amplified the anticonvulsant effect of citicoline.

The current results indicated that citicoline has anticonvulsant effects probably through the inhibition of NO.

Role of Citicoline in an in vitro AMD model

Citicoline is the exogenous form of the nootropic, Cytidine 5'-diphosphate-choline that exerts its neuroprotective effects in the brain as well as in the eye. The current study characterized the cytoprotective effects of purified Citicoline in transmitochondrial AMD (Age-related Macular Degeneration) RPE cybrid cells which carry diseased mitochondria from clinically characterized AMD patients. The effects of Citicoline were examined via flow cytometry analysis of AnnexinV/ PI-stained cells, IncuCyte live-cell imaging analysis to quantify cells undergoing caspase-3/7-mediated apoptosis, analyses of gene expression profiles of apoptosis, hypoxia, and angiogenesis markers, and measurement of ROS levels and cell viability. Our results demonstrated that Citicoline when added exogenously alleviates apoptotic effects as evidenced by diminished AnnexinV/PI and Caspase-3/7 staining, downregulation of apoptosis genes, enhanced cell viability, and reduced oxidative stress in AMD RPE cybrid cells. In conclusion, our study identified Citicoline as a protector in AMD RPE cybrid cells in vitro. However, further studies are required to establish the merit of Citicoline as a cytoprotective molecule in AMD and to decipher the molecular underpinnings of its mechanism of action in AMD.

The CITIMEM study: A pilot study. Optimizing pharmacological treatment in dementia

INTRODUCTION

Citicoline can have beneficial effects both in degenerative and in vascular cognitive decline; it works through an increase in acetylcholine intrasynaptic levels and promoting phospholipid synthesis, (chiefly phosphatidylcholine), cellular function, and neuronal repair. Memantine is an N-methyl-D-aspartate (NMDA) receptor antagonist used for the treatment of mild to moderate Alzheimer's disease (AD). When co-administered they could have a synergistic action in patients affected with AD and mixed dementia (MD) too.

SCOPE

The aim of the present study was to show the effectiveness of oral citicoline plus memantine in patients affected with AD and MD.

PATIENTS AND METHODS

This was a retrospective study between 2015 and 2017 on 126 patients aged 65 years old or older affected with AD or MD (mean age 80.7 ± 5.2 years old). The study involved four different centers for dementia all over Italy. Diagnosis of AD was made according to clinical symptoms, neuropsychological tests and brain imaging. Diagnosis of MD was made when symptoms typical of AD such as memory loss were associated to symptoms due to cerebrovascular deficits, i.e., impaired judgement, ability to make decisions, plan or organize, and brain imaging. 58 patients were treated with memantine (group A), 68 patients with memantine plus citicoline 1 g/day given orally (group B). In both groups memantine dosage was 10-20 mg/day according to its tolerability. 24 patients of group A and 29 patients of group B were affected with MD. Cognitive functions were assessed by MMSE, daily life functions by ADL and IADL, behavioral symptoms by NPI, comorbidities by CIRS, and mood by GDS-short form. Tests were administered at baseline (T0), after 6 (T1), and 12 months (T2). The primary outcomes were the effects of combined treatment versus memantine alone on cognitive functions assessed by MMSE. The secondary outcomes were the possible side effects or adverse events of combination therapy versus memantine alone, influence on daily life functions and behavioral symptoms.

RESULTS AND CONCLUSIONS

Patients treated with citicoline plus memantine showed an increase in MMSE between T0 and T1 (16.6 ± 2.9 vs 17.4 ± 2.7) and between T1 and T2 (17.4 ± 2.7 vs 17.7 ± 2.8). The difference in MMSE score was significant when comparing the two groups, both at T1 (p = 0.003) and T2 (p = 0.000). Since it is important to maximize the pharmacological means in AD and MD, the present study encourages the role of combined administration of memantine plus citicoline in disease management and in slowing down the progression of disease.

Neuroprotective Agents in the Intensive Care Unit: -Neuroprotective Agents in ICU

Neuroprotection or prevention of neuronal loss is a complicated molecular process that is mediated by various cellular pathways. Use of different pharmacological agents as neuroprotectants has been reported especially in the last decades. These neuroprotective agents act through inhibition of inflammatory processes and apoptosis, attenuation of oxidative stress and reduction of free radicals. Control of this injurious molecular process is essential to the reduction of neuronal injuries and is associated with improved functional outcomes and recovery of the patients admitted to the intensive care unit. This study reviews neuroprotective agents and their mechanisms of action against central nervous system damages.

