Involvement of cysteinyl leukotriene receptor 1 in Aβ1–42-induced neurotoxicity in vitro and in vivo

TL-2 attenuates β-amyloid induced neuronal apoptosis through the AKT/GSK-3β/β-catenin pathway

β-amyloid (Aβ)-mediated neuronal apoptosis contributes to the progression of Alzheimer's disease (AD), although the exact mechanism remains unclear. This study aimed to investigate whether Dalesconol B (TL-2), a potent immunosuppressive agent with an unusual carbon skeleton, could inhibit Aβ-induced apoptosis in vitro and in vivo and to explore the underlying mechanisms. Aβ(1-42) was injected to bilateral hippocampus of mice to make the AD models in vivo. TL-2 was able to cross the blood-brain barrier and attenuate memory deficits in the AD mice. TL-2 also inhibited Aβ(1-42)-induced neuronal apoptosis in vitro and in vivo. In addition, TL-2 could activate the AKT/GSK-3β pathway, and inhibition of AKT and activation of GSK-3β partially eliminated the neuroprotective effects of TL-2. Furthermore, TL-2 induced the nuclear translocation of β-catenin and enhanced its transcriptional activity through the AKT/GSK-3β pathway to promote neuronal survival. These results suggest that TL-2 might be a potential drug for AD treatment.

Pretreatment with antiasthmatic drug ibudilast ameliorates Aβ 1-42-induced memory impairment and neurotoxicity in mice

Amyloid-β peptide (Aβ) is thought to be associated with the progressive neuronal death observed in Alzheimer's disease (AD). However, effective neuroprotective approaches against Aβ neurotoxicity are unavailable. Here, we investigated possible preventive effects of ibudilast, as a pharmacologic phosphodiesterase inhibitor, currently used for treatment of inflammatory diseases such as asthma, on Aβ 1-42-induced neuroinflammatory, apoptotic responses and memory impairment. We found that pretreatment with ibudilast (4 or 12 mg/kg, i.p.) significantly ameliorated impaired spatial learning and memory in intracerebroventricularly (ICV) Aβ 1-42-injected mice, as evidenced by decrease in escape latency during acquisition trials and increase in exploratory activities in the probe trial in Morris water maze (MWM) task, and by increase in the number of correct choices and decrease in latency to enter the shock-free compartment in Y-maze test. Further study showed that ibudilast prevented generation of pro-inflammatory cytokines such as NF-κB p65 and TNF-α as well as pro-apoptotic molecule caspase-3 activation and anti-apoptotic protein Bcl-2 downregulation in both hippocampus and cortex of ICV Aβ 1-42-injected mice. Taken together, our findings suggest that ibudilast has preventive effects on Aβ-induced cognitive impairment via inhibiting neuroinflammatory and apoptotic responses.