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Updated: May 15, 2026
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Bladder Smooth Muscle Strip Contractility as a Method to Evaluate Lower Urinary Tract Pharmacology
Published on: August 18, 2014
Naftopidil inhibits 5-hydroxytryptamine-induced bladder contraction in rats
Takumi Sakai1, Ken-ichi Kasahara, Ken-ichi Tomita
1Laboratory for Development Pharmacology, Pharmaceuticals Research Center, Asahi Kasei Pharma Corporation, 632-1 Mifuku, Izunokuni-shi, Shizuoka 410-2321, Japan.
European Journal of Pharmacology
|January 1, 2013
Summary
Naftopidil effectively inhibits 5-hydroxytryptamine (5-HT)-induced bladder contractions in rats by blocking serotonin 5-HT(2A) and 5-HT(2B) receptors. This mechanism may contribute to naftopidil
Area of Science:
- Pharmacology
- Urology
Background:
- Benign prostatic hyperplasia (BPH) is associated with lower urinary tract symptoms.
- Naftopidil is an alpha-1 adrenoceptor antagonist used for BPH treatment.
- Serotonin (5-HT) plays a role in bladder function and contraction.
Purpose of the Study:
- To investigate the effects of naftopidil on 5-HT-induced rat bladder contractions.
- To determine the specific serotonin receptor subtypes involved in naftopidil's action.
- To explore the potential mechanism underlying naftopidil's therapeutic effects in BPH.
Main Methods:
- In vitro assessment of naftopidil's effect on 5-HT-induced rat bladder contractions.
- Evaluation of other alpha-1 adrenoceptor antagonists (tamsulosin, silodosin, prazosin).
- Testing of selective serotonin 5-HT(2A) and 5-HT(2B) receptor antagonists and agonists.
- Assessment of naftopidil's binding affinity to human 5-HT(2A) and 5-HT(2B) receptors.
- Investigation in bladder strips from rats with bladder outlet obstruction.
Main Results:
- Naftopidil inhibited 5-HT-induced bladder contractions concentration-dependently.
- Other alpha-1 antagonists did not affect 5-HT-induced contractions.
- Ketanserin (5-HT(2A) antagonist) and RS127445 (5-HT(2B) antagonist) inhibited contractions.
- DOI (5-HT(2A) agonist) and α-methyl-5-HT (5-HT(2) agonist) induced contractions.
- Naftopidil inhibited contractions induced by 5-HT(2A) and 5-HT(2) receptor agonists.
- Naftopidil demonstrated binding affinity for human 5-HT(2A) and 5-HT(2B) receptors.
- Naftopidil inhibited enhanced 5-HT-induced contractions in obstructed rat bladders.
Conclusions:
- Naftopidil inhibits 5-HT-induced bladder contraction in rats primarily via blockade of 5-HT(2A) and 5-HT(2B) receptors.
- This mechanism may contribute to the beneficial effects of naftopidil on storage symptoms in BPH patients.
- Naftopidil's action on serotonin receptors offers a potential therapeutic target for managing lower urinary tract symptoms.
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