Corticotropin-releasing hormone acts on CRH-R1 to inhibit the spontaneous contractility of non-labouring human myometrium at term.
OBJECTIVE
Corticotropin-releasing hormone (CRH) has been implicated in the mechanisms controlling human parturition. The aims of the present study were to explore effects of CRH on contractility of human term myometrium and compare these effects in labouring and non-labouring myometrial strips.


METHODS
The cumulative effects of CRH (10(-10) to 10(-7) mol/l) on the spontaneous contractility of labouring and non-labouring myometrial samples were evaluated using isometric tension recordings.


RESULTS
CRH exhibited a concentration-dependent relaxant effect on spontaneous contractions in non-labouring term myometrium. This effect was mediated principally via a reduction in the amplitude rather than any changes in the frequency of contractions. The CRH-induced inhibitory effect on contractility could be blocked by pre-treatment with a CRH-R1 antagonist antalarmin, but not by pre-treatment with the CRH-R2 antagonist astressin 2B. CRH had no effect on spontaneous contractions in the labouring myometrium, as no change in either the amplitude or the frequency was observed.


CONCLUSIONS
Our findings indicate that CRH acts on CRH-R1 to inhibit spontaneous contractions in term myometrium from women who were not undergoing labour, but not those who were undergoing labour, supporting the hypothesis that CRH exerts dual effect on myometrium during pregnancy.
Zhang
Lan-Mei
LM
Department of Gynecology and Obstetric, Changhai Hospital, Second Military Medical University, Shanghai 200433, PR China.
Wang
Yang-Kai
YK
Hui
Ning
N
Sha
Jin-Yan
JY
Chen
Xiong
X
Guan
Rui
R
Dai
Ling
L
Gao
Lu
L
Yuan
Wen-Jun
WJ
Ni
Xin
X
D003346:Corticotropin-Releasing Hormone / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D005260:Female; D006801:Humans; D066298:In Vitro Techniques; D009215:Myometrium / Q000187:drug effects* / Q000502:physiology; D011247:Pregnancy / Q000502:physiology*; D018019:Receptors, Corticotropin-Releasing Hormone / Q000187:drug effects* / Q000502:physiology; D014590:Uterine Contraction / Q000187:drug effects*; D000099052:CRF Receptor, Type 1
D018019:Receptors, Corticotropin-Releasing Hormone; D000099052:CRF Receptor, Type 1; D003346:Corticotropin-Releasing Hormone