Retinoprotective Effect of 2-Ethyl-3-hydroxy-6-methylpyridine Nicotinate

Study to elucidate the pharmacological activity of retinalamin in a rat model of ischemic retinopathy

Introduction: Over the past few years, the incidence of retinal ischemic disorders has been increasing, due to a rising prevalence of such socially burdensome diseases as diabetes and hypertension, which ultimately lead to ocular vascular pathology. The identification of new treatment options that would prevent retinal neuron death is a crucial task of modern pharmacology.

Materials and methods: The research was carried out on male Wistar rats. Retinopathy was modeled by inducing a 30-min ischemic episode, with a 72-hour period of reperfusion and subsequent administration of Retinalamin and Emoxypine for 10 days. The effectiveness of the drugs was evaluated by electroretinographic, ophthalmoscopic and morphological assessments.

Results and discussion: On Day 14 of the experiment, a dose-dependent preservation of the electroretinogram b-wave/a-wave amplitude ratio was observed in the animals treated with Retinalamin depending on a dose (1.39±0.06, 1.46±0.03 and 1.49±0.04 in low (0.214 mg/kg), medium (0.428 mg/kg) and high (0.857 mg/kg) Retinalamin dose groups, respectively). The ophthalmoscopic picture of the fundus oculi also improved following the treatment with Retinalamin (1.42, 1.69 and 1.90 times lower ophthalmoscopic scores compared to placebo-treated animals in low, medium and high dose groups, respectively). The morphologic “coefficient of change” applied to ganglion cell layer was 2.2, 1.7 and 1.6 points in low, medium and high dose Retinalamin groups, respectively. These results are significantly different from both intact and placebo group (p<0.05). Based on the aforementioned experimental findings, we conclude that Retinalamin has a retinoprotective effect and is superior to the drug of comparison (Emoxypine).

Conclusion: The greatest neuroprotective effects were shown in the groups receiving Retinalamin. In these groups, the ERG b-wave/a-wave amplitude ratio was preserved, the ophthalmoscopic picture was less pathologic and retinal morphology features were close to those of the intact retina.

THE SEARCH FOR NEUROPROTECTIVE COMPOUNDS AMONG NEW ETHYLTHIADIAZOLE DERIVATIVES

The aim of the study is to search compounds with neuroprotective properties among new ethylthiadiazole derivatives in simulated traumatic brain injury.

Materials and methods. The experiment was carried out on 78 white male rats 270±20 g line “Wistar” 5–6 months of age and 120 outbred sexually mature mice weighing 20±2 grams. The article describes the search for compounds with neuroprotective properties among new ethylthiadiazole derivatives under the codes LKHT 4–15, LKHT 10–18, LKHT 11–18, and LKHT 12–18 in experimental traumatic brain injury in rats. Acute toxicity of the compounds was studied. Pharmacological screening was performed using behavioral and neurological research methods. The McGraw stroke score scale modified by I.V. Gannushkina and the mNSS psychometric scale were used in the study. The open field and Rota-rod tests were used to assess the behavioral status of the animals.

Results. The compound-LKHT 12–18 at a dose of 50 mg/kg was detected as a leader. In pharmacological correction of pathology, this compound had the lowest percentage of fatality among the studied compounds (8%), the severity of neurological deficit was significantly reduced, the lowest scores and a higher level of motor activity of the limbs were registered. The number of rearing in the group of animals receiving the compound LKHT 12–18 at the dose of 50 mg/kg increased by 1.5 times, statistically significant (p<0.05) in comparison with the control group. Based on the results of the “Rota-rod” test, the total time of holding animals on the rod for 3 attempts was statistically significantly different in the groups administered with LKHT 12–18 derivatives (1.5 times longer) at the dose of 50 mg/kg compared with the control (p<0.05).

Conclusion. Based on the results obtained in this study, it is planned to study in more detail the compound LKHT 12–18 at the dose of 50 mg/kg.

[Electroretinography in evaluation of neuroprotective effect in an experimental model of glaucoma]

For drugs that have a therapeutic effect on glaucoma through mechanisms not associated with decreasing intraocular pressure (IOP), special attention is paid to the choice of effectiveness criteria. The article examines the possibility of using a- and waves of electroretinography (ERG) in preclinical studies to predict the effectiveness of glaucoma drug candidates.

PURPOSE

To examine the possibility of reliably associating changes in the amplitude of a- and ERG waves with functional changes in the retina of experimental glaucoma rats with morphological evidence of loss of functional integrity of the retina.

MATERIAL AND METHODS

The study was carried out in the laboratory of the Research Institute of Pharmacology of Living Systems of the Belgorod State University. Adult outbred rats were used as a test system. Experimental glaucoma was modelled by multiple injections of hyaluronic acid into the anterior chamber of the eye; they were examined by recording the time history of intraocular pressure changes, and performing ERG, ophthalmoscopy, and histological examination of the retina and subcortical centers of vision. The following groups were formed: intact, pathology control, positive control.

RESULTS

The development of glaucoma in experimental rats was accompanied by neuronal death in the ganglionic layer of the retina; at the same time, characteristic changes were observed in the subcortical visual centers. A change in the ERG was recorded: for thewave, there was a dependence on the degree of changes in the ganglionic layer of the retina, change in the wave can also indicate the involvement of amacrine and horizontal cells in the process; for the a-wave, a correlation with the results of photoreceptor layer histology was noted, which was characterized as a deviation from the norm developing against the background of hydrodynamic load in the eye chambers.

CONCLUSION

ERG is suitable for use in preclinical studies of glaucoma drugs as an indicative in vivo method for diagnosing the state of the retina in animals. The use of this method is especially valuable for conducting preclinical studies of drugs that involve long-term use when ophthalmoscopy and intraocular pressure alone cannot fully characterize the course of glaucoma, and animal euthanasia seems unnecessary and inhumane.

New Insights for nicotinamide: Metabolic disease, autophagy, and mTOR

Metabolic disorders, such as diabetes mellitus (DM), are increasingly becoming significant risk factors for the health of the global population and consume substantial portions of the gross domestic product of all nations. Although conventional therapies that include early diagnosis, nutritional modification of diet, and pharmacological treatments may limit disease progression, tight serum glucose control cannot prevent the onset of future disease complications. With these concerns, novel strategies for the treatment of metabolic disorders that involve the vitamin nicotinamide, the mechanistic target of rapamycin (mTOR), mTOR Complex 1 (mTORC1), mTOR Complex 2 (mTORC2), AMP activated protein kinase (AMPK), and the cellular pathways of autophagy and apoptosis offer exceptional promise to provide new avenues of treatment. Oversight of these pathways can promote cellular energy homeostasis, maintain mitochondrial function, improve glucose utilization, and preserve pancreatic beta-cell function. Yet, the interplay among mTOR, AMPK, and autophagy pathways can be complex and affect desired clinical outcomes, necessitating further investigations to provide efficacious treatment strategies for metabolic dysfunction and DM.