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Published on: August 18, 2014
Serotonin induces a biphasic response in rabbit cavernosal smooth muscle: relevance to the erectile process
David H W Lau1, Cecil S Thompson, Faiz H Mumtaz
1Department of Urology, Royal Free Hospital and University College Medical School, University College London, London, UK.
Introduction:
Serotonin (5-hydroxytryptamine; 5-HT) can cause contraction in cavernosal smooth muscle. We further evaluated this effect of 5-HT.
Methods:
Organ bath studies were used.
Results:
5-HT induced a sustained contraction occasionally accompanied by a transient relaxation (in 30% of rabbit cavernosal tissues) that preceded the contraction. Ondansetron and Y-25130 (both 5-HT3 receptor antagonists) but not SB-269970 (a 5-HT7 receptor antagonist) significantly inhibited or abolished this transient relaxation. Doxazosin (dox, an alpha1-receptor antagonist) and ketanserin (ketan, a 5-HT2A receptor antagonist) significantly inhibited or abolished the sustained contraction. The effects of dox on 5-HT-mediated contraction were concentration-dependent.
Conclusions:
Our findings further confirm that the peripheral serotonergic pathway may play a part in the erectile process via 5-HT2A receptor-mediated contractile and 5-HT3 receptor-mediated relaxant activities. Our results also support the findings of human studies, which suggest that both ketan and dox may exert beneficial effects on the erectile process.
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