Curcumin inhibits apoptosis and brain edema induced by hypoxia-hypercapnia brain damage in rat models

The protective effects of curcumin in cerebral ischemia and reperfusion injury through PKC-θ signaling

Ischemic stroke is a common cerebrovascular disease with the main cause considered to be cerebral ischemia and reperfusion (I/R), which exerts irreparable injury on nerve cells. Thus, the development of neuroprotective drugs is an urgent concern. Curcumin, a known antioxidant, has been found to have neuroprotective effects. To determine the protective mechanism of curcumin in ischemic stroke, oxygen and glucose deprivation/reoxygenation (OGD/R) was used to treat PC12 cells to mimic the cerebral I/R cell model. Curcumin (20 μM) was applied to OGD/R PC12 cells, followed by Ca²⁺ concentration, transepithelial electrical resistance (TEER), and cell permeability measurements. The results showed that OGD/R injury induced a decrease in TEER and increases in Ca²⁺ concentration and cell permeability. In contrast, curcumin alleviated these effects. The protein kinase C θ (PKC-θ) was associated with the protective function of curcumin in the OGD/R cell model. Moreover, the middle cerebral artery occlusion and reperfusion model (MCAO/R) was applied to simulate the I/R rat model. Our results demonstrated that curcumin could reverse the MCAO/R-induced increase in Ca²⁺ concentration and blood-brain barrier (BBB) disruption. Our study demonstrates the mechanisms by which curcumin exhibited a protective function against cerebral I/R through PKC-θ signaling by reducing BBB dysfunction.

D4F prophylaxis enables redox and energy homeostasis while preventing inflammation during hypoxia exposure

Apo-A1 is correlated with conditions like hyperlipidemia, cardiovascular diseases, high altitude pulmonary edema and etc. where hypoxia constitutes an important facet.Hypoxia causes oxidative stress, vaso-destructive and inflammatory outcomes.Apo-A1 is reported to have vasoprotective, anti-oxidative, anti-apoptotic, and anti-inflammatory effects. However, effects of Apo-A1 augmentation during hypoxia exposure are unknown.In this study, we investigated the effects of exogenously supplementing Apo-A1-mimetic peptide on SD rats during hypoxia exposure. For easing the processes of delivery, absorption and bio-availability, Apo-A1 mimetic peptide D4F was used. The rats were given 10 mg/kg BW dose (i.p.) of D4F for 7 days and then exposed to hypoxia. D4F was observed to attenuate both oxidative stress and inflammation during hypoxic exposure. D4F improved energy homeostasis during hypoxic exposure. D4F did not affect HIF-1a levels during hypoxia but increased MnSOD levels while decreasing CRP and Apo-B levels. D4F showed promise as a prophylactic against hypoxia exposure.

Curcumin targets vascular endothelial growth factor via activating the PI3K/Akt signaling pathway and improves brain hypoxic-ischemic injury in neonatal rats

This study aimed to evaluate the effect of curcumin on brain hypoxic-ischemic (HI) damage in neonatal rats and whether the phosphoinositide 3-kinase (PI3K)/Akt/vascular endothelial growth factor (VEGF) signaling pathway is involved. Brain HI damage models were established in neonatal rats, which received the following treatments: curcumin by intraperitoneal injection before injury, insulin-like growth factor 1 (IGF-1) by subcutaneous injection after injury, and VEGF by intracerebroventricular injection after injury. This was followed by neurological evaluation, hemodynamic measurements, histopathological assessment, TUNEL assay, flow cytometry, and western blotting to assess the expression of p-PI3K, PI3K, p-Akt, Akt, and VEGF. Compared with rats that underwent sham operation, rats with brain HI damage showed remarkably increased neurological deficits, reduced right blood flow volume, elevated blood viscosity and haematocrit, and aggravated cell damage and apoptosis; these injuries were significantly improved by curcumin pretreatment. Meanwhile, brain HI damage induced the overexpression of p-PI3K, p-Akt, and VEGF, while curcumin pretreatment inhibited the expression of these proteins. In addition, IGF-1 treatment rescued the curcumin-induced down-regulated expression of p-PI3K, p-Akt, and VEGF, and VEGF overexpression counteracted the inhibitory effect of curcumin on brain HI damage. Overall, pretreatment with curcumin protected against brain HI damage by targeting VEGF via the PI3K/Akt signaling pathway in neonatal rats.

Propofol weakens hypoxia-aroused apoptosis and autophagy via elevating microRNA-137 in neurocytes

BACKGROUND

Hypoxia was proven to cause brain cell apoptosis and autophagy. Herein, we tested the influences of propofol, a commonly used intravenous sedative hypnotic drug, on apoptosis and autophagy aroused by hypoxia stimulation in PC-12 and HT-22 cells.

METHODS

Followed by hypoxia and/or propofol treatment, cell viability of PC-12 and HT-22 cells, apoptosis and autophagy, along with microRNA-137 (miR-137) expression were measured, respectively. Then, miR-137 inhibitor was transfected to silence miR-137. Whether miR-137 took part in the impacts of propofol on hypoxia-exposed cells was explored. Finally, the activities of PI3K/AKT/mTOR and ERK pathways were measured.

RESULTS

Hypoxia stimulation aroused cell apoptosis and elevated cell autophagy in PC-12 and HT-22 cells. Propofol weakened the apoptosis and autophagy of PC-12 and HT-22 cells aroused by hypoxia. Moreover, propofol elevated the miR-137 level in PC-12 and HT-22 cells. Silencing miR-137 declined the influences of propofol on hypoxia-induced injuries. Besides, propofol promoted PI3K/AKT/mTOR and ERK pathways activation in hypoxia-exposed cells through raising miR-137.

CONCLUSION

Propofol weakened hypoxia-aroused apoptosis and autophagy of PC-12 and HT-22 cells might be through raising miR-137 level and thereby promoting PI3K/AKT/mTOR and ERK pathways activation.

Curcumin protects against hepatic ischemia/reperfusion induced injury through inhibiting TLR4/NF-κB pathway

The TLR4/NF-κB pathway had important roles in hepatic ischemia/reperfusion (I/R) injury. In this study, we reported a protective effect of curcumin against hepatic I/R injury via TLR4/NF-κB pathway. Curcumin significantly inhibited cell apoptosis, and decreased levels of LDH and production of TNF-a, IL-1b, and IL-6 in the cell supernatant. In addition, curcumin ameliorated elevated TLR4 and NF-κB caused by hypoxia/reoxygenation stimulation in BRL-3A cells. In vivo assays revealed that curcumin reduce levels of ALT and AST, and reversed TLR4/NF-κB signaling pathway caused by hepatic I/R stimulation in liver tissues. These results suggested that curcumin ameliorates hepatic I/R injury, which may be mediated in part via the TLR4/NF-κB signaling pathway.