Role of the 5-HT1A Serotonergic System in Anxiolytic-Like Effects of Silymarin

Evaluation of the effect of Silybum marianum extract on menopausal symptoms: A randomized, double-blind placebo-controlled trial

The tendency to use herbs to manage menopausal symptoms has increased in recent years. The purpose of this study was to evaluate the effect of Silybum marianum (L.) compared with placebo in women with hot flashes. Eighty women were randomly allocated into two equal groups (S. marianum extract [400 mg/d] or placebo capsules). Hot flashes frequency and severity were evaluated in 12 weeks with the Greene Climacteric Scale (GCS) and the Hot Flash Related Daily Interference Scale (HFRDIS). The data were analyzed in SPSS software using t-test, Mann-Whitney, chi-square test and repeated measure analysis. Hot flashes frequency and severity decreased from 4.32 ± 0.20/day to 1.31 ± 0.15/day and from 5.25 ± 0.22 to 1.62 ± 0.08, respectively, during the study in test group (p < .001) which were significantly better than effects of placebo in all steps of study (p < .001). Significant decreases in GCS and HFRDIS scores were also detected in S. marianum group compared with placebo after 4, 8 and 12 weeks (p < .001). The results showed that S. marianum can decrease frequency and severity of hot flashes significantly. Considering the safety and high consumption of this herbal medicine worldwide, its use in women with menopausal symptoms can be helpful.

Possible involvement of nitric oxide in antidepressant-like effect of silymarin in male mice

CONTEXT

Silymarin (SM) is extracted from milk thistle Silybum marianum L. [Asteraceae (Compositae)] and known for antioxidative and anti-inflammatory effects.

OBJECTIVE

The potential antidepressant-like effect of acute SM and possible involvement of nitric oxide (NO) were determined in male mice.

MATERIAL AND METHODS

SM was administered orally (5, 10, 20, 50, 100, and 200 mg/kg; p.o.) 60 min before the tests. After assessment of locomotor activity, the immobility time was measured in forced swimming test (FST) and tail suspension test (TST). To assess the possible involvement of NO, a non-specific NO synthase inhibitor, L-NAME (10 mg/kg, i.p.), and a specific iNOS inhibitor, aminoguanidine (AG) (50 mg/kg, i.p.), were administered separately 30 min before SM (20 and 100 mg/kg).

RESULTS

SM at its effective doses 10, 20, 50, and 100 mg/kg decreased the immobility time in a dose-dependent manner (p < 0.01, p < 0.05, p < 0.05, and p < 0.001, respectively) in FST. SM (10, 20, 50, and 100 mg/kg) also lowered the immobility measure dose dependently in TST (p < 0.01, p < 0.05, p < 0.01, and p < 0.001, respectively). In addition, 50% of maximum response (ED50) of SM was around 10 mg/kg. The dose 100 mg/kg proved the most effective dose in both the tests. Further, this effect was not related to changes in locomotor activity. Moreover, L-NAME reversed the effect of SM (20 and 100 mg/kg) in FST and SM (100 mg/kg) in TST. However, AG did not influence this impact.

CONCLUSION

The antidepressant-like effect of SM is probably mediated at least in part through NO and SM may increase NO tune.

Neurophysiological and behavioural effects of lavender oil in rats with experimentally induced anxiety

This study examined anxiolytic effects of lavender oil on brain serotonin levels and anxiety‐related behaviours of rats. The experimental rats were divided into five groups, which respectively received inhalation of saline, 1.25% lavender oil, 2.5% lavender oil, chlordiazepoxide (CDP), and 2.5% lavender oil co‐administered with CDP. Anxiety was induced in rats using animal models including Elevated Plus Maze and Open Field. The levels of serotonin in the pre‐frontal cortex and striatum of the rats, the anxiolytic effects of lavender oil and its augmentation effect as to co‐administration with CDP were evaluated. The neurophysiological findings showed that groups receiving lavender oils, CDP, and 2.5% lavender oils co‐administered with CDP had significantly higher level of serotonin in the pre‐frontal cortex. However, the anxiolytic behavioural effects of lavender oil were found to have mixed results. This study provided preliminary evidence that inhalation of lavender oil paralleled effects of CDP in up‐regulating synthesis of serotonin in rat pre‐frontal cortex, and the co‐administration of CDP with 2.5% lavender oil tended to augment effect of CDP on serotonin in their pre‐frontal cortex and striatum. Copyright © 2013 John Wiley & Sons, Ltd.