Extracts of Liriopsis tuber protect AMPA induced brain damage and improve memory with the activation of insulin receptor and ERK I/II.
The brain insulin receptor and ERK I/II are known to play an important role in memory formation and neuroprotection. A series of experiments was designed to explore if Liriopsis tuber (LT) extracts could exhibit neuroprotection and memory enhancing actions. LT was extracted with 70% methanol and subsequently fractionated into chloroform (fraction C), chloroform/methanol-(3:1) (fraction CM), methanol-soluble (fraction M) and methanol-insoluble, water-soluble fractions (fraction A). The LT fractions (T, C, M, A) significantly inhibited the cortical depolarization induced by AMPA in cortical slices of rats. In addition, these fractions were also effective in promoting memory in the passive avoidance test in mice. To gain insight into the mechanism of memory enhancing effects by Liriopsis tuber extracts, the activities of hippocampal insulin receptors and ERK I/II were tested in rats. Extract of LT (T) dramatically stimulated tyrosine phosphorylation of the insulin receptor, while fraction C of LT also significantly stimulated the same. In addition, ERK I/II were stimulated and cholinesterase activities were inhibited by fractions T, C, M and A in the rat hippocampus. These results suggest that Liriopsis tuber extracts may exert neuroprotection and memory enhancing effects via activation of the insulin receptor and ERK I/II as well as inhibiting cholinesterase.
Kim
Sung-Jin
SJ
Department of Pharmacology, Metabolic Diseases Research Laboratory, School of Dentistry, Kyung Hee University, Seoul, Korea. kimsj@khu.ac.kr
Lee
Keun
K
D000818:Animals; D001362:Avoidance Learning; D001930:Brain Injuries / Q000188:drug therapy / Q000378:metabolism; D004594:Electrophysiology; D006624:Hippocampus / Q000187:drug effects / Q000378:metabolism; D000860:Hypoxia / Q000139:chemically induced; D019684:Magnoliopsida / Q000737:chemistry; D008297:Male; D008568:Memory / Q000187:drug effects*; D051379:Mice; D008813:Mice, Inbred ICR; D019950:Mitogen-Activated Protein Kinase 1 / Q000187:drug effects* / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3 / Q000187:drug effects* / Q000378:metabolism; D018696:Neuroprotective Agents / Q000494:pharmacology; D010766:Phosphorylation; D008517:Phytotherapy; D010936:Plant Extracts / Q000494:pharmacology*; D035281:Plant Tubers / Q000737:chemistry; D051381:Rats; D017207:Rats, Sprague-Dawley; D011972:Receptor, Insulin / Q000187:drug effects* / Q000378:metabolism; D012977:Sodium Nitrite / Q000633:toxicity; D018350:alpha-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic Acid / Q000494:pharmacology*
D018696:Neuroprotective Agents; D010936:Plant Extracts; D018350:alpha-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic Acid; D011972:Receptor, Insulin; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D012977:Sodium Nitrite