title: A preliminary study on progesterone antioxidation in promoting learning and memory of young ovariectomized mice.
abstract: BACKGROUND
  The aim of this preliminary study was to evaluate the effect of long-term progesterone (P4) treatment on structural and functional deficits associated with the hippocampus.
  
  
  METHODS
  Mice served as sham controls or were bilaterally ovariectomized (Ovx), and a 90-day regimen of placebo or P4 was applied to the animal. After the administration, the acquisition and retrieval of mice in contextual fear conditioning (CFC) and a water maze were examined. Hippocampal tissues from some mice in each group were stained with cresyl violet, and the remainder were taken for determining the antioxidant power.
  
  
  RESULTS
  Compared with placebo controls, the time spent on freezing was higher and the latencies were longer for mice given high-dose P4 (HP) (p < 0.05) in CFC, and the HP group also had longer searching time spent in the target quadrant (p < 0.05) in the water maze. Compared with placebo controls, the cell number of hippocampus CA1, CA3 and DG was significantly higher in the HP group (p < 0.05), and the thickness of the cell layer in CA1 and DG was also higher in the HP group (p < 0.05). All the oxidative stress biomarkers show that the antioxidative activity in hippocampus tissue from the HP and LP groups is higher than that in placebo controls (p < 0.05).
  
  
  CONCLUSIONS
  Ovx impairs learning and memory of mice, which can be rescued by a long-term regimen of HP via its antioxidant effects.
authors.affiliation: Department of Anatomy and Neurobiology, Tianjin Medical University, China.
authors.forename: Lu
authors.initials: L
authors.lastname: He
authors.forename: Hui
authors.initials: H
authors.lastname: Yang
authors.forename: Li-Dong
authors.initials: LD
authors.lastname: Zhai
authors.forename: Heng
authors.initials: H
authors.lastname: Shao
authors.forename: Yun-Sheng
authors.initials: YS
authors.lastname: Li