The aim was to study interaction of aqueous leaf extract of Aegle marmelos (AM) with cholinergic, serotonergic, and adrenergic receptor systems using appropriate rat tissues-ileum, fundus and tracheal chain, respectively.
Materials and Methods:

Cumulative concentration-response curves (CRC) were constructed at various doses on each tissue for AM and respective standard agonist. The CRC was again plotted in presence and absence of respective standard antagonist to confirm the interaction of receptor system and AM.
Results:

AM induced concentration-dependent contractions in isolated rat ileum (0.2–6.4 mg/ml) and fundus (0.2–3.2 mg/ml) that were inhibited significantly (P < 0.05) in the presence of atropine (10−7 M) and ketanserin (10−6 M), respectively. The relaxant effect, produced by AM (0.2 mg/ml) on carbachol (10−5 M) precontracted rat tracheal chain, was also inhibited significantly (P < 0.05) by propranolol (1 ng/ml).
Conclusion:

It may be concluded that AM possesses agonistic activity on cholinergic, serotonergic and adrenergic receptors.