Reduced expression of CRH receptor type 1 in upper segment human myometrium during labour.
BACKGROUND
Corticotropin-releasing hormone (CRH) and CRH-related peptide are shown to modulate uterine contractility through two CRH receptor subtype, CRH-R1 and CRH-R2 during pregnancy. Through different signaling pathways, CRH-R1 maintains myometrial quiescence whereas CRH-R2 promotes smooth muscle contractility. We hypothesized that the expression of CRH receptors in myometrium might be changed during pregnancy and labour.


METHODS
Immunohistochemistry, Western blot and RT-PCR were used to quantify the cellular localization, the protein levels and the mRNA variants of both CRH-R1 and CRH-R2 in upper segment (US) and lower segment (LS) myometrium from nonpregnant and pregnant women at term before or after labour.


RESULTS
CRH-R1 and CRH-R2 were predominately localized to myometrial smooth muscle cells in US and LS. The protein level of CRH-R1 in US was significantly down-regulated in pregnancy, with a further decrease at the onset of labour. However, the expression of CRH-R1 in LS remained unchanged during pregnancy and labour. No significant changes in CRH-R2 expression were observed in US or LS. Six variants of CRH-R1, CRH-R1alpha,-R1beta,-R1c, -R1e,-R1f and -R1g, were identified in nonpregnant and pregnant myometrium. CRH-R2alpha was identified in pregnant myometrium, whereas CRH-R2beta was identified in nonpregnant myometrium


CONCLUSIONS
CRH-R1 and CRH-R2 are expressed in nonpregnant and pregnant US and LS myometrium. Changed expression of CRH receptors during labour may underlie the initiation of uterine contractility during parturition.
Department of Physiology, Second Military Medical University, Shanghai, PR China. congbh2003@yahoo.com.cn
Binhai
B
Cong
Lanmei
L
Zhang
Lu
L
Gao
Xin
X
Ni
D017398:Alternative Splicing / Q000502:physiology; D015153:Blotting, Western; D005260:Female; D015870:Gene Expression / Q000502:physiology; D006801:Humans; D007150:Immunohistochemistry; D007743:Labor, Obstetric / Q000502:physiology*; D009215:Myometrium / Q000502:physiology*; D011247:Pregnancy; D012333:RNA, Messenger / Q000378:metabolism; D018019:Receptors, Corticotropin-Releasing Hormone / Q000235:genetics* / Q000378:metabolism*; D015398:Signal Transduction / Q000502:physiology; D014590:Uterine Contraction / Q000502:physiology; D000099052:CRF Receptor, Type 1
C101531:CRF receptor type 2; D012333:RNA, Messenger; D018019:Receptors, Corticotropin-Releasing Hormone; D000099052:CRF Receptor, Type 1