A combination of four active compounds alleviates cerebral ischemia–reperfusion injury in correlation with inhibition of autophagy and modulation of AMPK/mTOR and JNK pathways

Abstract

SMXZF is a combination of Rb1, Rg1, schizandrin, and DT-13 (6:9:5:4) derived from Sheng-mai San, a widely used Chinese traditional medicine for the treatment of cardiovascular and cerebral diseases. The present study explores the inhibitory effects and signaling pathways of SMXZF on autophagy induced by cerebral ischemia-reperfusion injury. Male C57BL/6 mice were subjected to ischemia-reperfusion insult by right middle cerebral artery occlusion (MCAO) for 1 hr with subsequent 24 hr reperfusion. Three doses of SMXZF (4.5, 9, and 18 mg/kg) were administered intraperitoneally (i.p.) after ischemia for 1 hr. An autophagic inhibitor, 3-methyladenine (3-MA; 300 μg/kg), was administered i.p. 20 min before ischemia as a positive drug. We found that SMXZF significantly increased cerebral blood flow and reduced the infarct volume, brain water content, and the neurological deficits in a dose-dependent manner. Similar to the positive control, SMXZF at 18 mg/kg also significantly inhibited autophagosome formation. Immunofluorescence staining and Western blotting demonstrated that SMXZF could significantly decrease the expression levels of beclin1 and microtubule-associated protein 1 light chain 3. SMXZF also remarkably inhibited the phosphorylation of adenosine monophosphate-activated protein kinase (AMPK) and mammalian target of rapamycin (mTOR) as well as the expression of c-Jun N-terminal kinase (JNK) and its phosphorylation induced by 24 hr reperfusion. Finally, we demonstrated that the optimal administration time of SMXZF was at the early period of reperfusion. This study reveals that SMXZF displays neuroprotective effect against focal ischemia-reperfusion injury, possibly associated with autophagy inactivation through AMPK/mTOR and JNK pathways.

Activation of AMPK/mTORC1-Mediated Autophagy by Metformin Reverses Clk1 Deficiency-Sensitized Dopaminergic Neuronal Death

“…metabolic sensor, such that activation of AMPK protects neuronal survival through regulating mitochondrial biogenesis and maintaining energy balance (Egan et al, 2011). Activation of AMPK inhibits mTOR and induces autophagy (Li et al, 2013;Guo et al, 2014). We have previously shown that Clk1 modulates AMPK activity and energy metabolism in microglia cells; therefore, we investigated the role of the AMPK/mTORC1 signaling pathway in inhibition of autophagy by Clk1 deficiency in dopaminergic neurons.…”

Identification of natural products with neuronal and metabolic benefits through autophagy induction

“…[61][62][63][64] However, it is not yet clear whether these other ginsenosides play activating or inhibitory roles on autophagy activity, as based on currently published data it seems that they may exert opposing functions in autophagy regulation in response to different stress. [65][66][67][68][69][70] Ginsenosides are a group of steroid glycoside compounds structurally similar to steroid hormones, and they differ with each other in the position and number of a variety of sugar chains. Hence, we suspect that ginsenosides may not belong to a common category of AMPK activators; rather, we propose that it is the ginsenoside-specific sugar chains that determine the physiological effects of ginsenosides.…”

Sex differences in mitochondrial (dys)function: Implications for neuroprotection

“…This process is necessary for normal cellular protein and lipid turnover and augmented following excitotoxic, ischemic and traumatic CNS injury (Diskin et al 2005; Guo et al 2014; Lin et al 2014; Ginet et al 2014; Zheng et al 2014; Zhou et al 2014). Recent studies reveal that during starvation induced autophagy, mitochondria supply membranes for autophagasome formation via association with autophagy mediating protein Atg5 and subsequent association with autophagasome protein microtubule-associated-protein-1 light chain 3 (LC3) (Hailey et al 2010) thus suggesting a critical role for mitochondria in the induction of autophagy.…”