The Therapeutic Action And Mechanism Of PNSL On Late-Life

Objective:As a common mental disorder, anxiety and anxiety symptoms has a high prevalence rate in elderly. Benzodiazepine(BDZ) and 5-HT selective reuptake inhibitors(SSRIs) are represented drugs treatment of anxiety disorders in clinic currently, but are restricted on application because of adverse events. The development of new anxiolytic drugs for late-life anxiety is urgently. Previous of our lab studies showed that Panax notoginseng saponin from leaves(PNSL) has the effect of anxiolytic on late-life anxiety. This study is designed to explore the characteristics and superiority of PNSL compares to BDZ and SSRI on anti-anxiety in aging mice, to provide a foundation for its further development and utilization.Methods:Aging male mice(12 months) were divided randomly into vehicle group(Normal saline), fluoxetine group(20 mg/kg), diazepam group(2 mg/kg), PNSL low dose group(PNSL-L, 100 mg/kg) and high dose group(PNSL-H, 500 mg/kg). Animals were administered with drugs by intragastric administration for short-term(3 days) or long-term(21 days). Then the behavior and biochemical indicator were detected:1 Anxiolytic effects of PNSL: using the elevated plus maze and light-dark box to assay anxiety behavior, and morris water maze to assay learning and memory ability.2 The machenism of PNSL on late-life anxiety: GABA levels in the hippocampus and cortex of aging mice were detected by enzyme-linked immunosorbent assay(Elisa) method, and the BDNF level, GABAA receptor subuints α1, α2, α5 expression were analyzed by Western-blot.Results:1 The anxiolytic effects of PNSL in aging mice1.1 Elevated plus mazeIn short-term administration test, compared with vehicle, fluoxetine group, diazepam group, PNSL-L and PNSL-H group have no effect on the percentage of open arm time(OT%) and the percentage of open arm entry(OE%).In long-term administration test, compared with vehicle, diazepam group increased significantly the OE%(P<0.05); fluoxetine group, PNSL-L group and PNSL-H group increased significantly the OE%(P<0.001).1.2 Light-dark boxIn short-term administration test, compared with vehicle, PNSL-H group prolonged the first entry time from light box into dark box(P<0.05) and increased the percentage of residence time in light box significantly(P<0.05). Compared with vehicle, fluoxetine group, diazepam group, PNSL-L group have no effect on the the first entry time from light box into dark box and the percentage of residence time in light box.In long-term administration test, compared with vehicle, PNSL-L group prolonged significantly the first entry time from light box into dark box(P<0.05); both of PNSL-L group and diazepam group increased the percentage of residence time in light box significantly(P<0.05); fluoxetine group and PNSL-H group have no effect on the the first entry time from light box into dark box and the percentage of residence time in light box.1.3 Morris water mazeIn short-term administration test, compared with vehicle, the searching time and searching distance were increased in diazepam group significantly(P<0.05). Compared with diazepam group, the searching time and searching distance of PNSL-L group were decreased significantly(P<0.05). Compared with vehicle, diazepam, fluoxetine group, PNSL-L group and PNSL-H group had no influence on percentage of searching time and distance in platform quadrant.In long-term administration test, compared with vehicle, the searching time of diazepam group was extended and the percentage of searching time and distance in platform quadrant was decreased significantly(P<0.05). Compared with diazepam group, the searching time of PNSL-L group was reduced and the percentage of searching time and distance in platform quadrant was increased significantly(P<0.05).2 The mechanism of PNSLon late-life anxiety2.1 Effect of PNSL on GABA levels in aging miceIn short-term administration test, compared with vehicle, diazepam, fluoxetine, PNSL-L group and PNSL-H group had no influence in GABA levels of hippocampus, but PNSL-H group increased GABA levels in cortex significantly(P<0.05).In long-term administration test, compared with vehicle, diazepam, fluoxetine, PNSL-L group and PNSL-H group had no influence on GABA levels of hippocampus and cortex.2.2 Effect of PNSL on GABAA-R expression in aging miceIn short-term administration test, compared with vehicle, fluoxetine group, diazepam group, PNSL-L group and PNSL-H group had no effect on the expression of GABAA-R protein in hippocampus and cortex.In long-term administration, compared with vehicle, diazepam group increased the expression of GABAA-R α1、α2 protein in hippocampus(P<0.01) significantly, but decreased the expression of GABAA-R α5 protein in hippocampus(P<0.05). Compared with vehicle, PNSL-H group tended to increase the expression of GABAA-R α2 protein in hippocampus. Compared with the diazepam group, PNSL-L group increased the expression of GABAA-R α5 protein in hippocampus(P<0.05) significantly. Compared with vehicle, diazepam group increased the expression of GABAA-R α1 protein(P<0.05) and GABAA-R α2 protein in cortex(P<0.001) significantly. Compared with vehicle, fluoxetine group, PNSL-L group and PNSL-H group had no effect on the expression of GABAA-R protein in cortex.2.3 The influence of PNSL on BDNF level in aging miceIn short-term administration test, compared with vehicle, fluoxetine group and PNSL-L group could increase the expression of BDNF protein in hippocampus(P<0.01), diazepam group and PNSL-H group could increase the expression of BDNF protein in hippocampus(P<0.001) significantly. Compared with vehicle, PNSL-H group tended to increase the expression of BDNF protein in cortex of aging mice.In long-term administration test, compared with vehicle, diazepam group could increase the expression of BDNF protein in hippocampus(P<0.01) significantly, diazepam group tended to increase the expression of BDNF protein in cortex. Compared with vehicle, PNSL-H group tended to increase the expression of BDNF protein in hippocampus and cortex. Compared with diazepam, PNSL-L group and PNSL-H group had no effect on the expression of BDNF protein in hippocampus and cortex.Conclusions:1 PNSL had a rapid effect of anti-anxiety in aging mice compared with SSIR, meantime it had no effect on spatial learning and memory ability of the aging mice by long-term administration comepared with BDZ. It indicated that PNSL had pharmacological advantages of rapid effect and less adverse reaction on late-life anxity.2 The mechanism of PNSL on late-life anxiety is related to increasing of GABA level in cortex and the expression of GABAA-R and BDNF in the hippocampus.3 PNSL is a promising potential candidate of late-life anxiety.