title: Effects of ovariectomy and hormone replacement on submucosal collagen and blood vessels of the anal canal of rats.
abstract: OBJECTIVE
  To study the effects of oestrogen and progesterone on submucosal collagen fibres and vascular plexus of the anal canal.
  
  
  METHODS
  Experiments were performed on sections of the anal canal of ovariectomized rats following 28 daily subcutaneous injections of 17-beta oestradiol (n = 6, OVX + E, Group 1), medroxyprogesterone acetate (n = 6, OVX + P, Group 2), both drugs (n = 6, OVX + E + P, Group 3) or vehicle (n = 6, OVX) and after sham surgery without castration or injection (n = 6). Investigations included immunohistochemistry of oestrogen and progesterone receptors and collagen fibres, Western blot analysis of collagen types I and III and counting of perianal vessels by light microscopy.
  
  
  RESULTS
  There was positive immunostaining for oestrogen and progesterone receptors in the mucosa and for collagen types I and III in the submucosa in all samples. Type I collagen levels increased significantly with ovariectomy but were normalized with treatment with oestrogen and progesterone. Type III collagen levels decreased after ovariectomy. Administration of oestrogen and progesterone appeared to restore level to near sham values. Semi-quantitative measurement of Type I/III collagen ratios by signal intensity demonstrated a very high ratio after ovariectomy. This appeared to be restored by both oestrogen and progesterone administration either individually or in combination. Mean vessel count was significantly lower in sham animals compared to values in OVX animals (P = 0.006). However, while only oestrogen treatment increased significantly the number of vessels compared to sham animals (P = 0.04), replacement with progesterone did not affect and in combination with oestrogen reduced submucosal vessel number.
  
  
  CONCLUSIONS
  Oestrogen and progesterone have synergistic effects on collagen types I and III and probably antagonistic effects on the vascular plexus of the anal canal submucosa in adult female rats.
authors.affiliation: Department of Anatomy, Faculty of Medicine and Health Sciences, United Arab Emirates University, Al-Ain, United Arab Emirates.
authors.forename: E P
authors.initials: EP
authors.lastname: Mensah-Brown
authors.forename: Diaa E E
authors.initials: DE
authors.lastname: Rizk
authors.forename: Mahendra
authors.initials: M
authors.lastname: Patel
authors.forename: Swaminathan I
authors.initials: SI
authors.lastname: Chandranath
authors.forename: Abdu
authors.initials: A
authors.lastname: Adem
mesh_terms: D001003:Anal Canal / Q000187:drug effects* / Q000473:pathology*; D000818:Animals; D001707:Biopsy, Needle; D015153:Blotting, Western; D024042:Collagen Type I / Q000378:metabolism*; D024061:Collagen Type III / Q000378:metabolism*; D004195:Disease Models, Animal; D004958:Estradiol / Q000494:pharmacology*; D005260:Female; D007150:Immunohistochemistry; D007413:Intestinal Mucosa / Q000187:drug effects / Q000473:pathology; D008525:Medroxyprogesterone / Q000494:pharmacology*; D010052:Ovariectomy; D011336:Probability; D051381:Rats; D017208:Rats, Wistar; D012016:Reference Values; D012680:Sensitivity and Specificity
chemical_list: D024042:Collagen Type I; D024061:Collagen Type III; D004958:Estradiol; D008525:Medroxyprogesterone