The Role of Sirt1 in Ischemic Stroke: Pathogenesis and Therapeutic Strategies

Silent mating type information regulation 2 homolog 1 (Sirt1), a nicotine adenine dinucleotide (NAD⁺)-dependent enzyme, is well-known in playing a part in longevity. Ischemic stroke is a major neurological disorder and is a leading cause of death and adult disability worldwide. Recently, many studies have focused on the role of Sirt1 in ischemic stroke. Numerous studies consider Sirt1 as a protective factor and investigate the signaling pathways involved in the process under ischemic stress. However, the answer to whether upregulation of Sirt1 improves the outcome of stroke is still a controversy. In this review, we discuss the role and mechanisms of Sirt1 in the setting of ischemic stroke.

Effects of Liposomal Formulation of Citicoline in Experimental Diabetes-Induced Retinal Neurodegeneration

Diabetic retinopathy (DR) has been classically considered a microcirculatory disease of the retina. However, there is growing evidence to suggest that retinal neurodegeneration is also an early event in the pathogenesis of DR. Citicoline has been successfully used as a neuroprotective agent in the treatment of glaucoma but their effects on DR remain to be elucidated. On this basis, the main aim of the present study was to evaluate the effect of topical administration of citicoline in liposomal formulation on retinal neurodegeneration in db/db mouse and to investigate the underlying mechanisms of action. The treatment (citicoline or vehicle) was topically administered twice daily for 15 days. Retinal analyses were performed in vivo by electroretinography and ex vivo by using Western blot and immunofluorescence measurements. We found that the liposomal formulation of citicoline prevented glial activation and neural apoptosis in the diabetic retina. The main mechanism implicated in these beneficial effects were the inhibition of the downregulation of synaptophysin and its anti-inflammatory properties by means of preventing the upregulation of NF-κB and TNF-α (Tumor Necrosis Factor α) induced by diabetes. Overall, these results suggest that topical administration of citicoline in liposomal formulation could be considered as a new strategy for treating the early stages of DR.

CDP-choline circumvents mercury-induced mitochondrial damage and renal dysfunction

Heavy metal ions are known to produce harmful alterations on kidney function. Specifically, the accumulation of Hg²⁺ in kidney tissue may induce renal failure. In this work, the protective effect of CDP-choline against the deleterious effects induced by Hg²⁺ on renal function was studied. CDP-choline administered ip at a dose of 125 mg/kg body weight prevented the damage induced by Hg²⁺ administration at a dose of 3 mg/kg body weight. The findings indicate that CDP-choline guards mitochondria against Hg²⁺ -toxicity by preserving their ability to retain matrix content, such as accumulated Ca²⁺ . This nucleotide also protected mitochondria from Hg²⁺ -induced loss of the transmembrane electric gradient and from the generation of hydrogen peroxide and membrane TBARS. In addition, CDP-choline avoided the oxidative damage of mtDNA and inhibited the release of the interleukins IL-1 and IL6, recognized as markers of acute inflammatory reaction. After the administration of Hg²⁺ and CDP, CDP-choline maintained nearly normal levels of renal function and creatinine clearance, as well as blood urea nitrogen (BUN) and serum creatinine.

SIRT1 plays a neuroprotective role in traumatic brain injury in rats via inhibiting the p38 MAPK pathway

