The GABAergic system contributes to the anxiolytic-like effect of essential oil from Cymbopogon citratus (lemongrass)

Ethnobotanical study of medicinal plants by population of Valley of Juruena Region, Legal Amazon, Mato Grosso, Brazil

ETHNOPHARMACOLOGICAL IMPORTANCE

The use of medicinal plants for treatment, cure and prevention of diseases has been described by many people since time immemorial. Because of this use, commercial and scientific interests have emerged, making it necessary to realize ethnobotanical surveys of medicinal plants species, which is important for subsequent chemical and pharmacological bioprospections.

AIM OF THE STUDY

This study aimed at surveying, identifying, cataloging and documenting the medicinal plants species used in the Valley of Juruena, Northwestern Mato Grosso, Legal Amazon Brazil for the treatment of various human diseases, as well as assessed the species of interest for bioprospecting potential.

MATERIALS AND METHODS

Informants were interviewed using semi-structured form to capture information on socio-demographic and ethnopharmacological data of medicinal plants such as vernacular name, uses, geographic origin, habit, form of preparation and part used. Results were analyzed using descriptive and quantitative means: indices of use-report (Ur) and informant consensus factor (ICF), for the selection of plant species with therapeutic potential.

RESULTS

Three hundred and thirty two (332) plants species belonging to 90 families were reported for medicinal purposes and totaling 3973 use-reports were reported by 365 (92.9%) of the people interviewed. Asteraceae (32.2%), Fabaceae (26.7%) and Lamiaceae (24.4%) families were the most represented, with majority being species native (64.45%) to Brazil. Leaves (64.5%) were the part of the plant most used and infusion (45.7%) was the most utilized form. Gastrointestinal disorders followed by respiratory complaints topped the list of use-reports. The native or naturalized plants with the highest use reports in the order of decreasing absolute frequency per each emic-category are Cymbopogon citratus (DC.) Stapfc (104), Mentha pulegium L. (94), Arrabidaea chica (Humb. & Bonpl.) B. Verl. (97), Alternanthera brasiliana (L.) Kuntze (71), Baccharis crispa Spreng (57), Phyllanthus niruri L. (48), Gossypium barbadense L. (44), Solidago microglossa DC. (40) and Bauhinia forficata L. (20). And the most cited exotics are: Chenopodium ambrosioides L. (151), Aloe vera (L.) Burm. f., (89) and Rosmarinus officinalis L. (72). In some cases, high ICF values were found, which reflects high degree of homogeneity of consensus among informants in this region on medicinal plants.

CONCLUSION

The population of Valle of Juruena makes use of a wide array of medicinal plants distributed in all use categories with predominance of those use in the treatments of gastrointestinal and respiratory ailments. The therapeutic potential of some of the species of medicinal importance extensively utilized by the population of the region have been scientifically validated, and are therefore promising prototype of new drugs. However, there are some of these species whose ethnomedicinal uses are yet to be scientifically verified and thus constitute an unexplored terrain for future biological/pharmacological studies.

Kososan, a standardized traditional Japanese herbal medicine, reverses sleep disturbance in socially isolated mice via GABAA-benzodiazepine receptor complex activation

PURPOSE

Kososan (KSS), a traditional Japanese medicine with a distinct aroma, is clinically used to treat affective disorders but its antidepressant-like effect has not been thoroughly investigated. In this study, we investigated the effects of inhaled and orally administered KSS on sleep disturbances in socially isolated mice.

METHODS

Four-weeks-old male ddy mice were housed either in social isolation or in groups for 4-6 weeks before the experiment. KSS was orally administered (0.5 or 1.0 g/kg) or inhaled (0.5, 1.0, or 2.5 g/0.125 m(3)) 60 min before pentobarbital administration. Stress levels in mice were evaluated by the duration of pentobarbital-induced sleeping time.

RESULTS

Sleeping time was shorter in socially-isolated mice than in group-housed mice. Oral and inhaled KSS prolonged sleeping time in stressed mice, but had no effect on sleeping time of group-housed mice. Prolonged sleeping time after oral KSS was significantly inhibited (p<0.05) by bicuculline (3 mg/kg, i.p.), a GABAA antagonist, but not by flumazenil (3 mg/kg, i.p.), a selective benzodiazepine antagonist. Prolonged sleeping time after KSS inhalation was significantly inhibited (p<0.05) by flumazenil but not by bicuculline.

