Sulforaphane (SFA) protects neuronal cells from oxygen & glucose deprivation (OGD)

Abstract

Background Perinatal brain injury results in neurodevelopmental disabilities (neuroDDs) that include cerebral palsy, autism, attention deficit disorder, epilepsy, learning disabilities and others. Commonly, injury occurs when placental circulation, that is responsible for transporting nutrients and oxygen to the fetus, is compromised. Placental insufficiency (PI) is a reduced supply of blood and oxygen to the fetus and results in a hypoxic-ischemic (HI) environment. A significant HI state in-utero leads to perinatal compromise, characterized by fetal growth restriction and brain injury. Given that over 80% of perinatal brain injuries that result in neuroDDs occur during gestation, prior to birth, preventive approaches are needed to reduce or eliminate the potential for injury and subsequent neuroDDs. Sulforaphane (SFA) derived from cruciferous vegetables such as broccoli sprouts (BrSps) is a phase-II enzyme inducer that acts via cytoplasmic Nrf2 to enhance the production of anti-oxidants in the brain through the glutathione pathway. We have previously shown a profound in vivo neuro-protective effect of BrSps/SFA as a dietary supplement in pregnant rat models of both PI and fetal inflammation. Strong evidence also points to a role for SFA as treatment for various cancers. Paradoxically, then SFA has the ability to enhance cell survival, and with conditions of cancer, enhance cell death. Given our findings of the benefit of SFA/Broccoli Sprouts as a dietary supplement during pregnancy, with improvement to the fetus, it is important to determine the beneficial and toxic dosing range of SFA. We therefore explored, in vitro, the dosing range of SFA for neuronal and glial protection and toxicity in normal and oxygen/glucose deprived (OGD) cell cultures. Methods OGD simulates, in vitro, the condition experienced by the fetal brain due to PI. We developed a cell culture model of primary cortical neuronal, astrocyte and combined brain cell co-cultures from newborn rodent brains. The cultures were exposed to an OGD environment for various durations of time to determine the LD50 (duration of OGD required for 50% cell death). Using the LD50 as the time point, we evaluated the efficacy of varying doses of SFA for neuroprotective and neurotoxicity effects. Control cultures were exposed to normal media without OGD, and cytotoxicity of varying doses of SFA was also evaluated. Immunofluorescence (IF) and Western blot analysis of cell specific markers were used for culture characterization, and quantification of LD50. Efficacy and toxicity effect of SFA was assessed by IF/high content microscopy and by AlamarBlue viability assay, respectively. Results We determined the LD50 to be 2 hours for neurons, 8 hours for astrocytes, and 10 hours for co-cultures. The protective effect of SFA was noticeable at 2.5 μM and 5 μM for neurons, although it was not significant. There was a significant protective effect of SFA at 2.5 μM (p<0.05) for astrocytes and co-cultures. Significant toxicity ranges were also confirmed in OGD cultures as ≥ 100 μM (p<0.05) for astrocytes, ≥ 50 μM (p<0.01) for co-cultures, but not toxic in neurons; and toxic in control cultures as ≥ 100 μM (p<0.01) for neurons, and ≥ 50 μM (p<0.01) for astrocytes and co-cultures. One Way ANOVA and Dunnett’s Multiple Comparison Test were used for statistical analysis. Conclusions Our results indicate that cell death shows a trend to reduction in neuronal and astrocyte cultures, and is significantly reduced in co-cultures treated with low doses of SFA exposed to OGD. Doses of SFA that were 10 times higher were toxic, not only under conditions of OGD, but in normal control cultures as well. The findings suggest that: 1. SFA shows promise as a preventative agent for fetal ischemic brain injury, and 2. Because the fetus is a rapidly growing organism with profound cell multiplication, dosing parameters must be established to insure safety within efficacious ranges. This study will influence the development of innovative therapies for the prevention of childhood neuroDD.

Reduction of Deuterium Level Supports Resistance of Neurons to Glucose Deprivation and Hypoxia: Study in Cultures of Neurons and on Animals

“…This fact indicates that the results obtained in biochemical tests, as well as in experiments in the T-maze, are stipulated precisely by the change in the concentration of deuterium. This is also consistent with the results of experiments on cerebellar cell cultures, which showed that placing neurons in a medium containing δ 2 H equal to −357‰ increases their resistance to glucose deprivation, which was used to model pathological processes in cerebral ischemia [ 66 , 67 ]. In this case, the response of cultured neurons is generally comparable to the response of brain cells in vivo, when intensification of free radicals’ synthesis, lipid peroxidation, and changes in the activity of antioxidant enzymes are observed [ 68 , 69 ].…”

miR‐432‐5p Inhibits the Ferroptosis in Cardiomyocytes Induced by Hypoxia/Reoxygenation via Activating Nrf2/SLC7A11 Axis by Degrading Keap1

“…Nrf2 activator can upregulate the expression of antioxidant protein and scavenge ROS. After activation, Nrf2 reduces the maturation and expression of inflammatory factors such as interleukin-1 β (IL-1 β ), tumor necrosis factor- α (TNF- α ), and IL-18 to inhibit the inflammatory response after cerebral I/R injury [ 40 , 41 ]. Under physiological conditions, Nrf2 exists in the cytoplasm and Keap1 protein anchors Nrf2 to the cytoskeleton of actin, preventing Nrf2 from entering the nucleus to exert its transcriptional activity.…”

Sulforaphane’s Multifaceted Potential: From Neuroprotection to Anticancer Action

“…Neuroprotection refers to the mechanisms and strategies used to defend the central nervous system (CNS) (Figure 3) against injury due to both acute (e.g., trauma or stroke) and chronic neurodegenerative disorders (e.g., dementia, Parkinson's, Alzheimer's, epilepsy) [13]; by extension, neuroprotective agents comprise a category of agents that generally are used to protect neuronal structure and/or function. Research on the neuroprotective effects of SFN began in 2004 with studies that showed its effects protecting neurons [14] and microglia [15] against oxidative stress via activation of nuclear factor erythroid 2-related factor 2 (Nrf2). The research literature is replete with studies that support the vital role played by the Nrf2 pathway in the neuroprotective effects of SFN [14,[16][17][18][19][20][21], evidenced by lack of neuroprotection from toxins in Nrf2-knockout mice treated with SFN [22,23].…”

“…Research on the neuroprotective effects of SFN began in 2004 with studies that showed its effects protecting neurons [14] and microglia [15] against oxidative stress via activation of nuclear factor erythroid 2-related factor 2 (Nrf2). The research literature is replete with studies that support the vital role played by the Nrf2 pathway in the neuroprotective effects of SFN [14,[16][17][18][19][20][21], evidenced by lack of neuroprotection from toxins in Nrf2-knockout mice treated with SFN [22,23]. In a study of Parkinson's disease that used a 6-hydroxydopamine-Parkinson's disease mouse model, treatment of SH-SY5Y cells with SFN was found to have a protective effect on the neurons, which was attributed to the observed increases in active nuclear Nrf2 protein, Nrf2 mRNA, and total glutathione levels and inhibition of neuronal tissue apoptosis [24].…”