Effects of Dexamethasone and Brain-Derived Neurotropic Factor in NT2 Cells

Stress is a major risk factor that can evoke neuropathological changes within the cortico-limbic system in neuropsychiatric, neurodegenerative, and metabolic disorders. Many of these disorders implicate the regulation of glucocorticoids (GCs) and neurotrophins, such as the brain-derived neurotropic factor (BDNF). GCs are steroidal hormones that have anti-inflammatory and immunosuppressive effects. They are widely used to treat allergy, inflammation and autoimmune diseases. GCs’ roles and functions in the central nervous system (CNS) is varied and not well understood at this time. BDNF is commonly known to play important roles in the survival, growth-promoting and synaptic plasticity of the CNS. However, it has also been reported that continuous exposure to BDNF results in widespread neuronal death. While several studies have shown functional interactions between BDNF and GCs in neural events, the relationship between these interactions has not been clearly defined. The goal of this study was to determine the effects of dexamethasone (DEX) and BDNF in Ntera-2 (NT2) cells. Our results show a decline in cell viability and proliferation in a time and dose dependent manner when NT2 cells were treated with DEX alone. Treatment with BDNF did not affect NT2 cell viability. Interestingly, when NT2 cells were treated with a combination of DEX and BDNF, there appeared to be greater loss of cell viability and cell proliferation compared to the treatment with DEX alone. This synergistic effect possibly occurred via the co-activation of the BDNF receptor p75 and glucocorticoid receptor common pathways that may be responsible for apoptosis and cellular death. &nbsp

Neuroprotective Role of SRT1720 Against Hydrogen Peroxide Induced Oxidative Stress in NT2 Cells

Neurodegenerative diseases such as Alzheimer’s disease (AD) and Parkinson’s disease (PD) are characterized by a significant increase in neuronal loss. Oxidative stress (OS) plays a significant role on neuronal damage. Reactive oxygen species (ROS) generated from agents such as hydrogen peroxide (H2O2) leads to cell damage and reduction of cell viability. Sirtuin 1 (SIRT1) is a therapeutic target for neurodegenerative disorders because it regulates several cellular functions and biological processes that promote cellular longevity. This study was undertaken to examine the role of SRT1720 in protecting cells from H2O2 induced stress in Ntera-2 cl.D1(NT2), which has been proven to be a useful in vitro system for the investigation of functions related to human neuronal and glial systems. The results provide evidence that H2O2 significantly induced oxidative stress in a concentration dependent manner. Moreover, pre-treatment with low concentrations of SRT1720 for 48 hours protected against the effects of H2O2. Also, a combination of H2O2 and SRT1720 improved cell viability. Interestingly, apoptotic or necrotic cell death was not detected after H2O2 treatment in the cell culture model system employed

Dysfunction in Fatty Acid Amide Hydrolase Is Associated with Depressive-Like Behavior in Wistar Kyoto Rats

BACKGROUND: While the etiology of depression is not clearly understood at the present time, this mental disorder is thought be a complex and multifactorial trait with important genetic and environmental contributing factors. METHODOLOGY/PRINCIPAL FINDINGS: The role of the endocannabinoid (eCB) system in depressive behavior was examined in Wistar Kyoto (WKY) rat strain, a genetic model of depression. Our findings revealed selective abnormalities in the eCB system in the brains of WKY rats compared to Wistar (WIS) rats. Immunoblot analysis indicated significantly higher levels of fatty acid amide hydrolase (FAAH) in frontal cortex and hippocampus of WKY rats with no alteration in the level of N-arachidonyl phosphatidyl ethanolamine specific phospholipase-D (NAPE-PLD). Significantly higher levels of CB1 receptor-mediated G-protein coupling and lower levels of anandamide (AEA) were found in frontal cortex and hippocampus of WKY rats. While the levels of brain derived neurotropic factor (BDNF) were significantly lower in frontal cortex and hippocampus of WKY rats compared to WIS rats, pharmacological inhibition of FAAH elevated BDNF levels in WKY rats. Inhibition of FAAH enzyme also significantly increased sucrose consumption and decreased immobility in the forced swim test in WKY rats. CONCLUSIONS/SIGNIFICANCE: These findings suggest a critical role for the eCB system and BDNF in the genetic predisposition to depressive-like behavior in WKY rats and point to the potential therapeutic utility of eCB enhancing agents in depressive disorder

Effect of FAAH inhibition on depressive-like behavior in WKY rats.

<p>Treatment with URB597 (0.3 mg/kg, i.p. for 7 days) elicited a significant decrease in total time spent in immobility (50%, p<0.01; A) and a marked increase in sucrose intake (48%, p<0.05; B) without any effect on the spontaneous locomotor activity in the open field (C) in WKY rats compared to vehicle treated WKY rats.</p

Basal levels of NAPE-PLD in the brain of WKY rats.

<p>There were no significant differences in the levels of NAPE-PLD enzyme in frontal cortex and hippocampus of WKY rats compared to WIS rats (A). A representative immunoblot for hippocampus is provided in the upper panel (B). Hippo; Hippocampus.</p

Effect of FAAH inhibition on BDNF, AEA and CB1 function in the brain of WKY rats.

<p>Basal BDNF levels were found to be significantly lower in frontal cortex (27%) and hippocampus (26%) of WKY compared to WIS rats (p<0.05; A). Subchronic treatment with URB597 (0.3 mg/kg, i.p. for 7 days) significantly elevated BDNF levels in frontal cortex (64%) and hippocampus (45%) of WKY rats compared to vehicle treated WKY rats (p<0.05; B). Inhibition of FAAH was accompanied by significant increase in AEA levels in frontal cortex (31%, p<0.01; C) and hippocampus (42%, p<0.001; C), and a subsequent decrease in CB1 receptor-mediated G-protein activation in frontal cortex of WKY rats (21%, p<0.05; D). Hippo; Hippocampus.</p

Basal differences in AEA and FAAH levels in the brain of WKY rats.

<p>The level of eCB, AEA was found to be significantly lower in hippocampus of WKY rats compared to WIS rats (31%, p<0.01; A). Conversely, the level of FAAH enzyme was significantly higher in frontal cortex (40%, p<0.05) and hippocampus (40%, p<0.05; B) of WKY rats. A representative immunoblot for hippocampus is provided in the upper panel (B). The qPCR analysis also indicated higher levels of mFAAH in hippocampus of WKY rats (24%, p<0.05; C). The qPCR data on FAAH, normalized to β-Actin (internal standard) is presented as the fold change relative to the control value of 1.0. The FAAH activity was slightly higher in frontal cortex (15%, p<0.05) and hippocampus (17%, p<0.05) of WKY rats compared to WIS rats (D). Hippo; Hippocampus.</p

Basal differences in CB1 receptor in the brain of WKY rats.

<p>The CB1 receptor agonist-stimulated [³⁵S]GTPγS binding was significantly higher in frontal cortex (24%, p<0.05) and hippocampus (44%, p<0.01) of WKY rats compared to WIS rats (A). Data is presented as percentage of stimulation over basal binding. Western blot analysis revealed significantly higher levels of CB1 receptors in hippocampus (45%, p<0.05), while they were found to be slightly higher in frontal cortex of WKY rats (18%, B). Hippo; Hippocampus.</p