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.
Cong
Binhai
B
Department of Physiology, Second Military Medical University, Shanghai, PR China. congbh2003@yahoo.com.cn
Zhang
Lanmei
L
Gao
Lu
L
Ni
Xin
X
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