The Comparison of the Effects of Estrogen and Melatonin against Corneal Disorders in Ovariectomized and Pinealectomized Rats

The aim of the current study was to evaluate the role of estrogen (E) and melatonin (M) in preventing corneal disorders in ovariectomized (Ovx) and pinealectomized (Px) rats. Rats were randomly grouped into seven as follows: Sham-operated, Px, Bilateral Ovx, Ovx+Px, Ovx+Px+M, Ovx+Px+E, Ovx+Px+EM. Rats with Px, Ovx or Ovx+Px were housed for 5 months before the beginning of treatment. Melatonin-treated animals were injected with 5 mg/kg melatonin for 28 days. Estro-gen-treated animals received subcutaneous injections of 250 μg/kg β-estradiol17-cypionate once a week for 4 weeks. At the end of the study eyes tissues were fixed in 10%formol and was embedded in paraffin. Sections of tissue were cut at 5 µm, mounted on slides, stained with hematoxylin-eosin. The mean thicknesses of the total cornea, corneal epithelium, stroma and descement membrane from three different areas of each cornea were measured. Pinealectomy and ovariectomy caused an increase in the thickness of the epithelium, stroma, descement membrane and total cornea. The corneal thicknesses was higher in Ovx group than Px group. Making of ovariectomy and pinealectomy together didn’t more affect the corneal thicknesses according to the individual. In conclusions, e strogen administration was more effective than melatonin in respect to preservation of corneal structures. Ovx group, d Significant decrease (P<0.05), vs. Px group, e Significant decrease (P<0.05), vs. Ovx+Px+M group, f Significant increase (P<0.05), vs. Ovx+Px group. g Significant decrease (P<0.05), vs. Ovx+Px group