| Part I Effects of Vitamin A Deficiency on Embryonic Brain Development And It's Mechanisms in Rats LObiectivel To study the effects of vitamin A deficiency (VAD) on embryonic brain development and it's mechanisms in rats. IMethodsl 9 female Wistar rats were randomly divided into severe VAD (SVAD), marginal VAD (MVAD) and Control groups. The rats were fed with vitamin A (VA) 0 lU/kg, 400 lU/kg and 6500 lU/kg diets, respectively, starting from 3 weeks before pregnant onwards. Body and brain weights, serum VA level, brain VA and protein contents, brain cells proliferative cycle and the expression of RARa , RARa, RXRa and D2R mRNA were measured at birth. IResultsl (1) The VA levels of serum and brain tissue in SVAD and MVAD rats were decreased compared with the control, that of SVAD rats were also lower than MVAD. (2) The body and brain weights, brain protein content and cell proliferative index (P1) in SVAD rats were decreased compared with the control, the whole brain content in SVAD rats were also lower than MVAD, there were not significant differences between MVAD and the control. (3) The expression of RARO, and D2R mRNA in SVAD rats were lower than those of the control and MVAD, and the expression of RARa and RXRa in SVAD can't be seen; while the expression of RARO, RX% and D2R mRNA in MVAD were decreased compared with the control. tConclusionl (1) SVAD caused an altered brain development in terms of body and brain weights loss, decreased of brain protein content, brain cell proliferation inactive, decreased the expression of RAR a and D2R mRNA and the expression of RAR and RXR disappeared. (2) There were no significant difference in body and brain weights, protein content and cell proliferation between MVAD and the control, but MVAD can decrease the expression of RARO, RXRa and D2R mRNA. (3) The expression of RA receptors were more sensitive to VAD than other indicators; the expression of RXRa mRNA were more sensitive to VAD than RARa. |
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