The beneficial effect of salubrinal on neuroinflammation and neuronal loss in intranigral LPS-induced hemi-Parkinson disease model in rats.

OBJECTIVE: Endoplasmic reticulum stress (ERS) and neuroinflammation are triggers for neurodegenerative disorders. Salubrinal is a selective inhibitor of protein phosphatase 1 (PP1) complex involving dephosphorylation of phosphorylated eukaryotic initiation factor-2α (eIF2α), the key crucial pathway in the ERS. Therefore, this study assessed the effects of inhibition of the ERS with salubrinal in the intranigral hemi-Parkinson disease (PD) model. MATERIALS AND METHODS: Animals were treated with salubrinal for one week after the PD model was created by intranigral lipopolysaccharide (LPS) administration. Apomorphine-induced rotation, rotarod, cylinder, and pole tests were performed to evaluate behavioral changes. Proinflammatory cytokines and the expression level of the dual specificity protein phosphatase 2 (DUSP2), PP1, and p-eIF2α were evaluated. Nigral expression of inducible nitric oxide synthase (iNOS), nuclear factor kappaB (Nf-κB), and cyclooxygenase (COX)-2 was determined. Finally, tyrosine hydroxylase and caspase-3/ caspase-9 expressions were assessed by immunohistochemistry. RESULTS: Salubrinal reduced the motor impairments and dopamine-related behavioral deficiencies caused by the LPS. Salubrinal attenuated the LPS-induced increased levels of interleukin (IL)-1ß, IL-6, tumor necrosis factor-α, and salubrinal rescued the loss of TH expression and dopamine levels and prevented the caspase-3/9 increase in the substantial nigra (SN). LPS potently increased iNOS, Nf-κB, and COX-2 expression, but this effect was reduced after salubrinal treatment. Additionally, salubrinal attenuated the LPS-induced PP1 and DUSP2 increase. CONCLUSION: Our results reveal that salubrinal is attenuating several inflammatory mediators and thereby decreased the inflammatory effects of LPS in the neurons of the SN. Together this results in increased cellular survival and maintained integrity of SN. Taken together our data show the beneficial effects of inhibition of ERS to restrict neuroinflammatory progression and neuronal loss in a PD model.

Role of TRPV1 channels on glycogen synthase kinase-3ß and oxidative stress in ouabain-induced bipolar disease.

Bipolar disorder (BD) is a multifactorial chronic and refractory disease characterized by manic, depressive, and mixed mood episodes. Although epidemiological, and pathophysiological studies demonstrated a strong correlation between bipolar disorder and oxidative stress, precise etiology is still missing. Recent studies suggested the possible role of transient receptor potential channels (TRP) in the BD but, current knowledge is limited. Therefore, the current study investigates the possible role of TRPV1 in the ouabain-induced model of BD. The model was created with intracerebroventricular single dose ouabain (10-3 M) administration. Animals were treated with capsaicin, capsazepine, and lithium for seven days. Mania and depressive-like states were investigated with open-field, sucrose preference, and elevated plus maze tests. Oxidative stress was assessed by measuring total antioxidant and oxidant states, spectrophotometrically. The phosphorylation Glycogen synthase kinase-3ß (GSK-3ß) evaluated by western blotting. Our results demonstrated that capsaicin dose-dependently inhibited the ouabain-induced hyperlocomotion and depression. Although capsazepine exacerbated behavioral impairment, it did not show a significant effect on the antioxidant and oxidant states, and the effects of capsazepine on behaviors were abolished by combination with capsaicin. Additionally, capsaicin potently prevented the ouabain-induced decrease in GSK-3ß phosphorylation. In contrast, capsazepine potentiated ouabain-induced decrease in GSK-3ß phosphorylation and combination with capsaicin, suppressed the effect of capsazepine on GSK-3ß phosphorylation. The effects of TRPV1 activation on oxidative stress and mania-like behaviors in the ouabain-induced BD model might be regulated by GSK-3ß phosphorylation.