MATERNAL ORAL MORPHINE CONSUMPTION DELAYES OLFACTORY CORTEX DEVELOPMENT IN WISTAR RATS DURING EMBRYONIC PERIOD: A MORPHOMETRIC STUDY

Background and Objectives: Previous studies have shown that morphine consumption during pregnancy may delay embryo development or cause abnormal nervous system function. This study focused on the effects of maternal morphine consumption on olfactory cortex development in Wistar rats. Material and Methods: In this experimental study, 12 wistar rats (250-300g) were used. The experimental group received morphine solution (0.05 mg/ml) where as the control group received tap water. On the 19 th day the pregnant rats were killed by chloroform, and the embryos were removed surgically. The embryos were fixed in formalin 10% for 2 weeks. Then the weight of fixed embryos was calculated by a digital balance. In addition, animal sizes including Crump-Rump (C-R), Dorsal-Ventral (D-V), Frontal-Occipital (F-O), Abdominal Width, and Biparietal Axis length were measured by a caliper . Tissue processing, sectioning and staining (both hematoxylin and eosin (H;E) and silver nitrate staining) were then applied for the embryos. The sections were examined for olfactory cortex development by light microscope. Results: Reductions in D-V lengths as well as embryonic weight was observed in the experimental group (p less-than 0.01, p less-than 0.05). On the microscopic view, a growth retardation was observed in all three olfactory cortex layers in the experimental group. In addition cell compression in cortex layers and neuronal process was also reduced in the experimental group (p less-than 0.05). Conclusion: This study showed that oral morphine consumption during pregnancy causes defect in the development and growth retardation in olfactory cortex region. The study also showed that oral morphine consumption reduced both the weight and length of the embryos. These defects may be the cause of behavioral problems observed in the animals who have been born to addicted mothers. Key words : Morphometry, Olfactory Cortex, Morphine, Wistar Rats Funding: This study was supported by a grant from applied Neuroscience Research Center, Baqiyatallah (a.s.) University of Medical Sciences. Conflict of Interest: None declared. Ethical approval: All experiments were conducted in accordance with standard ethical guidelines and approved by the local ethical committee (The Baqyiatallah (a.s.) University of Medical Committee on the Use and Care of Animals, 81/021, July 10, 2002).