Imbalance of synaptic and extrasynaptic NMDA receptors induced by the deletion of CRMP1 accelerates age-related cognitive decline in mice.

Collapsin response mediator protein 1 (CRMP1) is involved in semaphorin 3A signaling pathway, promoting neurite extension and growth cone collapse. It is highly expressed in the nervous system, especially the hippocampus. The crmp1 knockout (KO) mice display impaired spatial learning and memory, and this phenomenon seemingly tends to deteriorate with age. Here we investigated whether CRMP1 is involved in age-related cognitive decline in WT and crmp1 KO mice at adult, middle-aged and older stages. The results revealed that cognitive dysfunction in the Morris water maze task became more severe and decreased glutamate and glutamine level in middle-aged crmp1 KO mice. Additionally, increasing levels of extrasynaptic NMDA receptors and phosphorylation of Tau were observed in middle-aged crmp1 KO mice, leading to synaptic and neuronal loss in the CA3 regions of hippocampus. These findings suggest that deletion of CRMP1 accelerates age-related cognitive decline by disrupting the balance between synaptic and extrasynaptic NMDA receptors, resulting in the loss of synapses and neurons.

Hericium erinaceus Mycelium and Its Isolated Compound, Erinacine A, Ameliorate High-Fat High-Sucrose Diet-Induced Metabolic Dysfunction and Spatial Learning Deficits in Aging Mice.

Aging and lifestyle factors, including high-sugar and high-fat diets, promote a systemic metabolic imbalance that promotes neurodegeneration. Hericium erinaceus has long been used in traditional Chinese medicine. Recently, its functional activities, such as antimetabolic dysfunction, antineuroinflammatory activities, and stimulation of nerve growth factor (NGF) synthesis, have been revealed. This study demonstrated that Hericium erinaceus mycelium (HEM) and an isolated diterpenoid derivative, erinacine A (EA), may reverse spatial learning disabilities in aging mice (15 months old) fed with a high-fat and high-sucrose diet (HFSD). Aging mice were randomly assigned to one of four treatment groups: (1) a chow diet (control), (2) an HFSD, and an HFSD supplemented with either (3) HEM or (4) EA for 18 weeks. The Morris water maze (MWM) and Y-maze were used for behavioral assessments. Both HEM- and EA-treated mice had shorter mean daily escape latencies than HFSD-treated mice in the MWM. In addition, HEM-treated mice had a slightly increased exploratory time and frequency in the novel arm in the Y-maze. Quantitative PCR revealed that both HEM- and EA-treated mice exhibited reduced messenger RNA (mRNA) expression of tumor necrosis factor-α, interleukin-1ß, and HEM-treated mice exhibited increased mRNA expression of NGF and NeuN in the hippocampus. Moreover, HEM and EA also decreased body weight, abdominal fat, plasma glucose, serum and liver total cholesterol, and liver triacylglycerol. Thus, HEM may be a potential health-promoting supplement for minimizing the progression of aging and obesity-induced neurodegeneration by reducing metabolic abnormalities and neuroinflammatory cytokines and increasing neurogenesis factors.