Effects of intraperitoneal administration of Silexan, an essential oil from flowers of Lavandula angustifolia on extracellular levels of noradrenaline, dopamine and serotonin in the prefrontal cortex of freely moving rats

Abstract

Silexan is an essential oil of selected quality produced from Lavandula angustifolia flowers by steam distillation. The essential oil is the active pharmaceutical ingredient of Lasea®, a new phytochemical preparation, which is approved in Germany for the treatment of restlessness and mild anxiety. Native preparations of lavender oil have traditionally been used in aromatherapy as the scent has a calming effect. The aim of the present study was to investigate the effects of acute treatment with Silexan on extracellular levels of noradrenalin (NA), dopamine (DA) and serotonin (5-HT) in the prefrontal cortex of freely moving rats applying microdialysis technique. The microdialysis probe was inserted into the medial prefrontal cortex as described elsewhere (1). Following a stabilization period, the samples were collected every 60 minutes. The first sample was taken for determination of basal levels. Thereafter, Silexan was given at doses of 3,10 or 30mg/kg intraperitoneally and additional fractions were collected 60 and 120min after Silexan administration. Silexan at doses of 10 and 30mg/kg, significantly increased the NA concentrations by 30% and 36%, respectively, whereas the DA concentrations increased already at the dose of 3mg/kg by 34% and by 43% and 44%, respectively at the two higher doses. The 5-HT levels increased by 34% only at the highest dose tested. These data demonstrate that Silexan after a single acute administration increases the extracellular levels of monoamines in the prefrontal cortex of awake rats and this activity may contribute to the clinically observed relaxing and anxiolytic action of Silexan.