Action of citicoline on rat retinal expression of extracellular-signal-regulated kinase (ERK1/2)

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.

Combined use of coenzyme Q10 and citicoline: A new possibility for patients with glaucoma

Glaucoma is the leading cause of irreversible blindness worldwide. Several risk factors have been involved in the pathogenesis of the disease. By now, the main treatable risk factor is elevated intraocular pressure. Nevertheless, some patients, whose intraocular pressure is considered in the target level, still experience a progression of the disease. Glaucoma is a form of multifactorial ocular neurodegeneration with complex etiology, pathogenesis, and pathology. New evidence strongly suggests brain involvement in all aspects of this disease. This hypothesis and the need to prevent glaucomatous progression led to a growing interest in the pharmacological research of new neuroprotective, non-IOP-lowering, agents. The aim of this paper is to report evidence of the usefulness of Coenzyme Q10 and Citicoline, eventually combined, in the prevention of glaucomatous neurodegeneration.

Natural Products: Evidence for Neuroprotection to Be Exploited in Glaucoma

Glaucoma, a leading cause of irreversible blindness worldwide, is an optic neuropathy characterized by the progressive death of retinal ganglion cells (RGCs). Elevated intraocular pressure (IOP) is recognized as the main risk factor. Despite effective IOP-lowering therapies, the disease progresses in a significant number of patients. Therefore, alternative IOP-independent strategies aiming at halting or delaying RGC degeneration is the current therapeutic challenge for glaucoma management. Here, we review the literature on the neuroprotective activities, and the underlying mechanisms, of natural compounds and dietary supplements in experimental and clinical glaucoma.

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.

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.

Rational Basis for Nutraceuticals in the Treatment of Glaucoma

BACKGROUND

Glaucoma, the second leading cause of blindness worldwide, is a chronic optic neuropathy characterized by progressive retinal ganglion cell (RGC) axons degeneration and death. Primary open-angle glaucoma (OAG), the most common type, is often associated with increased intraocular pressure (IOP), however other factors have been recognized to partecipate to the patogenesis of the optic neuropathy. IOP-independent mechanisms that contribute to the glaucoma-related neurodegeneration include oxidative stress, excitotoxicity, neuroinflammation, and impaired ocular blood flow. The involvement of several and diverse factors is one of the reasons for the progression of glaucoma observed even under efficient IOP control with the currently available drugs.

METHODS

Current research and online content related to the potential of nutritional supplements for limiting retinal damage and improving RGC survival is reviewed.

RESULTS

Recent studies have suggested a link between dietary factors and glaucoma risk. Particularly, some nutrients have proven capable of lowering IOP, increase circulation to the optic nerve, modulate excitotoxicity and promote RGC survival. However, the lack of clinical trials limit their current therapeutic use. The appropriate use of nutraceuticals that may be able to modify the risk of glaucoma may provide insight into glaucoma pathogenesis and decrease the need for, and therefore the side effects from, conventional therapies.

CONCLUSION

The effects of nutrients with anti-oxidant and neuroprotective properties are of great interest and nutraceuticals may offer some therapeutic potential although a further rigorous evaluation of nutraceuticals in the treatment of glaucoma is needed to determine their safety and efficacy.

Citicoline: A Food Beneficial for Patients Suffering from or Threated with Glaucoma

Oral form of citicoline, a nootropic and neuroprotective drug in use for almost five decades, recently was pronounced a food supplement in both USA and EU. The idea of adding citicoline to topical treatment of primary open angle glaucoma (POAG) aimed at decreasing intraocular pressure (IOP) appeared as a logical consequence of accepting neurodegenerative character of this disease. Experimental data, and also few clinical studies indicate that this substance has potential to counteract some important pathological mechanisms which seem to contribute to POAG initiation and progression, such as excitotoxicity and oxidative stress.

Citicoline retards myopia progression following form deprivation in guinea pigs

The retinal dopaminergic system is involved in the myopic shift following form deprivation. Citicoline has been demonstrated to stimulate the dopaminergic system in the brain and retina. Furthermore, citicoline has been used in many neurogenic diseases, such as senile cognitive impairment, stroke and Parkinson's disease as well as in amblyopia and glaucoma. Our aim was to investigate the effect of citicoline on the refractive state and retinal dopamine level in form deprivation myopia of guinea pigs. Guinea pigs, at an age of four weeks, were randomly divided into normal control, deprivation, deprived + citicoline and deprived + vehicle groups. Form deprivation myopia was induced by a translucent eye shield covering the right eye. Citicoline was injected intraperitoneally twice a day (500 mg/kg, 9 am and 9 pm) for 10 days. In vitro, retinal explants were cultured with citicoline for 24 h, with a final citicoline concentration of 100 µmol/L. The ocular refractive parameters and retinal dopamine content were measured. After occlusion for 10 days, the form-deprived eyes became myopic with an increase in axial length and a decrease in retinal dopamine content. The intraperitoneal injection of citicoline reduced the myopic degree (from -3.25 ± 0.77D to -0.62 ± 0.47D, P < 0.001) and partially raised retinal dopamine levels (from 0.55 ± 0.21 ng to 0.81 ± 0.24 ng, P < 0.01) in the form-deprived eyes. After 24 h of culturing retinal explants with citicoline, retinal dopamine content increased significantly (from 0.42 ± 0.14 ng to 0.62 ± 0.21 ng, P < 0.05). These results demonstrated that an intraperitoneal injection of citicoline could retard the myopic shift induced by form deprivation in guinea pigs, which was mediated by an increase in the retinal dopamine levels.

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.