EFFECTS OF MARGINAL VITAMIN A DEFICIENCY ON LONG-TERM POTENTIATION IN YOUNG RATS

Abstract

INTRODUCTION: Vitamin A is an essential micronutrient for brain development. Marginal vitamin A deficiency (MVAD) remains a subclinical public health problem in children, but little is known about the mechanism by which it affects brain development beginning from embryonic period and early postnatal period. OBJECTIVE: The objective of this study was to study the effects of MVAD on the hippocampal CA1 long-term potentiation (LTP) in young rats. METHODS: The MVAD group was fed a vitamin A–deficient diet (400 IU/kg vitamin A), and the control group was fed a vitamin A–sufficient diet (6500 IU/kg vitamin A) at 3 weeks before coitus. Serum vitamin A was assessed by high-performance liquid chromatography. Hippocampal CA1 LTP was detected by electrophysiologic technique, and the ultrastructure of synapses was observed by electron microscope. RESULTS: The changes of field excitatory postsynaptic potentials slope (25.4% ± 2.01%) in MVAD rats aged 7 weeks was much lower than that in the control group (57.5% ± 8.6%). The changes of slope of field excitatory postsynaptic potentials induced by MVAD in young rats could be replenished after addition of retinoic acid (RA); however, LTP impairment was observed again after addition of RA antagonist into the solution of the control group. No differences of LTP were found after addition of FeSO4 or ZnSO4. The curvature of the synaptic interface of the MVAD group was less than that of the MVAD group that was supplemented with RA and of the control group. CONCLUSIONS: MVAD during the embryonic and early postnatal period can directly impair the hippocampal CA1 LTP of young rats.