Olive (Olea europaea L.) leaf extract elicits antinociceptive activity, potentiates morphine analgesia and suppresses morphine hyperalgesia in rats.
OBJECTIVE
Olive (Olea europaea) leaves are used as anti-rheumatic, anti-inflammatory, antinociceptive, antipyretic, vasodilatory, hypotensive, antidiuretic and hypoglycemic agents in traditional medicine. Recently, it has been shown that olive leaf extract (OLE) has calcium channel blocker property; however, its influences on nociceptive threshold and morphine effects have not yet been clarified.


METHODS
All experiments were carried out on male Wistar rats. The tail-flick, hot-plate and formalin tests were used to assess the effect of OLE on nociceptive threshold. To determine the effect of OLE on analgesic and hyperalgesic effects of morphine, OLE (6, 12 and 25 mg/kg i.p.) that had no significant nociceptive effect, was injected concomitant with morphine (5 mg/kg and 1 μg/kg i.p., respectively). The tail-flick test was used to assess the effect of OLE on anti- and pro-nociceptive effects of morphine.


RESULTS
The data showed that OLE (50-200 mg/kg i.p.) could produce dose-dependent analgesic effect on tail-flick and hot-plate tests. Administration of 200 mg/kg OLE (i.p.) caused significant decrease in pain responses in the first and the second phases of formalin test. In addition, OLE could potentiate the antinociceptive effect of 5 mg/kg morphine and block low-dose morphine-induced hyperalgesia.


CONCLUSIONS
Our results indicate that olive leaf extract has analgesic property in several models of pain and useful influence on morphine analgesia in rats. Therefore, it can be used for the treatment and/or management of painful conditions.
Esmaeili-Mahani
Saeed
S
Department of Biology, Faculty of Sciences, Shahid Bahonar University of Kerman, Kerman, Iran. semahani@yahoo.com
Rezaeezadeh-Roukerd
Maryam
M
Esmaeilpour
Khadije
K
Abbasnejad
Mehdi
M
Rasoulian
Bahram
B
Sheibani
Vahid
V
Kaeidi
Ayat
A
Hajializadeh
Zahra
Z
D000698:Analgesia; D000700:Analgesics / Q000302:isolation & purification / Q000494:pharmacology / Q000627:therapeutic use*; D000818:Animals; D006930:Hyperalgesia / Q000139:chemically induced / Q000188:drug therapy*; D008297:Male; D009020:Morphine / Q000009:adverse effects / Q000494:pharmacology*; D031658:Olea / Q000737:chemistry*; D010146:Pain / Q000188:drug therapy*; D010147:Pain Measurement; D017288:Pain Threshold / Q000187:drug effects; D010936:Plant Extracts / Q000302:isolation & purification / Q000494:pharmacology / Q000627:therapeutic use*; D018515:Plant Leaves / Q000737:chemistry; D051381:Rats; D017208:Rats, Wistar
D000700:Analgesics; D010936:Plant Extracts; D009020:Morphine