Volume 12, Number 3 (11-1998)                   Med J Islam Repub Iran 1998 | Back to browse issues page


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JALALI M, FAZEL A. HYPERVITAMINOSIS A-INDUCED CENTRAL NERVOUS SYSTEM DEFECTS. Med J Islam Repub Iran. 1998; 12 (3) :279-283
URL: http://mjiri.iums.ac.ir/article-1-1007-en.html

From the Department of Anatomy, School of Medicine, Mashhad University of Medical Sciences, Mashhad, Islamic Republic of Iran.
Abstract:   (1963 Views)
In this investigation the effects of excess vitamin A administration during the early embryonic period were studied. Intramuscular injection of a single dose of 15000,20000 or 25000 IU/kg vitamin A to pregnant Balb/c strain mice on either day 7,8,9 or 10 of gestation (vaginal plug= day 0 of gestation) produced major malformations in the central nervous system (CNS) including exencephaly, hydrocephalus, microcephalia, spina bifid a and myelocystocele and also a few other defects such as limb malformations. The incidence and severity of these malformations was positively correlated with the dosage and time of exposure. Among experimental groups, the most effective dose of vitamin A which produced a high incidence of CNS defects was 25000 IU/kg injected on day 8 of gestation (35%) compared to the control group (0%). Histological studies on 18 day old experimental fetuses revealed spina bifid a with and/or without spinal cord defect. These studies showed excessive embryonic cell death localized in the neural tube region following vitamin A exposure. In conclusion, excess vitamin A exposure in the early days and critical periods of development may interfere with certain developmental phenomena, resulting in various detectable CNS defects among newborn infants.
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