Neuroprotection by dipeptidyl-peptidase-4 inhibitors and glucagonlike peptide-1 analogs via the modulation of AKT-signaling pathway in Alzheimer’s disease

摘要

Alzheimer’s disease(AD)is the most common reason for progressive dementia in the elderly.It has been shown that disorders of the mammalian/mechanistic target of rapamycin(mTOR)signaling pathways are related to the AD.On the other hand,diabetes mellitus(DM)is a risk factor for the cognitive dysfunction.The pathogenesis of the neuronal impairment caused by diabetic hyperglycemia is intricate,which contains neuro-inflammation and/or neurodegeneration and dementia.Glucagon-like peptide-1(GLP1)is interesting as a possible link between metabolism and brain impairment.Modulation of GLP1 activity can influence amyloid-beta peptide aggregation via the phosphoinositide-3 kinase/AKT/mTOR signaling pathway in AD.The GLP1 receptor agonists have been shown to have favorable actions on the brain such as the improvement of neurological deficit.They might also exert a beneficial effect with refining learning and memory on the cognitive impairment induced by diabetes.Recent experimental and clinical evidence indicates that dipeptidyl-peptidase-4(DPP4)inhibitors,being currently used for DM therapy,may also be effective for AD treatment.The DPP-4 inhibitors have demonstrated neuroprotection and cognitive improvements in animal models.Although further studies for mTOR,GLP1,and DPP4 signaling pathways in humans would be intensively required,they seem to be a promising approach for innovative AD-treatments.We would like to review the characteristics of AD pathogenesis,the key roles of mTOR in AD and the preventive and/or therapeutic suggestions of directing the mTOR signaling pathway.