Melatonin promotes peripheral nerve repair through Parkin-mediated mitophagy.

Schwann cells (SCs) are the major glial cells in peripheral nervous system. They unsheathe and myelinate axons and play an essential role in peripheral nerve regeneration. Several studies report that Parkin-mediated mitophagy is associated with various diseases. Melatonin promotes proliferation of central glial cells. Little is known about the effect of melatonin and Parkin-mediated mitophagy on peripheral nerve repair. In this study, using a rat model of a peripheral nerve injury (PNI) and in vitro model established by RSC96 cells treated with tert-butyl hydroperoxide (TBHP), we found that Parkin-mediated mitophagy can effectively reduce the production of mitochondrial reactive oxygen species (ROS), maintain the balance of mitochondrial membrane potential, maintain autophagic flux, and inhibit mitochondrial apoptosis. At the same time, we found that the increase of Parkin under stress is a manifestation of the RSC96 cells' resistance to oxidative stress to maintain RSC96 cells' balance. In our experiment, melatonin is similar to a Parkin agonist, up-regulating the expression of Parkin, enhancing all the positive results of Parkin in a stress state, such as inhibiting active oxygen production, maintaining autophagic flux, and inhibiting mitochondrial apoptosis. In addition, we design in vivo experiments to verify in In vitro experiments. In in vivo, melatonin promotes the expression of Parkin, maintains autophagic flux, inhibits apoptosis, promotes myelin regeneration, reduces the regeneration of collagen fibers around damaged tissues, and promotes peripheral nerve repair. When adenovirus was used to down-regulate the expression of Parkin, we found that all the positive effects of melatonin were attenuated. Collectively, these findings indicate that melatonin upregulates Parkin-mediated mitophagy and promotes peripheral nerve repair. The results provide a basis for development of effective drugs for PNI treatment.

STAT3 activation by catalpol promotes osteogenesis-angiogenesis coupling, thus accelerating osteoporotic bone repair.

BACKGROUND: Bone fracture repair has gained a lot of attention due to the high incidence of delayed union or even nonunion especially in osteoporotic patients, resulting in a dreadful impact on the quality of life. However, current therapies involve the costly expense and hence become unaffordable strategies for fracture recovery. Herein, developing new strategies for better bone repair is essential and urgent. Catalpol treatment has been reported to attenuate bone loss and promote bone formation. However, the mechanisms underlying its effects remain unraveled. METHODS: Rat bone marrow mesenchymal stem cells (BMSCs) were isolated from rat femurs. BMSC osteogenic ability was assessed using ALP and ARS staining, immunofluorescence, and western blot analysis. BMSC-mediated angiogenic potentials were determined using the western blot analysis, ELISA testing, scratch wound assay, transwell migration assay, and tube formation assay. To investigate the molecular mechanism, the lentivirus transfection was used. Ovariectomized and sham-operated rats with calvaria defect were analyzed using micro-CT, H&E staining, Masson's trichrome staining, microfil perfusion, sequential fluorescent labeling, and immunohistochemistry assessment after administrated with/without catalpol. RESULTS: Our results manifested that catalpol enhanced BMSC osteoblastic differentiation and promoted BMSC-mediated angiogenesis in vitro. More importantly, this was conducted via the JAK2/STAT3 pathway, as knockdown of STAT3 partially abolished beneficial effects in BMSCs. Besides, catalpol administration facilitated bone regeneration as well as vessel formation in an OVX-induced osteoporosis calvarial defect rat model. CONCLUSIONS: The data above showed that catalpol could promote osteogenic ability of BMSC and BMSC-dependent angiogenesis through activation of the JAK2/STAT3 axis, suggesting it may be an ideal therapeutic agent for clinical medication of osteoporotic bone fracture.

Trans-Cinnamaldehyde Increases Random Pattern Flap Survival Through Activation of the Nitric Oxide Pathway.

