Gastrouterine Smooth Muscle Tone Modulatory Action of Neem Fruit Extract is Mediated via Muscarinic Receptors and Ca2+ Channels

Muhammad Nabeel Ghayur1,2,*, Naima Waqar Butt1, Maria Adnan Parekh1,3, Saeed Ahmad1, Anwarul Hassan Gilani1,4
1Department of Biological and Biomedical Sciences, Aga Khan University, Karachi, Sind, PAKISTAN.
2Kentucky College of Osteopathic Medicine, University of Pikeville, Pikeville, KY, USA.
3Department of Neurology, Baylor College of Medicine, Houston, TX, USA.
4The University of Haripur, Haripur, Khyber Pakhtunkhwa, PAKISTAN.

Pharmacognosy Communications,2021,11,3,162-167.
Published: August 2021
Type: Original Article


Introduction: Neem (scientific name Azadirachta indica A. Juss) is a popular medicinal plant in South Asia. We show here the smooth muscle stimulant and relaxant properties of the neem fruit extract. Materials and Methods: Neem fruit were soaked in 70% aqueous-methanol, then dried to obtain a thick brown extract (Ai.Cr). Different isolated gastrointestinal and uterine tissue preparations were obtained and were maintained in tissue baths with a physiological salt solution. Results: The extract exhibited a stimulant effect in increasing concentrations (0.03 to 3.0 mg/ml) in isolated rabbit jejunum. When this activity of the extract was challenged with a ganglion blocker hexamethonium, it was not blocked. It was completely antagonized when challenged with atropine, a cholinergic blocker. Once the spasmogenic effect was blocked, Ai.Cr exhibited a spasmolytic effect (1-10 mg/ml). Ai.Cr was also able to suppress K+ (80 mM) sustained contractions in jejunum in increasing concentrations (0.03-3 mg/ml), indicating calcium channel blockade (CCB). Likewise, Ai.Cr exhibited an atropine-sensitive stimulant response (0.03-5 mg/ml) followed by a CCB-type relaxant effect (0.3-3 mg/ ml) in stomach fundus and ileum preparations of rat. In rat uterus, the crude extract in increasing concentrations (0.1-10 mg/ml), exhibited uterotonic activity that was partially sensitive to atropine. This indicated that there is an additional stimulant component(s) active in uterine tissues. Conclusion: These results show a combination of spasmogenic and spasmolytic effects of Ai.Cr on smooth muscles from rabbits and rats mediated possibly via muscarinic and CCB mechanisms.

Key words: Azadirachta indica, Rabbit jejunum, Rat stomach fundus, Rat ileum, Rat uterus.

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