Traumatic brain injury (TBI) is a major cause of disability and death in patients who experience a traumatic injury. Mitochondrial dysfunction is one of the main factors contributing to secondary injury in TBI-associated brain damage. Evidence of compromised mitochondrial function after TBI has been, but the molecular mechanisms underlying the pathogenesis of TBI are not well understood. Silent information regulator family protein 1 (SIRT1), a member of the NAD⁺-dependent protein deacetylases, has been shown to exhibit neuroprotective activities in animal models of various pathologies, including ischemic brain injury, subarachnoid hemorrhage and several neurodegenerative diseases. In this study, we investigated whether SIRT1 also exert neuroprotective effect post-TBI, and further explored the possible regulatory mechanisms involved in TBI pathogenesis. A lateral fluid-percussion (LFP) brain injury model was established in rats to mimic the insults of TBI. The expression levels of SIRT1, p-p38, cleaved caspase-9 and cleaved caspase-3 were all markedly increased and reached a maximum at 12 h post-TBI. In addition, mitochondrial function was impaired, evidenced by the presence of swollen and irregularly shaped mitochondria with disrupted and poorly defined cristae, a relative increase of the percentage of neurons with low ΔΨm, the opening of mPTP, and a decrease in neuronal ATP content, especially at 12 h post-TBI. Pretreatment with the SIRT1 inhibitor sirtinol (10 mg/kg, ip) induced p-p38 activation, exacerbated mitochondrial damage, and promoted the activation of the mitochondrial apoptosis pathway. In contrast, pretreatment with the p38 inhibitor SB203580 (200 μg/kg, ip) significantly attenuated post-TBI-induced expression of both cleaved caspase-9 and cleaved caspase-3 and mitochondrial damage, whereas it had no effects on SIRT1 expression. Together, these results reveal that the 12 h after TBI may be a crucial time at which secondary damage occurs; the activation of SIRT1 expression and inhibition of the p38 MAPK pathway may play a neuroprotective role in preventing secondary damage post-TBI. For this reason, both SIRT1 and p38 are likely to be important targets to prevent secondary damage post-TBI.

The CITIRIVAD Study: CITIcoline plus RIVAstigmine in Elderly Patients Affected with Dementia Study

BACKGROUND

Acetylcholinesterase inhibitors (AchEIs), such as rivastigmine, coadministered with cholinergic precursors, such as citicoline, could be effective in Alzheimer's disease (AD) and in mixed dementia (MD), because they are able to increase the intrasynaptic levels of acetylcholine more than the single drugs given alone.

OBJECTIVE

The aim of the present study was to show the effectiveness of oral citicoline plus rivastigmine in patients with AD and MD.

METHODS

The CITIRIVAD study was a retrospective case-control study on 174 consecutive outpatients aged ≥65 years, affected with AD or MD, mean age 81.3 ± 4.5 years. Of the 174 patients, 92 had been treated with rivastigmine + citicoline 1000 mg/day given orally (group A); 82 patients had been treated with rivastigmine (group B). In both groups rivastigmine patch had been used for at least six months at the highest tolerated dosage. Group A comprised 62 patients affected with AD and 30 patients with MD. Group B comprised 53 patients affected with AD and 29 with MD. Cognitive functions had been assessed by Mini Mental State Examination (MMSE), daily life functions by activities of daily living (ADL) and instrumental activities (IADL), behavioral symptoms by neuropsychiatric inventory (NPI), comorbidities by the Cumulative Illness Rating Scale and mood by geriatric depression scale (GDS)-short form tests, which had been administered at baseline, 3 and 9 months.

RESULTS AND CONCLUSIONS

Data show the effectiveness of combined administration versus the AchEI alone, mainly in slowing disease progression and consequently in disease management, both in AD and in MD. No differences regarding the combined treatment were found between the two groups. Treatment with citicoline plus rivastigmine was safe and well tolerated.

The Citicholinage Study: Citicoline Plus Cholinesterase Inhibitors in Aged Patients Affected with Alzheimer's Disease Study

BACKGROUND

Citicoline can have beneficial effects both in degenerative and in vascular cognitive decline in a variety of ways (apoptosis inhibition, neuroplasticity potentiation, phospholipid, and acetylcholine (ACh) synthesis). Acetylcholinesterase inhibitors (AChEIs) have been used for treatment of Alzheimer's disease (AD). When co-administered with cholinergic precursors, they are able to increase the intrasynaptic levels of ACh more than when the single drugs given alone.

OBJECTIVE

The aim of the present study was to show the effectiveness of oral citicoline plus AChEIs in patients affected with AD.

METHODS

This was a retrospective multi-centric case-control study, involving seven Centers for Cognitive Impairment and Dementia in Italy, on 448 consecutive patients aged 65 years old or older affected with AD. 197 patients were treated with an AChEI while 251 were treated with an AchEI + citicoline 1000 mg/day given orally. Cognitive functions were assessed by MMSE, daily life functions by ADL and IADL, behavioral symptoms by NPI, comorbidities by CIRS, and mood by GDS-short form. Tests were administered at baseline (T0), after 3 (T1), and 9 months (T2). The primary outcomes were effects of combined administration versus AChEIs given alone on cognitive functions assessed by MMSE. The secondary outcomes were possible side effects or adverse events of combination therapy versus AChEIs alone.

