Evaluation of the effects of Astragalus mongholicus Bunge saponin extract on central nervous system functions

Ethnopharmacological relevance

In traditional medicine, Astragalus mongholicus (AM) has been used for the treatment of general weakness, chronic illness, and to increase overall vitality.

Aim of the study

The present study investigated possible effects of the saponin fraction of AM on the central nervous system. Moreover, its effects on locomotor activity, anxiety, and hippocampal morphology were studied.

Material and methods

AM extract was tested for its effects on locomotor activity using the Moti-Test, for situational anxiety in the elevated plus maze, and for anticonvulsant activity against acute pentylenetetrazole (PTZ)-induced seizures and in the PTZ kindling model.

Results

It was shown that AM (50, 100, 200 mg/kg) did not interfere with locomotor activity and situational anxiety as measured in the elevated plus maze. In these doses, AM significantly suppressed pentylenetetrazole (PTZ)-induced seizures (p < 0.05). Its anticonvulsant efficacy was also evident against repeated PTZ seizures (p < 0.05). This suggests potential therapeutic usefulness. After subchronic application, the number of cells in hippocampal CA1 was reduced, whilst the cell number in CA3 and hilus remained unaffected.

Conclusions

Doses of AM extract which did not interfere with locomotor acticity and situational anxiety appear to be useful in the treatment of convulsive disorders. The mechanisms underlying this effect on hippocampal morphology are not yet understood.     

Ethanol Iris tenuifolia extract reduces brain damage in a mouse model of cerebral ischaemia

In the previous experiments, the neuroprotective role of Iris tenuifolia Pall. (IT) in the model of middle cerebral artery occlusion (MCAO) was investigated. In addition, the concentrations of the cytokines tumour necrosis factor‐alpha and interleukin‐6 in blood plasma were measured. It was found that IT administered 1 hr prior to MCAO or immediately after MCAO reduced infarct volume significantly. IT application 1 and 4 hr after MCAO, respectively, was without any effect on infarct volume. There were no significant changes as regards tumour necrosis factor‐alpha, whereas interleukin‐6 concentrations were increased in blood plasma. This is the first evidence that flavonoids from Iris tenuifolia exert protective effects in the in vivo MCAO model. Our results suggest that these flavonoids are likely to be beneficial to humans by virtue of their ability to reduce infarct volume.     

Stress-induced alteration of the anticonflict effect of anxiolytics

The influence of stress of various etiology (prolonged isolation, anavoidable electrostimulation, paradoxical sleep deprivation, transport stress) on the activity of anxiolytics (tranquilizers) in the conflict situation was studied in inbreed white male rats. It was established that the anticonflict effect of highly effective anxiolytics decreases under the action of stress, the activity of gidazepam remains unchanged, while the drugs of moderate efficacy loose their activity. The degree of changes and the rate of restoration of the initial activity depends on the efficacy of anxiolytics, the strength and duration of stress, and on the duration of drug administration after stress. The possible mechanism of this phenomenon can be the stress-induced activation of the endogenous system of anxiogenic ligands.     

Stress-induced alteration of the antiaggressive effect of anxiolytics

The influence of stresses of various etiology (prolonged isolation, inescapable electrostimulation) on the antiaggressive effect of anxiolytics was studied in outbread white male rats. It was established that, in contrast to the anticonflict effect (decreasing under the action of stress), then antiaggressive action of the drugs studied (diazepam, phenazepam, clonazepam, alprazolam) exhibits qualitative changes. In the absence of stress, the threshold of aggressive reaction is low and anxiolytics increase this level. Under the action of stress, the threshold of aggressive reaction increases, and the same drugs reduce this threshold to the normal level, thus producing proaggressive action. The degree of changes and the rate of restoration of the initial activity depend on the efficacy of anxiolytics, the strength and duration of stress, and on the duration of drug administration during the stress aftereffect. A possible mechanism of this phenomenon can be the interaction of the GABA-benzodiazepine and opiate endogenous systems.     

Psychotropic effect of the Astragalus mongolicus preparation

Study of the pharmacological properties of a preparation from the plants of Mongolian milk vetch (Astragalus mongolicus) of the Leguminosae Juss. family showed evidence of a pronounced psychotropic activity. The main action components are the anxiolytic (tranquilizer), antidepressant, antiamnesic, and antiaggressive effects.     

Behavioral and electrophysiological analysis of anxiolytic effect of mongolian astragalus

Medical herb Mongolian astragalus has anxiolytic activity in conflict situation imposed on random-bred male albino rats, and evokes changes in electroencephalogram which are characteristic of tranquilizers. The drug moderates the τ-rhythm in cerebral hemispheres and hippocampus. In contrast to benzodiazepine tranquilizers, it does not affect the frequencies in other bands. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 125, No. 4, pp. 407–409, April, 1998.