Objective:

2

To explore the anti-nociceptive effect of patchouli alcohol (PA)

the essential oil isolated from

Pogostemon cablin

(Blanco) Bent

and determine the mechanism in molecular levels.

Methods:

2

The acetic acid-induced writhing test and formalin-induced plantar injection test in mice were employed to confirm the effect in vivo. Intracellular calcium ion was imaged to verify PA on mu-opioid receptor (MOR). Cyclooxygenase 2 (COX2) and MOR of mouse brain were expressed for determination of PA's target. Cellular experiments were carried out to find out COX2 and MOR expression induced by PA.

Results:

2

PA significantly reduced latency period of visceral pain and writhing induced by acetic acid saline solution (

P

<

0.01) and allodynia after intra-plantar formalin (

P

<

0.01) in mice. PA also up-regulated COX2 mRNA and protein (

P

<

0.05) with a down-regulation of MOR (

P

<

0.05) both in

in vivo

and

in vitro

experiments

which devote to the analgesic effect of PA. A decrease in the intracellular calcium level (

P

<

0.05) induced by PA may play an important role in its anti-nociceptive effect. PA showed the characters of enhancing the MOR expression and reducing the intracellular calcium ion similar to opioid effect.

Conclusions:

2

Both COX2 and MOR are involved in the mechanism of PA's anti-nociceptive effect

and the up-regulation of the receptor expression and the inhibition of intracellular calcium are a new perspective to PA's effect on MOR.