Characterization of the Antinociceptive Mechanisms of Khat Extract (Catha edulis) in Mice.
This study investigated the antinociceptive mechanisms of khat extract (100, 200, and 400 mg/kg, i.p.) in four pain models: two thermic (hot plate, tail-flick) and two chemical (acetic acid, formalin) models. Male mice were pretreated intraperitoneally (i.p.) with the opioid receptor blocker naloxone (5 mg/kg), the cholinergic antagonist atropine (2 mg/kg), the selective α1blocker prazosin (1 mg/kg), the dopamine D2antagonist haloperidol (1.5 mg/kg), or the GABAAreceptor antagonist, bicuculline (1 mg/kg) 15 minutes prior to i.p. injection of khat extract (400 mg/kg). Khat extract reduced the nociceptive response of mice in the four pain tests. Naloxone significantly inhibited the antinociceptive effect of khat extract in the hot plate, tail-flick, and the first phase of formalin tests. Bicuculline significantly antagonized the antinociceptive effect of khat extract on the hot plate and tail-flick tests. Haloperidol significantly reversed the antinociceptive effect of khat extract on the tail-flick test and the first phase of formalin test. These results provide strong evidence that the antinociceptive activity of khat extract is mediatedviaopioidergic, GABAergic, and dopaminergic pathways. The mechanism of the antinociceptive action of khat may be linked to the different types of pain generated in animal models.
Faculty of Pharmacy, Alexandria University, Alexandria, Egypt; Department of Pharmacology and Toxicology, Faculty of Pharmacy, King Abdulaziz University, Jeddah, Saudi Arabia.
Elham A
EA
Afify
Faculty of Medicine, Department of Pharmacology, King Abdulaziz University , Jeddah , Saudi Arabia.
Huda M
HM
Alkreathy
Faculty of Medicine, Department of Pharmacology, King Abdulaziz University , Jeddah , Saudi Arabia.
Ahmed S
AS
Ali
Faculty of Medicine, Department of Pharmacology, King Abdulaziz University , Jeddah , Saudi Arabia.
Hassan A
HA
Alfaifi
Faculty of Medicine, Department of Pharmacology, King Abdulaziz University , Jeddah , Saudi Arabia.
Lateef M
LM
Khan
GABAergic; dopaminergic; formalin; hot plate; khat (Catha edulis); opioidergic; tail flick