RESULTS

Patients treated with citicoline plus an AChEI showed a statistically significant increase in MMSE between T0 and T1 (16.88±3.38 versus 17.62±3.64; p = 0.000) and between T1 and T2 (17.62±3.64 versus 17.89±3.54; p = 0.000).

CONCLUSION

The present study encourages the role of combined administration in disease management by slowing disease progression.

Current knowledge on the neuroprotective and neuroregenerative properties of citicoline in acute ischemic stroke

Ischemic stroke is one of the leading causes of long-lasting disability and death. Two main strategies have been proposed for the treatment of ischemic stroke: restoration of blood flow by thrombolysis or mechanical thrombus extraction during the first few hours of ischemic stroke, which is one of the most effective treatments and leads to a better functional and clinical outcome. The other direction of treatment, which is potentially applicable to most of the patients with ischemic stroke, is neuroprotection. Initially, neuroprotection was mainly targeted at protecting gray matter, but during the past few years there has been a transition from a neuron-oriented approach toward salvaging the whole neurovascular unit using multimodal drugs. Citicoline is a multimodal drug that exhibits neuroprotective and neuroregenerative effects in a variety of experimental and clinical disorders of the central nervous system, including acute and chronic cerebral ischemia, intracerebral hemorrhage, and global cerebral hypoxia. Citicoline has a prolonged therapeutic window and is active at various temporal and biochemical stages of the ischemic cascade. In acute ischemic stroke, citicoline provides neuroprotection by attenuating glutamate exitotoxicity, oxidative stress, apoptosis, and blood–brain barrier dysfunction. In the subacute and chronic phases of ischemic stroke, citicoline exhibits neuroregenerative effects and activates neurogenesis, synaptogenesis, and angiogenesis and enhances neurotransmitter metabolism. Acute and long-term treatment with citicoline is safe and in most clinical studies is effective and improves functional outcome.

The role of citicoline in cognitive impairment: pharmacological characteristics, possible advantages, and doubts for an old drug with new perspectives

BACKGROUND

Citicoline is able to potentiate neuroplasticity and is a natural precursor of phospholipid synthesis, or rather serves as a choline source in the metabolic pathways for biosynthesis of acetylcholine. Several studies have shown that it can have beneficial effects both in degenerative and in vascular cognitive decline. The aim of the present study was to review the pharmacokinetics and pharmacodynamics of this drug and its role in cognitive impairment according to the present medical literature.

METHODS

A MEDLINE(®) search was made using the following key words: citicoline, pharmacokinetics, pharmacodynamics, elderly, cognitive impairment, vascular dementia, and Alzheimer's disease. Recent studies on the possible role of citicoline in increasing sirtuin 1 (SIRT1) expression were assessed. Some personal studies were also considered, such as the VITA study and the IDEALE study.

RESULTS

Administered by both oral and intravenous routes, citicoline is converted into two major circulating metabolites, cytidine and choline. It is metabolized in the gut wall and liver. Pharmacokinetic studies suggested that it is well absorbed and highly bioavailable with oral dosing. A number of studies have clearly shown the possible role of citicoline in cognitive impairment of diverse etiology. It can also modulate the activity/expression of some protein kinases involved in neuronal death and increases SIRT1 expression in the central nervous system. The VITA study and the IDEALE study suggested that both parenteral and oral citicoline are effective and safe. Other studies have clearly demonstrated citicoline's effects on several cognitive domains. Conversely, some studies did not point out any evidence of efficacy of this drug.

CONCLUSION

Citicoline appears to be a promising agent to improve cognitive impairment, especially of vascular origin. In fact, so far it appears as a drug with the ability to promote "safe" neuroprotection, capable of enhancing endogenous protective. Large clinical trials are needed to confirm its benefits.

Saponins from Panax japonicus attenuate D-galactose-induced cognitive impairment through its anti-oxidative and anti-apoptotic effects in rats

OBJECTIVE

To investigate the neuroprotective effects of saponins from Panax japonicus (SPJ) on D-galactose (D-gal)-induced brain ageing, and further explore the underlying mechanisms.

