Effects of direct exposure of green odour components on dopamine release from rat brain striatal slices and PC12 cells

The effects of odour components on dopamine release from rat brain striatal slices and rat pheochromocytoma (PC12) cells were examined. The striatal slices were directly stimulated with 0.5% odour-including Krebs buffer using a superfusion method. In this experiment, (Z)-3-hexenol, (E)-2-hexenal, n-hexanal, 1,8-cineole or Eucalyptus globulus essential oil was used as an odour component. The concentrations of monoamines released in perfusate were measured by HPLC-ECD. Dopamine release from brain slices was significantly enhanced by perfusion of each odour-including solution. In particular, administration of n-hexanal caused a 9-fold increase in dopamine release. The dopamine release by n-hexanal increased linearly with the concentration of n-hexanal up to 0.5% and was maximal at 0.5%. Since PC12 cells have the ability to release dopamine, the effects of four green odour compounds, (Z)-3-hexenol, (E)-2-hexenal, n-hexanal and n-hexanol, on dopamine release were examined. These odour compounds dose dependently increased dopamine release from PC12 cells, and different patterns of dopamine release were observed with aldehyde or alcohol. Odour compounds thus appear to increase dopamine release from dopamine-releasing cells, with differences between aldehydes and alcohols in pattern of release. Dopamine regulates brain functions such as reward, mood, and attention. Green odours may in turn regulate such brain functions through the stimulation of dopamine release.