**10. Muscarinic receptors in quail**

The first report of muscarinic acetylcholine receptors in Japanese quail intestine was evaluated by recording the contractile responses of quail ileum to the agonist and agonist in presence of antagonists, also relaxant effect of muscarinic receptor antagonists with submaximal contraction of Ach using an isometric transducer. In the study, EC50 values of ACh increased in the presence of atropine (nonselective muscarinic antagonist) and pirenzepine (M1/M2 muscarinic antagonist) compared to EC50 value of ACh alone. Also, the EC50 value of Ach was higher in the presence of atropine when compared to EC50 of ACh in presence of solifenacin (M3 muscarinic antagonist). It was also found that EC50 of ACh was increased 3.48 times in presence of atropine, 2.65 times in presence of pirenzepine and 1.56 times in presence of solifenacin. These findings indicate that the muscarinic receptor subtypes responsible for contraction of small intestine in Japanese quail is contributed by both M2 and M3 muscarinic receptor subtypes, and it was substantiated using molecular studies which revealed the absence of M1 receptor gene in Japanese quail and this finding is in accordance with the reports in chicken. The results of the study indicated that muscarinic receptors are distributed with the same propensity in quails like that of other avian and other mammalian species [34].
