Veronica B Maphanga1, Krystyna Skalicka-Woźniak2, Barbara Budzynska3, Gill M Enslin1, Alvaro M Viljoen4,5. 1. Department of Pharmaceutical Sciences, Tshwane University of Technology, Private Bag X680, Pretoria, 0001, South Africa. 2. Department of Pharmacognosy with Medicinal Plant Unit, Medical University of Lublin, 1 Chodzki Street, 20-093, Lublin, Poland. 3. Independent Laboratory of Behavioral Studies, Medical University of Lublin, Jaczewskiego 4, 20-090, Lublin, Poland. 4. Department of Pharmaceutical Sciences, Tshwane University of Technology, Private Bag X680, Pretoria, 0001, South Africa. ViljoenAM@tut.ac.za. 5. SAMRC Herbal Drugs Research Unit, Tshwane University of Technology, Pretoria, 0001, South Africa. ViljoenAM@tut.ac.za.
Abstract
RATIONALE: Medicinal plants are used extensively in many countries to treat conditions related to the central nervous system (CNS), and there is renewed interest to explore natural products, which may exhibit CNS activity. OBJECTIVE: In this study, seven plants were selected based on literature reports of their ethnopharmacological use in treating anxiety-related conditions and assayed in a zebrafish model. METHODS: Crude extracts were prepared with solvents of different polarities, and the maximum tolerated concentration (MTC) of these crude extracts was established. The anxiolytic activity of the crude extracts was determined using 5-day post-fertilization (dpf) zebrafish larvae. General locomotor activity and reverse-thigmotaxis behavior (indicative of anxiolytic activity) were analyzed under continuous illumination and alternating light-dark challenges, which induced anxiety in the zebrafish larvae. RESULTS: Of the 28 extracts tested, 13 were toxic according to the MTC values obtained. Larvae were subsequently treated with the 15 non-toxic extracts, at a dose determined in the MTC assay or with 1% DMSO as control. The anxiolytic activity (reverse-thigmotaxis) was demonstrated by an increase in the percentage time spent by the larvae in the central arena of the well. Of the 15 non-toxic extracts tested, the Sceletium tortuosum water extract exhibited the most promising anxiolytic activity. CONCLUSIONS: The zebrafish model was effective in studying anxiety-related behavior. Thus, the study confirmed that S. tortuosum mitigates anxiety in zebrafish larvae, a step towards the full in vivo validation of the traditional use of the plant.
RATIONALE: Medicinal plants are used extensively in many countries to treat conditions related to the central nervous system (CNS), and there is renewed interest to explore natural products, which may exhibit CNS activity. OBJECTIVE: In this study, seven plants were selected based on literature reports of their ethnopharmacological use in treating anxiety-related conditions and assayed in a zebrafish model. METHODS: Crude extracts were prepared with solvents of different polarities, and the maximum tolerated concentration (MTC) of these crude extracts was established. The anxiolytic activity of the crude extracts was determined using 5-day post-fertilization (dpf) zebrafish larvae. General locomotor activity and reverse-thigmotaxis behavior (indicative of anxiolytic activity) were analyzed under continuous illumination and alternating light-dark challenges, which induced anxiety in the zebrafish larvae. RESULTS: Of the 28 extracts tested, 13 were toxic according to the MTC values obtained. Larvae were subsequently treated with the 15 non-toxic extracts, at a dose determined in the MTC assay or with 1% DMSO as control. The anxiolytic activity (reverse-thigmotaxis) was demonstrated by an increase in the percentage time spent by the larvae in the central arena of the well. Of the 15 non-toxic extracts tested, the Sceletium tortuosumwater extract exhibited the most promising anxiolytic activity. CONCLUSIONS: The zebrafish model was effective in studying anxiety-related behavior. Thus, the study confirmed that S. tortuosum mitigates anxiety in zebrafish larvae, a step towards the full in vivo validation of the traditional use of the plant.
Entities:
Keywords:
Anxiety; Anxiolytic activity; Light-dark transitions; Zebrafish model
Authors: T Burne; E Scott; B van Swinderen; M Hilliard; J Reinhard; C Claudianos; D Eyles; J McGrath Journal: Mol Psychiatry Date: 2010-03-30 Impact factor: 15.992
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