Mitigating Effects of Liriope platyphylla on Nicotine-Induced Behavioral Sensitization and Quality Control of Compounds

In this study we investigated the mitigating effects ofLiriope platyphyllaWang et Tang extract on behavioral sensitization and the quantification of its major compounds. The extract ofL. platyphyllareduces the expression of tyrosine hydroxylase (TH) protein, which is increased by nicotine, back to normal levels, and increases the expression of dopamine transporter (DAT) protein, which is reduced by nicotine, back to normal levels in PC12 cells. In this study, rats received nicotine (0.4 mg/kg, subcutaneously) only for seven days and then received extract ofL. platyphylla(200 or 400 mg/kg, oral) 1 h prior to nicotine administration for an additional seven days. The extract ofL. platyphyllareduced locomotor activity compared to the nicotine control group in rats. The extract ofL. platyphyllasignificantly attenuated the repeated nicotine-induced DAT protein expression in the nucleus accumbens (NAc), but there was no effect on increased TH protein expression in the dorsal striatum. These findings suggest thatL. platyphyllaextract has a mitigating effect on nicotine-induced behavioral sensitization by modulating DAT protein expression in the NAc. For quality control ofL. plathyphylla, spicatoside A and D, which are saponin compounds, were quantified in theL. platyphyllaextract. The amounts of spicatoside A and D inL. platyphyllaextract obtained from ultra-high-performance liquid chromatography with tandem mass spectrometry were 0.148 and 0.272 mg/g, respectively. The identification of these compounds inL. platyphylla, which can be used for quality control, provides important information for the development of drugs to treat nicotine dependence.