METHODS

SPJ were analysed using high-pressure liquid chromatography. Male Wistar rats weighing 200 ± 20 g were randomly divided into four groups: control group (saline), D-gal-treated group (400 mg/kg, subcutaneously), D-gal + SPJ groups (50, 100 and 200 mg/kg, orally) and vitamin E group (100 mg/kg). Rats were injected corresponding drugs once daily for 8 weeks. Neuroprotective effects of SPJ were evaluated by Morris water maze, histopathological observations, biochemical assays, western blot analysis and quantitative real-time polymerase chain reaction (PCR) analysis in vivo as well as reactive oxygen species (ROS) measurement and apoptosis assay in vitro.

KEY FINDINGS

Our present study showed that D-gal had a neurotoxic effect in rats and in SH-SY5Y cells due to oxidative stress induction, including decreased total anti-oxidant capacity, superoxide dismutase (SOD) and glutathione peroxidase activity, ultimately leading to spatial learning and memory impairment in rats and ROS accumulation in SH-SY5Y cells. SPJ improved spatial learning and memory deficits, attenuated hippocampus histopathological injury and restored impaired anti-oxidative as well as anti-apoptotic capacities in D-gal-induced ageing rats. In addition, SPJ remarkably decreased lipofuscin levels, increased hippocampus nuclear factor erythroid 2-related factor 2 (Nrf2) and silent mating type information regulation 2 homologue (SIRT1) protein levels and anti-oxidant genes expression such as manganese superoxide dismutase (Mn-SOD), heme oxygenase (HO-1), NAD(P)H quinone oxidoreductase 1 (NQO1) and cysteine ligase catalytic (GCLC) in D-gal-induced brain ageing.

CONCLUSIONS

Our data suggested that D-gal induced multiple molecular and functional changes in brain similar to natural ageing process. SPJ protected brain from D-gal-induced neuronal injury through decreasing oxidative stress and apoptosis, and ultimately improving cognitive performance in D-gal-induced brain ageing. It is possibly related to Nrf2 and SIRT1-mediated anti-oxidant signalling pathways.

Neuroprotective effects of citicoline in in vitro models of retinal neurodegeneration

In recent years, citicoline has been the object of remarkable interest as a possible neuroprotectant. The aim of this study was to investigate if citicoline affected cell survival in primary retinal cultures and if it exerted neuroprotective activity in conditions modeling retinal neurodegeneration. Primary retinal cultures, obtained from rat embryos, were first treated with increasing concentrations of citicoline (up to 1000 μM) and analyzed in terms of apoptosis and caspase activation and characterized by immunocytochemistry to identify neuronal and glial cells. Subsequently, excitotoxic concentration of glutamate or High Glucose-containing cell culture medium (HG) was administered as well-known conditions modeling neurodegeneration. Glutamate or HG treatments were performed in the presence or not of citicoline. Neuronal degeneration was evaluated in terms of apoptosis and loss of synapses. The results showed that citicoline did not cause any damage to the retinal neuroglial population up to 1000 μM. At the concentration of 100 μM, it was able to counteract neuronal cell damage both in glutamate- and HG-treated retinal cultures by decreasing proapoptotic effects and contrasting synapse loss. These data confirm that citicoline can efficiently exert a neuroprotective activity. In addition, the results suggest that primary retinal cultures, under conditions inducing neurodegeneration, may represent a useful system to investigate citicoline neuroprotective mechanisms.

Neuroprotective properties of citicoline: facts, doubts and unresolved issues

Citicoline is the generic name of the pharmaceutical substance that chemically is cytidine-5'-diphosphocholine (CDP-choline), which is identical to the natural intracellular precursor of phospholipid phosphatidylcholine. Following injection or ingestion, citicoline is believed to undergo quick hydrolysis and dephosphorylation to yield cytidine and choline, which then enter the brain separately and are used to resynthesize CDP-choline inside brain cells. Neuroprotective activity of citicoline has been repeatedly shown in preclinical models of brain ischaemia and trauma, but two recent, large, pivotal clinical trials have revealed no benefits in ischaemic stroke and traumatic brain injury. However, the substance seems to be beneficial in some slowly advancing neurodegenerative disorders such as glaucoma and mild vascular cognitive impairment. This paper critically discusses issues related to the clinical pharmacology of citicoline, including its pharmacokinetics/biotransformation and pharmacodynamics/mode of action. It is concluded that at present, there is no adequate description of the mechanism(s) of the pharmacological actions of this substance. The possibility should be considered and tested that, in spite of apparently fast catabolism, the intact citicoline molecule or the phosphorylated intermediate products of its hydrolysis, cytidine monophosphate and phosphocholine, are pharmacologically active.