Title

 

Authors

E. Esposito¹, S. Cuzzocrea<sup>1,2

1</sup>Dept. Clinical and Experimental Medicine and Pharmacology, School of Medicine, University of Messina, Italy; ²IRCCS Centro Neurolesi "Bonino-Pulejo", Messina, Italy

 

Abstract

Since oxidative stress is a common feature of the neurodegenerative processes, we studied a possible effect of palmitoylethanolamide (PEA) against oxidative stress in vitro. PEA partially prevented hydrogen peroxide (H₂0₂, 500 μM for 24 hr)-induced cell death, whereas it was ineffective against the L-glutamate (1 mM; 24 hr)-induced excitotoxicity at all concentrations tested (0.01-30 μM) in macrophages. We then used a combinatorial approach: a natural dietary flavonoid that exhibits antioxidant properties, luteolin, in combination with PEA. In this study we found that the combination at low concentrations (at which single agents induce minimal effect) synergistically increased the viability of cells subjected to oxidative stress in two different cell lines: murine macrophage cell line J-774A.1 and rat astrocytoma cells C6. Mechanistic studies revealed that the association reduced mitochondria-dependent and mitochondria-independent apoptosis in both cell lines. Pre-treatment of cells with combination of PEA (1μM) and luteolin (1μM) inhibited H₂O₂-induced cell viability loss, and lipid peroxidation. Moreover, the mitochondrial dysfunction associated with cell apoptosis including the release of cytochrome c, the downregulation of Bcl-2, upregulation of Bax induced by H₂O₂ were also abrogated by PEA/luteolin co-stimulation. Moreover, pre-treatment of PEA in association with luteolin strongly suppressed the production of nitric oxide (NO) as well as the expression of inducible NO synthase and cyclooxygenase-2 in lipopolysaccharide-activated J774A.1 cells. Taken together, our results for the first time suggest that the treatment of PEA in combination with luteolin has synergistic/additive effects and provides an important rationale for future treatments in many neurodegenerative disorders based on oxidative stress or in aging and age-associated neurodegenerative diseases.