Modulatory effects of vitamin B3 and its derivative on the levels of apoptotic and vascular regulators and cytoskeletal proteins in diabetic rat brain as signs of neuroprotection

Nicotinamide and Nicotinoyl-Gamma-Aminobutyric Acid as Neuroprotective Agents Against Type 1 Diabetes-Induced Nervous System Impairments in Rats

Diabetes is a multifunctional chronic disease that affects both the central and/or peripheral nervous systems. This study assessed whether nicotinamide (NAm) or conjugate of nicotinic acid with gamma-aminobutyric acid (N-GABA) could be potential neuroprotective agents against type 1 diabetes (T1D)-induced nervous system impairments in rats. After six weeks of T1D, induced by streptozotocin, nonlinear male Wistar rats were treated for two weeks with NAm (100 mg/kg, i. p.) or N-GABA (55 mg/kg, i. p.). Expression levels of myelin basic protein (MBP) were analyzed by immunoblotting. Polyol pathway parameters of the sciatic nerves were assessed spectrophotometrically, and their structure was examined histologically. NAm had no effect on blood glucose or body weight in T1D, while N-GABA reduced glucose by 1.5-fold. N-GABA also increased MBP expression by 1.48-fold, enhancing neuronal myelination, while NAm showed no such effect. Activation of the polyol pathway was observed in the T1D sciatic nerves. Both compounds decreased sorbitol content and aldose reductase activity, thereby alleviating changes similar to primary degeneration in the sciatic nerves and preventing peripheral neuropathy development. These results demonstrate that NAm and, more notably, N-GABA may exert neuroprotective effects against T1D-induced nervous system impairments by increasing MBP expression levels, improving myelination processes in the brain, inhibiting the polyol pathway, and partially restoring morphometric parameters in the sciatic nerves. This suggests their potential therapeutic efficacy as promising agents for the prevention of T1D-induced nervous system alterations.

Nicotinic acid attenuates amyloid β1-42-induced mitochondrial dysfunction and inhibits the mitochondrial pathway of apoptosis in differentiated SH-SY5Y cells

Alzheimer's disease (AD) is a chronic neurodegenerative disease characterized by progressive memory loss and behavioral disorders. The excessive accumulation of amyloid β (Aβ) and the formation of neurofibrillary tangles (NFTs) damage synaptic connections and the death of neurons. However, the underlying mechanisms of pathogenesis of AD remain unclear. Growing evidence indicates that impaired mitochondrial function may play a crucial role in the development of AD. In the current study, we investigated whether nicotinic acid (NA) could protect against amyloid β1-42-induced cytotoxicity in differentiated SH-SY5Y cells. Our results revealed the neuroprotective effects of NA on the differentiated SH-SY5Y cells treated with Aβ1-42. In detail, the 1-h pre-incubation with NA increased cell viability and lowered LDH levels. NA pre-incubation abolished Aβ1-42 treatment-associated alterations of mRNA levels of synaptic genes and enhanced the relative β3 Tubulin fluorescence intensity. NA eliminated the Aβ1-42-induced mitochondrial dysfunction by increasing the potential of mitochondrial membranes and maintaining a balance between the fusion and fission of mitochondria. Moreover, Aβ1-42 decreased mRNA levels of anti-apoptotic bcl2 and increased mRNA levels of pro-apoptotic: bim, bak, cytochrome c, and caspase 9. At the same time, the NA pre-treatment reduced Aβ1-42-dependent apoptotic death of differentiated SH-SY5Y cells. The above data suggest that NA presents a protective activity against Aβ1-42-induced cytotoxicity in differentiated SH-SY5Y cells by inhibiting the mitochondrial pathway of apoptosis and restoring the proper function of mitochondria.

[Integrative assessment of the effectiveness and safety of outpatient use of Picamilon]

OBJECTIVE

To study the efficacy and safety of the use of the drug Picamilon with various therapy regimens in patients with stage I of chronic cerebral ischemia (CCI).

