title: Intermedin in rat uterus: changes in gene expression and peptide levels across the estrous cycle and its effects on uterine contraction.
abstract: BACKGROUND
  The present study demonstrates the expression of intermedin (IMD) and its receptor components in the uterus of the female rat during the estrous cycle and its effect on uterine contraction.
  
  
  METHODS
  The gene expression level of intermedin and its receptor components and the peptide level of intermedin were studied by real-time RT-PCR and enzyme immunoassay (EIA) respectively. The separation of precursor and mature IMD was studied by gel filtration chromatography and EIA. The localization of IMD in the uterus was investigated by immunohistochemistry. The effect of IMD on in vitro uterine contraction was studied by organ bath technique.
  
  
  RESULTS
  Uterine mRNAs of Imd and its receptor components and IMD levels displayed cyclic changes across the estrous cycle. Imd mRNA level was the highest at proestrus while the IMD level was the highest at diestrus. IMD was found in the luminal and glandular epithelia and IMD treatment significantly reduced the amplitude and frequency of uterine contraction but not the basal tone. Both calcitonin gene-related peptide (CGRP) receptor antagonist hCGRP8-37 and adrenomedullin (ADM) receptor antagonist hADM22-52 partially abolished the inhibitory effect of IMD on uterine contraction while the specific IMD receptor antagonist hIMD17-47 completely blocked the actions. The enzyme inhibitors of NO (L-NAME) and PI3K (Wortmannin) pathways diminished the IMD effects on uterine contraction while the cAMP/PKA blocker, KT5720, had no effect, indicating an involvement of NO and PI3K/Akt but not PKA.
  
  
  CONCLUSIONS
  IMD and the gene expression of its receptor components are differentially regulated in the uterus during the estrous cycle and IMD inhibits uterine contraction by decreasing the amplitude and frequency.
authors: Departments of Physiology, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Pokfulam, Hong Kong SAR, China.
authors: Chi-Wai
authors: CW
authors: Wong
authors: Wai-Sum
authors: WS
authors: O
authors: Fai
authors: F
authors: Tang
mesh_terms: D053607:Adrenomedullin / Q000096:biosynthesis / Q000235:genetics* / Q000502:physiology; D000818:Animals; D030762:Estrous Cycle / Q000235:genetics / Q000378:metabolism*; D005260:Female; D005786:Gene Expression Regulation; D009479:Neuropeptides / Q000096:biosynthesis / Q000235:genetics / Q000502:physiology*; D009924:Organ Culture Techniques; D051381:Rats; D017207:Rats, Sprague-Dawley; D014590:Uterine Contraction / Q000235:genetics / Q000378:metabolism*
chemical_list: C499411:Adm2 protein, rat; D009479:Neuropeptides; D053607:Adrenomedullin