CONCLUSIONS

Our findings suggest that KSS activates GABAA-benzodiazepine receptor complex and reverses shortened pentobarbital-induced sleep caused by social isolation.

Antistress Effects of the Ethanolic Extract from Cymbopogon schoenanthus Growing Wild in Tunisia

This study aimed to investigate the antistress properties of the ethanol extract of Cymbopogon schoenanthus (CSEE), growing wild in the southern part of Tunisia. The effect of extracts on H2O2-induced cytotoxicity and stress in human neuroblastoma SH-SY5Y cells. Its effect on stress-induced in ICR mice was exposed to force swim and tail suspension, in concordance with heat shock protein expression (HSP27 and HSP90), corticosterone, and catecholamine neurotransmitters level. Our results demonstrated that pretreatment of SH-SY5Y cells with CSEE at 1/2000, 1/1000, and 1/500 v/v dilutions significantly inversed H2O2-induced neurotoxicity. Moreover, CSEE treatments significantly reversed heat shock protein expression in heat-stressed HSP47-transformed cells (42°C, for 90 min) and mRNA expression of HSP27 and HSP90 in H2O2-treated SH-SY5Y. Daily oral administration of 100 mg/kg and 200 mg/kg CSEE was conducted to ICR mice for 2 weeks. It was resulted in a significant decrease of immobility time in forced swimming and tail suspension tests. The effect of CSEE on animal behavior was concordant with a significant regulation of blood serum corticosterone and cerebral cortex levels of catecholamine (dopamine, adrenaline, and noradrenaline). Therefore, this study was attempted to demonstrate the preventive potential of CSEE against stress disorders at in vitro and in vivo levels.

Allosteric modulators of α4β2 nicotinic acetylcholine receptors: a new direction for antidepressant drug discovery

Allosteric modulation of ligand-gated ion channels has been intensively studied in the past three decades and is now an established strategy to control receptor function in numerous disease states. Allosteric sites on the GABA(A) receptor are targets for widely prescribed drugs that are used for a variety of pathophysiological states including insomnia and epilepsy. Modulators might be especially valuable to control receptors for which the design of selective orthosteric drugs has proven difficult due to safety issues (e.g., α4β2 nicotinic acetylcholine receptors and might have several advantages over orthosteric ligands. Modulators influence the action of the endogenous agonist but generally have no effect of their own on the unoccupied receptor. Moreover, the higher subtype selectivity exerted by modulators and that the effects of modulators depend on the simultaneous presence of agonist help to overcome safety problems by preventing over-dosage compared with the administration of orthosteric drugs.

Citrus aurantium L. essential oil exhibits anxiolytic-like activity mediated by 5-HT(1A)-receptors and reduces cholesterol after repeated oral treatment

Background

The current treatments for anxiety disorders and depression have multiple adverse effects in addition to a delayed onset of action, which has prompted efforts to find new substances with potential activity in these disorders. Citrus aurantium was chosen based on ethnopharmacological data because traditional medicine refers to the Citrus genus as useful in diminishing the symptoms of anxiety or insomnia, and C. aurantium has more recently been proposed as an adjuvant for antidepressants. In the present work, we investigated the biological activity underlying the anxiolytic and antidepressant effects of C. aurantium essential oil (EO), the putative mechanism of the anxiolytic-like effect, and the neurochemical changes in specific brain structures of mice after acute treatment. We also monitored the mice for possible signs of toxicity after a 14-day treatment.

Methods

The anxiolytic-like activity of the EO was investigated in a light/dark box, and the antidepressant activity was investigated in a forced swim test. Flumazenil, a competitive antagonist of benzodiazepine binding, and the selective 5-HT_1A receptor antagonist WAY100635 were used in the experimental procedures to determine the mechanism of action of the EO. To exclude false positive results due to motor impairment, the mice were submitted to the rotarod test.

