title: All-trans retinoic acid protects against arsenic-induced uterine toxicity in female Sprague-Dawley rats.
abstract: OBJECTIVE
  Arsenic exposure frequently leads to reproductive failures by disrupting the rat uterine histology, hormonal integrity and estrogen signaling components of the rat uterus, possibly by generating reactive oxygen species. All-trans retinoic acid (ATRA) was assessed as a prospective therapeutic agent for reversing reproductive disorders.
  
  
  METHODS
  Rats exposed to arsenic for 28 days were allowed to either recover naturally or were treated simultaneously with ATRA for 28 days or treatment continued up to 56 days. Hematoxylin-eosin double staining was used to evaluate changes in the uterine histology. Serum gonadotropins and estradiol were assayed by ELISA. Expression of the estrogen receptor (ERα), an estrogen responsive gene vascular endothelial growth factor (VEGF), and cell cycle regulatory proteins, cyclin D1 and CDK4, was assessed by RT-PCR, immunohistochemistry and western blot analysis.
  
  
  RESULTS
  ATRA ameliorated sodium arsenite-induced decrease in circulating estradiol and gonadotropin levels in a dose- and time-dependent manner, along with recovery of luminal epithelial cells and endometrial glands. Concomitant up regulation of ERα, VEGF, cyclin D1, CDK4 and Ki-67 was also observed to be more prominent for ATRA-treated rats as compared to the rats that were allowed to recover naturally for 56 days.
  
  
  CONCLUSIONS
  Collectively, the results reveal that ATRA reverses arsenic-induced disruption of the circulating levels of gonadotropins and estradiol, and degeneration of luminal epithelial cells and endometrial glands of the rat uterus, indicating resumption of their functional status. Since structural and functional maintenance of the pubertal uterus is under the influence of estradiol, ATRA consequently up regulated the estrogen receptor and resumed cellular proliferation, possibly by an antioxidant therapeutic approach against arsenic toxicity.
authors.affiliation: Department of Zoology, University of Calcutta, 35 Ballygunge Circular Road, Kolkata, India.
authors.forename: A
authors.initials: A
authors.lastname: Chatterjee
authors.forename: U
authors.initials: U
authors.lastname: Chatterji
mesh_terms: D000818:Animals; D001151:Arsenic / Q000037:antagonists & inhibitors / Q000633:toxicity; D018053:Arsenites / Q000037:antagonists & inhibitors / Q000633:toxicity*; D005260:Female; D011897:Random Allocation; D051381:Rats; D017207:Rats, Sprague-Dawley; D012102:Reproductive Control Agents / Q000037:antagonists & inhibitors / Q000633:toxicity*; D017670:Sodium Compounds / Q000037:antagonists & inhibitors / Q000633:toxicity*; D014212:Tretinoin / Q000008:administration & dosage / Q000627:therapeutic use*; D014599:Uterus / Q000187:drug effects* / Q000378:metabolism*
chemical_list: D018053:Arsenites; D012102:Reproductive Control Agents; D017670:Sodium Compounds; C017947:sodium arsenite; D014212:Tretinoin; D001151:Arsenic