Congenital hypothyroidism may cause stunted physical and mental growth (cretinism). In the western world this is prevented by neonatal screening combined with hormonal substitution of affected individuals, but the condition is still common in non-western regions where maternal nutritional deficiency of iodine occurs.
Even though the screening program is a success, some studies do suggest that motor and cognitive abilities may be lower than normal in children treated for congenital hypothyroidism. This may indicate that low levels of thyroid hormones prior to birth may have permanent effects on the brain.
We have tested whether hypothyreodism induced by Methimazole treatment disturbs the rates of mitosis and apoptosis of cerebellar granule neurones in the chicken embryo.
Eggs were injected with three different concentrations of Methimazole or control NaCL on embryonic day (ED) 16 and sacrificed on ED 17 when the mitotic and apoptotic rate peaks in cerebellar granule neurones.
We found a tendency that some doses of Methimazole reduced the mitotic rate while no increase in apoptotic rate was detected. We propse that larger scaled experiments should be performed in order to obtain statistically significant results.