A. Adebiyi, P. G. Adaikan, R. N. V. Prasad
Oxytocic activity of thrombin: modulation of thrombin-induced gravid rat myometrial contractions by 5-hydroxytryptamine receptor antagonists
Background: Thrombin possesses potent oxytocic
activity in vitro and in vivo. This activity has been proposed
to play a role in post-parturitional uterine contractions
and possibly, preterm birth related to intrauterine
hemorrhage. Previous workers have demonstrated that
cyclo-oxygenase pathway may not play a significant role
in oxytocic activity of thrombin. However, the role of 5-hydroxytryptamine (a mediator of some of the biological
activities of thrombin) in the oxytocic activity of thrombin
is unknown. The present study therefore aimed to examine
the possible involvement of 5-hydroxytryptamine in
thrombin-induced myometrial contractions.
Methods: Effect of 5-hydroxytryptamine receptor antagonists
on thrombin-induced contractions of isolated
gravid rat myometrium was studied using isolated tissue
bath system.
Results: Thrombin-induced myometrial contractions
were significantly and concentration-dependently inhibited
by ketanserin and methysergide. Furthermore,
12±2% increase in the force of contractions of gravid
rat myometrium pre-contracted with 5-hydroxytryptamine
(1 ?M) was provoked by 1 U/ml of thrombin.
Thrombin-induced augmentation of the uterine stimulating
effect of 5-hydroxytryptamine was characterized by
pronounced increase in the contractile tone.
Conclusions: 5-hydroxytryptamine may possibly play a
role in oxytocic activity of thrombin. Uterine hyperactivity
associated with intrauterine hemorrhage could hence
involve thrombin-induced 5-hydroxytryptamine production
in the uterus.
Journal of Perinatal Medicine, Walter de Gruyter
Print ISSN: 1619-3997
Volume: 32, 03/2004
Pages: 126 - 131
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