Anxiolytic effects of Lavender (Lavandula angustifolia) odour on the mongolian gerbil (Meriones unguiculatus) elevated plus-maze

The prolonged effects of (Lavandula angustifolia L.) lavender odour inhalation were examined in gerbils on the elevated plus maze. Mature male and female gerbils were exposed to lavender odour over two week or 24 hour periods, and compared to a no-lavender condition. This pattern of results was compared with the effects of diazepam (1mg/kg) i.p. after two week administration.

The Jonckheere- Terpstra test for ordered alternatives was used, with the Mann Whitney U test to examine group differences within significant trends. Traditional measures of open entries showed an increasing trend over the two weeks exposure, (chronic lavender odour vs. no odour control U=166, p<0.05). Whereas, stretch-attend frequency, an ethological measure indicative of anxiety, decreased after exposure to lavender odour (acute vs. control U=71, p<0.001 and chronic vs. control U=25, p<0.001). Likewise, exploratory behaviour, total head-dip frequency, increased after lavender exposure (acute U=35, p<0.001 and chronic exposure U=28, P, 0.001). These results are comparable with chronic diazepam administration.

There were sex differences in protected head-dip, an ethological indicator of anxiety: after two weeks exposure females showed a significant decrease in protected head-dips compared to both males (U=39, p<0.05) and to female controls (U=10, p<0.01).

In conclusion, exposure to lavender odour may have an anxiolytic profile in gerbils similar to that of the anxiolytic diazepam. In addition, prolonged, two week lavender odour exposure increased exploratory behaviour in females indicating a further decrease in anxiety in this sex.