Coumestrol is a phytoestrogen widely known for its anti-diabetic, anti-oxidant, and anti-inflammatory properties. Thus, it gets a lot of attention as a potential agent in the nutritional therapy of diseases such as obesity and type 2 diabetes. In our study, we evaluated whether coumestrol affects insulin resistance development via the sphingolipid signaling pathway in primary rat hepatocytes. The cells were isolated from the male Wistar rat's liver with the use of collagenase perfusion. Next, we incubated the cells with the presence or absence of palmitic acid and/or coumestrol. Additionally, some groups were incubated with insulin. The sphingolipid concentrations were assessed by HPLC whereas the expression of all the proteins was evaluated by Western blot. Coumestrol markedly reduced the accumulation of sphingolipids, namely, ceramide and sphinganine through noticeable inhibition of the ceramide de novo synthesis pathway in insulin-resistant hepatocytes. Moreover, coumestrol augmented the expression of fatty acid transport proteins, especially FATP5 and FAT/CD36, which also were responsible for excessive sphingolipid accumulation. Furthermore, coumestrol altered the sphingolipid salvage pathway, which was observed as the excessive deposition of the sphingosine-1-phosphate and sphingosine. Our study clearly showed that coumestrol ameliorated hepatic insulin resistance in primary rat hepatocytes. Thus, we believe that our study may contribute to the discovery of novel preventive and therapeutic methods for metabolic disorders.

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The aim of the study was to evaluate the influence of vitamin K2 (VK2) supplementation on the sphingolipid metabolism pathway in palmitate-induced insulin resistant hepatocytes. The study was carried out on human hepatocellular carcinoma cells (HepG2) incubated with VK2 and/or palmitic acid (PA). The concentrations of sphingolipids were measured by high-performance liquid chromatography. The expression of enzymes from the sphingolipid pathway was assessed by Western blotting. The same technique was used in order to determine changes in the expression of the proteins from the insulin signaling pathway in the cells. Simultaneous incubation of HepG2 cells with palmitate and VK2 elevated accumulation of sphinganine and ceramide with increased expression of enzymes from the ceramide de novo synthesis pathway. HepG2 treatment with palmitate and VK2 significantly decreased the insulin-stimulated expression ratio of insulin signaling proteins. Moreover, we observed that the presence of PA w VK2 increased fatty acid transport protein 2 expression. Our study showed that VK2 activated the ceramide de novo synthesis pathway, which was confirmed by the increase in enzymes expression. VK2 also intensified fatty acid uptake, ensuring substrates for sphingolipid synthesis through the de novo pathway. Furthermore, increased concentration of sphingolipids, mainly sphinganine, inhibited insulin pathway proteins phosphorylation, increasing insulin resistance development.

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Background Neurodegeneration characterizes by dysfunction, progressive atrophy and loss of neurons, which is presented in both neurodegenerative as well as demyelinating disorders. Both groups of diseases share common pathological hallmarks: neuroinflammation and gradual loss of neurons and axons, which lead to the central nervous system (CNS) damage and the development of these disorders. Mounting evidence has supported the reticulon4A (RTN4A) role in the pathogenesis of some neurodegenerative and demyelinating disorders, including MS. RTN4A also known as Nogo‐A protein, contributes to neuroinflammation and demyelination. Moreover, this protein acts as a relevant inhibitor of neurite outgrowth and axonal regeneration. Therefore, the objectives of the present study were evaluation of Nogo‐A and Tau levels in the cerebrospinal fluid (CSF) of MS patients and subjects from the control group, as well as the assessment of a relationships between concentrations of immunoglobulins, albumin, immunoglobulins and albumin quotients, as well as oligoclonal bands. Method The concentrations of Nogo‐A and Tau proteins were measured in the CSF of 15 MS patients and 16 subjects from control group by means of quantitative technique ELISA. CSF and serum concentrations of albumin and immunoglobulins were measured by using nephelometer. To evaluate the integrity of the blood‐CSF barrier and intrathecal immunoglobulins production, albumin and immunoglobulins quotients were calculated. Furthermore, the oligioclonal bands were assessed by using isoelectofocusing method. Result The CSF concentrations of Nogo‐A was significantly higher in MS group in comparison with controls. The increased CSF level of the protein was observed significantly correlate with the concentration of Tau protein in MS patients. Furthermore, we revealed associations between Nogo‐A protein and CSF levels of albumin, Tau and QIgG in the whole study group. Conclusion Our preliminary results indicate a potential role of Nogo‐A protein in the neurodegenerative pathology of MS. Moreover, it seems that reticuon4A is a promising candidate biomarker for demyelinating disorders, including MS, but these investigations need to be further clarified using a larger study group. The study was conducted with the use of equipment purchased by Medical University of Białystok as part of the RPOWP 2007‐2013 funding, Priority I, Axis 1.1, contract No. UDA‐RPPD.01.01.00‐20‐001/15‐00 dated 26.06.2015.