Results

The data suggest that the anxiolytic-like activity observed in the light/dark box procedure after acute (5 mg/kg) or 14-day repeated (1 mg/kg/day) dosing was mediated by the serotonergic system (5-HT_1A receptors). Acute treatment with the EO showed no activity in the forced swim test, which is sensitive to antidepressants. A neurochemical evaluation showed no alterations in neurotransmitter levels in the cortex, the striatum, the pons, and the hypothalamus. Furthermore, no locomotor impairment or signs of toxicity or biochemical changes, except a reduction in cholesterol levels, were observed after treatment with the EO.

Conclusion

This work contributes to a better understanding of the biological activity of C. aurantium EO by characterizing the mechanism of action underlying its anxiolytic-like activity.

The aqueous crude extract of Montanoa frutescens produces anxiolytic-like effects similarly to diazepam in Wistar rats: involvement of GABAA receptor

ETHNOPHARMACOLOGICAL RELEVANCE

Cihuapatli is the Nahuatl name assigned to some medicinal plants grouped in the genus Montanoa, where Montanoa frutescens (Family: Asteraceae, Tribe: Heliantheae) is included. The crude extract from these plants has been used for centuries in the Mexican traditional medicine as a remedy for reproductive impairments and mood disorders. Experimental studies have systematically corroborated the traditional use of cihuapatli on reproductive impairments and sexual motivation, however, the effect on mood and "nervous" disorders, remains to be explored.

MATERIALS AND METHODS

The anxiolytic-like effect of aqueous crude extract of M. frutescens (25, 50 and 75 mg/kg) was investigated in male Wistar rats evaluated in the elevated plus-maze and compared with several doses of diazepam (1, 2 and 4 mg/kg) as a reference anxiolytic drug. Picrotoxin (1 mg/kg), a noncompetitive antagonist of the GABA(A) receptor, was used in experimental procedures to evaluate if this receptor could be involved in the anxiolytic-like effects produced by M. frutescens. To discard hypoactivity, hyperactivity, or no changes associated with treatments, which could interfere with the behavioral activity in the elevated plus-maze, rats were subjected to the open field test.

RESULTS

M. frutescens at 50 mg/kg showed anxiolytic-like activity similarly to 2 mg/kg of diazepam, without disrupts in general motor activity. The anxiolytic-like effect of M. frutescens detected in the elevated plus-maze was blocked by picrotoxin, indicating that GABA(A) receptors are involved in the modulation of this effect.

CONCLUSIONS

The results corroborate the use of M. frutescens in folk Mexican ethnomedicine as a potential anxiolytic agent and suggest that this effect is mediated by the GABA(A) receptors. Additionally, some sedative effects with high doses of M. frutescens were detected in the present study.

Anxiolytic-like effects of acute and chronic treatment with Achillea millefolium L. extract

ETHNOPHARMACOLOGICAL RELEVANCE

Achillea millefolium L. (Asteraceae), known as yarrow ("mil folhas"), has been used as folk medicine for gastrointestinal disorders, inflammation, anxiety, and insomnia.

AIM

To evaluate the potential anxiolytic-like effect of hydroalcoholic extract of Achillea millefolium L. in animal models.

METHODS

The present study evaluated the effects of the hydroalcoholic extract from the aerial parts of Achillea millefolium L. in mice subjected to the elevated plus-maze, marble-burying, and open-field tests. Additionally, the GABA(A)/benzodiazepine (BDZ) mediation of the effects of Achillea millefolium was evaluated by pretreatment with the noncompetitive GABA(A) receptor antagonist picrotoxin and the BDZ antagonist flumazenil and by [(3)H]-flunitrazepam binding to the BDZ site on the GABA(A) receptor.

RESULTS

Achillea millefolium exerted anxiolytic-like effects in the elevated plus-maze and marble-burying test after acute and chronic (25 days) administration at doses that did not alter locomotor activity. This behavioral profile was similar to diazepam. The effects of Achillea millefolium in the elevated plus-maze were not altered by picrotoxin pretreatment but were partially blocked by flumazenil. Furthermore, Achillea millefolium did not induce any changes in [(3)H]-flunitrazepam binding.

CONCLUSION

The results indicate that the orally administered hydroalcoholic extract of Achillea millefolium L. exerted anxiolytic-like effects that likely were not mediated by GABA(A)/BDZ neurotransmission and did not present tolerance after short-term, repeated administration.