Endoplasmic reticulum stress (ERS) and neuroinflammation are triggers for neurodegenerative disorders. Salubrinal is a selective inhibitor of protein phosphatase 1 (PP1) complex involving dephospho...

Aim: Gastric ulcers are the most common gastrointestinal disease, due to several factors in the industrialized world. They may also occur after many pharmacological agents, combined with gastroprotective agents such as proton pump inhibitors (PPI) or anti-acids, are used as a preferred approach to maintaining gastrointestinal health. Unexpected adverse effects in these combinations make natural products an important alternative option. Methods: Therefore, the main aim of this study is to investigate one natural compound, the Tarantula cubensis extract (TCE), in the experimental peptic ulcer model which was created by a single administration of indomethacin (40 mg/kg, body weight) to fed state Wistar-albino rats. The animals were pre-treated with two-doses of the TCE (0.2 ml/kg) before the indomethacin administration. After six hours, they were euthanized and the stomach tissue was isolated for biochemical and immunohistochemical analysis. Total antioxidant status/total oxidant status (TAS/TOS), prostaglandin E2 (PGE2), and nuclear factor kappa-B (NF-κB) levels were determined with ELISA in tissue homogenates. Caspase-3, cyclooxygenase-2 (COX-2), inducible nitric oxide synthase (iNOS) and tumor necrosis factor-alpha (TNF-α), were visualized with immunohistochemistry in intact tissues. Results: Pre-treatment with TCE increased PGE2 levels and decreased total oxidative status (TAS/TOS). Additionally, TCE alleviated the increase of (NF-κB) levels due to the indomethacin administration. Histopathological and immunostaining results showed that TCE mitigated elevated immunoreactivity of the caspase-3, COX-2, iNOS, and TNF-α which were the results of the indomethacin administration. Conclusion: Our study demonstrated that pre-TCE treatment ameliorated indomethacin-induced peptic ulcers via antioxidant and anti-inflammatory actions.

Background and Objectives: Ocular alkaline burn is a clinical emergency that can cause permanent vision loss due to limbal stem cell deficiency and corneal neovascularization (CNV). Although the basic pathogenetic mechanisms are considered to be acute oxidative stress and corneal neovascularization triggered by inflammation, the underlying intracellular mechanisms have not been clearly elucidated. The aim of this study was to investigate the role of endoplasmic reticulum (ER) stress on inflammation and neovascularization, and the effect of the ER stress inhibitor salubrinal (SLB), as a novel treatment in a corneal alkaline burn model in rats. Methods: Chemical burns were created by cautery for 4 s using a rod coated with 75% silver nitrate and 25% potassium nitrate in the corneal center for the corneal neovascularization (CNV) model. Twenty-eight Wistar albino rats were divided into four groups: SHAM, CNV, CNV + SLB, and CNV + bevacizumab (BVC). After the CNV model was applied to the right eye, a single subconjunctival dose (0.05 mL) of 1 mg/kg salubrinal was injected into both eyes in the CNV + SLB group. A total of 1.25 mg/mL of subconjunctival BVC was administered to the CNV + BVC group. Fourteen days after experimental modeling and drug administration, half of the globes were placed in liquid nitrogen and stored at −20 °C until biochemical analysis. The remaining tissues were collected and fixed in 10% buffered formalin for histopathological and immunohistochemical analysis. Three qualitative agents from three different pathways were chosen: TNFR for inflammation, endothelial nitric oxide synthase (e-NOS) for vascular endothelial growth factor (VEGF)-mediated vascular permeability, and caspase-3 for cellular apoptosis. Results: Significantly lower caspase-3 and eNOS levels were detected in the CNV + SLB and CNV + BVC groups than in the CNV group. Additionally, histopathological evaluation revealed a significant decrease in neovascularization, inflammatory cell infiltration, and fibroblast activity in the CNV + SLB and CNV + BVC groups. The endoplasmic reticulum stress inhibitor, salubrinal, administered to the treatment group, attenuated apoptosis (caspase-3) and inflammation (e-NOS). In the control group (left eyes of the SLB group), salubrinal did not have a toxic effect on the healthy corneas. Conclusion: The ER stress pathway plays an important role in angiogenesis after alkaline corneal burns, and treatment with SLB modulates this pathway, reducing caspase-3 and eNOS levels. Further studies are needed to understand the molecular mechanisms altered by SLB-mediated therapy. The fact that more than one mechanism plays a role in the pathogenesis of CNV may require the use of more than one molecule in treatment. SLB has the potential to affect multiple steps in CNV pathogenesis, both in terms of reducing ER stress and regulating cellular homeostasis by inhibiting the core event of integrated stress response (ISR). Therefore, it can be used as a new treatment option and as a strengthening agent for existing treatments. Although blockade of intracellular organelle stress pathways has shown promising results in experimental studies, more in-depth research is needed before it can be used in routine practice. To the best of our knowledge, this study is the first to report the role of ER stress in corneal injury.

Microglial antigen generation (MAG) is an essential process in regulating disease states and homeostasis of the central nervous system. MAG is considered as responsible autoimmune mechanism in neurodegenerative diseases such as Alzheimer's, Parkinson's, and Huntington's diseases. Neuroprotective and regulator effects of cannabinoid receptors on these disease states and modulation with pharmacological agents are urgent subjects in recent decades. Although different aspects of microglial immune response have been investigated, specific effects of these receptor subtypes in the MAG are still unclear. Therefore, in the current study, we have investigated the effects of CB₁ and CB₂ receptors on antigen generation by investigating MHC-II and its master regulator CIITA by specific cannabinoid agents (ACEA, AM-251, CP 55,940, and SR144528) in the LPS-induced BV-2 cells. Additionally, the effects of drug treatments on inflammatory status were measured by determining IL-1β, IL-6, and TNF-α levels. LPS-induced increase in MHC-II and CIITA expression was inhibited by specific CB₁ agonist, ACEA, and nonselective cannabinoid agonist CP 55,940. A combination with specific CB₁ antagonist AM-251 prevented these inhibitory effects of ACEA and CP 55,940 on both MHC-II and CIITA expression. Although specific CB₂ antagonist, SR144528, also prevented the inhibitory effect of CP 55,940 on MHC-II, it did not affect CIITA expression. LPS-induced IL-1β, IL-6, and TNF-α increase both attenuated with CP 55,940 and ACEA treatments. Although both selective cannabinoid antagonists inhibited this effect, preventive effects were more dominant on CB₁ receptors. Our results demonstrated that CB₁ receptors majorly mediates LPS-induced MHC-II and its regulator CIITA expression in microglial cells.