Abstract
The anxiolytic-like and stress reduction effects following inhaled administration of essential oil from Chamaecyparis obtusa (EOCO) have been reported. Volatile components are thought to produce these effects of EOCO by neurological transfer and pharmacological transfer. The regions of the brain in which inhaled compounds are found due to pharmacological transfer of EOCO are not known. This research was undertaken to clarify the relationship between the intracerebral distribution of α-pinene, which is the main component of EOCO, and emotional behavior. α-Pinene was detected as the main component of volatile EOCO. The amount of α-pinene in each region of the brain was measured following inhaled administration of EOCO. The amount of α-pinene was different in each region of the brain. With inhaled administration of 32 μL/L air EOCO, a high concentration of α-pinene was observed. However, no significant differences in the concentration of α-pinene among brain regions were found. A therapeutic concentration of α-pinene (8 μL/L air EOCO) in each region of the brain may induce an anxiolytic-like effect, and a high concentration of α-pinene (32 μL/L air EOCO) in each region of the brain may induce an excitatory-like effect. The increases in the concentration of α-pinene from 8 to 32 μL/L air EOCO in the striatum and the hippocampus were significantly lower compared with the increases in other brain regions. These results indicate that regions besides the striatum and the hippocampus participated in the increase in locomotor activity due to the high concentration of α-pinene in the brain.