Antinociceptive and anti-inflammatory effects of Stachytarpheta jamaicensis (L.) Vahl (Verbenaceae) in experimental animal models.
OBJECTIVE
The present study was carried out to explore the antinociceptive as well as the anti-inflammatory effects of an ethanol extract of Stachytarpheta jamaicensis (L.) Vahl (EESJ) using 3 models of nociception and 2 models of inflammation in experimental animals.


METHODS
EESJ was prepared by overnight soaking of the oven-dried (50 degrees C; 72 h) ground leaves (500 g) in 80% ethanol (1:5; w/v). The filtrate was evaporated to dryness (50 degrees C), resuspended in distilled water at concentrations to provide the desired doses of 50, 100 and 150 mg/kg. For antinociceptive effects, 3 models were used: acetic acid-induced abdominal writhing, hot-plate- and formalin-induced paw-licking tests; for anti-inflammatory effects, 2 models were used--carrageenan-induced paw edema and cotton-pellet-induced granuloma tests. Appropriate doses were administered intraperitoneally (i.p.) to mice/rats prior to each test. The mechanisms of antinociceptive action of the extract were also investigated by pretreatment with naloxone (5 mg/kg, i.p.).


RESULTS
The extract exhibited significant (p < 0.05) antinociceptive activity in all nociceptive models tested with dose-dependent activity observed using the abdominal writhing and formalin tests. Pretreatment with naloxone partially, but significantly (p < 0.05) reversed the antinociceptive activity of the extract when assessed using the abdominal-writhing- and formalin-induced paw-licking tests, and completely inhibited its activity when the hot-plate test was used. The extract also showed significant (p < 0.05) anti-inflammatory activity in both the acute (carrageenan-induced paw edema test) and the chronic (cotton-pellet granuloma test) tests.


CONCLUSIONS
This study showed the potential of EESJ to exert antinociceptive and anti-inflammatory activities, the former being modulated via peripheral and central mechanisms and involving, in part, activation of the opioid receptor system.
Sulaiman
M R
MR
Department of Biomedical Sciences, Faculty of Medicine and Health Sciences, Universiti Putra Malaysia, Serdang, Malaysia. shaza8174@yahoo.com
Zakaria
Z A
ZA
Chiong
H S
HS
Lai
S K
SK
Israf
D A
DA
Azam Shah
T M Tg
TM
D000700:Analgesics / Q000494:pharmacology* / Q000627:therapeutic use; D000818:Animals; D000893:Anti-Inflammatory Agents / Q000494:pharmacology* / Q000627:therapeutic use; D001241:Aspirin / Q000494:pharmacology; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D009020:Morphine / Q000494:pharmacology; D010147:Pain Measurement; D008517:Phytotherapy; D010936:Plant Extracts; D018515:Plant Leaves; D051381:Rats; D017207:Rats, Sprague-Dawley; D029648:Verbenaceae
D000700:Analgesics; D000893:Anti-Inflammatory Agents; D010936:Plant Extracts; D009020:Morphine; D001241:Aspirin