TY  - JOUR
T1  - Effects of Various Receptor Antagonists, pH and Enzymes on <I>Muntingia calabura</I> Antinociception in Mice
AU - , Z.A. Zakaria AU - , M.N. Somchit AU - , M.R. Sulaiman AU - , A.M. Mat Jais AU - , C.A. Fatimah 
JO  - Research Journal of Pharmacology
VL  - 2
IS  - 3
SP  - 31
EP  - 37
PY  - 2008
DA  - 2001/08/19
SN  - 1815-9362
DO  - rjpharm.2008.31.37
UR  - https://makhillpublications.co/view-article.php?doi=rjpharm.2008.31.37
KW  - Muntingia calabura
KW  -antinociception
KW  -abdominal constriction test
KW  -opioid
KW  -non-opioid
KW  -pH
KW  -enzymes
AB  - The present study was carried out to determine the involvement of various receptor antagonists in and the effect of pH and enzymes on the recently reported antinociceptive activity of aqueous extract of <I>Muntingia calabura</I> leaves (MCAE) using the abdominal constriction test. The extract was prepared by soaking the dried powdered leaves of <I>M. calabura</I> in distilled water (dH<SUB>2</SUB>O) overnight and the supernatant obtained was considered as a stock solution with 100% concentration/strength. The MCAE, administered s.c. at the concentrations of 5, 50 and 100%, were found to show significant antinociceptive activity in a concentration-dependent manner. The 50% concentration MCAE was further used to study on the above mentioned  parameters.  The  extract  exhibited  significant  (p&lt;0.05)  decreased  in  activity  when  pre-treated (s.c.)  against  10  mg kg<SUP>-1</SUP>  naloxonazine,  10  mg kg<SUP>-1</SUP>  pindolol  and  5  mg kg<SUP>-1</SUP> atropine, but not 10 mg kg<SUP>-1</SUP>  -funaltreaxamine, 10 mg kg<SUP>-1</SUP> naltrindole, 10 mg kg<SUP>-1</SUP> phenoxybenzamine, 10 mg kg<SUP>-1</SUP> bicuculine or 5 mg kg<SUP>-1</SUP> mecamylamine, respectively. The extract exhibited significant (p&lt;0.05) increased in activity after pre-treatment at  alkaline  pH  (pH  9  and  11)  while  maintaining  the  activity  at  the  extreme  acidic  and  alkaline  conditions (pH 2 and pH 13), respectively. The extract activity was not changed after pre-treatment against  -amylase, protease, lipase or their combination, when compared to the dH<SUB>2</SUB>O-pre-treated group, respectively. Based on the results, we conclude that the <I>M. calabura</I> leaves peripheral antinociception involved, at least in part, activation of µ-opioid,  -adrenergic and muscarinic receptors and resist the effect of extreme acidic and alkaline conditions as well as various enzymes.
ER  -