Salidroside protects cortical neurons against glutamate-induced cytotoxicity by inhibiting autophagy.

Recent evidence suggests that glutamate-induced cytotoxicity contributes to autophagic neuron death and is partially mediated by increased oxidative stress. Salidroside has been demonstrated to have neuroprotective effects in glutamate-induced neuronal damage. The precise mechanism of its regulatory role in neuronal autophagy is, however, poorly understood. This study aimed to probe the effects and mechanisms of salidroside in glutamate-induced autophagy activation in cultured rat cortical neurons. Cell viability assay, Western blotting, coimmunoprecipitation, and small interfering RNA were performed to analyze autophagy activities during glutamate-evoked oxidative injury. We found that salidroside protected neonatal neurons from glutamate-induced apoptotic cell death. Salidroside significantly attenuated the LC3-II/LC3-I ratio and expression of Beclin-1, but increased (SQSTM1)/p62 expression under glutamate exposure. Pretreatment with 3-methyladenine (3-MA), an autophagy inhibitor, decreased LC3-II/LC3-I ratio, attenuated glutamate-induced cell injury, and mimicked some of the protective effects of salidroside against glutamate-induced cell injury. Molecular analysis demonstrated that salidroside inhibited cortical neuron autophagy in response to glutamate exposure through p53 signaling by increasing the accumulation of cytoplasmic p53. Salidroside inhibited the glutamate-induced dissociation of the Bcl-2-Beclin-1 complex with minor affects on the PI3K/Akt/mTOR signaling pathways. These data demonstrate that the inhibition of autophagy could be responsible for the neuroprotective effects of salidroside on glutamate-induced neuronal injury.

Brain protection conferred by long-term administration of 2-(2-benzofuranyl)-2-imidazoline against experimental autoimmune encephalomyelitis.

Our previous studies showed that 2-(2-benzofuranyl)-2-imidazoline (2-BFI), a ligand to type 2 imidazoline receptor, was protective against brain and spinal cord injury caused by experimental autoimmune encephalomyelitis (EAE). In the present study, we investigated the effect of long-term administration of 2-BFI and the dose-dependent response relationship of long-term administration of 2-BFI with neuroprotection. Treatment with 2-BFI at doses of 5, 10, and 20 mg/kg for 14 days significantly reduced hind limb paralysis and the severity of EAE compared with the EAE control group. Long-term use of 2-BFI was not only safe to mice, but also dose-dependently reduced the expression of inflammatory cytokines, including TNF-α, Interferon-γ and Interleukin-17A, compared with the EAE control group. Expressions of neuronal injury markers, including cytochrome c, AIF and ß-APP, were also reduced significantly in response to long-term 2-BFI treatment. Together, these results provided new evidence to demonstrate that 2-BFI is a safe and effective candidate for further development as a therapeutic drug for treatment of multiple sclerosis.

The adenosine A2A receptor antagonist SCH58261 reduces macrophage/microglia activation and protects against experimental autoimmune encephalomyelitis in mice.

Multiple sclerosis (MS) is a chronic autoimmune inflammatory disease of the central nervous system (CNS) affecting more than 2.5 million individuals worldwide. In the present study, myelin oligodendrocyte glycoprotein (MOG)-induced experimental autoimmune encephalomyelitis (EAE) mice were treated with adenosine receptor A2A antagonist SCH58261 at different periods of EAE development. The administration of SCH58261 at 11-28 days post-immunization (d.p.i.) with MOG improved the neurological deficits. This time window corresponds to the therapeutic time window for MS treatment. SCH58261 significantly reduced the CNS neuroinflammation including reduced local infiltration of inflammatory cells, demyelination, and the numbers of macrophage/microglia in the spinal cord. Importantly, SCH58261 ameliorated the EAE-induced neurobehavioral deficits. By contrast, the SCH58261 treatment was ineffective when administered at the beginning of the onset of EAE (i.e., 1-10 d.p.i). The identification of the effective therapeutic window of A2A receptor antagonist provide insight into the role of A2A receptor signaling in EAE, and support SCH58261 as a candidate for the treatment of MS in human.