RESUMEN
OBJECTIVES: ß-Amyloid protein (Aß) plays pivotal roles in pathogenesis of Alzheimer's disease (AD) and triggers various pathophysiological events. Lycopene is a promising neuroprotector with multiple bioactivities, while its bioavailability is limited. Lycopene-loaded microemulsion (LME) possessing superior bioavailability and brain-targeting efficiency was developed in our previous study. In this investigation, we aimed to comprehensively evaluate its neuroprotective effects and underlying mechanisms using intracerebroventricular (ICV) Aß1-42 injection mice. METHODS: Mice were assigned to the Sham, Aß, Aß + LME and Aß + lycopene dissolved in olive oil (LOO) groups. ICV Aß1-42 administration was performed, followed by oral gavage of brain-targeted LME or conventional LOO formulation for 3 weeks. Brain samples were harvested for immunohistochemistry, biochemical assays and western blotting analyses. RESULTS: Our findings verified Aß-induced neurotoxicity on neuroinflammation, oxidative stress, apoptosis, Aß metabolisms and synaptic plasticity. LME supplementation dramatically attenuated astrocytosis and microgliosis, decreased malondialdehyde production and rescued antioxidant capacities, normalized apoptotic parameters and alleviated neuronal loss, inhibited amyloidogenic processing and activated non-amyloidogenic pathway, together with upregulating synaptic protein expressions and restoring synaptic plasticity. Nevertheless, most of these phenomena were not observed for mice treated with LOO, implying that LME showed significantly higher therapeutic efficacy against Aß injury. DISCUSSION: In summary, brain-targeted LME could exert neuroprotective function via suppressing a series of cascades triggered by Aß aggregates, thus ameliorating Aß neurotoxicity and associated abnormalities. Given this, LME may serve as an attractive candidate for AD prevention and treatment, and superiority of brain-targeting delivery is highlighted.
Asunto(s)
Enfermedad de Alzheimer , Ratones , Animales , Enfermedad de Alzheimer/metabolismo , Péptidos beta-Amiloides/toxicidad , Péptidos beta-Amiloides/metabolismo , Licopeno/efectos adversos , Licopeno/metabolismo , Enfermedades Neuroinflamatorias , Estrés Oxidativo , Encéfalo/patología , Plasticidad Neuronal , Apoptosis , Modelos Animales de Enfermedad , Fragmentos de Péptidos/toxicidad , Fragmentos de Péptidos/metabolismoRESUMEN
Transient receptor potential vanilloid 4 (TRPV4) is a Ca2+-permeable non-selective cation channel that is involved in the development of neuropathic pain. P2X7 receptor (P2X7) belongs to a class of ATP-gated nonselective cation channels that plays an important role in neuropathic pain. Nevertheless, little is known about the interaction between them for neuropathic pain. In this paper, we investigated role of TRPV4-P2X7 pathway in neuropathic pain. We evaluated the effect of TRPV4-P2X7 pathway on neuropathic pain in a chronic compression of the dorsal root ganglion (DRG) (hereafter termed CCD) model. We analyzed the effect of P2X7 on mechanical and thermal hyperalgesia mediated by TRPV4 in CCD. Furthermore, we assessed the effect of TRPV4 on the expression of P2X7 and the release of IL-1ß and IL-6 in DRG after CCD. We found that intraperitoneal injection of TRPV4 agonist GSK-1016790A led to a significant increase of mechanical and thermal hyperalgesia in CCD, which was partially suppressed by P2X7 blockade with antagonist Brilliant Blue G (BBG). Then, we further noticed that GSK-1016790A injection increased the P2X7 expression of CCD, which was decreased by TRPV4 blockade with antagonist RN-1734 and HC-067047. Furthermore, we also discovered that the expressions of IL-1ß and IL-6 were upregulated by GSK-1016790A injection but reduced by RN-1734 and HC-067047. Our results provide evidence that P2X7 contributes to development of neuropathic pain mediated by TRPV4 in the CCD model, which may be the basis for treatment of neuropathic pain relief.