ABSTRACT
Neuropathic pain affects millions of people in the worldwide, but the major therapeutics perform limited effectiveness. Paeonol (PAE) is widely distributed in Paeonis albiflora, and has manifested anti-inflammatory and antioxidative effects in multiple diseases. The present study aims to elucidate the effect of Paeonol (PAE) on neuropathic pain (NP) and the potential targets. Chronic constriction injury model was established to mimic NP in vivo in rats. The expression of GFAP, HDAC2, AHDAC3, Ac-H3K9, Histone-H3, Ac-H4K12, Histone-H4, TNF-α, IL-1ß, and IL-6 was assessed by real-time polymerase chain reaction, western blot, and/or enzyme-linked immunosorbent assay kits. Ultimately, results indicated that intervention of PAE significantly blocked neuroinflammation and astrocytic activation via blocking HDAC/miR-15a signaling in CCI rats. These data revealed PAE is a novel therapeutic target for the treatment of neuropathic pain.
Subject(s)
MicroRNAs , Neuralgia , Rats , Animals , Rats, Sprague-Dawley , Constriction , Neuroinflammatory Diseases , Histones , MicroRNAs/genetics , MicroRNAs/metabolism , Neuralgia/drug therapyABSTRACT
Type 2 diabetes (T2D)-related neurological complication is the risk factor for neurodegenerative disorders. The pathological changes from T2D-caused blood-brain barrier (BBB) dysfunction plays a critical role in developing neurodegeneration. The hyper-activation of the Angiotensin II type 1 receptor (AT1R) in the brain is associated with neurovascular impairment. The AT1R antagonist Valsartan is commonly prescribed to control high blood pressure, heart failure, and diabetic kidney diseases. In this study, we investigated the beneficial effects of Valsartan in db/db diabetic mice and isolated brain endothelial cells. We showed that 2 weeks of Valsartan administration (30 mg/Kg body weight) mitigated the increased permeability of the brain-blood barrier and the reduction of gap junction proteins VE-Cadherin and Claudin 2. In human brain microvascular cells (HBMVECs), we found that Valsartan treatment ameliorated high glucose-induced hyperpermeability by measuring Dextran uptake and transendothelial electrical resistance (TEER). Furthermore, Valsartan treatment recovered high glucose-repressed endothelial VE-Cadherin and Claudin 2 expression. Moreover, Valsartan significantly suppressed the expressions of pro-inflammatory cytokines such as macrophage chemoattractant protein-1 (MCP-1) and interleukin-6 (IL-6) against high glucose. Mechanistically, Valsartan ameliorated high glucose-repressed endothelial cAMP-responsive element-binding protein (CREB) signaling activation. The blockage of CREB activation by PKA inhibitor H89 abolished the action of Valsartan, suggesting its dependence on CREB signaling. In conclusion, Valsartan shows a neuroprotective effect in diabetic mice by ameliorating BBB dysfunction. These effects of Valsartan require cellular CREB signaling in brain endothelial cells.
Subject(s)
Blood-Brain Barrier/drug effects , Brain/drug effects , Diabetes Mellitus, Experimental/complications , Diabetes Mellitus, Type 2/complications , Endothelial Cells/drug effects , Inflammation/drug therapy , Valsartan/pharmacology , Angiotensin II Type 1 Receptor Blockers/pharmacology , Animals , Blood-Brain Barrier/metabolism , Blood-Brain Barrier/pathology , Brain/metabolism , Brain/pathology , Endothelial Cells/metabolism , Endothelial Cells/pathology , Inflammation/etiology , Inflammation/metabolism , Inflammation/pathology , Male , Mice , Vascular Diseases/drug therapy , Vascular Diseases/etiology , Vascular Diseases/metabolism , Vascular Diseases/pathologyABSTRACT
OBJECTIVE: Aim of this study was to detect the expression of miR-15a in rats following chronic constriction injury (CCI) and to investigate the regulatory functions of miR-15a during neuropathic pain (NP) development. METHODS: CCI was performed in adult Sprague-Dawley rats to set up the rat model of neuropathic pain. MiR-15a agomir and scrambled control were delivered into the implanted catheter of rats. The mechanical allodynia and thermal hyperalgesia were assessed in both CCI- and sham-operated groups. Rat lumbar spinal cord tissues were harvested for mRNA and protein analyses. The primary spinal microglia were isolated from adult Sprague-Dawley rats and transfected with miR-15a mimics, scramble miRNA, miR-15a inhibitor or its corresponding negative control. Cell lysates were collected for mRNA and protein analyses. RESULTS: Compared to sham-operated group, the expression of miR-15a in CCI rats was significantly reduced, whereas neuroinflammation in spinal cord tissues was increased. Intrathecal administration of miR-15a agomir significantly attenuated CCI-induced NP and the levels of proinflammatory cytokines, including IL-6, IL-1ß, and TNF-α. AKT3 was predicted and confirmed as a miR-15a-regulated gene. We further demonstrated that miR-15a overexpression downregulated the level of AKT3 in primary rat microglia and rat CCI model. Moreover, the upregulation of miR-15a induced the expressions of autophagy-associated proteins, suggesting that the regulation mechanism of miR-15a in NP development involves AKT3-mediated autophagy via inhibiting the expression of AKT3. CONCLUSION: Our findings indicated that miR-15a might serve as a promising therapeutic target for the management of NP through the stimulation of autophagic process.
