Experimental Study Of Cerebellar Morphology And C-fos, C-jun And GAP-43 Expression In The Cerebellum Of Iodine Deficient Pup Rats

ObjectiveTo gain insight into the mechanism of iodine and thyroid hormone action in brain development. We have observed the difference of cerebellar morphology between iodine deficient dam rats and the normal ones and have tested whether congenital iodine deficiency could regulate immediate early gene proteins c -fos, c - jun and growth - associated protein - 43 ( GAP - 43) in pup cerebellums.MethodsFemale Wistar rats (N =45) weighting 250 -280g were obtained from the Center of Experimental Animals, China Medical University. Female rats were randomly divided into two groups (n = 15 each) : control group and iodine deficient group. Animals were observed for one week before mating. The day that a vaginal plug was identified was taken as gestational day 0 ( GDO). The control group was fed a normal diet and tap water during the experiment. The iodine deficient group was fed an iodine - deficient diet and deionized - water from one week prior to mating through to postnatal day PN 30. On PN20, PN30 and PN60, 10 pups in each group were weighed and blood samples were taken for the FT₃ and FT₄ radioimmunoassay ( RIA). The part of the cerebellum was separated from the brain and the brains were observed by use of hematoxylin and immersed with 4% paraformaldehyde for histological and immunochemistrical assays.Results1. Pup body weight and thyroid hormone levels;For the pup rats, pups from iodine deficient were significantly smaller than controls on PN20, PN30 and PN60 (P <0. 01);the concentrations of serum FT₃ and FT₄ in iodine deficiency groups were also significantly lower than controls ( P <0.01).2. On PN20, PN30,The cerebellar morphology in iodine deficient group are different from the ones in control group, but there is no difference between iodine deficient group and control group on PN 60.3. Effects of iodine deficiency on c -fos and c -jun expression;the intensity of staining and expression of c - fos and c - jun in iodine deficient group were lower than those of controls. IOD total of c - fos and c - jun in the cerebellum of iodine deficient rats was significantly lower than ones in control group (P4. Effects of iodine deficiency on GAP - 43 expression: On PN30 and PN60, the distributions of GAP - 43 expression in iodine deficient group were consistent with that of the control group. However, the intensity of staining and expression of GAP - 43 in iodine deficient group were lower than those of controls. IOD total of GAP -43 in the cerebellum of iodine deficient rats was significantly lower than control ( P <0.01).Conclusion1. iodine deficiency can change cerebellar morphology.2. Iodine deficiency may reduce the expression of c - fos and c - jun in cerebellum.3. Iodine deficiency may reduce the expression of GAP -43 in cerebellum.