5-Hydroxytryptamine modulation of electrically induced twitch responses of mouse vas deferens: involvement of multiple 5-hydroxytryptamine receptors.
The actions of 5-hydroxytryptamine (5-HT) on the electrically induced twitch responses of mouse vas deferens were studied. 5-HT at the concentration range of 10(-8) to 10(-4) M produced a "bell-shaped" concentration-response curve on the field-stimulated twitch contractions; the enhancement of the contractions was maximum at 10(-5) M and progressively reduced at the concentrations of more than 10(-5) M. In the presence of ketanserin, whereas the stimulatory response to low concentrations of 5-HT (less than or equal to 10(-6) M) was not changed, that to high concentrations was reversed. The stimulation by 5-HT (less than or equal to 10(-5) M) was principally antagonized by MDL 72222. In the presence of both MDL 72222 and ketanserin, 5-HT inhibited the twitch contractions in a dose-dependent manner. 8-Hydroxy-2-(di-n-propylamino)tetralin (8-OH-DPAT) and BP-554 (1-[3-(3,4-methylenedioxyphenoxy)propyl]-4-phenyl piperazine), selective 5-HT1A agonists, only inhibited the twitch contractions. Downward slope of the contraction-response curve of 5-HT (greater than or equal to 10(-5) 5 M) was shifted to right in the presence of 8-OH-DPAT. 5-HT and 8-OH-DPAT had no effect on the tension of unstimulated organs. Contractions elicited by ATP were potentiated by 5-HT, which was antagonized by ketanserin. 8-OH-DAPT did not affect ATP-elicited contractions. These results suggest the presence of presynaptic 5-HT1, maybe 5-HT1A and 5-HT3 receptors mediating inhibition and potentiation, respectively, of neurotransmitter release and of postsynaptic responsible for enhancing neurogenic contractions in mouse vas deferens.
Department of Pharmacology, Faculty of Pharmaceutical Sciences, Osaka University, Japan.
Y H
YH
Seong
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A
Baba
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T
Matsuda
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Iwata
D000818:Animals; D004305:Dose-Response Relationship, Drug; D004558:Electric Stimulation; D008297:Male; D051379:Mice; D009119:Muscle Contraction / Q000187:drug effects*; D011985:Receptors, Serotonin / Q000187:drug effects; D012701:Serotonin / Q000494:pharmacology*; D012702:Serotonin Antagonists / Q000494:pharmacology*; D014649:Vas Deferens / Q000187:drug effects* / Q000294:innervation
D011985:Receptors, Serotonin; D012702:Serotonin Antagonists; D012701:Serotonin