Evaluation of the analgesic effect of Umbellipreninand Umbelliprenin-morphine co-administration on the acute, chronic and neuropathic pain

Abstract:

Background and purpose: Neuropathic pain (NP) is a complex and chronic pain which is accompanied by nerve injury. Umbelliprenin (UMB) is a naturally occurring prenylatedcoumarin with anticancer, antioxidant, anti-inflammatory, antibacterial and antileishmanial activities. This study aimedto investigate the antinociceptive effects of UMB on acute, chronic and neuropathic pain and its combination therapy with morphine on the neuropathic pain. Methods: Albino mice weighing 20-25g were randomly divided into 13 groups (n=7),subjected to hot plate with groups including morphine 1mg+UMB (0.01μM/kg), morphine (1mg/kg, i.p.), UMB (0.01mM/kg), Imipramin 40 mg/kg and NS (normal saline) (0.9%) as vehicle), formalin test with groups including (NS, Imipramine (40mg/kg, i.p.), morphine (9mg/kg, i.p.) and UMB (0.01μM/kg)) and morphine tests with groups including (NS (0.9%), imipramine (40 mg/kg, i.p.), morphine (1mg/kg, i.p.)+UMB (0.01mM/kg) and morphine (1mg/kg, i.p.).The acute and neuropathic pain were evaluated using hot-plate and formalin and morphine tests. Results: Administration of UMB single dose (0.01mM) reduced NP significantly (p<0.05) compared tothe negative control and didn’t change acute pain against Diclofenac. Antinociceptive effects of UMB were comparable to Imipramine as a standard positive control. UMB potentiated morphine 1 mg/kg response onNP. Conclusions: This research indicates that UMB alone reduces NP and its combination with morphine potentiates morphine effects. Therefore, UMB-morphine co-administrationis proposed to be used instead of conventional treatment.

Key words: Umbelliprenin, Neuropathic Pain, Morphine, Sciatic Nerve Ligation.