The in vivo pharmacological manipulation of the Nrf-2 pathway and its therapeutic significance in brain diseases, with a possible implication in H2S-regulated lipidic metabolism

Nuclear factor erythroid 2-related factor 2 (Nrf2), a redox-sensitive transcription factor, plays a critical role in the regulation of cellular defence and contributes to a number of cellular processes. Nrf2 is regulated through an interplay of complex transcriptional and post-translational mechanisms that modulates its activity during cellular perturbations or other biological processes thereby ensuring cellular homeostasis is maintained through the orchestration of adaptive responses. Therefore, an ability to modulate the activity of the Nrf2 pathway holds promise as a therapeutic strategy in certain disease settings. In this thesis, the role of Nrf2 was evaluated in a mouse model of traumatic brain injury (TBI). TBI is a serious neuropathology that causes secondary injury mechanisms, including dynamic interplay between ischemic, inflammatory and cytotoxic processes. Fumaric acid esters (FAEs) showed beneficial effects in preclinical models of neuroinflammation and toxic oxidative stress, so the aim of the present work was to evaluate the potential beneficial effects of dimethyl fumarate (DMF), the most pharmacologically effective molecules among the FAEs, in a mouse model of TBI induced by controlled cortical impact (CCI). Mice were orally administered with DMF at the doses of 1, 10 and 30 mg/Kg, 1h and 4h after CCI. We performed histological, molecular, and immunohistochemistry analysis on the traumatic penumbral areas of the brain 24 hours after CCI. DMF treatment notably reduced histological damage and behavioral impairments, reducing neurodegeneration as evidenced by assessments of neuronal loss, Fluoro‐jade C and TUNEL staining; also, treatment with DMF blocked apoptosis process increasing B‐cell lymphoma 2 (Bcl‐2) expression in injured cortex. Furthermore, DMF treatment up‐regulated antioxidant Kelch‐ like ECH‐associated protein 1/ Nuclear factor erythroid 2‐ related factor (Keap‐1/Nrf2) pathway, inducing activation of manganese superoxide dismutase (Mn‐SOD) and heme‐ oxygenase‐1 (HO‐1) and reducing 4‐hydroxy‐2‐9 nonenal (4‐HNE) staining. Also, regulating NF‐κB pathway, DMF treatment decreased the severity of inflammation through a modulation of neuronal nitrite oxide synthase (nNOS), interleukin 1 (Il‐1β), tumor necrosis factor (TNF‐α), cyclooxygenase 2 (COX‐2) and myeloperoxidase (MPO) activity, reducing ionized calcium‐binding adapter molecule 1 (Iba‐1) and glial fibrillary acidic protein (GFAP) expression. Moreover, the role of Nrf2 pathway, was discusses in a mouse model of nitroglycerin -induced migraine (NTG). Oxidative stress and inflammatory pathways are involved in NTG and endogenous antioxidant defense system has a role in the prevention of hyperalgesia in migraine. In this study, we aimed to evaluate the role of DMF in regulating the hypersensitivity in a mouse model of NTG-induced migraine. Mice were orally administered with DMF at the doses of 10, 30 and 100 mg/kg, 5 minutes after NTG intraperitoneal injections. We performed histological and molecular analysis on the whole brain and behavioral tests after 4 h by NTG-migraine induction. The expression of nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) subunit p65, nuclear factor of kappa light polypeptide gene enhancer in B-cells inhibitor alpha (IκBα), inducible nitrite oxide synthase (iNOS), cyclooxygenase 2 (COX-2), Nrf2, manganese superoxide dismutase (Mn-SOD) and heme-oxygenase-1 (HO-1) were detected by Western blot. Tail flick, hot plate, formalin and photophobia tests were used to evaluate neuropathic pain and migraine-related light sensitivity. DMF treatment notably reduced histological damage as showed by cresyl violet staining; also, regulating both NF-κB and Nrf2 pathway, DMF treatment decreased the severity of inflammation and increased the protective antioxidant action. Moreover, the headache-associated neuropathic pain was significantly reduced. These results provide the evidence that DMF restores neurological in damaged-brain and it has modulating effect on central sensitization, suggesting a new insight into the potential therapeutical application of DMF on Nrf2 pathway modulation.