Neuroprotective effects of liquiritin on cognitive deficits induced by soluble amyloid-β_1–42 oligomers injected into the hippocampus

Abstract

This study assessed the modulating effects of liquiritin against cognitive deficits, oxidative damage, and neuronal apoptosis induced by subsequent bilateral intrahippocampal injections of aggregated amyloid-β (Aβ). This study also explored the molecular mechanisms underlying the above phenomena. Liquiritin was orally administered to rats with Aβ-induced cognitive deficits for 2 weeks. The protective effects of liquiritin on the learning and memory impairment induced by Aβ were examined in vivo by using Morris water maze. The rats were then euthanized for further studies. The antioxidant activities of liquiritin in the hippocampus of the rats were investigated by biochemical and immunohistochemical methods. The apoptosis of the neurons was assessed by terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick end-labeling assay. Liquiritin at doses of 50-100 mg/kg significantly improved the cognitive ability, restored the abnormal activities of glutathione peroxidase and superoxide dismutase, and decreased the levels of malondialdehyde，8-hydroxy-2'-deoxyguanosine and protein carbonyl in the hippocampus of rats with Alzheimer's disease. Moreover, neural apoptosis in the hippocampus of Aβ-treated rats was reversed by liquiritin. Liquiritin can significantly ameliorate Aβ-induced spatial learning and memory impairment by inhibiting oxidative stress and neural apoptosis.

Beneficial Effects of Gagam‐Palmultang on Scopolamine‐Induced Memory Deficits in Mice

“…Many of these components are associated with cognition. Hydroxymethylfurfural is a potential therapeutic agent for AD [ 41 ]; liquiritin and ferulic acid are useful for amelioration of amyloid β peptide-induced cognitive impairment [ 42 , 43 ]; paeoniflorin reverses the muscarinic receptor-mediated inhibition of long-term potentiation [ 44 ]; nodakenin enhances adult hippocampal neurogenesis [ 45 ], ginsenoside Rg1 delays cognitive decline and promotes neurogenesis [ 46 , 47 ], and glycyrrhizin ameliorates cognitive decline via anti-inflammatory effects [ 48 ]. Further studies of the efficacy and underlying mechanism of these Palmultang constituents should continue to elucidate their effects on cognitive dysfunction comprehensively.…”

Neurogenic Traditional Chinese Medicine as a Promising Strategy for the Treatment of Alzheimer’s Disease

“…Recent studies have shown that liquiritin is beneficial in the treatment of neurodegenerative diseases such as AD [102]. Treating cells with liquiritin along with low doses of NGF aids in the enhancement of neurite outgrowth probably by increasing the expression levels of important neuronal related genes such as Neurog 3, Nf 1, Notch 2, Nmur 2 and Ntf 5, ultimately leading to neural regeneration, differentiation and synapse formation [103].…”

Preliminary Studies on Liquiritin, Deoxyschizandrin, and Tanshinone II A as Potential Anti-Neurodegenerative Disease Agent: Determination by Reverse-Phase Liquid Chromatography in Tianwang Buxin Pills

“…Three bioactive components in TWBXP, liquiritin, deoxyschizandrin, and tanshinone II A, have been proven to be closely related to the therapy effect of neurodegenerative disease. Liquiritin is a major ingredient in Glycyrrhizae radix which has been proven to significantly ameliorate spatial learning, cognitive ability, and memory impairment of rats with Alzheimer's disease [9]. It possessed various pharmacological activities and exhibited various positive biological effects, including neuroprotective [10], anticancer [11], and antidepressant [12] effect.…”