BACKGROUND: The application of random pattern skin flaps is limited in plastic surgery reconstruction due to necrosis. Trans-cinnamaldehyde has antibacterial, anticancer, and antioxidant properties. In this study, we aimed to investigate the effect of trans-cinnamaldehyde on skin flap survival and its possible mechanism regarding nitric oxide. MATERIALS AND METHODS: One hundred forty male Sprague-Dawley rats were randomly divided into seven groups (n = 20 each group). After the dorsal flap was raised, different doses of trans-cinnamaldehyde (10, 20, and 30 mg/kg) were immediately given by oral gavage in the three different groups. To assess the possible involvement of the nitric oxide system, NG-nitro-L-arginine methyl ester (L-NAME, a nonselective nitric oxide synthase inhibitor) was used in this study. All flap samples were incised on postoperative day 7. RESULTS: Our results showed that flap survival was increased significantly in the 20 mg/kg (P < 0.001) trans-cinnamaldehyde (TC) group compared to the control group or 30 mg/kg TC group. This protective function was restrained by coadministration of L-NAME with 20 mg/kg TC. The results of histopathology, laser Doppler, arteriography mediated with oxide-gelatine, and fluorescent staining all showed a significant increase in capillary count, collagen deposition, angiogenesis, and flap perfusion. Immunohistochemistry results revealed a significant increase in the expression of CD34, eNOS, and VEGF. CONCLUSION: Trans-cinnamaldehyde increased flap survival through the nitric oxide synthase pathway and contributed to angiogenesis. A concentration of 20 mg/kg trans-cinnamaldehyde was recommended in this study.

Inhibition of PI3K/Akt/NF-κB signaling by Aloin for ameliorating the progression of osteoarthritis: In vitro and in vivo studies.

Osteoarthritis (OA) is a progressive and degenerative joint disease. Aloin is a bitter and yellow-brown-coloured compound from the Aloe plant and is allowed for use in foods as a "natural flavour". In our study, we examined the protective effects of Aloin on the inhibition of OA development as well as its underlying mechanism in both in vitro and vivo experiments. In in-vitro experiments, the protective effect of aloin on the anabolism and catabolism of the extracellular matrix (ECM) induced by IL-1 ß in chondrocytes by inhibiting the expression of pro-inflammatory factors, including TNF-α (p = 0.016), IL-6 (p = 0.006), iNOS (p = 0.001) and COX-2 (p = 0.006). Mechanistically, Aloin suppressed the IL-1ß-induced activation of the PI3K/Akt/NF-κB signalling pathway cascades. Moreover, molecular docking studies demonstrated that Aloin bound strongly to PI3K. In vivo, Aloin ameliorated the OA process in the destabilization of the medial meniscus (DMM) model. In summary, our findings demonstrate that Aloin ameliorates the progression of OA via the PI3K/Akt/NF-κB signalling pathways, which supports Aloin as a promising therapeutic agent for the treatment of OA.

Vitexin reduces hypoxia-ischemia neonatal brain injury by the inhibition of HIF-1alpha in a rat pup model.

Previous studies have demonstrated that the early suppression of HIF-1α after hypoxia-ischemia (HI) injury provides neuroprotection. Vitexin (5, 7, 4-trihydroxyflavone-8-glucoside), an HIF-1α inhibitor, is a c-glycosylated flavone that has been identified in medicinal plants. Therefore, we hypothesized that treatment with vitexin would protect against HI brain injury. Newborn rat pups were subjected to unilateral carotid artery ligation followed by 2.5 h of hypoxia (8% O2 at 37 °C). Vitexin (30, 45 or 60 mg/kg) was administered intraperitoneally at 5 min or 3 h after HI. Vitexin, administered 5 min after HI, was neuroprotective as seen by decreased infarct volume evaluated at 48 h post-HI. This neuroprotection was removed when vitexin was administered 3 h after HI. Neuronal cell death, blood-brain barrier (BBB) integrity, brain edema, HIF-1α and VEGF protein levels were evaluated using a combination of Nissl staining, IgG staining, brain water content, immunohistochemistry and Western blot at 24 and 48 h after HI. The long-term effects of vitexin were evaluated by brain atrophy measurement, Nissl staining and neurobehavioral tests. Vitexin (45 mg/kg) ameliorated brain edema, BBB disruption and neuronal cell death; Upregulation of HIF-1α by dimethyloxalylglycine (DMOG) increased the BBB permeability and brain edema compared to HI alone. Vitexin attenuated the increase in HIF-1α and VEGF. Vitexin also had long-term effects of protecting against the loss of ipsilateral brain and improveing neurobehavioral outcomes. In conclusion, our data indicate early HIF-1α inhibition with vitexin provides both acute and long-term neuroprotection in the developing brain after neonatal HI injury.