Morphine delays fovea development in the eyes of Wistar rat embryos;possible involvement of corticosterone

Visual system have been considered as among important sensory system in animals’ life span and their survival is closely related to normal visual system functioning. Since in previous studies it have been revealed that morphine consumption during pregnancy could lead to defect and delay in nervous system development in the embryos, in the present study, changes induced by morphine in Fovea area in the ayes of embryos whom their mothers received oral morphine during pregnancy period were studied. Female Wistar rats (250-300 g) were used in this study. 24 hours after mating with male rats, the females were separated and their vaginal smear was obtained for sperm detection. This day was considered as embryonic day zero (E0). The females then were divided randomly into experimental or control group. Controls received tap water where as experiments received morphine (0.05 mg/ml) in their waters. On the E13 blood samples were collected from the retro-orbital sinus of all animals for plasma corticosterone detection. On the E17, the animals were killed by chloroform over dose and their embryos were taken out surgically. The embryos were fixed in formalin 10% for 30 days. Their length and weight were determined by digital scale and kalper respectively. At this time, the embryos head was removed for tissue processing, cutting and Hematoxylin -Eosin (H&E) staining. The samples were evaluated using light microscope and MOTIC soft ware. Our data indicated that plasma corticosterone level was dramatically increased in experimental group. Interestingly, neither weight nor the length of the embryos did not statistically differ in experimental compare with controls. In addition, the Fovea area was thinner in experimental group and there was space between cells. This results indicated that oral morphine consumption during pregnancy may induces defect or delay in Fovea development and at least a part of this defect may be due to an increase in plasma corticosterone level in experimental group. Keywords: Visual System, Fovea, Morphine, Corticosterone, Rat. *Corresponding