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Contractile serotonergic receptor in rat stomach fundus
1Lilly Research Laboratories, Eli Lilly and Company, Lilly Corporate Center, Indianapolis, Indiana.
The Journal of Pharmacology and Experimental Therapeutics
|October 1, 1987
Summary
Serotonin (5HT) strongly contracts rat stomach fundus, but not via 5HT1A, 5HT1B, 5HT1C, or 5HT3 receptors. The specific receptor involved in this serotonin-mediated contraction remains unidentified.
Area of Science:
- Pharmacology
- Gastroenterology
- Neuroscience
Background:
- Serotonin (5HT) is known to induce contractions in the rat stomach fundus.
- The specific serotonin receptor subtype responsible for this effect has not been definitively identified.
Purpose of the Study:
- To investigate whether serotonin-induced contractions in the rat stomach fundus are mediated by 5HT1A, 5HT1B, 5HT1C, or 5HT3 receptors.
- To characterize the serotonergic receptor involved in rat stomach fundus contraction.
Main Methods:
- Obtained contractile concentration-response curves for various 5HT agonists in the rat stomach fundus.
- Utilized receptor antagonists, including 1-(1-naphthyl) piperazine, WB4101, spiroxatrine, and cyanopindolol, to assess receptor involvement.
- Compared agonist potency and maximal response with their known affinities at different 5HT receptor binding sites.
Main Results:
- Agonist potency and maximal contractile responses in the rat stomach fundus did not correlate with affinities at 5HT1A, 5HT1B, or 5HT1C binding sites.
- 1-(1-naphthyl) piperazine antagonized contractions, indicating interaction with a 5HT receptor.
- Selective 5HT1A antagonists (WB4101, spiroxatrine) and a nonselective 5HT1A/5HT1B antagonist (cyanopindolol) failed to block 5HT-induced contractions.
Conclusions:
- Serotonin-induced contractions in the rat stomach fundus are not mediated by 5HT1A, 5HT1B, 5HT1C, or 5HT3 receptors.
- The specific serotonergic receptor subtype responsible for mediating contractions in the rat stomach fundus remains to be identified.