Open Access Research article

Citrus aurantium L. essential oil exhibits anxiolytic-like activity mediated by 5-HT1A-receptors and reduces cholesterol after repeated oral treatment

Celso A R A Costa1, Thaís C Cury1, Bruna O Cassettari1, Regina K Takahira2, Jorge C Flório3 and Mirtes Costa1*

Author Affiliations

1 Department of Pharmacology, Institute of Biosciences, Unesp - Univ Estadual Paulista, P.O. Box 510, 18618-970, Botucatu, São Paulo, Brazil

2 Department of Pathology, School of Veterinary Medicine and Animal Science, Unesp - Univ Estadual Paulista, Laboratório Clínico Veterinário, 18618-970, Botucatu, SP, Brazil

3 Department of Pathology, School of Veterinary Medicine, USP - University of São Paulo, Av. Orlando Marques de Paiva, 87, São Paulo, SP, Brazil

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BMC Complementary and Alternative Medicine 2013, 13:42  doi:10.1186/1472-6882-13-42

Published: 23 February 2013

Abstract

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-HT1A 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-HT1A 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.

Keywords:
Anxiolytic; Citrus aurantium; Essential oil; Mice; Neurochemistry; Serotonin