MATERIAL AND METHODS

Material and methods. An open randomized comparative clinical trial included 44 patients with stage CCI aged 46 to 67 years (average age 55.6±6.76 years). Patients were randomized into two groups, patients of group 1 (n=23) received Picamilon orally in tablets of 50 mg 3 times/day for 60 days; group 2 (n=21) received Picamilon first parenterally at 100 mg i/m for 10 days, then in tablets of 50 mg 3 times/day for 50 days. The total duration of therapy was 60 days. The study included 4 visits (before treatment, 10 days later, 60 days later, 1.5 months after completion of treatment). The dynamics of cognitive status were assessed according to the Montreal Cognitive Function Assessment Scale (MoCA), vegetative disorders on the A.M. Wayne scale, neurological disorders on the A.I. Fedin scale, and sleep quality on the Ya.I. Levin scale. The study of the state of cerebral blood flow (dopplerography of intracranial vessels) and endothelial function (assessment of the level of methylation.

RESULTS

During treatment, in the total sample of patients, there was a positive trend in the results of the MoCA scale, increasing in the delayed period (24.9/26.5/28.3 points, p=0.022 and p<0.001); improvement in sleep quality in 50% of patients by visit 3 and in 84% by visit 4, in the 2nd group the effect occurred in 28% of patients, in the 1st - in 11%, by the end of the study the effect was comparable (p=0.508). Improvement according to Fedin A.I. scale noted in 77% of patients, values decreased from 11.9±8.3 to 6±6.1 points (p<0.0001) and to 2.77±4.43 points by visit 4 (p<0.0001). Normalization of autonomic functions was observed in 29% of patients (p=0.024) without intergroup differences. Picamilon therapy showed high efficacy in terms of clinical outcomes (up to 89%), good tolerability (98% of patients) and a favorable safety profile (less than 8.6% of AEs). The use of Picamilon was accompanied by an increase in the linear velocity of blood flow, a decrease in the thickness of the intima-media complex and the resistance index; a decrease in elevated ADMA concentrations and ADMA/MMA and (ADMA+SDMA)/MMA ratios.

CONCLUSION

The use of Picamilon is effective in patients with stage I CCI, contributes to a significant regression of neurological deficits, cognitive impairment, improved sleep quality and autonomic function; improves vascular endothelial function, reduces the risk of atherosclerosis and cardiovascular complications in patients. The optimal duration of therapy with Picamilon in stage I of chronic cerebral ischemia is 2 months.

Nicotinamide prevention in diabetes-induced alterations in the rat liver

Objective. The study was performed to elucidate whether nicotinamide (NAm) can attenuate the diabetes-induced liver damage by correction of ammonia detoxifying function and disbalance of NAD-dependent processes in diabetic rats. Methods. After four weeks of streptozotocin-induced diabetes, Wistar male rats were treated for two weeks with or without NAm. Urea concentration, arginase, and glutamine synthetase activities, NAD+ levels, and NAD+/NADH ratio were measured in cytosolic liver extracts. Expression of parp-1 gene in the liver was estimated by quantitative polymerase chain reaction and PARP-1 cleavage evaluated by Western blotting. Results. Despite the blood plasma lipid peroxidation products in diabetic rats were increased by 60%, the activity of superoxide dismutase (SOD) was reduced. NAm attenuated the oxidative stress, but did not affect the enzyme activity in diabetic rats. In liver of the diabetic rats, urea concentration and arginase activity were significantly higher than in the controls. The glutamine synthetase activity was decreased. Decline in NAD+ level and cytosolic NAD+/NADH ratio in the liver of diabetic rats was observed. Western blot analysis demonstrated a significant up-regulation of PARP-1 expression accompanied by the enzyme cleavage in the diabetic rat liver. However, no correlation was seen between mRNA expression of parp-1 gene and PARP-1 protein in the liver of diabetic rats. NAm markedly attenuated PARP-1 cleavage induced by diabetes, but did not affect the parp-1 gene expression. Conclusions. NAm counteracts diabetes-induced impairments in the rat liver through improvement of its detoxifying function, partial restoration of oxidative stress, NAD+ level, normalization of redox state of free cytosolic NAD+/NADH-couples, and prevention of PARP-1 cleavage.